1. business and industrial
2. business operations
3. business plans

ICES WKGMSFDD4-II REPORT 2015
ICES ACOM C OMMITTEE
ICES CM 2015\ACOM:49
Report of the Workshop on guidance for the
review of MSFD decision descriptor 4 –
foodwebs II (WKGMSFDD4-II)
24-25 February 2015
ICES Headquarters, Denmark
International Council for the Exploration of the Sea Conseil International pour l’Exploration de la Mer H. C. Andersens Boulevard 44–46 DK‐1553 Copenhagen V Denmark Telephone (+45) 33 38 67 00 Telefax (+45) 33 93 42 15 www.ices.dk info@ices.dk Recommended format for purposes of citation: ICES. 2015. Report of the Workshop on guidance for the review of MSFD decision de‐
scriptor 4 – foodwebs II (WKGMSFDD4‐II), 24‐25 February 2015, ICES Headquarters, Denmark. ICES CM 2015\ACOM:49. 52 pp. For permission to reproduce material from this publication, please apply to the Gen‐
eral Secretary. The document is a report of an Expert Group under the auspices of the International Council for the Exploration of the Sea and does not necessarily represent the views of the Council. © 2015 International Council for the Exploration of the Sea ICES WKGMSFDD4-II REPORT 2015
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C on t en t s
Executive Summary ............................................................................................................... 1 1 Introduction .................................................................................................................... 3 1.1 2 3 Background ........................................................................................................... 3 Approach of the workshop .......................................................................................... 4 2.1 Participation .......................................................................................................... 4 2.2 Structure of the workshop ................................................................................... 4 Issues relevant to a potential revision ....................................................................... 5 3.1 Definition of terms ................................................................................................ 5 3.2 Suggested Revision of the foodweb criteria ...................................................... 5 3.3 Technical Guidance on the setting of indicator targets and limits ................. 7 3.3.1 Methods to derive limits for indicators ................................................ 8 3.3.2 Data and knowledge available is very limited .................................. 11 3.3.3 Data exists, no undesirable effects have been observed but knowledge is limited ............................................................................. 11 3.3.4 Data are available and good knowledge exists about the indicator and its relation to other ecosystem characteristics ........... 13 3.3.5 Defining limits where ecosystem trends or changes occur .............. 15 3.3.6 Determining if the indicator is within limits or not .......................... 16 3.4 Technical guidance on aggregating indicator assessments for determining if GES has been achieved under D4 ........................................... 18 3.4.1 3.4.2 3.4.3 3.4.4 3.4.5 3.4.6 3.5 4 5 The specific nature of the foodweb indicator ..................................... 18 Consideration of pressure‐state relationships ................................... 18 Surveillance indicatorsvs.state indicators .......................................... 18 Aggregation of indicator assessments ................................................ 19 Aggregation across criteria ................................................................... 19 Response to reviewers’ comments in relation to GES aggregation ............................................................................................. 19 Potential for gaps and overlaps in relation to Descriptor 1 .......................... 20 Comments on the previous version of the D4 manual ......................................... 21 4.1 Suggestion to modify the three criteria to two criteria .................................. 21 4.2 The issue of trophic guilds ................................................................................ 21 4.3 Methods and clarification of the concepts associated with boundaries, GES definition, and use of surveillance indicators. .................. 22 4.4 Approaches to aggregation of GES decisions (e.g. OOAO). ......................... 22 4.5 Future potential indicators and the knowledge base. .................................... 22 Roadmap for future development of science for implementation and evaluation ...................................................................................................................... 28 5.1 Regional and Cross‐regional scientific advice process .................................. 28 5.2 Information flow between descriptors: Gaps and overlaps .......................... 28 ii |
ICES WKGMSFDD4-II REPORT 2015
5.3 Uncertainty and GES .......................................................................................... 29 5.4 Indicator development ....................................................................................... 30 5.5 Aggregation for GES assessment within D4, including spatial integration ............................................................................................................ 31 6 Conclusions .................................................................................................................. 34 7 References ..................................................................................................................... 35 Annex 1. List of participants ............................................................................................... 38 Annex 2. Agenda ................................................................................................................... 39 Annex 3. Compilation of national, scientist and NGO comments on previous version of the manual. ................................................................................................ 40 Annex 4. Review Group Technical Minutes ................................................................... 46 ICES WKGMSFDD4-II REPORT 2015
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Executive Summary
The second Workshop to review the 2010 Commission Decision on criteria and meth‐
odological standards on good environmental status (GES) of marine waters (2010/477/EC); Descriptor 4 Foodwebs met in Copenhagen, 24‐25 February 2015. It met to provide input to the review of the possible approach to amend Decision 2010/477/EC and respond to comments from Member States, scientists and other stakeholders on the previous version of the D4 Manual. The workshop participants were experts in MSFD implementation and/or scientists specialising in assessing foodwebs. The submitted comments and this workshop supported the proposal of WKMSFDD4 (2014) to replace the three criteria in the Commission Decision under Descriptor 4 with two criteria: 4.1 Foodweb Structure; 4.2 Foodweb Function. For GES under Descriptor 4 to be achieved, both the structure and function of foodwebs need to be at appropriate levels. Many foodweb indicators show substantial variation due to factors not related to an‐
thropogenic pressures (weak or indirect links to human pressure). Indicators often re‐
flect the desire to achieve a balanced ecosystem, and hence having very high or very low indicator values could be considered equally undesirable. The desired level of a specific indicator may be related to avoiding undesirable effects on other ecosystem components and hence requires information and knowledge of the relationship be‐
tween different foodweb components. Given these special considerations, a foodweb indicator may be associated with different combinations of available data (monitoring time‐series) and knowledge (about the relationship of the indicator with foodweb com‐
ponents). Guidelines were developed to derive indicator limits, according to the avail‐
ability of data and knowledge. Common to these guidelines are the principles that: i.
ii.
iii.
indicators should be reported together with estimates of their precision; highly variable indicator estimates should not lead to changes in limits; a lack of knowledge of limits and effects of falling outside limits should not be used as an excuse for lack of action. This would allow the use of precautionary principles when deciding on management actions. Such use of surveillance indicators, based on monitoring, triggers action when indicators move beyond the limits. This action should determine whether anthropo‐
genic pressures are causing changes to the foodweb. Indicator limits should relate to current conditions of the ecosystem, implying that limits will need to be reviewed reg‐
ularly and updated where necessary in response to natural variability of the ecosystem. For the GES assessment of foodwebs at the criterion level, the application of simple aggregation or averaging rules is not considered suitable. Assessments should follow a decision tree that takes into account different pressure‐state relationships; varying levels of uncertainty in the indicators; their interrelationships and whether indicators are surveillance indicators. State indicators that have clear links to pressures require both pressure and state indicators to be within limits, lag periods should be taken into account. Surveillance and non‐surveillance indicators can either be assessed and re‐
ported separately, due to their different response requirements (i.e. further investiga‐
tion or management action) or combined by applying different weightings. Although methods to aggregate indicators can differ across the two D4 criteria, both structure and function need to be at GES for overall GES to be achieved. 2 |
ICES WKGMSFDD4-II REPORT 2015
The workshop also clarified issued raised about the definition and use of trophic guilds and commented on potential gaps in coverage of ecosystem properties between de‐
scribed approaches for D4 and D1. It also provided a road map for further research for the implementation and development of foodweb indicators to support the MSFD. It highlighted regional and cross‐regional coordination, information flow between de‐
scriptors (gaps and overlaps), how to account for uncertainty when assessing GES and aggregation issues as important for further development. ICES WKGMSFDD4-II REPORT 2015
1
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Introduction
This report documents the main discussions at the second ICES workshop to review the 2010 Commission Decision on criteria and methodological standards on good en‐
vironmental status (GES) of marine waters (2010/477/EC); Descriptor 4 Foodwebs. The aim of the workshop was to provide a forum for scientists to provide input into the review process of the Marine Strategy Framework Directive (MSFD), especially with regards to Descriptor 4 ‐ Foodwebs. This workshop is part of the ICES led process to review the MSFD 2010 Commission Decision on fisheries, foodwebs, seafloor integ‐
rity and introduced energy (noise). The process has been instigated by the European Commission DG Environment to inform the national Marine Directors about the chal‐
lenges facing the implementation of the current MFSD decision. It was carried out through the MoU between EC and ICES. 1.1
Background
In accordance with the Commission Staff Working Document 2014, all Member States who have reported have defined indicators for Descriptor 4. Only two Member States were judged to have an adequate definition of GES, six were found to have a partially adequate definition whereas eight were found to be inadequate (CSWD, 2014). Four Member States have not defined GES for this descriptor. The definitions provided ap‐
plied to their entire marine waters, with one exception where a Member State makes a minor differentiation between its subregions. The GES definitions vary enormously in their content and level of detail; most were qualitative and many were rather vague, lacking definitions of key terms used or spec‐
ificity as to which elements of foodwebs were addressed (CSWD, 2014). Most Member States have referred to specific foodweb components in their GES definition, some‐
times in addition to defining it for all foodweb components. In the Baltic region, most Member States have put an emphasis on fish communities. Most Member States re‐
ferred to components such as “key” species or “functional groups”, and/or to “top predators” or “species at the top of the foodweb”. Very few Member States included in their GES definitions specific species or habitats as indicators of change. Indicator species include the harbour porpoise and the harbour seal and indicator habitats in‐
clude Posidonia meadows. Only three Member States included a reference to the pres‐
sures of foodweb components, in particular fisheries. MSFD Descriptor 4 Foodwebs
All elements of the marine foodwebs, to the extent that they are known, occur at normal abundance and diversity and levels capable of ensuring the long‐term abundance of the species and the retention of their full reproductive ca‐
pacity. 4 |
ICES WKGMSFDD4-II REPORT 2015
2
Approach of the workshop
2.1
Participation
Experts in MSFD implementation or scientific issues regarding the descriptors were invited to participate through national representatives allowing each country to nom‐
inate 1–2 participants. If nominations exceeded the meeting space available ICES re‐
served the right to reject participants. No timely nomination was refused for this workshop. Participants joined the workshop at national expense. Participants were not limited to those nominated by ICES Delegates and ACOM and participants from non‐
ICES EU countries were specifically encouraged via an invitation from DGENV to the national marine directors. To conform to best practice and ICES policy, NGOs and stakeholders were permitted to attend the workshop on the understanding that policy statements were not permit‐
ted. Regional Sea Conventions were encouraged to participate through their member countries. The 19 participants present consisted of scientists, industry representatives, NGO rep‐
resentatives and managers. Scientists came from the NE Atlantic, Baltic and Mediter‐
ranean MSFD regions and the USA. 2.2
Structure of the workshop
The workshop was planned and organized by the six chairs with expertise in foodwebs and MSFD implementation. The Chairs came from Denmark, Ireland, USA, UK, Fin‐
land, JRC and the ICES secretariat. The workshop began with an introduction and setting of the scene. The agenda was discussed and agreed. The workshop was basically structured around the following issues: 
Definition of terms 
Potential revision of the foodweb criteria 
Technical Guidance on the setting of indicator targets and limits 
Methods to derive limits for aggregate indicators at criteria level 
Remaining comments on the previous version of the D4 manual 
Road map for future development of science for implementation and eval‐
uation. Each of the topics was addressed by parallel subgroups after a common introduction to that topic to ensure that all participants understood the task at hand. The subgroup participants were selected at random and no groups were the same between different sessions. Group work was facilitated by a designated member of the group and re‐
ported by summarizing the conclusion in plenary after each subgroup session. Gener‐
ally participants were divided into four groups. This approach was used to ensure the widest possible participation in the workshop considerations and to prevent the over dominance of any individual opinions. The majority of participants contributed ac‐
tively to discussions in the subgroups.
ICES WKGMSFDD4-II REPORT 2015
3
Issues relevant to a potential revision
3.1
Definition of terms
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The workshop participants came from different backgrounds and interpreted certain terms very differently from each other. For example, the term ‘reference level’ was per‐
ceived by some as describing the ‘normal’ or baseline variability of an indicator; yet OSPAR defined ‘Reference state’ or ‘Reference condition’ as “The value or range of values of state at which impacts from anthropogenic pressures are absent or negligible. “ (OSPARʹs MSFD Advice Manual on Biodiversity v.3 [5/12/2011] – see meeting paper ICG‐
MSFD(4) 11/2/3 –E). As a result of this, the following common terminology is used in this document: Foodweb Surveillance Indicators: The aim of surveillance indicators is to monitor key aspects of the foodweb structure and function and, by doing so, gain evidence to better understand the relationship between the monitored aspect and other ecosystem com‐
ponents as well as pressure/state relationship for these indicators. Surveillance indica‐
tors are defined as indicators of aspects of the structure or function of the foodweb, for which it is either not possible (through lack of evidence) to define limits based on knowledge of the system or where the link to anthropogenic pressures a weak or un‐
clear, so direct management actions cannot be prescribed. Limit: a limit defines the indicator value(s) at which a Foodweb Indicator changes be‐
tween a desirable and undesirable state. Within limits: Foodweb Indicators are defined as ‘within limits’ when they are in the ‘desirable state’. Target: The target equates to the values or range of values that are ‘within limits’ and represent a ‘desirable state’. GES of criteria: GES is measured for each Foodweb criterion. The assessment of GES is based on indicators under each criterion The exact link between the number, level and other aspects of indicator that need to be ‘within limits’ in order to achieve GES depends on the specific aggregation methods that are used to combine indicator as‐
sessments and the methods used to set GES boundaries (sec. 3.4). GES boundaries: GES boundaries define the difference between GES and sub‐GES in assessments of Criteria and Descriptors. GES boundaries are defined according to the assessments of an agreed set of indicators and according to agreed methods of aggre‐
gating these indictor‐level assessments (sec. 3.3). GES of Descriptor 4: Descriptor 4 should be assessed as achieving GES when both D4 criteria are assessed as being at GES. 3.2
Suggested Revision of the foodweb criteria
WKGMSFDD4 (ICES 2014) proposed the revision of the three criteria in the Commis‐
sion Decision under Descriptor 4 into two criteria: 4.1 Foodweb Structure; 4.2 Foodweb Function (see Figure 3.1). The workshop supported this proposal, as did the comments received on the WKGMSFDD4 Report (ICES 2014). Foodweb structure and function each represent different ambitions of the MSFD in achieving GES. The MSFD defines GES as follows: ‘good environmental status’ means the environmental status of marine waters where these provide ecologically diverse and dynamic 6 |
ICES WKGMSFDD4-II REPORT 2015
oceans and seas which are clean, healthy and productive within their intrinsic conditions, and the use of the marine environment is at a level that is sustainable, thus safeguarding the poten‐
tial for uses and activities by current and future generations [...]. As Rossberg et al., (2015) point out, this definition of GES makes reference to “potential for uses and activities by [...] future generations”. In doing so, the MSFD recognizes the needs of future generations might be different from those of the present generation. The structure of foodwebs could be relevant to identifying ecosystem characteristics that we, as a society, would want to preserve for potential use by future generations. This aspect of GES relates to the concept of ‘strong sustainability’, as used in environ‐
mental economics (e.g. Figge, 2005), where ecological “capital” is preserved, irrespec‐
tive of current needs or uses. Alternatively, ‘weak sustainable use’ aims to maintain current patterns of use into the future. In order to achieve GES, as defined above, ‘strong sustainable use’ would be required. The proposed criterion 4.1 on foodweb structure will provide the framework within which to assess whether the ecosystem is subjected to sufficiently ‘strong sustainable use’. GES also requires that ecosystems effectively support current uses by being suffi‐
ciently “productive”. A productive ecosystem requires fully functioning foodwebs. The proposed criterion 4.2 on foodweb function will provide the framework within which the following can be assessed: a) functioning of foodweb, b) negative human impacts of overexploitation can be identified, and c) responses to management. WKGMSFDD4‐II warned that the two proposed foodweb criteria – structure and func‐
tion, should not be assessed in isolation. Structure is sensitive to overexploitation, but could recover with appropriate management. However, if foodweb functioning in sig‐
nificantly affected, recovery of the foodweb may be much more difficult to achieve. Hence, for GES to be achieved, both the structure and function of foodwebs need to be at appropriate levels. The aggregation of assessments of the criteria for structure and function are considered in section 3.3. The relationship between foodweb structure and function in examples of benthic macro invertebrate communities and associated benthic‐feeding fish in the Baltic Sea was discussed. Direct anthropogenic pressure alters structural properties of foodwebs, for example seen as reduced diversity and complexity of trophic networks for soft‐
sediment macrofauna along a gradient of increasing organic enrichment and decreas‐
ing oxygen levels (Nordström and Bonsdorff, in prep.). There are non‐random patterns of functional diversity in benthic foodwebs, structured by trophic interactions and bi‐
ological traits such as body size. Degradation of interaction networks is thereby likely to affect the functioning of the foodweb by reducing the range of interacting compo‐
nents/nodes that maintain processes of consumption and energy flow in the commu‐
nity (Nordström et al., in review). However, even drastic changes in community composition do not always imply immediate alteration of trophic processes. Despite the regime shift seen for Baltic Sea pelagic biota in the late 1980’s (Österholm et al., 2007), the main processes remain dominant in the foodweb, as shown by a network motif approach examining foodweb processes before and after the regime shift in Baltic Sea offshore and coastal areas (Yletyinen et al., in prep.). ICES WKGMSFDD4-II REPORT 2015
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Figure 3.1 Suggested revision of criteria under D4. 3.3
Technical Guidance on the setting of indicator targets and limits
Foodweb indicators differ from indicators of other descriptors in a number of ways. First, many foodweb indicators have weak or indirect links to human pressure and may show substantial variation due to factors not related to anthropogenic activities. With such indicators, it is difficult or impossible to identify values of the indictor that are desirable or undesirable in relation to human impacts. Further, indicators often re‐
flect the desire to achieve a balanced ecosystem, and hence having very high or very low indicator values can be equally undesirable. This is in contrast to, for example, indicators for environmental contaminants, where an upper limit alone constraints the desired range of values. Finally, the desired level of a specific indicator may be re‐
lated to avoiding undesirable effects on other ecosystem components and hence re‐
quires information and knowledge of the relationship between different foodweb components. Given these special considerations, a foodweb indicator may be associated with differ‐
ent combinations of available data with which to construct the indicator and knowledge of the relationship of the indicator with the foodweb components in the specific ecosys‐
tem, as illustrated in Figure 3.2. Each combination of knowledge and data availability requires associated guidance for setting indicator limits. Below, in sections 3.3.2‐3.3.5, we have provided examples of existing indicators that have set limits foodweb indica‐
tor application within each knowledge/data scenario. 8 |
ICES WKGMSFDD4-II REPORT 2015
Figure 3.2. Illustration of the scenarios explored for setting of indicator limits and ranges, consid‐
ering data (time‐series) and the available knowledge of the relationship of the indicator with the foodweb components in the specific ecosystem. Low data and knowledge, higher date and low knowledge, high data and knowledge. 3.3.1
Methods to derive limits for indicators
Limits for indicators can be determined by several methods. For many foodweb indi‐
cators, there is little knowledge of what values of the indicator should be considered desirable or undesirable. In such cases, limits can be derived from the range of varia‐
tion in the indicator, which is known from past time‐series or from historical knowledge, where limits could be set at, for example, ± 1 SD of the mean of the previous time‐series (e.g. Gaichas et al., 2014). Other options are available when more knowledge exists, including expert elicitation, empirical analysis, and modelling (also reviewed by WKFooWI 2014). Expert elicitation allows for synthesis across a range of understandings between indi‐
cators and associated pressures. Link (2005) and Shin et al., (2010) summarize candidate limit reference points from literature (Link 2005) and a team of experts from many ma‐
rine systems (Shin et al., 2010, Figure 3.3). Formal stakeholder participation processes that form part of a risk assessment procedure to identify and test candidate reference points for indicators can also be used (e.g. Levin et al., 2009, Samhouri et al., 2011, Smith et al., 2007). Empirical analyses to determine limits have focused on identifying critical points (with or without relation to a specific pressure‐response relationship) associated with large changes in the value for indicators. Time‐series methods have included CUSUM con‐
trol charts (Hinkley, 1970) and sequential t‐tests (e.g. STARS, Rodionov, 2004). Vert‐
Pre et al., (2013) used the STARS approach to define change‐points in productivity (sur‐
plus production) of fish stocks over time, and Szuwalski et al., (in press) related esti‐
mated changes to possible shifts at ecosystem level. Large et al., (2013) used GAMs to estimate thresholds in foodweb indicators in pressure‐state relationships, identifying empirical thresholds in indicator responses to both fishing pressure and environmental drivers (Figure 3.4). These statistical approaches have also been applied to identify threshold levels in response to multiple pressures concurrently, allowing for change in targets and limits with changing environmental conditions (Large et al., 2015, Figure 3.5. Non‐parametric methods (e.g. gradient forests, Baker et al., 2014, Large et al., in ICES WKGMSFDD4-II REPORT 2015
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press) have also been used to evaluate points for which changes occur across a suite of indicators and also investigate the influence of a range of pressures. Simulation modelling exercises offer the opportunity to investigate expected indicator behaviour across a range of scenarios for system dynamics and management strategies (e.g. Fay et al., 2013). Models can therefore be used to identify limit levels for indicators but also to evaluate expectations for the frequency of indicators falling outside limits, useful for determining decision rules for when indicators should be considered falling outside targets for determination of status. Samhouri et al., (2010) combined the results of ecosystem models with piece‐wise regressions to identify breakpoints in indicators related to fishing pressures. The desirable range can also be determined from the prin‐
ciple of strong sustainable use. For example, the DEVOTES project (Rossberg et al., 2015) proposed that the desirable range is that from which the indicator could revert to its natural (in the sense of pressure‐free) range of variation within a fixed, given time interval. Model testing of indicators, for example using a Management Strategy Eval‐
uation (MSE) framework, can be used to identify the suitability of limit levels for indi‐
cators for achieving objectives (Fay et al., in press), and to test robustness of alternatives for deciding when indicators are outside limits (e.g. probabilities of indicators having crossed limits given a mean of recent values for the indicator). The suitability of alter‐
native approaches depends on the feasibility of measuring the indicators, the availa‐
bility of data, and on the pressure pressures affecting on the indicator, and on our ability to detect these impacts. Figure 3.3Density distributions of Indicator Limit Reference Levels (LRL) from surveys of scientific experts (from Shin et al., 2010) 10 |
ICES WKGMSFDD4-II REPORT 2015
Figure 3.4 Indicator (pelagic to demersal ratio) response to fishing pressure. (f) Dashed line repre‐
sents a GAM smoother, grey polygon represents 95% bootstrap CI, points represent the raw data, black solid line indicates significant positive or negative trends, and grey solid lines indicate sig‐
nificant thresholds. (h) First derivative of the GAM smoother with black polygon and arrow indi‐
cating direction (positive or negative) of the trend where the 95% CI pass above or below zero ; from Large et al., 2013. Figure 3.5 Topographic surfaces representing the pressure−environment−state fi t of 2 covariate gen‐
eralized additive models. (a) Mean length and (b) pelagic to demersal ratio response to fishing pressure and environment summarized using dynamic factor analysis (DynFA) 2. From Large et al., 2015. ICES WKGMSFDD4-II REPORT 2015
3.3.2
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Data and knowledge available is very limited
When the data and knowledge available is very limited, for example, when sampling has only just begun, appropriate limits can be suggested based on expert knowledge from similar ecosystems, theoretical considerations or a desired direction of change. In all cases, the estimated limits are highly uncertain and this should be reported together with the indicator. Limits should be updated regularly as more information becomes available. 3.3.3
Data exists, no undesirable effects have been observed but knowledge
is limited
Where data exists, no undesirable effects have been observed but knowledge of the direct relationship between the indicator and other ecosystem characteristics is lim‐
ited, the indicator limits should described the observed range of known indicator val‐
ues. Protocols should be in place, such that, when the indicator is not within‐limits, this triggers further investigation to determine the cause of the change as well as the effects on other ecosystem components. The likely impacting pressures should also be re‐
viewed. As there is limited knowledge of the relationship between the indicator and other components, there is a possibility that undesirable effects occurred but were not recorded. This should be reflected in the reported uncertainty of assessments. 3.3.3.1 Structure indicator example: Biomass of demersal fish trophic guilds in the North
Sea
Biomass of demersal fish trophic guilds in the North Sea shows substantial historic variation followed by pronounced recent trend (Figure 3.6.). Guild membership was determined taking account of both variation in the diet between species and ontoge‐
netic development of the diet within species. Numbers‐at‐length of each species were determined using data derived from the ICES coordinated first quarter (Q1) Interna‐
tional Bottom Trawl Survey (IBTS) that were raised to take account of both between‐
species and within‐species (length‐related) variation in catchability in the GOV trawl (Fraser et al., 2007). Species abundance‐at‐length were converted to estimates of bio‐
mass at length using both published and unpublished species‐specific weight‐at‐length power function relationships. Both the demersal benthivore and demersal piscivore fish guilds display trends that show a marked increase in biomass towards the end of the time‐series. However, our lack of understanding of foodweb structure in the North Sea prevents us from concluding that these recent marked increases in the biomass of both guilds is necessarily “good”. We cannot therefore determine boundary levels as other than the historical range. In both instances, the most recent guild biomass estimates represent the highest level observed throughout the Q1 IBTS time‐series. In the case of demersal benthivorous fish, biomass in 2011 was over twice that recorded at the start of the time‐series. Given our lack of understanding as to what exactly GES for each guild would look like, the fact that both time‐series are moving out of the bounds of our empirical experience is perhaps worrying. This suggest the need for additional research to determine whether such biomass levels in each guild represent the foodweb moving towards a more de‐
sirable state, or conversely whether such trends might indicate a departure away from GES. 12 |
ICES WKGMSFDD4-II REPORT 2015
Figure 3.6. Biomass of piscivore and benthivore fish trophic guilds (taking ontogenetic develop‐
ment in the diet into account,), derived from Q1 IBTS estimates of species biomass density at length estimates raised to take account of species‐ and size‐related catchability in the GOV trawl (solid line shows total). Dashed horizontal lines show the boundaries of GES of an assessment made 6 years before the most recent data point. 3.3.3.2 F unction indicator example: Eastern Baltic cod weight-at-age
The mean body size (weight‐at‐age, length‐at‐age and condition) of the Eastern Baltic cod has declined since the early 1990s (ICES 2014a). The reasons for the decline are not fully understood, but it might be a consequence of the combination of several factors such as density‐dependent effects, food availability, anoxic areas and parasites. Recent changes in cod mean weight in stock are presented in Figure 3.7. A strong statistical relationship between cod body size and hypoxic areas can be ex‐
plained by different mechanisms (ICES 2014a), such as increased density‐dependence (same or higher amount of fish concentrated in a more restricted area, resulting in in‐
creasing competition), decrease in benthic food, reallocation of cod into the pelagic wa‐
ter mass, and direct physiological effects. Density‐dependence and food limitation were also significantly correlated to cod mean body size, although these correlations were much weaker than the one with hypoxic areas. Due to increasing numbers of grey seals, an increasing cod parasite infestation (in prev‐
alence and intensity) is recently observed (ICES 2014a). Seals act as the final host for parasites, such as cod worm (Pseudoterranova decipiens) and liver worm (Contracaecum osculatum), with crustaceans/polychaetes and cod constituting first and second transport hosts, respectively. ICES WKGMSFDD4-II REPORT 2015
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7
Age 2
Age 3
6
WEST: Mean weight in Stock (kg)
Age 4
Age 5
5
Age 6
Age 7
4
Age 8+
3
2
1
2 014
2 012
2 013
2 010
2 011
2 009
2 007
2 008
2 005
2 006
2 003
2 004
2 002
2 000
2 001
1 998
1 999
1 996
1 997
1 995
1 993
1 994
1 991
1 992
1 990
0
Figure 3.7 COD in SD 25 ‐ 32. WEST: Mean weight in stock (kg). Based on ICES WGBFAS 2014b report (Table 2.4.13). Dashed horizontal lines show the potential boundaries of GES of an assess‐
ment of age 8+ made 6 years before the most recent data point. 3.3.4
Data are available and good knowledge exists about the indicator and
its relation to other ecosystem characteristics
Where data exists and undesirable effects on other ecosystem components has been observed or is predicted based on solid knowledge of the direct relationship be‐
tween the indicator and other ecosystem aspects, the range of indicator values asso‐
ciated with no (substantial) undesirable effects on other components should be used to set limits that denote the desirable range of indicator values. If the indicator is not within‐limits, means action should be triggered. This action would involve further in‐
vestigation to determine the cause of the deviation from the desired range, as well as the effect on other ecosystem components. The presence of (substantial) undesirable effects on ecosystem components can be de‐
termined based on a variety of measures. Ideally, the evaluation includes both expert judgment, analyses of historic data and investigation of model results. 3.3.4.1 Structure indicator example: Baltic Sea zooplankton community
The dominating role in the Central Baltic Sea zooplankton community is played by the copepod species Acartia spp., Temora longicornis and Pseudocalanus acuspes dominate in the Central Baltic Sea zooplankton community (Figure 3.8). During spring, a clear shift has occurred from a dominance of P. acuspes until the end of the 1980s to Acartia spp. and T. longicornis afterwards. This shift in taxonomic composition might be explained by decreased salinity and high sprat predation pressure (P. acuspes) and increased tem‐
perature (Acartia spp., T. longicornis) (Möllmann and Köster, 2002; Möllmann et al., 2003). Despite much higher variability during summer, the shift can still visible (ICES 2007). Replacement of big copepods (i.e. Pseudocalanus) by smaller species had pronounced consequences for feeding conditions of larval cod and adult sprat and herring. This shift in species composition is considered to be a reason for a decrease in the growth 14 |
ICES WKGMSFDD4-II REPORT 2015
rate of herring since the early 1980s and of sprat since the early 1990s (Möllmann et al., 2000). Figure 3.8. Changes in zooplankton species composition in the Central Baltic Sea: Anomalies of Pseudocalanus acuspes in spring and summer (ICES 2007). Dashed horizontal lines show the pos‐
sible limit of copepod biomass, below which six there are undesirable effects on the growth of dependent species (clupeids). 3.3.4.2 Structure indicator example: LFI in the North Sea
The Large Fish Indicator (LFI) is an example of a situation where the historical indica‐
tor trajectory is considered to be at least partly outside the limits, and the appropriate limit assumed to be above the range of the historical data. The indicator is defined as the proportion by biomass of large fish in demersal trawl surveys, where fish are con‐
sidered as large if they exceed a length threshold, for example, 40 cm (Greenstreet et al., 2011). The pressure‐state relation for the LFI is well understood (Fung et al., 2013) and historical time‐series can be reproduced by models (Figure 3.9). The indicator is sensitive and specific to fishing pressure (Houle et al., 2012) that truncates the upper end of the fish size spectrum (Sheldon et al., 1972). Exhibiting recovery times on the order of magnitude of decades (Greenstreet 2011, Fung et al., 2012, 2013), the indicator quantifies a characteristic of marine foodwebs that are slow to recover and often under intense pressure. In many EU waters, indicator values are considered outside appro‐
priate limits over most of the documented time intervals (Greenstreet et al., 2011, Shephard et al., 2011, Modica et al., 2014); the observed low indicator values have been found to be inconsistent with sustainable fishing (Greenstreet et al., 2011), fast and se‐
cure indicator recovery (Shephard et al., 2013), and conservation of biodiversity (Fung et al., 2013). Proposed indicator limits are therefore larger than the values observed. Reference levels for the LFI have been set using historic time‐series of the LFI and com‐
bined fishing pressure (Greenstreet et al., 2011). Fish stocks were thought to be ex‐
ploited at a sustainable rate in the early 1980s, so in a process echoing the precautionary approach to fish stock management, this was considered the reference period for the LFI, suggesting a value of 0.3 as appropriate. ICES WKGMSFDD4-II REPORT 2015
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Figure 3.9 Variation in the redefined proportion of LFI calculated for both the Q1 IBTS and the SAGFS datasets. The current LFI value is indicated, as is the EcoQO level for the indicator of 0.3 for the North Sea demersal fish community (Greenstreet et al., 2011). 3.3.5
Defining limits where ecosystem trends or changes occur
Foodweb indicators are often influenced by a combination of several factors including climatic conditions, changes in other ecosystem components and anthropogenic pres‐
sures. To ensure that the limits continue to be relevant, the limits should relate to cur‐
rent conditions of the ecosystem. Hence, if the foodweb has exhibited pronounced regime shifts, the limit level should reflect the current regime rather than historic re‐
gimes. This conclusion also applies to the case where the regime shift is caused by ex‐
cessive human pressure at an earlier time, for example, excessive removal of top predators have led to an increase in forage fish and a subsequent decrease of zooplank‐
ton (trophic cascade), but the system appears stable in the present regime. In this case, the current limit level for zooplankton biomass should reflect the current regime rather 16 |
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than a regime where predators have returned. If top predators are returning to the system, limit levels should be updated accordingly. When ecosystem trends are more gradual, such as is often the case with the effect of climate change on foodwebs, a grad‐
ual change in the limit level should be implemented. Another example is the introduction of alien species with apparent disruption of food‐
web structure and/or function. Examples of this include Pacific oysters in the Wadden Sea, American jackknife clam along the southern North Sea coast, and Red Sea fish entering the eastern Mediterranean. All of these introductions are irreversible and have a likely effect on the foodweb and may limit the use of historical data for determination of assessment limits. Concluding that limit levels should reflect current conditions implies that limit levels will need to be reviewed regularly and updated where necessary. This applies even in cases where there is a known effect of, for example, temperature, as it is necessary to review and update the relationship regularly to ensure that it is still present. 3.3.5.1 Function indicator example: Kittiwake breeding success in the North Sea
An example of an indicator of foodweb function where the limit depends on environ‐
mental conditions is kittiwake breeding success (Cook et al., 2014). This indicator is constructed from data on annual mean breeding success (number of chicks fledged per pair) of black‐legged kittiwakes (Rissa tridactyla) at colonies on the UK North Sea coast. The indicator is based on previous work by Frederiksen et al., (2004, 2007), which found kittiwake breeding success at seven colonies along the North Sea coast of the UK to be significantly negatively correlated with local mean sea surface temperature (SST) two winters previously (SST‐1). The relationship is thought to be related to larval sandeel survival and the subsequent availability of 1 year‐class (1‐group) sandeels for kitti‐
wakes to rear their chicks on. The premise of the indicator is that any statistically sig‐
nificant negative deviation from the relationship of annual breeding success and SST‐1, may indicate a detrimental anthropogenic impact (Figure 3.10). A statistically signifi‐
cant negative relationship between annual breeding success and SST‐1 was found at 29 colonies (Figure 3.11). Cook et al., (2014) also found a significant effect on kittiwake breeding success from a fishing pressure factor denoted by the interaction between the annual North Sea stock size of lesser sandeels and the proportion of the stock that was harvested. 3.3.6
Determining if the indicator is within limits or not
There are three types of uncertainty in determining the location of current state of the indicators relative to their limit or limits: uncertainty about the correct limit level, un‐
certainty about the precision of the indicator estimated from data and uncertainty about the effect of pressures on the indicator and hence about the potential effect of management measures. Ideally, the indicator relative to the limit is determined from properly determined limit levels, an accurate estimate of the indicator and a strong and well‐known relationship between management, pressure and indicator. In this case, pressures should be managed in accordance with the defined acceptable risk of falling outside limits. ICES WKGMSFDD4-II REPORT 2015
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Figure 3.10: Kittiwake breeding success indicator at Isle of May and Sumburgh Head colonies be‐
tween 1986 and 2010 (Cook et al., 2014). Solid line shows level of breeding success expected at each colony given the Sea Surface Temperature in February and March of the previous year. The lower 95% confidence limit of the relationship, shown by the broken line, is the limit of the indicator, so points below the broken line are considered outside the limit. Figure 3.11: Change in kittiwake breeding success indicator in relation to the presence of the Wee Bankie sandeel fishery (From Cook et al., 2014). Following Frederiksen et al., (2004) the sandeel fishery was assessed as present from 1990 – 1998. Each pie chart represents a kittiwake breeding colony, green indicates that breeding success reflected the underlying environmental conditions in the target year, red indicates that breeding success was lower than expected given the underlying environmental conditions and black/white indicates colony was not recorded in the target year. Darker segments indicate the proportion of the preceding years in which the target level of breed‐
ing success was not achieved in the pre‐fishery (1986‐1989), operational fishery (1990‐1998) and closed fishery (1999‐2010) periods. In the case of foodwebs, one or more of these uncertainties are often considerable. De‐
spite this, the advice format should remain the same: the probability that the indicator is not within limits should be derived from the observed variance of the estimated in‐
dicator. If the estimated indicator is being measured with a poor precision, there is a strong likelihood that the indicator will be recorded as outside the limits. It is important that this does not lead to revised (wider) limits. Instead, the frequent occurrence of indicators outside limits, or a high probability of being outside limits, should provide 18 |
ICES WKGMSFDD4-II REPORT 2015
the incentive to improve the precision of the indicator. Where the link between man‐
agement, pressure and state of the indicator is poorly understood, assessments of such indicators, should include explicit advice on a) the probability of the indicator being outside the agreed limits, b) the quality and reliability of the limits, and c) the strength of the link with pressures and management. This information can be used when aggre‐
gating assessments of different in order to determine if GES has been achieved at the criterion or Descriptor level (section 3.4). 3.4
Technical guidance on aggregating indicator assessments for determining if GES has been achieved under D4
3.4.1
The specific nature of the foodweb indicator
When deciding on methods for aggregation or combination of different indicators within criterion and across the two criteria structure and function, the specific nature of the foodweb descriptor must be considered. Most foodweb indicators do not have clear pressure‐state relationships; there are many indirect impacts and close linkages between different foodweb components exist. For instance, rebuilding predator popu‐
lations may cause cascading effects through the ecosystem or cyclic behaviour, in which case not even an undisturbed and perfectly monitored ecosystem will neces‐
sarily show all indicators within limits at a specific point in time. In addition, there are indicators that are used for surveillance purposes which induce further investigation. This aspect means that the application of simple aggregation or averaging rules (e.g. one out all out, % agreed targets) are not suitable for foodweb criteria. Assessments of different indicators should be aggregated using a decision‐tree that takes into account the varying qualities of each indicator, in terms of their pressure‐state relationships, levels of uncertainty in their estimation, relationships with other foodweb indictors and whether or not they state indicators or surveillance indicators. The aggregation method for foodweb indicator assessments will depend on the suite of indicators being assessed. Not all indicators will be considered equally important. Not all indicators will be assessed with equal confidence, due to differences in precision and/or accuracy of indicator values and the degree to which the indicator’s limits relate to changes be‐
tween desirable and undesirable states. 3.4.2
Consideration of pressure-state relationships
Foodweb indicators can show multiple pressure‐state relationships that may be indi‐
rect and difficult to observe. When there are known linkages between indicator state and pressures, these should be listed, even if only qualitative. State indicators that have clear links to pressures, would require associated pressure indicators to also be within desirable limits. There will likely be scenarios where pressure indicators are within limits, while state indicators are not. These mismatches may be due to lag periods (e.g. slow recovery times), other forcing, or different requirements for determining status. Relevant pressures should be listed with estimated response time required for status to reach GES to incorporate time‐lags. 3.4.3
Surveillance indicatorsvs.state indicators
As defined in section 3.1, foodweb state indicators are constructed from attributes that can either be qualitatively described or quantitatively assessed as ‘desirable’ or ‘unde‐
sirable’, where a ‘desirable state’ will contribute to achieving GES at the Criterion and Descriptor level and an undesirable state will detract from GES. The distinction be‐
tween desirable and undesirable is not possible for surveillance indicators. It is still ICES WKGMSFDD4-II REPORT 2015
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possible to set limits for surveillance indicators (see section 3.3.), but when an indicator is not within limits, it is unclear what it means for the foodweb. Aggregation of indicator assessments with respect to limits needs to consider how to combine assessments of both surveillance and state indicators. One option is to assess and report the assessment results of the two types of indicators separately. The out‐
come of the assessment on surveillance indicators will inform on the required response in relation to further investigation and/or monitoring. The outcome of the assessment of state indicators should provide guidance for required management actions. A sec‐
ond option is to apply different weightings to the two types of indicators in a combined assessment at the criterion level. 3.4.4
Aggregation of indicator assessments
Some form of aggregation of individual indicator assessment results is necessary to determine whether foodwebs are at GES at the criterion level and/or to measure pro‐
gress towards GES. This summary of GES should not replace the reporting of the out‐
come of individual indicator assessment results towards GES to ensure all the information is available to determine adequate management actions. Prior to combining foodweb indicator assessments, indicators must be assigned to cri‐
teria and a decision needs to be made on whether to weight indicator assessments and how to do so. For example, indicator assessments could be weighted according to the precision of the indicators estimation and/or the perceived importance of the indicator the assessment of foodweb structure or function. In many cases, spatial aggregation of indicators is required, for example, where different time‐series are used to cover one assessment area. The assessment result of each indicator can be scored as either 0 or 1 depending on whether the current value for the indicator is outside or within limits. As stated above, weighting procedures for D4 indicators should not be one‐out‐all‐out (OOAO). Borja et al., (2014) reviewed methods for weighting, as well as considering the pros and cons of different methods. Borja et al., (2014) is a useful to guide for choosing the most appropriate aggregation method. Various possible aggregation scenarios can be tried and compared to find the most preferable approach, given the properties of the indicators being assessed. For some indicators that receive a very high weighting (e.g. they are tightly linked to management) it may be appropriate to provoke a one‐
out‐all‐out response if such indicators are not within limits. The historical development of the aggregated assessment results should be evaluated. It is important not to make the assumption that indicators behave independently; many foodweb indicators are highly correlated. Assumption of independence of indicators can be tested by quantifying the covariance and modelling indicator behaviour. Pro‐
jections of possible indicator behaviour should incorporate stochasticity, for example by using estimated indicator covariance. 3.4.5
Aggregation across criteria
Although methods to aggregate indicators within the D4 criteria might differ, there was broad agreement that both structure and function need to be at GES for overall GES to be achieved. 3.4.6
Response to reviewers’ comments in relation to GES aggregation
Comments 8, 14 and 29 relate to the guidance in aggregation methods at criterion and descriptor level. Comments 8 and 29 are addressed in the paragraphs on surveil‐
lancevs.non‐surveillance indicators and construction of composite indicators, while 20 |
ICES WKGMSFDD4-II REPORT 2015
comments 14 and 29 are addressed in the paragraph on aggregation across criteria. The issue raised in comment 29 on GES assessment across descriptors was raised and it was highlighted that GES targets need to be considered for each descriptor and in the con‐
text of each descriptor. 3.5
Potential for gaps and overlaps in relation to Descriptor 1
As the workshop was tasked with considering cross cutting issues, the concepts of D4 compared to D1 were briefly discussed. Some in the workshop considered that some of the biodiversity issues covered by the forthcoming D1 manual failed to address foodweb biodiversity in a coherent manner. One of the functions of foodwebs is to harbour biodiversity. Feeding interactions lead to many ecological niches beyond those provided by habitat alone, which lead to the characteristic pyramidal structure of foodwebs (Rossberg 2013). This aspect of ecosys‐
tem structure is often seen to be more genuine to D1 than to D4 (see, e.g. WKFooWI report), which is why only few D4 indicators cover it. To identify potential for gaps or overlaps between the scope of a revised COM DEC for D4 and D1, Sections 5.2 and 5.3 of the current draft D1 review template (version 2.2 dated 30/11/2014) are useful. Ac‐
cording to the suggested revisions for D1, the species‐level criteria will concentrate on: i )
species listed under EU Directives and international agreements ; ii )
Key species (as representatives of key structural components or functions of the ecosystem); iii )
commercially exploited species (in relation to Descriptor 3); iv )
genetically distinct forms of indigenous species. Species under (a) are mostly species of immediate conservation concern. It is explained that GES for the listed species is equivalent to the “favourable conservation status” as defined by the Habitats Directive. In addition to typical and endangered species, GES is required for the commercially exploited species addressed by the Common fisheries policy legislation (EC 2008b), the criteria and indicators for healthy stocks detailed in Descriptor 3. Indicators addressing changes in or pressures on biodiversity over large proportions of ecological communities, such as OSPARʹs indicators B‐1, FC‐1 or FW‐1 (addressing general trends in abundances of birds and fish) might therefore not be within the scope of the species‐level criterion. The criterion for “ecosystem structure” remains restricted to “Composition and relative proportions of ecosystem components (habitats and spe‐
cies)”, so excluding, for example, biodiversity indicators modelled after SEBI2010 indi‐
cator number 1. In discussion of potential additional indicators, it is noted that “these indicators should be complementary (rather than overlapping) to ecosystem function‐
ing elements already addressed in descriptors D4 (foodwebs) and D6 (sea‐floor integ‐
rity).” Overall, the wording of the draft D1 review template therefore suggests that there is a larger potential for gaps in scope between D1 and D4, and for overlaps. ICES WKGMSFDD4-II REPORT 2015
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Comments on the previous version of the D4 manual
Eight submissions in response to the previous draft of the manual were received from various countries, scientists and stakeholders (Table 4.1). Seven of the eight were sup‐
portive, or required clarification of the approach. One respondent was more critical of the approach suggested. The comments on the suggest revision of the criteria, the set‐
ting of reference boundaries and surveillance indicators, approaches to aggregation have been addressed above in section 3. 4.1
Suggestion to modify the three criteria to two criteria
The majority of the respondents (three out of four) suggested that the proposed revi‐
sion from to two criteria on structure and function was appropriate and a useful devel‐
opment. See section 3.1. 4.2
The issue of trophic guilds
Seven comments from five respondents ranged from extremely supportive of the pro‐
posed approach, to requesting clarification or potential methods to one respondent ap‐
parently disagreeing with the proposed approach. It was clear that clarification was required on how trophic guilds could be defined, selected and whether the proposed approach was exclusive. The workshop decided to include the table from the previous report in the manual (Table 4.1). The clarification required would explain that MS can monitor as many guilds as deemed appropriate (with a minimum of three), but that at least two non‐fish guilds were required to ensure that not only fish are monitored. The workshop also agreed that the manual should clarify that guild groups can refer to important prey groups (defined by who eats them) as well as predators (a group that eats the same thing). The proposed approach does not exclude other approaches to determining guilds, such as using information on taxonomy or habitat. Table 4.1. Trophic guilds. X denotes where the taxonomic groups contribute significantly to each guild. Nekton includes bony fish, elasmobranchs and squids Phytoplank
Zooplankto
Guild\Taxonomic group
ton1
n
Benthos
warmblooded
Seabirds
mammals
Primary producers X Secondary producers X Filter‐feeders X Deposit‐feeders X Planktivores X X X X Sub‐apex pelagic predators X X X Sub‐apex demersal predators X X X X Apex predators X X X 1
Nekton excl.
In shallower waters, macrophytes may also be important. Marine
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4.3
ICES WKGMSFDD4-II REPORT 2015
Methods and clarification of the concepts associated with boundaries,
GES definition, and use of surveillance indicators.
It is clear from the comments from respondents (nine comments submitted) that this issue was most unclear, and least developed in the previous manual. Thus the work‐
shop focused mostly of this issue. See section 3.3. In response to comment 2, the workshop agreed that the GES definition must ensure that undesirable effects on other foodweb components should be avoided with high probability i.e. precautionary principle should be used, also when knowledge is lim‐
ited. Measurement uncertainty should be low enough to ensure that false positives are rare. Policy discussion is required whether false Good or false Bads are more danger‐
ous. However, as reference levels are often poorly defined and the discussion of pre‐
cautionary limits may be premature. 4.4
Approaches to aggregation of GES decisions (e.g. OOAO).
Three comments were received related to aggregation issues. See section 3.4. 4.5
Future potential indicators and the knowledge base.
Four comments. The discussions provided input into the future roadmap (see section 5). ICES WKGMSFDD4-II REPORT 2015
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Table 4.1. Compilation into subject areas of comments from national authorities, scientists and other stakeholders. C OMMENT
C OUNTRY
S UBMITTED
C OMMENT / INPUT
NUMBER
Relates to modification of the criteria from 3 to 2 (structure and function) 16 Malta M. Rizzo Malta agrees with the proposed way forward with respect to the amalgamation of the current indicators into ‘foodweb structure’ and ‘foodweb function’, noting that further discussions are required to identify the trophic guilds that need to be considered by Member States. 6 Italy C. Silvestri, S. Raicevich We agree on the rearrangement of the criteria according to the proposal into 4.1 and 4.2 criteria. We believe that the revision of the Decision (or annexes) should better define the definition of the boundaries for the indicators taking into account (and specifying) different options like historical baselines, historical range of variability, current/recent data, modelling data, expert judgment as well as specifying the need to associate to boundaries an assessment of the scientific validity (trust) into the defined thresholds. 9 France I. Terrier It is really important to change the 3 present criteria into the 2 proposed new criteria to have a more holistic view of foodwebs and to allow the inclusion of a wide variety of indicators in this descriptor : 4.1 Foodweb structure – Abundance/biomass of, and size distribution within trophic guilds. 4.2 Foodweb function – Productivity of trophic guilds. 12 France Isabelle Terrier Structure and functions of foodwebs are closely linked and both included in the concept of resilience. Both of them should be considered. 20 UK A. Scarsbrook The decision D4 criteria should be simplified to 4.1 Foodweb structure and 4.2 Foodweb function. It is difficult to reconcile ICES analysis of the implementation of Descriptor so far (as per ICES advice book 11.2.1.4) with ICES recommendation for a way forward. Citing the related JRC report, ICES criticize the low degree of consistency and coherence in the D4 implementation. This is the outcome of vague language in the Commission Decision. The logical conclusion would then be to propose more specific guidelines for proven methodological standards, such as those developed in the WKFooWI workshop held at ICES in March‐April and the ICES advice building on this. Unfortunately, ICES miss this opportunity in their advice for the indicator revision; it remains vague and helps little to overcome current issues with consistency and coherence of implementations. Relates to definition and use trophic guilds representing differences between D4 and D1 in terms of ecosystem functioning 16 Malta M. Rizzo Discussions should also take into consideration the difficulties which may be encountered in assigning trophic guilds, noting that the information available through literature may be of a general nature. 7 Italy C. Silvestri, S. Raicevich We agree on the opportunity to consider at least three trophic guilds, however the selection of them should be pragmatic but also should ensure that relevant processes (and components) of the ecosystems are taken into account. 10 France I. Terrier The notion of trophic guilds should replace all the other terms used (functional/key trophic group or species), because from a 24 |
ICES WKGMSFDD4-II REPORT 2015
foodweb point of view, the conservation of functions in ecosystems is more important than the conservation of species themselves, which is more a D1 objective. 11 France I. Terrier The minimum of 3 trophic guilds to be monitored, covering different parts of the foodweb (low, middle, high trophic levels), is also an essential requirement. 21 UK A. Scarsbrook The criteria should be applied to trophic guilds, not taxonomic groups. An indicative list of guilds is provided. The categorization of foodwebs using taxonomy should be removed from the decision. In their advice, ICES insist that any taxonomic grouping used to define indicators for D4 should be replaced by groupings by trophic guild (defined though food type or feeding mode), without providing any clear rationale. It is well known among foodweb experts (e.g. Rossberg et al., Journal of Theoretical Biology, 241, 2006:552—563. Naisbit, et al. Proceedings of the Royal Society B, 279, 2012:3291—3297) that taxonomy is closely related to the roles species play in foodwebs as prey, although it is only loosely related their roles are predators. Therefore, taxonomic groupings can make good sense for foodweb indicators. By ICES proposal to work with trophic guilds and the indicative list for guilds they provide, foodweb indicators would group basking sharks into the same guild as mussels (both are “filter‐feeders”), and many seabirds into the same group as marine mammals and most large fish, as far as these are “pelagic piscivores”. There is a high risk that indicators based on such groupings would be difficult to define, to interpret and to manage. Other issues with the proposal are that, upon closer inspection, trophic guilds are not sharply defined and many species run through several trophic guilds during different life stages (all of which are equally important for the survival of the species). 22 UK A. Scarsbrook Of the minimum requirement of three trophic guilds per region, a maximum of one should be an exclusive fish guild. There is no sensible way of restricting all fish to a single trophic guild and still have something than makes any sense in foodweb terms! The theory of size structured foodwebs when applied to fish only should be sufficient to suggest that this is non‐sensical. Fish operate at different trophic levels as they increase in size, and within marine foodwebs fish perform many quite different trophic fundctions. The ERSEM model for example uses four fish guilds dmersal piscivores and benthivores, and pelagic piscivores and planktivores. The ERSEM model would not produce meaningful output with fewer fishi guilds. I would argue that in order to comfortably assign all fish in the North Sea to trophic functional guilds, a fifth guild, demersal planktivores, is actually required. 28 RSPB E. Dunn Included in elements to be taken out of the Decision and included in the guidance document is: • ʺThe recommendation that not all trophic guilds in each ecosystem need to be assessed but that, by region, a minimum of at least three trophic guilds should be monitored. [...] Of the minimum requirement of three trophic guilds per region, a maximum of one should be an exclusive fish guild.ʺ • The choice of trophic guilds is expected to reflect regional differences in priorities and ecosystem dynamics. This guidance, while necessary, is not sufficiently explicit. The advice in the WKGMSFD D4 report (page 9) states that: ‘As a general rule, at least three trophic guilds should be considered [for monitoring] spanning as widely as possible from primary producers to apex predators’. The manual text should be revised to capture more precisely this guidance on selecting for monitoring a set of trophic guilds representative of the spectrum of foodwebs. This guidance is also relevant to the fact that currently some Member States consider only higher trophic levels (see Criterion 4.3 Abundance/distribution of key trophic groups/species). Relates methods and clarification of the concepts associated with boundaries, GES definition, and use of surveillance indicators. ICES WKGMSFDD4-II REPORT 2015
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2 Italy C. Silvestri, S. Raicevich Possibly would be needed to specify that the indicators should be within acceptable ranges that ensure the high probability to maintain the full reproductive capacity 5 Italy C. Silvestri, S. Raicevich We agree on considering most of (in not all) D4 indicators as surveillance indicators due to the lack of indicators reflecting strong pressure‐state relationships (and lack of scientific knowledge/methods to disentangling the relative role of different pressures). However, the revision of the Decision should clearly specify the procedure to be adopted when surveillance indicators show to reach values that are considered to be critical. Without setting a common and agreed approach, it is likely that such surveillance indicators will be little use and have little influence on the challenge to reach GES. 13 France I. Terrier The notion of surveillance indicators is really important for D4, because changes and shifts in foodwebs are possible to detect but the direct pressure‐state relationships are often not yet established considering the complexity of foodwebs and the lack of knowledge. 15 France I. Terrier Agreement on methodological standards for defining GES: the precautionary principle should be followed when surveillance indicators are out of bounds (known experience) because of the lack of knowledge of foodwebs (to the extent that they are known): investigation needed. 17 NL F. van den Ende “ Movements beyond those bounds should be seen as possibly/potentially leaving GES..” When the cause turns out not to be human activity (or is climate change) the GES bounds should be adapted 18 Germany A. Weiß We consider the two important questions raised within the document crucial to the development of an indicator supporting the main objectives of the MSFD, i. e. to set up measurement programmes which allow to measure GES. The two questions are: how do we determine GES thresholds or boundaries. 24 UK A. Scarsbrook GES can only be considered if 4.1 and 4.2 are within the GES boundaries. This is key to development of the foodweb indicators. With changing climate it will become increasingly difficult to set specific targets representing GES. Particularly for foodwebs, if we see trophic guild biomass indicators heading off into regions that have never been seen before, either higher or lower than previously observed, this should be cause for concern, and froma precautionary perspective, we should ensure that human activity is not the cause of such a trend. 25 UK A. Scarsbrook ʺUsually environmental influence has a high impact on foodweb structure and function. Current scientific understanding is such that anthropogenic pressure is difficult to distinguish from the environmentally influenced variability.[..] In the absence of strong indicators reflecting pressure‐state relationships, the indicators of D4 should be treated as surveillance indicators (monitoring change in the foodweb across the minimum three guilds).ʺ In their advice, ICES reiterate that, based on their scientific understanding, anthropogenic pressures are difficult to distinguish from the environmentally influenced variability. It is hard to reconcile this finding with the role ICES plays in fisheries management. The scientific literature describes for several aspects of foodweb structure how these are affected by anthropogenic pressures. What ICES might have meant to say when negating existence of human‐attributable change in foodwebs is that, for many conceivable foodweb indicators, indicator values fluctuate widely and these fluctuations are difficult to attribute to causes. However, this just means that such indicators are poorly designed. They should neither be used for “surveillance”, as ICES suggest, nor for management. Another reason might be that some aspects of foodwebs simply are not vulnerable to anthropogenic pressures. Indicators properly designed to quantify vulnerable high‐level properties of foodwebs do not suffer from these problems 26 |
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Comment above highlighted in yellow (UK n.6) also relevant here (page 18; lines 18‐20). 26 UK A. Scarsbrook ʺMethodological standards for defining GES should describe a state within prescribed bounds based on our known experience of natural variability of that foodweb’s state. Movement beyond those bounds should be seen as leaving GES, and lead to an investigation into the cause or the change in GES status and, when relevant, trigger more precautionary management.ʺ Please clarify what ‘natural’ means here. Comment above in yellow also relevant here. ICES propose that GES for D4 would correspond to indicator values within the natural range of variation. Depending on what ICES mean by “natural” , this stipulation, too, seems to be add odds with ICES role in fisheries management. More appropriate might be a recent proposal developed by the DEVOTES project (Rossberg et al., unpublished ms): GES corresponds to indicator values such that these would return to the natural range of variability within [30 year] if, hypothetically, all anthropogenic pressures removed. Relates to Approaches to aggregation of GES decisions (e.g. OOAO). 8 Italy C. Silvestri, S. Raicevich Although we do understand the merit of having a pragmatic approach for GES determination within the criteria level (i.e. not using the OOAO approach), we do not necessarily agree on the fact that GES would never be reached. This is very depending on the range of variability that is set for the indicators and in the actual state of the marine environment. We agree on the need of better refining the GES interpretation for D4, also in the light of the precautionary approach. As already discussed, the procedure (management procedure? Monitoring procedure? Other?) triggered by falling apart from boundaries set for the definition of GES for indicators should be clearly defined for surveillance indicators. 14 France I. Terrier The principle of one out, all out at the criterion level appears to be the more suitable to D4: functions are as important as structure. 29 RSPB E. Dunn Regarding the following text: ”One out, all out was considered appropriate at the criterion level. Hence, there can only be GES of D4 if both structure and function are at GES. However, the effect of the one out, all out” method within each criterion would likely be a permanent state of D4 outside GES, with management action unlikely to succeed in bringing the indicator inside GES. This might be counterproductive as the perception of an indicator which is always outside the bounds of management action will likely lead to ignoring the issues which can be addressed through management.ʺ We agree with the rationale underlying that, within each D4 criterion, the OOAO rule for GES is inappropriate. However, given that some Member States perceive that D4 is covered by D1 targets, and don’t set any D4 targets at all, then the OOAO rule should apply to D1. We appreciate that this linkage is more relevant to the Review of the GES Decision 2010/477/EU and MSFD Annex III – cross‐cutting issues but make the comparative point again here for the sake of completeness. Relates to future potential indicators and the knowledge base. 18 Germany A. Weiß We consider the two important questions raised within the document crucial to the development of an indicator supporting the main objectives of the MSFD, i.e. to set up measurement programmes which allow to measure GES. The two questions are: (1) how can anthropogenic pressure be distinguished from environmentally influenced variability 3 Italy C. Silvestri, S. Raicevich It should be noted that this interpretation could determine a reduction in the efforts towards the understanding and monitoring of foodwebs. This is due in particular to the fact that only part of the FW components are at present well monitored and known, and such interpretation (while being pragmatical) could imply that no effort for new monitoring ICES WKGMSFDD4-II REPORT 2015
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could be enforced (also resulting in avoiding to consider some relevant trophic guild of relevance level). Therefore we suggest this interpretation to be amended quoting the need of filling gap of knowledge for those trophic guilds whose role is considered potentially relevant (or have been shown to be relevant thanks to modelling or experimental studies). 4 Italy C. Silvestri, S. Raicevich It is worth noting that some ecosystem indicators are being considered in the Barcelona Convention not in the EO4 (Foodweb) but, rather, under other Ecological objectives, for instance the EO3 related to fishing effects. A process for the integration/alignment of new MSFD definition and the work carried out so far by the RSC should be established, because the changes in the Decision could determine a mismatch with the current and ongoing definition/selection of foodweb indicators. 23 UK A. Scarsbrook The criterion 4.1 Foodweb structure should be subdivided into biomass of guilds over time and size structure within those guilds. There is more to foodweb function than productivity (e.g. the ability of foodwebs to regulate abundances along the food chain [oceans without zooplankton would be green] or their role of harbouring biodiversity [species richness is coupled across trophic levels, see e.g. Warren and Gaston, Phil Trans R Soc London B, 338, 1992:113‐210, Rossberg, “Foodwebs and Biodiversity”, Wiley 2013]), and more to foodweb structure than abundance and size structure within groups (e.g. a balance between benthivorous fish and benthic food available to them). WKFooWI acknowledged these complications, noting that they often cut across Descriptors, and recommended that these cross‐cutting issues are identified and addressed by the appropriate Descriptors. These insights and recommendations were not taken up by ICES in their advice for the D4 revision. General comments and text corrections 31 RSPB E. Dunn Amend to cite as 2014a and 2014b. 1 FI S. Korpinen Nothing to report 19 UK A. Scarsbrook Given the recent ICES advice on D4 it would be more useful for us to comment on the new Decision draft when it becomes available. This previous ICES advice to the Commission provided a useful Roadmap for D4 implementation, which should be referred to. There is also no reference to the need to consider the biodiversity descriptors D1, 3, 4 and 6 as an integrated set and where possible use a common suite of indicators. We find some of the wording is a bit vague, for example on the definition of guilds, and targets linked to natural variability. 27 RSPB E. Dunn The document faithfully reflects the outcomes of the ICES WKGMSFD D4, 26‐27 August 2014 which achieved a high level of consensus among stakeholders. 30 RSPB E. Dunn Rational and technical background for proposed revision: Presumably ‘Rationale’? 28 |
5
ICES WKGMSFDD4-II REPORT 2015
Roadmap for future development of science for implementation
and evaluation
The proposed roadmap considers the following two aspects: 
What needs to be done for the implementation for the current review of the Commis‐
sion Decision? 
What are the necessary steps for future reviews? Timelines considered were immediate steps in the next 24 months’ and longer‐term action within a 48 months’ time frame. The most important issues to address in the roadmap were identified as: 
Regional and Cross‐regional coordination 
Information flow between descriptors: Gaps and overlaps 
Uncertainty and GES 
Further steps in indicator development 
Aggregation for GES assessment within D4 including spatial integration This section should be considered an exploration of issues, rather than a specific road map. It is designed as a collection of issues and ideas. 5.1
Regional and Cross-regional scientific advice process
Closer cooperation is necessary between foodweb experts both within and between regional seas to facilitate the sharing of scientific knowledge, experience and expertise. Such cooperation will provide consistent interpretation and application of scientific evidence to the implementation of D4 within and between regions. Regional workshops or groups (OSPAR already has a D4‐foodweb expert working group) could focus on ensuring consistent interpretations of indicators, limits and es‐
timation methods within regions to facilitate a more consistent scientific advice to the individual Member States. In some Regions, comprehensive lists of indicators at the Regional or European level have already been agreed upon. At both Regional and Eu‐
ropean level, work should continue to gradually expand agreed lists of appropriate indicators. This would require broad participation of decision‐makers and scientist. A cross‐regional workshop should focus on identifying key research questions, nomi‐
nating groups of expert to work on each question and nominating groups to formulate research proposals. The recommendations from the workshop could include specific Terms of Reference for existing groups, such as ICES Working Groups, and the OSPAR expert group on Foodwebs or newly formed regional D4 assessment groups. This pro‐
cess will provide scientific input into the development of D4 indicators and assessment methods in all Regional Seas – starting immediately, ongoing into the future. In the longer term, a scientific review of the Article 8 assessments submitted by MSs in 2018 could help to inform any revision of the Commission Decision and the work towards the next assessment in 2024. 5.2
Information flow between descriptors: Gaps and overlaps
Biodiversity descriptors (D1, 4, 6) are often grouped together in reporting, but with different teams working on each descriptor. It is important to tease out foodweb inter‐
actions or specifics relating to each indicator. Whereas the same indicators may be used in different descriptors, their meaning, targets and interpretation may be different. The ICES WKGMSFDD4-II REPORT 2015
| 29
use of similar terminology can be misleading in different contexts and so it is important that the descriptor‐specific meanings are clear both within and across the biodiversity descriptors. Gap analysis between descriptors will ensure that all aspects of the marine ecosystem are sufficiently covered within the directive. Suggested biodiversity crosscutting issues to be addressed are: 
Overlaps of indicators ‐ do they measure the same thing, or do they have descriptor‐specific functions? Do they require different target settings? 
The understanding of ecosystem functioning ‐ is it common across the bio‐
diversity descriptor or does it merit specific definitions by descriptor? 
The concepts of biodiversity aspects as currently used by the MSFD (benthic and pelagic habitats, fish and cephalopods; marine mammals and reptiles; marine birds) vs. trophic guilds ‐ can these two concepts be combined into a three‐dimensional matrix (e.g. table in last D4 report) that can be aggregated as required or are descriptor specific groupings required? 
Gap analysis ‐ are all aspects of marine ecosystem’s biodiversity sufficiently covered by the Directive? It is important that communication between descriptor groups is initiated as soon as possible and continues through the process. This relates specifically with overlaps with D1 and D6, although also covers D3. A task group of representatives from each biodi‐
versity descriptor (JRC/ICES) may address biodiversity‐specific crosscutting issues ei‐
ther by correspondence or meetings. 5.3
Uncertainty and GES
ʺWe demand rigidly defined areas of doubt and uncertainty!ʺ (Vroomfondel, a philosopher) Douglas Adams Multiple sources of uncertainty affect the ability to determine how D4 indicator bounds and changes can be interpreted for GES. Without a framework for updating knowledge of implications for indicator bounds that reflect updating of the science it will be not be possible to interpret D4 indicators for GES. There are three issues that require fur‐
ther attention: statistical uncertainty with respect to measuring indicators, uncertainty reflecting whether the values for indicators relate to desirable or undesirable states, and how direct and indirect linkages between indicators and pressures affect D4 indi‐
cator behaviour. Identification and application of empirical, modelling and conceptual tools (e.g. expert elicitation) can be used to identify and test the performance of thresholds, and indicator behaviour that develops knowledge of reference levels and pressure‐state relationships with a goal to move surveillance indicators to better informed target ranges. These ap‐
proaches (e.g. simulation modelling) should enhance predictions of the consequences of perturbations, demonstrate the value of empirical data and help to better identify reference levels to determine status. There are two levels of work that need to be addressed. Broader scale methodological advances and review, and system‐specific work related to improving and refining in‐
dicator measurement. A lot of ongoing and existing research exists, and some of this may sit outside the MSFD community. 30 |
5.4
ICES WKGMSFDD4-II REPORT 2015
Indicator development
WKGMSFDD4‐II sees a The workshop stated the need to understand the relationship between variation in anthropogenic pressure and change in surveillance or state indi‐
cators used to monitor change in marine foodwebs, and in this process, to be able to distinguish between human‐driven and environmentally‐driven change in the food‐
web indicators. In order to be able to assess changes in foodweb structure and function that are primarily caused by a changing environment, there is a clear need for indica‐
tors that monitor change in lower trophic level guilds, such as phytoplankton, zoo‐
plankton and benthos. In attempting to meet the requirement to monitor three trophic guilds, of which at least two are non‐fish guilds, Member States might be tempted to focus their monitoring activity on higher trophic level guilds, such as seabirds or and marine mammals, and this could seriously hamper our capacity to interpret variation in foodweb structure as caused by either human activity or environmental change. There are many regions where few data on abundance of benthic guilds is available to inform assessments. Although important proportions of the benthic community are sampled in fisheries trawl surveys, additional efforts would be needed to systemati‐
cally evaluate these samples, to process and store the resulting data. Planning for these activities can start in the near future. The abundances of guilds in isolation do not tell the full story of the state and the pro‐
cesses occurring in a foodweb. Better assessments of whether (i) the foodweb is in a forced state from which recovery is difficult, (ii) behaves in an unexpected way, and (iii) does not function to its full capacity, will be possible when abundance‐indicator time‐series are interpreted through models. Such models also make it possible to dis‐
tinguish indirect effects of pressures from natural variability. Beyond the use of models in developing a better understanding of foodwebs and indicators, future assessments of GES should therefore make direct use of models in conjunction with the indicator data. Appropriate models, such as Strath2E2 are available (Heath et al., 2014a, b) and development of corresponding assessment methodologies can begin in the near future. As models and understanding improve, we can convert surveillance indicators into indicators associated with clear targets. The proposed D4 cross‐regional scientific ad‐
vice process could support these developments. Management strategy evaluations (MSE) are now well established in fisheries manage‐
ment. For the purpose of determining the validity and uncertainties of assessments of foodweb status and effectiveness of management measures, such MSE could be used. For the policy process, it is important that the potential value of MSE is recognized, especially in conjunction with model‐based assessments. Future MSFD assessment cy‐
cles might include MSE. The rationale for determining ecological guilds for the purpose of D4 assessment needs to be developed further. Feeding habits are an important criterion for grouping species, but they are not exclusive. Potential predators, preferred habitats, and, for the purpose of comparability, also taxonomic similarity can also be considered. Good choices of guilds can affect the quality of assessments. This becomes particularly clear for model‐
based assessments: it is known that models with “intermediate complexity”, i.e. mod‐
els resolving an intermediate number of carefully chosen guilds, are most effective (Fulton et al., 2003). Guilds should be chosen based on how effective they support as‐
sessments of status and function of the foodweb as a whole. Foodweb dynamics are characterized by both trophic (predator–prey) interactions and non‐trophic interactions, such as habitat modification, and therefore it is important to quantify both types of processes when trying to assess changes in both structural and ICES WKGMSFDD4-II REPORT 2015
| 31
functional properties in foodwebs (Kéfi et al., 2015). Habitat modification and species removal caused by human pressure, such as fishing activities and ecosystem change driven by environmental and climate conditions may be reflected in non‐trophic inter‐
actions in foodwebs and therefore, non‐trophic dimensions need to be considered in further development of foodweb indicators. We can increase our understanding of how complex ecological systems respond to dis‐
turbance by using non‐trophic interactions to explain variation not explained by trophic interactions (Kéfi et al., 2015; Pocock et al., 2012). Next steps would be to char‐
acterize ecological networks that occur among species and quantify both trophic and non‐trophic interactions. This aspect can be described by using available modelling tools for visualizing ecological networks (Kéfi et al., 2015; Thompson et al., 2012). Con‐
sideration of an ecological network approach for the development of foodweb indica‐
tors is currently on going. First there is a need to establish a robust approach and methodology to quantify trophic interactions. Secondly, future effort will benefit to in‐
corporate non‐trophic interactions in foodweb dynamics, to fully characterize the com‐
munity and assess the ecological status of the foodweb towards GES. 5.5
Aggregation for GES assessment within D4, including spatial integration
A scientific basis for rules of aggregation should be developed. To allow inclusion of all available information, aggregation rules are needed which account for that indica‐
tors vary in, for example, their degree of development, the length of time‐series of data, uncertainty (both statistical and conceptual), and the pressure‐state relationship. Ag‐
gregation guidelines are needed very quickly after the suite of indicators is agreed upon regionally, well in time before the next reporting of Member States to EC. A work‐
shop of foodweb experts either at regional scale, or preferably together (if agreed by RSCs), to agree on aggregation rules that can be applied both at the regional and na‐
tional level. Should Member States see the need for it, the MSFD allows for subregions to be split into spatial subdivisions for the purpose of assessment. For example, there is clear ev‐
idence of spatial heterogeneity within both the benthic invertebrate and the fish com‐
munities in the North Sea (Figure 5.1). Hence, it would make ecological sense to carry out assessments of state with ecological subunits. In the Baltic Sea (Figure 5.2.), the marked gradient in salinity, and all the ecological variation associated with this, sug‐
gests that single assessments made at the whole subregional scale could mask variabil‐
ity that would be apparent should assessment be made at an appropriate subdivisional scale. In some subregions, monitoring programmes do not cover the entire area; hence, assessments would most likely be carried out using the individual survey monitoring programmes. In both instances, in coming to an overall assessment of status for a par‐
ticular indicator at the subregional scale, integration of individual subdivisional scale assessments would be required. Subregional scale assessment outcome is strongly de‐
pendent upon the aggregation/integration methodology applied (Figure 5.3). A single subregional scale indicator assessment also gives a “Not GES” outcome; the same out‐
come is achieved using the OOAO rule or an “averaging” integration method. ICES WKGMSFDD4-II REPORT 2015
Degrees Latitude
32 |
Figure 5.1. Potential partitioning of the North Sea into five spatial subdivisions based on spatial heterogeneity in the composition of the demersal fish community and showing an east‐west split separating the UK EEZ from the remainder of the North Sea. Figure 5.2. Map of the Baltic Sea presenting subdivisions into 17 open sub‐basins and 42 coastal areas used for the HOLAS assessment. ICES WKGMSFDD4-II REPORT 2015
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Figure 5.3. Integration of separate subdivisional‐scale assessments to derive an overall assessment status based on a single indicator at the scale of an MSFD subregion and showing the effect of using five different aggregation methods. Deriving the “common indicator” is the first step in the aggregation process and this is simply done by dividing the observed indicator value by its target value. 34 |
6
ICES WKGMSFDD4-II REPORT 2015
Conclusions
The review comments and this workshop supported the proposal of WKMSFDD4 (ICES 2014) to replace the three criteria in the Commission Decision under Descriptor 4 with two criteria: 4.1 Foodweb Structure; 4.2 Foodweb Function. These two criteria will provide the framework within which to assess whether marine ecosystems are subjected to sufficiently ‘strong sustainable use’ (criterion 4.1 on foodweb structure) and whether the ecosystems can effectively support these uses by being sufficiently “productive” (criterion 4.2 on Foodweb Function). For GES under Descriptor 4 to be achieved, both the structure and function of foodwebs need to be at appropriate levels. Many foodweb indicators show substantial variation due to factors not related to an‐
thropogenic pressures (weak or indirect links to human pressure). Indicators often re‐
flect the desire to achieve a balanced ecosystem, and hence having very high or very low indicator values could be considered equally undesirable. The desired level of a specific indicator may be related to avoiding undesirable effects on other ecosystem components and hence requires information and knowledge of the relationship be‐
tween different foodweb components. Given these special considerations, a foodweb indicator may be associated with different combinations of available data (monitoring time‐series) and knowledge (about the relationship of the indicator with foodweb com‐
ponents). Guidelines were developed for varying data and knowledge scenarios to de‐
rive indicator limits (reference areas). Common to these guidelines are the principles that: i.
ii.
iii.
indicators should be reported together with estimates of their precision, highly variable indicator estimates should not lead to changes in limits a lack of knowledge of limits and effects of falling outside limits should not be used as an excuse for lack of action. This would allow the use of precautionary principles when deciding on management actions. This use of surveillance indicators, based on monitoring, triggers action when indicators move beyond the limits. This action should determine whether anthropo‐
genic pressures are causing changes to the foodweb. Indicator limits should relate to current conditions of the ecosystem, implying that limits will need to be reviewed reg‐
ularly and updated where necessary in response to natural variability of ecosystem. For the GES assessment of foodwebs at the criterion level, the applications of simple aggregation or averaging rules are not considered suitable. Assessments should follow a decision tree flow that takes into account different pressure‐state relationships; var‐
ying levels of uncertainty in the indicators; their interrelationships and whether indi‐
cators are surveillance indicators. State indicators that have clear links to pressures require both pressure and state indicators to be at within limits, however lag periods need to be taken into account. Surveillance and non‐surveillance indicators can either be assessed and reported on separately, due to their different response requirements (ii.e.., further investigation or management action) or combined by applying different weightings. Although methods to aggregate indicators can differ across the two D4 criteria, both structure and function need to be at GES for overall GES to be achieved. Comments submitted to ICES on the previous version of the manual also requested clarification and guidance with regards to the use and definition of trophic guilds. The workshop decided to add text to the manual and include a table on potential ap‐
proaches. Some of the comments related to the need for further work and these were used to create a roadmap for further research required for the implementation and de‐
velopment of foodweb indicators to support the MSFD. ICES WKGMSFDD4-II REPORT 2015
7
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ploited marine ecosystems. 2. Setting the Scene. ICES Journal of Marine Science, 67: 692–716. Smith, A. D. M., Fulton, E. J., Hobday, A. J., Smith, D. C., and Shoulder, P. 2007. Scientific tools to support the practical implementation of ecosystem‐based fisheries management. ICES Journal of Marine Science, 64: 633 – 639. Szuwalski, C. S., Vert‐Pre, K. A., Punt, A. E., Branch, T. A. and Hilborn, R. (in press), Examining common assumptions about recruitment: a meta‐analysis of recruitment dynamics for worldwide marine fisheries. Fish and Fisheries. doi: 10.1111/faf.12083 Thompson, R. M., et al. (2012) Food webs: reconciling the structure and function of biodiversity. TREE, 12, 689‐697. Vert‐pre, K. A., Amoroso, R. O., Jensen, O. P., and Hilborn, R. (2013). Frequency and intensity of productivity regime shifts in marine fish stocks. Proceedings of the National Academy of Sci‐
ences, 110(5), 1779‐1784. Yletyinen, J., Bodin, Ö., Weigel, B., Nordström, M.C., Bonsdorff, E., and Blenckner, T. (2014) Un‐
derstanding marine regime shifts: detecting possible changes in structures and functions of coastal and pelagic food webs. Manuscript in lic.thesis, University of Stockholm. 38 |
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Annex 1. List of participants
Name
Address
E-mail
Andrea Belgrano Swedish Institute for the Marine Environment (SIME) andrea.belgrano@slu.se Anna Karasszon European Commission anna.karasszon@ec.europa.eu Anna Rindorf (chair) DTU Aqua ar@aqua.dtu.dk Axel Rossberg Cefas axel.rossberg@cefas.co.uk Frank van den Ende Rijkswaterstaat WVL frank.vanden.ende@rws.nl Gavin Fay (vice‐chair) University of Massachusetts Dartmouth gavin.fay@umassd.edu Hugo Mendes IPMA hmendes@ipma.pt Ian Mitchell (vice‐chair) Joint Nature Conservation Committee ian.mitchell@jncc.gov.uk Joana Patrício (vice‐chair) JRC joana.patricio@jrc.ec.europa.eu Jurgen Bastleer VisNed jbatsleer@visned.nl Kenneth Coull Scottish Fishermenʹs Federation k.coull@sff.co.uk Leonie Dransfeld (vice‐chair) Marine Institute leonie.dransfeld@marine.ie Marie Nordström (vice‐chair) Åbo Akademi University marinord@abo.fi Mark Dickey‐Collas (support) ICES mark.dickey‐collas@ices.dk Natalie Crawley Milieu natalie@naturebureau.co.uk Pauline Vouriot CNRS pauline.vouriot@imbe.fr Piotr Margonski National Marine Fisheries Research Institute pmargon@mir.gdynia.pl Sandrine Serre CNRS sandrine.serre@imbe.fr Simon Greenstreet Marine Scotland simon.greenstreet@scotland.gsi.gov.uk ICES WKGMSFDD4-II REPORT 2015
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Annex 2. Agenda
Review the 2010 Commission Decision on criteria and
methodological standards on good environmental status (GES) of
marine waters; Descriptor 4 Foodwebs
ICES H.Q. Copenhagen, Denmark
09:00 24 February to 17:00 25 February
Chair: Anna Rindorf, Denmark
24 February 1. Introductions and welcome Participants will be welcomed to the workshop. 2. Aim of the workshop The agenda, aims of the workshop, and expected outcomes will be reviewed. Participants will be invited to provide initial feedback on the proposed agenda and process. 3. Potential revision of foodweb criteria The rationale for assessing structure and function separately is revisited and the comments by Member States and NGOs on the new criteria discussed 4. Technical guidance on reference level setting • Development in the concept of surveillance indicators • Guiding the setting of reference levels 5. Technical guidance on combining indicators in GES of D4 25 February 6. Addressing reviewer’s comments 7. Road map for assessing GES of D4 in the short and long term 8. Conclusion The main conclusions of the workshop will be reviewed and summarized. 40 |
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Annex 3. Compilation of national, scientist and NGO comments on previous version of the manual.
C OUNTRY
S UBMITTED
C OMMENT / INPUT
I NTERPRETATION
1 FI Samuli Korpinen Nothing to report No major objections 2 Italy Cecilia Silvestri, Saša Raicevich Possibly would be needed to specify that the indicators should be within acceptable ranges that ensure the high probability to maintain the full reproductive capacity Relates to boundaries and GEF definition, and use of surveillance indicators 3 Italy Cecilia Silvestri, Saša Raicevich It should be noted that this interpretation could determine a reduction in the efforts towards the understanding and monitoring of foodwebs. This is due in particular to the fact that only part of the FW components are at present well monitored and known, and such interpretation (while being pragmatical) could imply that no effort for new monitoring could be enforced (also resulting in avoiding to consider some relevant trophic guild of relevance level). Therefore we suggest this interpretation to be amended quoting the need of filling gap of knowledge for those trophic guilds whose role is considered potentially relevant (or have been shown to be relevant thanks to modelling or experimental studies). Relates to knowledge and understanding, future developments 4 Italy Cecilia Silvestri, Saša Raicevich It is worth noting that some ecosystem indicators are being considered in the Barcelona Convention not in the EO4 (Foodweb) but, rather, under other Ecological objectives, for instance the EO3 related to fishing effects. A process for the integration/alignment of new MSFD definition and the work carried out so far by the RSC should be established, because the changes in the Decision could determine a mismatch with the current and ongoing definition/selection of food web indicators. Relates to knowledge and understanding, future developments 5 Italy Cecilia Silvestri, Saša Raicevich We agree on considering most of (in not all) D4 indicators as surveillance indicators due to the lack of indicators reflecting strong pressure‐state relationships (and lack of scientific knowledge/methods to disentangling the relative role of different pressures). However, the revision of the Decision should clearly specify the procedure to be adopted when surveillance indicators show to reach values that are considered to be critical. Without setting a common and agreed approach, it is likely that such surveillance indicators will be little use and have little influence on the challenge to reach GES. Relates to boundaries and GEF definition, and use of surveillance indicators. 6 Italy Cecilia Silvestri, Saša We agree on the rearrangement of the criteria according to the proposal into 4.1 and 4.2 criteria. We believe that the revision of the Decision (or annexes) should better define the definition of the boundaries for the indicators taking into account (and specifying) different options like historical Relates to change of criteria C OMMENT
NUMBER
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Raicevich baselines, historical range of variability, current/recent data, modelling data, expert judgment as well as specifying the need to associate to boundaries an assessment of the scientific validity (trust) into the defined thresholds. 7 Italy Cecilia Silvestri, Saša Raicevich We agree on the opportunity to consider at least three trophic guilds, however the selection of them should be pragmatic but also should ensure that relevant processes (and components) of the ecosystems are taken into account. Relates to trophic guilds 8 Italy Cecilia Silvestri, Saša Raicevich Although we do understand the merit of having a pragmatic approach for GES determination within the criteria level (i.e. not using the OOAO approach), we do not necessarily agree on the fact that GES would never be reached. This is very depending on the range of variability that is set for the indicators and in the actual state of the marine environment. We agree on the need of better refining the GES interpretation for D4, also in the light of the precautionary approach. As already discussed, the procedure (management procedure? Monitoring procedure? Other?) triggered by falling apart from boundaries set for the definition of GES for indicators should be clearly defined for surveillance indicators. Relates to OOAO 9 France Isabelle Terrier It is really important to change the 3 present criteria into the 2 proposed new criteria to have a more holistic view of foodwebs and to allow the inclusion of a wide variety of indicators in this descriptor: 4.1 Foodweb structure – Abundance/biomass of, and size distribution within trophic guilds. 4.2 Foodweb function – Productivity of trophic guilds. Relates to change of criteria 10 France Isabelle Terrier The notion of trophic guilds should replace all the other terms used (functional/key trophic group or species), because from a foodweb point of view, the conservation of functions in ecosystems is more important than the conservation of species themselves, which is more a D1 objective. Relates to trophic guilds 11 France Isabelle Terrier The minimum of 3 trophic guilds to be monitored, covering different parts of the foodweb (low, middle, high trophic levels), is also an essential requirement. Relates to trophic guilds 12 France Isabelle Terrier Structure and functions of foodwebs are closely linked and both included in the concept of resilience. Both of them should be considered. Relates to change of criteria 13 France Isabelle Terrier The notion of surveillance indicators is really important for D4, because changes and shifts in foodwebs are possible to detect but the direct pressure‐state relationships are often not yet established considering the complexity of foodwebs and the lack of knowledge. Relates to boundaries and GEF definition, and use of surveillance indicators 14 France Isabelle Terrier The principle of one out, all out at the criterion level appears to be the more suitable to D4: functions are as important as structure. Relates to OOAO 15 France Isabelle Terrier Agreement on methodological standards for defining GES: the precautionary principle should be followed when surveillance indicators are out of bounds (known experience) because of the lack of Relates to boundaries and 42 |
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knowledge of foodwebs (to the extent that they are known): investigation needed. GEF definition, and use of surveillance indicators 16 Malta Miraine Rizzo General Comment: Malta agrees with the proposed way forward with respect to the amalgamation of the current indicators into ‘foodweb structure’ and ‘foodweb function’, noting that further discussions are required to identify the trophic guilds that need to be considered by Member States. Discussions should also take into consideration the difficulties, which may be encountered in assigning trophic guilds, noting that the information available through literature may be of a general nature. Relates to change in criteria and trophic guild definitions 17 NL Frank van den Ende “ Movements beyond those bounds should be seen as possibly/potentially leaving GES..” When the cause turns out not to be human activity (or is climate change) the GES bounds should be adapted Relates to boundaries and GEF definition, and use of surveillance indicators 18 Germany Andrea Weiß General comment: We consider the two important questions raised within the document crucial to the development of an indicator supporting the main objectives of the MSFD, i. e. to set up measurement programmes which allow to measure GES. The two questions are: (1) how can anthropogenic pressure be distinguished from environmentally influenced variability and (2) how do we determine GES thresholds or boundaries. Relates to boundaries and GEF definition, and use of surveillance indicators and knowledge base 19 UK Andrew Scarsbrook General comments: Given the recent ICES advice on D4 it would be more useful for us to comment on the new Decision draft when it becomes available. This previous ICES advice to the Commission provided a useful Roadmap for D4 implementation, which should be referred to. There is also no reference to the need to consider the biodiversity descriptors D1, 3, 4 and 6 as an integrated set and where possible use a common suite of indicators. We find some of the wording is a bit vague, for example on the definition of guilds, and targets linked to natural variability. Overall request for clarification 20 UK Andrew Scarsbrook The decision D4 criteria should be simplified to 4.1 Foodweb structure and 4.2 Foodweb function. It is difficult to reconcile ICES analysis of the implementation of Descriptor so far (as per ICES advice book 11.2.1.4) with ICES recommendation for a way forward. Citing the related JRC report, ICES criticize the low degree of consistency and coherence in the D4 implementation. This is the outcome of vague language in the Commission Decision. The logical conclusion would then be to propose more specific guidelines for proven methodological standards, such as those developed in the WKFooWI workshop held at ICES in March‐April and the ICES advice building on this. Unfortunately, ICES miss Relates to change of criteria ICES WKGMSFDD4-II REPORT 2015
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this opportunity in their advice for the indicator revision; it remains vague and helps little to overcome current issues with consistency and coherence of implementations. 21 UK Andrew Scarsbrook The criteria should be applied to trophic guilds, not taxonomic groups. An indicative list of guilds is provided. The categorization of foodwebs using taxonomy should be removed from the decision. In their advice, ICES insist that any taxonomic grouping used to define indicators for D4 should be replaced by groupings by trophic guild (defined though food type or feeding mode), without providing any clear rationale. It is well known among foodweb experts (e.g. Rossberg et al., Journal of Theoretical Biology, 241, 2006:552—563. Naisbit, et al. Proceedings of the Royal Society B, 279, 2012:3291—3297) that taxonomy is closely related to the roles species play in foodwebs as prey, although it is only loosely related their roles are predators. Therefore, taxonomic groupings can make good sense for foodweb indicators. By ICES proposal to work with trophic guilds and the indicative list for guilds they provide, foodweb indicators would group basking sharks into the same guild as mussels (both are “filter‐
feeders”), and many seabirds into the same group as marine mammals and most large fish, as far as these are “pelagic piscivores”. There is a high risk that indicators based on such groupings would be difficult to define, to interpret and to manage. Other issues with the proposal are that, upon closer inspection, trophic guilds are not sharply defined and many species run through several trophic guilds during different life stages (all of which are equally important for the survival of the species). Relates to trophic guilds 22 UK Andrew Scarsbrook Of the minimum requirement of three trophic guilds per region, a maximum of one should be an exclusive fish guild. There is no sensible way of restricting all fish to a single trophic guild and still have something than makes any sense in foodweb terms! The theory of size structured foodwebs when applied to fish only should be sufficient to suggest that this is non‐sensical. Fish operate at different trophic levels as they increase in size, and within marine foodwebs fish perform many quite different trophic functions. The ERSEM model for example uses four fish guilds demersal piscivores and benthivores, and pelagic piscivores and planktivores. The ERSEM model would not produce meaningful output with fewer fishi guilds. I would argue that in order to comfortably assign all fish in the North Sea to trophic functional guilds, a fifth guild, demersal planktivores, is actually required. Relates to trophic guilds 23 UK Andrew Scarsbrook The criterion 4.1 Foodweb structure should be subdivided into biomass of guilds over time and size structure within those guilds. There is more to foodweb function than productivity (e.g. the ability of foodwebs to regulate abundances along the food chain [oceans without zooplankton would be green] or their role of harbouring biodiversity [species richness is coupled across trophic levels, see e.g. Warren and Gaston, Phil Trans R Soc London B, 338, 1992:113‐210, Rossberg, “Foodwebs and Biodiversity”, Wiley 2013]), and more to foodweb structure than abundance and size structure within groups (e.g. a balance between benthivorous fish and benthic food available to them). WKFooWI acknowledged these complications, noting that they often cut across Descriptors, and recommended that these cross‐cutting issues are identified and addressed by the appropriate Descriptors. These insights and recommendations were not taken up by ICES in their advice for the D4 revision. Relates to knowledge and understanding, future developments 44 |
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24 UK Andrew Scarsbrook GES can only be considered if 4.1 and 4.2 are within the GES boundaries. This is key to development of the foodweb indicators. With changing climate it will become increasingly difficult to set specific targets representing GES. Particularly for foodwebs, if we see trophic guild biomass indicators heading off into regions that have never been seen before, either higher or lower than previously observed, this should be cause for concern, and from a precautionary perspective, we should ensure that human activity is not the cause of such a trend. Relates to boundaries and GEF definition, and use of surveillance indicators 25 UK Andrew Scarsbrook ʺUsually environmental influence has a high impact on foodweb structure and function. Current scientific understanding is such that anthropogenic pressure is difficult to distinguish from the environmentally influenced variability.[..] In the absence of strong indicators reflecting pressure‐state relationships, the indicators of D4 should be treated as surveillance indicators (monitoring change in the foodweb across the minimum three guilds).ʺ
In their advice, ICES reiterate that, based on their scientific understanding, anthropogenic pressures are difficult to distinguish from the environmentally influenced variability. It is hard to reconcile this finding with the role ICES plays in fisheries management. The scientific literature describes for several aspects of foodweb structure how these are affected by anthropogenic pressures. What ICES might have meant to say when negating existence of human‐attributable change in foodwebs is that, for many conceivable foodweb indicators, indicator values fluctuate widely and these fluctuations are difficult to attribute to causes. However, this just means that such indicators are poorly designed. They should neither be used for “surveillance”, as ICES suggest, nor for management. Another reason might be that some aspects of foodwebs simply are not vulnerable to anthropogenic pressures. Indicators properly designed to quantify vulnerable high‐level properties of foodwebs do not suffer from these problems Comment above highlighted in yellow (UK n.6) also relevant here (page 18; lines 18‐20). Relates to boundaries and GEF definition, and use of surveillance indicators 26 UK Andrew Scarsbrook ʺMethodological standards for defining GES should describe a state within prescribed bounds based on our known experience of natural variability of that foodweb’s state. Movement beyond those bounds should be seen as leaving GES, and lead to an investigation into the cause or the change in GES status and, when relevant, trigger more precautionary management.ʺ Please clarify what ‘natural’ means here. Comment above in yellow also relevant here. ICES propose that GES for D4 would correspond to indicator values within the natural range of variation. Depending on what ICES mean by “natural” , this stipulation, too, seems to be add odds with ICES role in fisheries management. More appropriate might be a recent proposal developed by the DEVOTES project (Rossberg et al., unpublished ms): GES corresponds to indicator values such that these would return to the natural range of variability within [30 year] if, hypothetically, all anthropogenic pressures removed. Relates to boundaries and GEF definition, and use of surveillance indicators 27 RSPB Euan Dunn General comment: The document faithfully reflects the outcomes of the ICES WKGMSFD D4, 26‐27 August 2014 which achieved a high level of consensus among stakeholders. Supportive Comment 28 RSPB Euan Included in elements to be taken out of the Decision and included in the guidance document is: Relates to trophic ICES WKGMSFDD4-II REPORT 2015
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• ʺThe recommendation that not all trophic guilds in each ecosystem need to be assessed but that, by region, a minimum of at least three trophic guilds should be monitored. [...] Of the minimum requirement of three trophic guilds per region, a maximum of one should be an exclusive fish guild.ʺ • The choice of trophic guilds is expected to reflect regional differences in priorities and ecosystem dynamics. This guidance, while necessary, is not sufficiently explicit. The advice in the WKGMSFD D4 report (page 9) states that: ‘As a general rule, at least three trophic guilds should be considered [for monitoring] spanning as widely as possible from primary producers to apex predators’. The manual text should be revised to capture more precisely this guidance on selecting for monitoring a set of trophic guilds representative of the spectrum of foodwebs. guilds This guidance is also relevant to the fact that currently some Member States consider only higher trophic levels (see Criterion 4.3 Abundance/distribution of key trophic groups/species). 29 RSPB Euan Dunn Regarding the following text: ”One out, all out was considered appropriate at the criterion level. Hence, there can only be GES of D4 if both structure and function are at GES. However, the effect of the one out, all out” method within each criterion would likely be a permanent state of D4 outside GES, with management action unlikely to succeed in bringing the indicator inside GES. This might be counterproductive as the perception of an indicator which is always outside the bounds of management action will likely lead to ignoring the issues which can be addressed through management.ʺ We agree with the rationale underlying that, within each D4 criterion, the OOAO rule for GES is inappropriate. However, given that some Member States perceive that D4 is covered by D1 targets, and don’t set any D4 targets at all, then the OOAO rule should apply to D1. We appreciate that this linkage is more relevant to the Review of the GES Decision 2010/477/EU and MSFD Annex III – cross‐cutting issues but make the comparative point again here for the sake of completeness. Relates to OOAO 30 RSPB Euan Dunn Rational and technical background for proposed revision: Presumably ‘Rationale’? Text correction 31 RSPB Euan Dunn Amend to cite as 2014a and 2014b. Citation correction 46 |
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Annex 4. Review Group Technical Minutes
MSFD D 3, 4 and 6 Review Group 2‐6 March 2015 (by correspondence) Reviewers: Carl O’Brien (chair) Eugene Nixon Samuli Korpinen This review group worked by correspondence during the week indicated. Two WebEx meetings were held during the review – one on the 2nd March to agree the approach to the review, ensure that all outstanding review documentation would be made avail‐
able during the week by the ICES’ Secretariat and assign tasks to the reviewers; and the second on the 5th March to ensure consistency in approach to the reviews of the three MSFD Descriptors and agree deadlines for completion. Review introduction
In the context of the revision of the 2010 MSFD Decision, the Commission (DG‐ENV) has asked ICES to provide guidance to address the scientific interpretation of the ideas and concepts of the Decision as part of a review process. This was the second set of ‘Workshops on guidance for the review of MSFD decision (WKGMSFD II)’ for de‐
scriptors on commercial fish and shellfish (D3), food webs (D4) and seafloor integrity (D6). The workshops have contributed towards revising the existing Manuals (together with workshop reports) addressing the relevant scientific comments received from WG GES, DG ENV, MS and stakeholders and commenting on implications for MSFD cross‐
cutting issues across descriptors. The reports, revised manuals and this review will underpin the ICES’ advisory process and publication by 20th of March. The ICES’ Advice (i.e. the revised Manuals) will contribute to the MSFD WG GES meeting (22‐23 April 2015) to inform the discussion on the revision of the 2010 Decision process. ICES’ review of the Marine Strategy Framework Directive Descriptor 4 –
Foodwebs
Good Environmental Status for Descriptor 4 ‐ All elements of the marine foodwebs, to the extent that they are known, occur at normal abundance and diversity and levels capable of en‐
suring the long‐term abundance of the species and the retention of their full reproductive capac‐
ity. GES Decision‐2010‐5956 on criteria and methodological standards on good environ‐
mental status of marine waters defines three criteria for Descriptor 4: (4.1) Productivity (production per unit biomass) of key species or trophic groups; (4.2) Proportion of se‐
lected species at the top of food webs; (4.3) Abundance/distribution of key trophic groups/species. The report (ICES CM 2015\ACOM:49) from the ICES WKGMSFDD4‐II has been tech‐
nically reviewed; together with the EU_Annex_I_D4_Manual_Milieu(1) and proposed amendments. ICES WKGMSFDD4-II REPORT 2015
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The objective of the second ICES workshop on D4 was to expand on the work done in the first workshop WKMSFDD4 and reported in ICES CM 2014\ACOM:60, to respond to comments from Member States, scientists and other stakeholders on the previous version of the D4 Manual and to make additional recommendations to the D4 Manual V3 prepared after the first Workshop. A total of 31 comments were received on the previous version of the manual and these were discussed in the report and, to the extent possible, addressed in the proposed changes to the manual. The submitted comments and WKGMSFDD4‐II supported the proposal of WKMSFDD4 (2014) to replace the three criteria in the Commission Decision under De‐
scriptor 4 with two criteria: 4.1 Foodweb Structure; 4.2 Foodweb Function. For GES under Descriptor 4 to be achieved, both the structure and function of foodwebs need to be at appropriate levels. These proposals are taken as a given. The discussions and outcome of the workshop is well represented in the pro‐
posed revisions of the D4 manual. Descriptor 4 refers to the extent of knowledge regarding foodwebs and both the workshop report and the manual recognise that foodwebs are complex, not only in structure but also in function. This complexity and lack of understanding of the interaction between human pressures and the foodweb state makes selection of indicators difficult. Use of surveillance indicators: There appears to be inconsistency within the workshop report and consequently the amendments to the manual as to how surveillance indica‐
tors can be used. Section 4 of the manual states that “Current scientific understanding is such that anthropogenic pressure is difficult to unequivocally distinguish from the environmentally influenced variability. In the absence of strong indicators reflecting pressure–state relationships, the indicators of D4 should be treated as surveillance in‐
dicators” Section 5 of the manual states that ‘Food web surveillance indicators’ are defined as indicators of aspects of the structure or function of the foodweb, for which it is either not possible (through lack of evidence) to define limits based on knowledge of the system or where the link to anthropogenic pressures a weak or unclear, so direct management actions cannot be prescribed.” This seems then to be forgotten in the remainder of the manual text. It would be helpful to qualify the type of indicator (state, surveillance, pressure) being discussed much more frequently in the text. The infer‐
ence is to assign “limits” and to assess GES using surveillance indicators does not ap‐
pear to be consistent with the understanding of surveillance indicators. The WK report makes the point in section 3.4.3 that “The distinction between desirable and undesira‐
ble is not possible for surveillance indicators” this aspect needs to be much better re‐
flected in the manual. In section 5 reference is made to “Passing beyond limits of indicators must rigger ac‐
tion.” Apart from the “t” in trigger this is a strong statement if, as it seems to do, refers to surveillance indicator. This again suggests the need to differentiate very clearly be‐
tween management action that may be taken where the indicator with direct links to anthropogenic pressure (state/pressure indicators) passes beyond the limit and actions, such as further research or monitoring, that could be taken when surveillance indicator (unknown or weak links to anthropogenic pressure) passes beyond a passes beyond a some type of a warning value. Section 8 states that provides for two options. The second option of combining state and surveillance indicators and assessing together with different weighting does not seem to be a consistent use of surveillance indicators. There is useful information and 48 |
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advice here on aggregation of indicators with different levels of uncertainty but this should not include combining surveillance and state indicators into the one assess‐
ment. Clarification of text in the Manual:

Section 4 states that “If transfer is efficient there is much consumer biomass. If structure is loose there is variability in transfer.” This is unclear and needs to be explained better or possibly deleted. What is “consumer biomass”? ‐ the biomass of the consuming species or the consumed species or both? What is “loose”?‐ is it changing, dynamic, broken? 
Section 4 on Trophic guilds and foodwebs contains the text “This is most appropriately done by dividing the structure and function into compart‐
ments which share common structural or functional aspects” should this read “This is most appropriately done by dividing the foodwebs into com‐
partments which share common structural or functional aspects” 
Throughout the text “other ecosystem components” are mentioned – an ex‐
ample of what “other ecosystem components” actually refers to might help understand this point better.