FISH INDICATORS in COASTAL- ESTUARINE ECOSYSTEMS Main
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FISH INDICATORS IN COASTAL- ESTUARINE ECOSYSTEMS Main approaches along the French coasts Anik Brind’Amour Ifremer Nantes, EMH Jérémy Lobry Ifremer Nantes, EMH GIP Loire Estuaire 1 Introduction Indicatorof what? • Context (ex. EAF, WFD, EMS) →→ Indicators • Ecosystemic and fish-based indicators assessing – changes in exploited fish communities (ex. Rice 2003; Rochet and Trenkel 2003; Babcock et al. 2005; Clua et al. 2005; Shin et al. 2005; Methratta and Link 2006) – ecological status of ecosystems (ex. Deegan et al. 1997; Harrison and Whitfield 2004; Breine et al. 2007; Coates et al. 2007) Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, 5-7 November 2008 1 Introduction Coastal areas Global change (temperature, sea level…) Urbanization Industry Chronic or/and punctual pollutions Agriculture (heavy metals, organic compounds) Shipping Fishing www.tetes-chercheuses.fr/.../ Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, 5-7 November 2008 1 Introduction • Neither a review nor a validation • a subjective presentation of our Aim opinion based on results of several years of research in coastal areas (Demostem/STRADA) 1. Introduction 2. Case study 1. Combining indicator trends to assess ongoing changes in exploited fish Outline communities 2. Defining a multi-metric index to assess ecological status of transitional waters 3. Methodological elements 4. Discussion Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, 5-7 November 2008 2 Case study: assessing ongoing changes in exploited fish communities Time-trends approach (Adapted from Rochet et al. 2005) • Dashboard-alike approach – Set of individual metrics or indicators – Interpretation framework for combining metrics Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, 5-7 November 2008 2 Case study: assessing ongoing changes in exploited fish communities Interpretation framework (e.g. mode-based metrics) ln(N G0 ) ↑ L G0 ↔ ↓ ↑ GOOD RECRUITMENT FASTER GROWTH POOR RECRUITMENT FASTER GROWTH FASTER GROWTH More recruits of larger size Early spawning/spatial shift Early spawning/spatial shift Early spawning/spatial shift Suitable env. conditions Suitable env. conditions Suitable env. conditions ↔ GOOD RECRUITMENT POOR RECRUITMENT Early spawning/spatial shift Early spawning Suitable env. conditions Unsuitable env. conditions GOOD RECRUITMENT SLOWER GROWTH POOR RECRUITMENT ↓ SLOWER GROWTH SLOWER GROWTH Late spawning/spatial shift Less recruits of smaller size Density dependence Late spawning/spatial shift Late spawning/spatial shift Suitable env. conditions Unsuitable env. conditions Unsuitable env. conditions PotentialBrind’Amour human-induced & Lobry – EAF symposium – stress Boulogne sur Mer, 5-7 November 2008 2 Case study: assessing ongoing changes in exploited fish communities Time-trends approach (Adapted from Rochet et al. 2005) • Dashboard-alike approach – Set of individual metrics or indicators – Interpretation framework for combining metrics – Reference state based on theoretical knowledge • Assessment of directions (i.e. linear trends) desired state desirable reference state direction referenceBrind’Amour & Lobry time – EAF symposium –current Boulogne sur time Mer, 5-7 November 2008 2 Case study: assessing ongoing changes in exploited fish communities Time-trends approach (Adapted from Rochet et al. 2005) • Dashboard-alike approach – Set of individual metrics or indicators – Interpretation framework for combining metrics – Reference state based on theoretical knowledge • Assessment of directions (i.e. linear trends) – Combining the metrics: potential mechanisms • 2 by 2: population metrics • Successively: community metrics – Diagnostic according to the reference state Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, 5-7 November 2008 2 Case study: a MMI to assess ecological status of estuaries NurseryEcological function of status estuaries Anthropogenic disturbances ΣΣΣ EcologicalPressure-impact functions ?? models Step 1 – Proxy: fish metrics (beam trawl scale) Step 2 – Proxy: descriptors of contaminations Step 3 – Variability due to the sampling protocol (gear, (Courrat et al.,in press) season, salinity, depth) Step 4 – Variability due to estuarine features (estuarine size, ecoregion) Step 5 – Estimation of the nursery function of each estuary Step 6 – Link with the descriptors of contamination Impact ofBrind’Amour anthropogenic & Lobry – EAF symposium disturbances – Boulogne sur Mer, 5-7 on November ecology 2008 2 Case study: a MMI to assess ecological status of estuaries MMI results 1 score by salinity class 2 2 1 Boundary 1 classes Log(densites) 2 0 1 Loire 0 Gironde 0.0 0.5 1.0 1.5 2.00 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Oligohaline Mesohaline Euhaline Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, 5-7 November 2008 2 Case study: a MMI to assess ecological status of estuaries MMI results BMSM Seine Canch Bidas Chare Gironde Adour Somme Veys Authie Seudre Orne Loire Coues Risle e soa nte non CA 0,36 0,28 0,80 0,47 0,60 0,60 0,80 1,00 0,90 1,00 0,93 1,00 1,00 B 0,20 0,36 0,40 0,33 0,80 0,40 0,60 1,00 0,80 0,80 0,93 0,73 1,00 MJ 0,20 0,36 0,40 0,73 0,60 0,80 0,80 0,60 0,70 0,80 0,87 0,87 0,80 densitétotal 0,28 0,44 0,40 0,47 0,40 1,00 0,80 0,60 0,80 0,80 0,87 1,00 1,00 densitytotale Finalnote 0,26 0,36 0,50 0,50 0,60 0,70 0,75 0,80 0,80 0,85 0,90 0,90 0,95 finalescore Poor Good Very good Medium Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, 5-7 November 2008 3 Methodological elements Baseline Mode-based → Population → Community Hierarchical metric Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, 5-7 November 2008 3 Methodological elements Candidate metrics Case study Metric Notation Frame. MMI Mode-based indices Average length for the first mode (G0) of population i L(G0)i,t x ln-transformed population abundance for the first mode (G0) of ln(N) (G0)i,t x species i Population indices ln-transformed population abundance for species i Li,t x Biomass for species i Bi,t x Community indices Taxonomic-based indices Diversity indices (Pielou’s evenness 1) J = x H/ln(S) Taxonomic diversity and distinctness indices ∆ and ∆* x Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, 5-7 November 2008 Case study Metric Notation Frame. MMI Community indices Taxonomic-free indices (Functional indices) Total abundance in community Nt Total biomass in community Bt Total density in community DT x Number of diadromous taxa CA x Relative abundance of dependent taxa NDep x 2 Ratio of dependent taxa over independent taxa RDep/Indep x Density of marine juveniles in community MJ x Density of benthic fish in community B x Discrete measures 3 Diversity of functional traits (Simpson index) FG Simp x Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, 5-7 November 2008 3 Methodological elements Baseline Dashboard Aggregative Combining method Mode-based → Population → Community Hierarchical metric Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, 5-7 November 2008 3 Methodological elements Combining metrics 2 main methods Multimetric Index Dashboard (MMI) – Set of individual – Suggested by WFD metrics or indicators – Weighted or not – Interpretation framework – Sum or … Strong theoretical In most cases not knowledge founded on ecological arguments Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, 5-7 November 2008 3 Methodological elements Baseline Dashboard Aggregative Indirect l Combining method e v e l Direct is s ly a n Mode-based → Population → Community A Hierarchical metric Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, 5-7 November 2008 3 Methodological elements Analysing the response to pressure Indicator, ok, but indicator of what? “an obvious requirement is that the indicators respond primarily to the anthropogenic activity being managed and are sufficiently sensitive that impacts of the activity and the responses to management action are clearly demonstrable.” (Greenstreet and Rogers 2006) Direct methods Indirect methods – Statistical models – Temporal or spatial gradient/evolution Strongly depends on – Concomitant trends data and descriptors Validation ? Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, 5-7 November 2008 3 Methodological elements Baseline Dashboard CombiningAggregative method CS1 Mode-based Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, CS2 Hierarchical→ metric Population → Community Direct Indirect Analysis level 5-7 November 2008 4 Discussion Case study • Both approaches are – Relevant regarding the context and objectives – Quantitative assessment ( precision ) • Complementary results – Regarding objectives • indirectly related to fishing pressure and other potential stresses affecting the recruitment and community structure • mainly focusing on heavy metal and organic contamination • Different references – unknown initial state defined by expert knowledge – virtual reference conditions Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, 5-7 November 2008 4 Discussion Emergent characteristics • Methodological convergence points – Integration of functional aspects of fish communities (use of functional guilds) – Gradient or contrasting states of pressure (on a geographical or temporal scale) – Use of quantitative methods (statistical models) – A certain degree of empiricism, such as expert judgement. Brind’Amour & Lobry – EAF symposium – Boulogne sur Mer, 5-7 November 2008 « LES INDICATEURS EN HALIEUTIQUE : PERTINENCE ET PRÉCISION » 9ème forum halieumétrique de l’AFH 30 juin – 2 juillet 2009, Bordeaux Acknowledgements This study was partly supported by the European program