Fish in transitional waters (workpackage 4.4)
The overall aim of this workpackage is to provide a better scientific basis for the assessment of fishes within the management of transitional waters. By combining data from across Europe in a pan-European database, which covers different types of transitional waters (estuaries, lagoons, coastal bays) and different anthropogenic pressures, we test the validity and comparability of indicators recently developed relating to structural and functional aspects of the fish communities. The workpackage will assess the responses of each indicator (e.g., diversity, abundance, mean trophic level) to environmental gradients to determine the degree of change in the environment required to obtain a change in the way we assign a quality status to a water body. The proposed predictive models for the ecology (e.g., species number, total biomass, nursery potential, etc.) will also describe underlying estuarine, lagoonal and coastal functioning related to fish assemblages. The specific objectives of workpackage 4.4 are:
- to derive, refine, validate and calibrate indices relating to structural and functional aspects of fishes in transitional waters with the ultimate goal of a multi-metric fish index applicable throughout Europe,
- to evaluate the uncertainty associated to assessment methods for fish in transitional waters and
- to propose, and where possible, test new approaches for the modelling of transitional water fish communities to be used in defining reference conditions.
In order to obtain a consistent and standardised data set, sampling using the same methods and the same field teams was carried out in 2009 along environmental gradients in the Mondego Estuary (Portugal), the Bay of Varna (Bulgaria), the Lesina Lagoon (Italy) and the Stour/Orwell estuaries (UK) (sampling sites). This exercise has shown the benefits and limitations of the field and analytical methods. The resulting field data have been incorporated with databases which include data from many countries. This has identified that while Member States produce and store data for their own purposes, this is not always comparable across countries.
Outcome and products
Workpackage 4.4 has produced a synthesis of approaches and available metrics, from both inside and outside Europe (WISER Deliverable D4.4-1), and is analysing data according to several indices and approaches (e.g., the biological health index, the Index of Biotic Integrity; AZTI's Fish Index; transitional fish classification index; Zone-specific Fish-based Estuarine Biotic Index; French Multimetric Fish Index). Altogether 16 published fish-based indices of estuarine habitat integrity were reviewed. The review study summarises common development strategies with the aim of improving fish-based monitoring tools in Europe. Most indices are computed from a number of independent fish diversity measures, presence-absence of key species and composition of functional guilds (i.e. group of fish that rely on the same quality attribute).
Relevance for end users
The workpackage will allow uncertainty analysis to quantify the probability of misclassification to be determined again giving confidence to the pan-European implementation of the Water Framework Directive. Accordingly, the level of redundancy between metrics and the level of precision and sensitivity of the indicators to changes will be determined. The synthesis and testing of metrics, the approach to standardised information, the pan-European summary and the increased confidence in approaches are needed to enhance the intercalibration process within the transitional and coastal water Geographical Intercalibration Groups.