Development of a fish-based index to assess the ecological quality of transitional waters: The case of French estuaries

Abstract

The Water Framework Directive requires the assessment of the ecological status of transitional waters considering the fish component. An original methodology, based on a pressure-impact approach, was established to develop a multimetric fish-based index to characterize the ecological quality of French estuaries. An index of contamination, based on the chemical pollution affecting aquatic systems, was used as a proxy of anthropogenic pressure. The fish metric selection was based on their response to disturbances tested via statistical models (generalized linear models) taking into account sampling strategy and estuarine features. Four metrics, for which discriminating responses to level of pressure were demonstrated, were retained to constitute the estuarine multimetric fish index. This new tool appeared particularly relevant to detect the contamination effects on fish communities in estuaries. It could help managers to take decisions in order to maintain or reach the good status required by the Water Framework Directive for 2015.

Abrupt shifts in the Gironde fish community: an indicator of ecological changes in an estuarine ecosystem

“…Thus, our results support the regime-shift theory (Scheffer et al 2001, Beaugrand et al 2014. Indeed, if we consider that the state of the fish community is a good indicator of the state of the ecosystem (Karr 1981, Hughes et al 1998, Delpech et al 2010, the fact that fish−environment relationships varied from one period to another would appear to suggest the existence of contrasting ecological 'states', and thus the occurrence of true ecological AES (Beaugrand et al 2014). This leads us to assume that this succession of homogeneous but contrasting periods is evidence that one or more 'regime shift(s)' (sensu Scheffer et al 2001, deYoung et al 2008) has occurred in the Gironde estuarine ecosystem.…”

“…These relationships are defined as the 'state' or 'dynamic regime' of the ecosystem (Scheffer et al 2001). In our approach, we assume that fish community structure is a good indicator of ecosystem health and function (Karr 1981, Hughes et al 1998, Delpech et al 2010. We also consider that the fish−environment relationship is an emergent property of underlying ecological processes shaping fish communities, based on the theory of 'environmental filters' (Tonn et al 1990, Keddy 1992.…”

Transitional and coastal waters ecological status assessment: advances and challenges resulting from implementing the European Water Framework Directive

“…for phytoplankton (McQuatters-Gollop et al, 2009;HELCOM, 2010;Garmendia et al, 2011), for macroalgae Orfanidis et al, 2011;Sfriso & Facca 2011), for seagrasses (López y Royo et al, 2009), for benthos (Quintino et al, 2006;Chainho et al, 2008;Josefson et al, 2009;Borja et al, 2009a;Neto et al, 2010) and for fishes (Uriarte & Borja, 2009;Delpech et al, 2010;Cardoso et al, 2011).…”

Strength and time lag of relationships between human pressures and fish-based metrics used to assess ecological quality of estuarine systems

“…In order to detect the impact of anthropogenic pressures on estuarine fish assemblages, a measure or a proxy of the stressor is often used to point out significant relationships (Deegan et al, 1997;Meng et al, 2002;Borja et al, 2006;Breine et al, 2007; Coates et al, 2007;Martinho et al, 2008;Franco et al, 2009;Uriarte and Borja, 2009;Breine et al, 2010;Delpech et al, 2010;Cabral et al, 2012), but it does not necessarily take into account all the diversity of anthropogenic disturbances. Furthermore, Courrat et al (2009) noticed that even if processes of biological response to pressures are known, they were never demonstrated in studies proposing fish-based indices for the assessment of estuarine systems.…”