Fish assemblages of small estuaries of the Portuguese coast: A functional approach

The importance of estuaries for coastal environments is widely acknowledged but their role, structure and ecological status have been the focus of recent scientific efforts mainly concerning large estuarine areas. In this work we used fish assemblages to establish, for the first time, the functional and ecological role of five small estuarine systems along the Portuguese south and southwest coasts. Our results showed that, at a functional approach, fish communities did not differ between estuaries, and that all systems presented a seasonal pattern in diversity values, ecological and feeding guilds. These small estuaries contribute to the support of coastal fish populations by providing temporary habitats to the critical life stages of marine species, shelter and feeding grounds, and should be considered in an ecological and conservation perspective.

► Five small estuaries with different levels of anthropogenic pressures were studied.
► Four fish based multimetric indices were used to differentiate ecological conditions.
► The correspondence of indices results to anthropogenic pressures was examined.
► The applied indices were able to differentiate ecological conditions among systems.
► Systems with equal levels of pressure were assign with different ecological status.
► Indicators were unable to distinguish natural from anthropogenic perturbations.