Do highly anthropized hydrological conditions in marshes influence fish communities according to their life‐history strategies?

AbstractAlterations of natural hydrology in aquatic ecosystems are known to strongly impact the community composition of different taxa. Surprisingly, literature on the potential influence of hydrology on fish community composition is still very scarce in agricultural marshes, where canals represent one of the few remaining aquatic habitats. This study is aimed to address this research gap by monitoring fish communities in independent hydrological units differing in hydrology management over a 6 years period. We predicted variable fish responses to the hydrological context according to different life‐history strategies (opportunistic, equilibrium, or periodic species). Periodic and opportunistic species were the most frequently observed. Despite differences in hydrology between canals (but little variation over years), we found that hydrology explained only a very low proportion of variation in the composition of fish communities. In particular, the flooding duration of meadows in early..., The study was conducted in the Marais poitevin, a ca. 1000-km2 French hypertrophic marshland located along the Atlantic coast. It has been historically divided into different hydrological units in which water management is controlled independently from the surrounding units because of different water regulations fixed by management committees. This leads to different hydrological patterns across units. We selected eleven hydrological units to represent the diversity of hydrology conditions in the study area.
Fish sampling
Each year, fish were sampled between the last week of June and the second week of July. Fish were sampled using the point abundance sampling approach (PAS; Copp and Persat, 1989; Nelva et al., 1979) with an electrofishing apparatus (Heron®, Aigrette®, or EFKO F.E.G. 8000® depending on the year, voltage during fishing operations 255±75V, amperage 7±5A). A total of 30 PAS were performed per canal, spaced out by at least 10 meters to provide independent samples. At each P...,