Fish assemblages in a mangrove shoreline lagoon of Guadeloupe (FWI): spatial and temporal distribution patterns along environmental gradients
Mangroves are recognized as important habitats for fish communities and serve as nurseries, feeding grounds or shelters. However, several studies have reported a worldwide regression of mangrove extent due to coastal management, land reclamation and wood cutting. Studies of fish assemblage patterns in mangroves are needed in order to understand the processes structuring fish communities and to evaluate the influence of environmental or anthropogenic changes on these distributions. Fish were collected with nets in 32 stations in the mangrove shoreline lagoon of the Grand Cul-de-Sac Marin (Guadeloupe, Lesser Antilles) during dry and wet seasons. A set of 21 environmental descriptors was recorded in each mangrove site in order to identify and explain spatial and temporal patterns of fish assemblages. A total of 106 fish species belonging to 44 families were recorded. Canonical analyses and classifications revealed the presence of four fish assemblages distributed along a gradient oriented from the coastal mangrove seawards. This environmental gradient was related to several variables, such as coral reef or river proximities, water transparency and salinity. It opposed fish communities dominated by either mangrove or coral reef fish species. Variation partitioning showed that physical, chemical and geographical descriptors were the most important variables, but thus accounted for only 29.6% of mangrove fish abundance variation. Considering trophic categories, second order carnivorous and omnivorous fishes dominated in biomass in river mouth stations, whereas first order carnivorous and piscivorous species dominated in mangrove areas close to coral reefs and seagrass beds. These differences in the structure of trophic categories among mangrove shoreline habitats suggest that food availability plays an important role in the structure of the mangrove fish communities, in addition to abiotic factors and the presence of neighbouring habitats, such as coral reefs or seagrass beds.