Mangroves are one of the most productive estuarine habitats. They are known to play an important role in fish nurseries throughout the world. With the high abundance of food and refuge from predation, mangroves are a suitable habitat for many fish species that spend all or part of their life cycle there. Mangroves in French Guiana are relatively well preserved but vulnerable to the increasing anthropogenic impact and global changes. Human activities such as urbanization, deforestation, mining and pollution are increasing in French Guiana mostly due to a fast-growing human population that has nearly doubled in 20 years. Despite the high socio-economic importance of the fishery species associated to mangroves, very little is still known about the nursery role of the different near-shore habitats in French Guiana. This study aims to investigate habitat preference as well as community assemblages and the effect of anthropogenic pressure on early life stages of fish.

Fish larvae and juveniles were collected during the dry and the wet season in the estuarine channels, mangroves habitats and in the adjacent shallow coastal areas (a total of 11 sites). Sampling was performed with different gears depending on the habitat type (plankton nets, bongo nets, epibenthic sleds and fyke nets). Physico-chemical parameters, organic matter content, heavy metals, chlorophyll a and nutrients concentrations were measured at each site and season.

Results shows that diversity and abundance of early life stages of fish varied significantly between sites. Four families (Engraulidae, Gobiidae, Sciaenidae and Clupeidae) were predominant in the community and represented almost 90% of the total abundance. Fish juveniles’ presence and diversity was linked to the environmental characteristics of the site suggesting that the nursery ground value is strongly dependent on the environmental factors. The results of this study can therefore constitute the bases for the development of an integrated ecosystem-based management plan.