Fish habitat use in a Caribbean mangrove lagoon system

Abstract

One of the most important ecosystem services of mangroves is their role as fish habitat. While this function has been studied in many Caribbean Islands, Indo-West Pacific areas and lagoon systems in the Americas, studies in turbid estuarine lagoon systems in the Caribbean are scarce. We surveyed fish in the Ciénaga Grande de Santa Marta (CGSM), Colombian Caribbean, at five sites which had different mangrove and physicochemical characteristics. Three gillnets, parallel to the mangroves, were set at each site over six sampling cycles (n = 84); one in the mangrove, one further (∼250 m) from the mangrove and a third one furthest from the mangrove (∼400 m). We hypothesized that fish abundance and diversity, would be higher in mangrove habitats compared to mudflats, whereas biomass would be higher away from mangroves. Total fish abundance and juvenile fish abundance differed across habitats and sites, while fish biomass and fish diversity differed across sites, but not across habitats. While mangroves may be critical habitats for fish in the CGSM, mudflats may be of similar importance. Some sites had very high salinity values that together with other anthropogenic activities may limit the benefits of mangrove as critical habitats. The proportion of juveniles (67%) relative to adults of estuarine species is of concern. We recommend urgent implementation of management strategies that focus on maintaining freshwater inputs and mitigate the impact of fisheries the system is suffering.