UC Santa Barbara

Nearshore marine habitats, such as seagrass beds and mangroves, are generally assumed to be key nurseries for many marine species. Few studies, however, have examined relationships between the characteristics of juvenile habitats and the size of adult populations, although such studies are essential for confirming and quantifying the nursery function of these habitats. In this paper I describe the results of surveys of adult populations of 2 coral reef fish species (the yellow-fin mojarra Gerres cinereus and the schoolmaster Lutjanus apodus) that are thought to be dependent on mangroves as nurseries in the Virgin Islands, Caribbean Sea, to determine if the size of nearby mangrove stands and their proximity to adult reef habitat are related to adult densities. The results indicate that these 2 factors do not affect adult fish densities on coral reef patches. However, evidence suggests that a relationship between the island-wide size of mangroves and adult fish densities and population sizes exists for at least 1 fish species at the island scale, indicating that juvenile habitat may limit adult fish numbers for some species at this scale.