Dependence of Caribbean reef fishes on mangroves and seagrass beds as nursery habitats: a comparison of fish faunas between bays with and without mangroves/seagrass beds

Abstract

Mangroves and seagrass beds are considered important nursery habitats for coral reef fish species in the Caribbean, but it is not known to what degree the fish depend on these habitats.The fish fauna of 11 different inland bays of the Caribbean island of Curaçao were compared; the bays contain 4 different habitat types: seagrass beds in bays containing mangroves, seagrass beds in bays lacking mangroves, mud flats in bays containing mangroves and seagrass beds, and mud flats in bays completely lacking mangroves and seagrass beds.Principal component analysis showed a high similarity of fish fauna among bays belonging to each of the 4 habitat types, despite some differences in habitat variables and human influence between bays.Juveniles of nursery species -fish species using mangroves and seagrass beds as juvenile nurseries before taking up residence on reefs -showed highest abundance and species richness on the seagrass beds, and on the mud flats near mangroves and seagrass beds, but were almost absent from bays containing only mud flats.The high abundance and species richness on the mud flats near nursery habitats can be explained by fishes migrating from the adjacent mangroves/seagrass beds to the mud flats.Seagrass beds near to mangroves showed a higher richness of nursery species than did seagrass beds alone, suggesting an interaction with the mangroves resulting in an enhancement of species richness.Comparison of fish densities from the 4 different habitat types indicates that for the nursery species the degree of dependence on a combination of mangroves and seagrass beds as nurseries for juvenile fish is high for Ocyurus chrysurus and Scarus iserti, the dependence on seagrass beds is high for Haemulon parrai, H. sciurus, Lutjanus apodus, L. griseus, Sparisoma chrysopterum and Sphyraena barracuda, and the dependence on mud flats near mangroves/seagrass beds is high for L. analis.The dependence on mangroves and/or seagrass beds is low for Chaetodon capistratus, Gerres cinereus, H. flavolineatum and L. mahogoni, which can also use alternative nursery habitats.