Demersal zooplankton communities from tropical habitats in the southwestern Atlantic

Demersal zooplankton were captured with traps from a set of tropical coastal habitats (seagrass bed, coral reef, gravel, and sand bottoms) to allow comparisons among communities. Sampling was carried out during dry and rainy seasons in 2000 and 2001. Traps with and without light were placed at 18:00 and removed at 06:00 the next day for three consecutive days. Eighty-eight zooplankton taxa were identified. Copepoda was the most abundant group, outranking in relative abundance in seagrass and in sandy bottoms. Copepoda was mainly represented by Oithona oculata, Pseudodiaptomus acutus, and Acartia lilljeborgi. No significant differences were found among substrates (P=0.1464); however, differences were significant between light and dark traps communities (P=0.0410). The average density was 7113 (+/- 3966) ind m-2 in the light and 4759 (+/- 4825) ind m-2 in the dark. In the light traps, Amphipoda and O. oculata were more representative. Without light, the main group was Foraminifera (40%). Cluster analysis presented two main groups, Itamaraca Island and Tamandare Bay; light and dark traps formed separate groups within these location groups. The results allow us to assess the efficiency of the used traps in a set of habitats of the tropical coastal area and gives information on the preference of specific organism groups in one of the tested substrates.