THE POLYCHAETE CRYPTOFAUNA FROM COZUMEL ISLAND, MEXICAN CARIBBEAN
Ochoa Rivera, V.; Granados Barba, A. & Solís-Weiss, V.
Laboratorio de Ecologia Costera, Instituto de Ciencias del Mar y Limnología, Circuito Exterior, s/n, Ciudad Universitaria, Apdo. Postal 70-305. México, D.F., 04510. Mexico
In this study we analyze the polychaete cryptofauna collected in the northeastern region of the insular shelf of Cozumel, mexican Caribbean. The samples (dead coral fragments) were taken with SCUBA diving on transects perpendicular to the coastline at depths ranging from 1 to 22 m. Nineteen families, 39 genera and 42 species were identified in this area, which represent high values of diversity if comparing with other areas sampled in the extensive mexican coral reef environments in the Gulf of Mexico. The dominant family was Eunicidae, with an average density of 315 organisms/m2 (46% of the total collected), represented by Eunice cariboea, characteristic species of coral reef areas in the Gulf of Mexico and found here to represent 36% of the total collected. Syllidae, the second important family, constitute 14% of the collected specimens, with a density of 94 orgs/m2. The faunistic composition is found to be similar in all the coral reef areas so far sampled in the Gulf of Mexico, being Eunice cariboea amply represented on them; however Syllis (Typosyllis) alosae found to be dominant species in the reefs of the Gulf of Mexico is replaced by S. (T.) ortizi in Cozumel. The depth seem to be play an important role in this systems. There are lower specific richness and densities in the shallower than the deeper zones (20 species, 332 orgs/m2 versus 32 species, 500 orgs/m2 respectively). We found that in Cozumel, the polychaetes families and species densities are high, which could be related to the effect of the intensive anthropogenic influence mainly due to touristic activities relative to the other regions studied.