Abstract

  The structural patterns and trophodynamics of the different fish species in the reef complex of Palancar-Chunchakaab, located in the South of Cozumel Island, Mexican Caribbean, were studied. A total of 166 species were identified for the whole reef complex. The analysis of 19,636 recorded and 2291 fish collected allowed the populations to be characterized in terms of diversity, distribution, abundance, dominant species and habitat-fish interactions. Using these parameters, three well defined reef-fish communities were described in relation to three zones: (I) Thalassia zone (THZ), (2) Lagoon (LA) and (3) Shelf-Edge Reef (SER). These communities included 64 species (39% of the total number) that were restricted to a single zone. The remaining 61% consisted of migratory species that interacted between the defined zones (interdependence of habitat): (1) THZ- LA, (2) THZ-LA-SER, and (3) LA-SER. Diversity was highest in the rainy season in SER (H' n = 3.3). Analysis of distribution and frequency of 42 of the recorded species revealed that for 25%, life cycle and THZ-SER were closely related. The remaining 75% were more associated with SER or THZ and they used these habitats for feeding, breeding and/or protection. In THZ, > 70% of the total number of species were juveniles; in LA, 40% were preadults-adults; and in SER 80% were adults. The obvious interdependence between habitats suggested a distinct use of the resources by means of migration patterns. By decreasing the order of importance, the major diet types can be ranked as follows: (I) type I carnivores, mainly active by day, preying on small organisms such as crustaceans, polychaetes, mollusks, echinoderms; (2) type II carnivores, nocturnal species consuming larger crustaceans and fish; (3) strict piscivores species; (4) herbivores species; (5) planktivores species; (6) omnivores species; and (7) sessile invertebrate browsers. With the exception of SER, 14%-44% of the type H invertebrate feeders were restricted to the three defined habitats. Of the migratory species, the large invertebrate feeders were the dominant group (21%-41%). The present study suggests that the variation of species diversity patterns and trophic structure are associated with sequential habitat use according to the life cycle. This type of study allowed us to compare the diversity and trophic community of reef fish of the same system and to recognize the energetic interdependence that exists between the habitats. © 1999 Elsevier Science Ltd and AEHMS. All rights reserved.

Keywords: Diversity; Trophic levels; Fish assemblages: Migration patterns