POLYCHAETOUS ANNELIDS ASSOCIATED WITH DIFFERENT FACIES OF THE PHOTOPHILIC ALGAE COMMUNITY IN THE CHAFARINAS ARCHIPELAGO (SW MEDITERRANEAN)
Tena, J.; Capaccioni-Azzati, R.; Torres-Gavila, F. J. & García-Carrascosa, A. M.
University of Valencia, Faculty of Biological Sciences, Department of Animal Biology. Dr. Moliner 50, Burjassot (Valencia) E-46100, Spain
This study is the first of a series of papers based on the global analysis of polychaete fauna on hard bottoms at the Chafarinas Islands. In the summer (July-August 1991) and autumn (October 1994), 18 samples (25 x 25 cm) were scraped off the bottom at depths of 0-6 m in the Photophilic Algae Community by SCUBA diving. Five facies of this community were sampled: 1) Facies with Stypocaulum scoparium-Cladostephus hirsutus, 2) Facies with Padina pavonica, 3) Facies of Crustose Calcareous Rhodophytes with sea-urchins, 4) Facies with Cystoseira tamariscifolia, and 5) Facies with Corallina elongata. A total of 105 species of polychaetes belonging to 21 families was found. The dominant family in both number of species (39) and number of specimens (1040) was Syllidae. Other well represented families were Nereidae (14 species and 923 specimens) and Sabellidae (7 species and 526 specimens). Frequency values of species in this community showed a contingent of constant species including Odontosyllis ctenostoma, Sphaerosyllis hystrix, Syllis prolifera, Perinereis cultrifera, Platynereis dumerili and Amphiglena mediterranea. For each facies, the abundance of individuals, number of species, diversity and evenness were computed in order to establish different grades of structuring and variety of micro-environments. So, Photophilic Algae Community in exposed areas (facies with Cystoseira tamariscifolia and facies with Corallina elongata) showed the highest diversity (H' = 2.44). This value suggests a high degree of structural complexity, due mainly to the facies with Cystoseira tamariscifolia. The greatest diversity values of shallow Cystoseira communities in the western Mediterranean are reached in summer-autumn coinciding with our sampling period. Finally, our results are compared with data on the same kinds of facies from other locations in the western Mediterranean: Catalan coast, Strait of Gibraltar, Balearic Islands, French Mediterranean, Italian coast, and Morocco.