Benthic assemblages in two Mediterranean caves: species diversity and coverage as a function of abiotic parameters and geographic distance
Journal of the Marine Biological Association of the United Kingdom
Benthic assemblages of two Mediterranean submarine caves were compared. Species coverage and number of species were lower in internal (dark) communities than external. This feature was specially marked in the less illuminated cave. Ordination analyses performed on species coverage per community for each cave separately, distinguished several benthic communities from the outermost to the innermost zone of each cave. Cluster analyses on species coverage, taking into account all communities in
... communities in both the caves, established similarities among communities: algal-dominated communities clustered according to the level of light received independently of the cave they inhabited, while animal-dominated communities were more similar within each cave than between the caves. Moreover, among the abiotic parameters measured irradiance was the only factor that clearly diminished from the entrance to the innermost zone in both the caves. In contrast, water movement and particulate organic matter varied di¡erently in each cave. Results indicate that the di¡erent topography, depth and geographic location of the two caves determine water movement, light penetration and nutrient availability along the caves. These factors are responsible for determining species abundance and diversity, as well as species growth habit in each community. Study sites The caves are located in the north-western Mediterranean (Iberian Peninsula): the Cabrera Archipelago (Balearic Islands, oligotrophic sea) and the Medes Islands (Catalan coast, a relatively eutrophic zone). The two caves (Figure 1 ) have in common the limestone nature of the substrate and the mainly rocky nature Figure 1. Cave morphology and location of the zones studied.