Bathymetric distribution and co-occurrence of the gorgonians Eunicella cavolini and Paramuricea clavata in the Gulf of Naples (Italy, Mediterranean Sea)
摘要
Understanding the spatial distribution and ecological relationships of habitat-forming gorgonians is crucial for assessing the biodiversity and conservation status of Mediterranean coralligenous assemblages. This study investigates the distribution and co-occurrence patterns of the yellow gorgonian Eunicella cavolini and the red gorgonian Paramuricea clavata along the Gulf of Naples (Tyrrhenian Sea, Italy). Remotely operated vehicle surveys were conducted in 2018, 2021, and 2024 at depths between 30 and 100 m across 6 sites around Capri Island and Punta Campanella Peninsula. Bathymetric distribution, density and size of the colonies were analysed. Spatial differences were observed among sites, whereas no significant temporal differences were detected among years. The populations of E. cavolini exhibited a wider bathymetric distribution (30–100 m), while the P. clavata ones were mainly confined to deeper and more stable environments (> 50 m). The densities of E. cavolini were also higher (from 93 ± 29 colonies/100m2 in 2018 to 105 ± 32 colonies/100m2 in 2024) than P. clavata (from 47 ± 23 colonies/100m2 in 2018 to 76 ± 46 colonies/100m2 in 2024). The colony sizes of E. cavolini were smaller (22–25 cm) compared to the larger P. clavata (28–35 cm). Both species exhibited medium-to-small colony sizes compared to other studies, suggesting recent recruitment. Positive correlation between densities of these two species suggests shared environmental preferences and potential facilitative interactions rather than competitive exclusion, possibly indicating that their co-occurrence can have a stabilizing effect on the community structure, increasing habitat structural complexity and resistance to environmental stress. These results highlight the ecological importance of gorgonian forests in enhancing three-dimensionality and biodiversity of coralligenous habitats.