Nguyễn Đức Thế, Nguyễn Văn Quân, Phạm Văn Chiến, Đặng Đỗ Hùng Việt,
Chu Thế Cường, Lăng Văn Kẻn
Viện Tài nguyên và Môi trường biển, Viện Hàn lâm Khoa học và Công nghệ Việt Nam
Examination of about 330 quadrats on six reefs in the Cat Ba World Biosphere Reserve – Vietnam in 2013 for the presence of associated corallivorous Drupella snails revealed specific aspects in term of distribution, microhabitat use, and prey selection of Drupella. Feeding aggregations of three corallivorous gastropods, Drupella cornus, D. argariticola and D. rugosa have been found, which the D. argariticola was the outstanding abundance species. The distribution and abundance of these three species on Cat Ba reef sites were pointed out with the spatial relationships among Drupella snails and their prey corals. The significant variation in distribution and abundance of Drupella snails strongly related with water depth and live coral cover. At the reef flat (0-3m water depth), that the individual density are more than at the reef slope (3-6m water depth). Similarly, the species composition also varied markedly according to depth level. Individuals were not aggregated, usually forming small clusters (2-3 individuals) on live coral colonies and separate on death coral or other substrate. Most habitat utilization was associated with live coral colonies, especially massive coral species belonged to the genus Galaxea and Goniopora. The population dynamic of the Drupella snails highly correlate with the body size, reef structure and free open access of the fishing practices in Cat Ba islands.
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