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Biological Community in Submerged Caves and Marine Lakes in ha Long-Cat Ba Area, Vietnam



Author(s)

Nguyen Dang Ngai, Dau Van Thao, Do Cong Thung, Le Thi Thuy, Dam Duc Tien, Nguyen Van Quan and Pham Van Chien

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DOI:10.17265/1934-7391/2015.11.006

Submerged caves and marine lakes are two iconic and common ecosystems in Ha Long-Cat Ba area. However, their biological characteristics are poorly known since very limited studies have been conducted. The aim of this study was to investigate biodiversity in these ecosystems. Three submerged caves (Hang Sang, Hang Toi and Qua Bang) and three marine lakes (Dau Be, Ang Du and Qua Bang) were chosen for study. The results showed that organism communities in submerged caves were abundant with over 142 species found. The popular groups comprised sponge and soft coral which were distributed along the length of the caves. Several species with high economic value were widespread in the caves, including stone crab Myomenippe hardwickii, flower crab Portunus pelagicus, cone snails Trochus pyramis, shoemaker spinefoot Siganus sutor, snapper Lutjanus russellii. Species that permanently live in caves were not detected. In the lakes where water is well exchanged to the sea, coral reefs were found and they usually formed a narrow band around the lakes. Sandy beaches were often observed around the lakes at the depths of 0.5-2 m, containing specialty species as clam (Sanguinolaria diphos), snout otter clam (Lutraria rhychaena), sea cucumbers with high density (in Dau Be, Qua Bang). There was no coral reef in the enclosed lake (Ang Du) because of low salinity.

Karst, habitat, biodiversity, organism, environment