Biodiversity of the underground caves and salt lakes in Ha Long Bay

"Research on the Value of Underground Caves and Saltwater Lakes in Ha Long Bay" is a science and technology research project of the Ha Long Bay Management Board, which received provincial-level approval in October 2017. To date, the research results are gradually being applied in practice to conserve and promote the heritage value of Ha Long Bay.

The research team conducts a survey at a saltwater lake in Ha Long Bay. Photo provided by the unit.

Survey results from 30 saltwater lakes in Ha Long Bay, conducted for this research project, revealed two main types: enclosed lakes and lakes connected to the sea, varying in size from under 1 hectare to over 5 hectares. Ten underground caves were surveyed, primarily those with two entrances (connected caves) and those with one entrance (enclosed caves). Four types of habitats were identified in these underground caves and saltwater lakes: rocky-gravel beaches, sandy-muddy beaches, coral reefs, and muddy bottoms, each corresponding to a specific biological community. The study also identified 206 species of phytoplankton, 63 species of zooplankton, 23 species of fish, 34 species of seaweed, 1 species of seagrass, 41 species of sponges, 46 species of coral, and 124 species of benthic animals, many of which have economic value or are used in processing industries and medicine.

Among the aforementioned fish species, the research team discovered 5 species added to the Ha Long Bay fish catalog (2 species added to the Vietnamese marine fish catalog): Scorpaenodes minor, Scatophagus argus, Istigobius ornatus, Istigobius decoratus, and Valenciennea strigata. Regarding seaweed, one new species was recorded for the northern seaweed fauna (Caulerpa verticilatata), three species endemic to Ha Long Bay (Gracilaria sp., Enteromorpha sp., and Ulva sp.), and one new species recorded for the Vietnamese seaweed fauna (Lomentaria corallicola Boerg). No groups of species living exclusively in the underwater caves and saltwater lakes in the bay were detected.

Coral reefs live in a lake in Ha Long Bay. Photo provided by the source.

Based on the research results on biodiversity value in underground caves and saltwater lakes, the group continues to propose new scientific studies to further clarify the biodiversity value at several important sites. For example, in Ba Ham 1 Lake, a specimen of the spotted eel, a newly recorded species, has been collected; the tissue sample has been sent to Japan for scientific identification. In Bo Hung 1 Lake, there are various species of plate-shaped and columnar corals, as well as various species of seaweed such as Gracilaria, Sargassum, and Fan-shaped seaweed. Similarly, in Ca Hong Lagoon, the seagrass species Ruppia maritima, which is now very rare in Ha Long Bay, has appeared. Simultaneously, it is possible to develop environmental education programs and biodiversity conservation initiatives in Ha Long Bay at several locations with high biodiversity value, such as: Hang So Lake, Chan Voi Lake, Ba Hang Cave, Bu Xam Lagoon, and Du Lagoon…

From the surveys and research, the project team discovered saltwater lakes and underground caves with unique landscape and biodiversity characteristics that can be used for tourism development. Therefore, the team proposed investing in infrastructure and creating new tourism products for Ba Ham, Ang Du, and Ang Ca Hong lakes with services such as: mountain climbing, sightseeing, relaxing fishing in the saltwater lakes, kayaking to explore the underground caves, etc. It is also possible to invest in building attractions for visiting the underground caves and saltwater lakes. Specifically, Ba Hang cave could be visited by small boat or kayak. Hang So and Chan Voi lakes could offer mountain climbing, sightseeing, and exploration of the vegetation. Hang Chay could offer visits to the underground caves by small boat or kayak. The lakes of Bu Xam, Cong Do, Ca Ro, Tra San, Bo Hung, Vung Ha, the caves of Trai, Coc Cheo, the lake of Ang Hang Thay, and Island 289 offer services such as mountain climbing, sightseeing, exploring natural vegetation, and organizing educational classes on protecting natural resources and the environment.

However, the research team also recommended caution, selecting appropriate forms of tourism to avoid damaging the landscape and ecosystem of the lakes and caves in Ha Long Bay.

Source: https://baoquangninh.vn/da-dang-sinh-hoc-cac-hang-ngam-va-ho-nuoc-man-tren-vinh-ha-long-2439543.html