Yu. Ya. Latypov

Reef-Building Corals of Vietnam as a Part of the Indo-Pacific Reef Ecosystem

The paper analyzes both published and unpublished results of the investigations of Vietnamese reef-building corals and reefs performed in the last decades of the twentieth century. The state of the art in the study of reef-building scleractinian corals and reefs is presented. The scleractinian fauna of Vietnam is shown to match in species diversity (366 species of 70 genera) the tropical coral fauna of the Indonesian-Malacca fertile center, from which Indo-Pacific reef-building corals originated. The whole Vietnam coast from the Gulf of Tonkin to the Gulf of Siam is a biogeographically single whole and is a part of the Indo-Polynesian Province of the Indo-Pacific Area.

Changes in the composition and structure of coral communities of Mju and Moon islands, Nha Trang Bay, South China Sea

In October 2003 and January 2005, comparative observations were made on the reefs of Mju and Moon islands near the city and port of Nha Trang, which we first investigated in 1981. Appreciable changes due to anthropogenic impact have occurred on the reefs that are the nearest to the city. There was a reduction in substrate cover by reef-building corals, a substitution of dominant scleractinian species, and a decrease in the numbers and diversity of common species of corallobionts. The index of species diversity for scleractinians also decreased. The seaweeds Chnoospora and Halimeda spread into all zones of the reefs. Changes in coral communities on more distant and protected reefs were not so marked.

Reef-Building Corals and Reefs of Vietnam: 1. The Gulf of Thailand

This paper deals with the history and investigations of the reefs and coral communities of the Gulf of Thailand based on published and unpublished materials, including the authors. The state of the art in the study of reef-building scleractinian corals and reefs of this region is presented. Characterized by remarkable distinctive features, the coral fauna and reefs of the Gulf of Thailand exhibit high similarity in coral species composition to other regions of Vietnam and form a single complex of species of the equatorial Indo-Pacific.

Macrobenthos communities on reefs of the An Thoi archipelago of the South China Sea

Macrobenthos communities were studied on fringing reefs of the An Thoi Islands using scuba-diving techniques. The islands are located in the turbid and highly eutrophic waters of the eastern Gulf of Siam. We studied species composition and population densities and biomasses in common species of algae, coelenterates, mollusks, and echinoderms and also the degree of substrate coverage by macrophytes and corals. A pronounced vertical zonation is revealed in the spatial succession of different macrobenthos communities. The domination of massive porites in almost all reefs of the Gulf of Siam is due to their capability to survive under conditions that are stressful for many corals. They predominate over other scleractinians in terms of the productivity of organic matter, degree of substrate coverage, and species diversity. They also constitute the reef skeleton and play a significant role in the expansion of the reef area in the muddy bottoms of the Gulf of Siam.

Species composition and structure of coral community of a platform reef at Bach Long Vi Island in the South China Sea

A platform reef at Bach Long Vi Island (Gulf of Tonkin in the South China Sea) was investigated for the first time. In all, 264 species of corals and their accompanying species of macrobenthos were found. Among the scleractinian corals, acroporids, poritids, and mussids dominated. Monospecific aggregations of alcyonarians Sinularia and Lobophytum and the hydroid Millepora were rather numerous. Based on its geomorphological characteristics, coral species diversity and zonal distribution, the investigated reef is comparable with ribbon and platform reefs on the Great Barrier Reef in Australia and in the Indian Ocean.

Current status of coral reefs of islands in the Gulf of Siam and Southern Vietnam

In 2010, an expedition of the Institute of Marine Biology on the R/V Akademik Oparin revisited and surveyed a number of coral reefs of Vietnam, whose species composition and structure had been first described a quarter of century ago. No substantial changes were found in the geomorphological structure of reefs of the Nam Su and Tho Chu islands in the Gulf of Siam and the Con Dao and Thu islands situated outside the gulf. Marked changes were found in the abundance of some species of associated macrobenthos. The current status of coral reefs is described and the causes of the observed changes are analyzed (anthropogenic influence, etc.).

Distribution pattern, population structure, and growth of Septifer bilocularis (Bivalvia: Mytilidae) on reefs of Southern Vietnam

The features of the spatial distribution, size and age structure of populations, and growth of the bivalve mollusk Septifer bilocularis (Linnaeus, 1758) were investigated for the first time in the waters of Vietnam. It is shown that in the subtidal area, on reefs well protected from wave effects, S. bilocularis occupies a corallogenous substrate constructed of dead branchy colonies of Acropora and Porites and forms settlements there with a population density and biomass exceeding those in populations located along the open coast and developing on massive coral colonies of the genera Porites, Favia, and Favites. The extensive accumulation of sediments in the inner part of Vanphong Bay (Khanh Hoa Province) correlated with a decrease in the size and age ranges for populations of S. bilocularis. It is found that in places with regularly active hydrodynamics the mollusks grew somewhat more slowly and formed a more convex shell than on reefs protected from surf. The longevity of S. bilocularis estimated both from the greatest observed age and from the growth equation of Bertalanffy was somewhat greater in the former case compared with the latter one, but in general did not exceed 11 years for both cases. The results of the studies are discussed from the position of morphophysiological adaptations of sessile bivalve mollusks to life in contrasting environmental conditions of the upper subtidal zone.

Transplantation and cultivation of fragments of coral colonies of various scleractinian species on a reef in Vietnam

Six coral species of the genus Acropora and two species of the genus Porites were studied during experiments on cultivation of reef-building scleractinian corals. The research has established species-specific factors and others affecting regeneration of fragments and growth of new colonies in these coral species. The accretion of donor fragments and new branches averaged from 40 to 160 mm per year, depending on the coral species, colony size, and season of transplantation. An average monthly accretion of medium and larger transplants and growth of new branches were 1.2–1.3 times higher at spring cultivation than at autumn transplanting. When transplanted, coral fragments of medium and larger sizes survived well and showed higher growth rates in all species studied. These transplants developed the highest number of new branches, and their buds and formed the largest colonies. Prolongation of the cultivation time from 1 to 1.5 years caused a 1.2–1.4 fold accretion of transplants.

Communities of Coral Reefs of Central Vietnam

Communities of macrobenthos on fringing reefs of central Vietnam were studied by the hydrobiological method using scuba diving. The species composition (more than 600 species), population densities of common species of the macrobenthos, and the degree of coverage of the substrate by corals and macrophytes were examined. Bottom communities classified on the basis of these data are indicative of the similarity of the investigated reefs with those of southern and northern Vietnam.

Coral communities of barrier reefs of Vietnam

The composition and spatial distribution of the coral communities of the barrier reefs of Jiang Bo and of Re Island were described in detail for the first time for Vietnamese waters. Their comparability to the ribbon reefs of the Great Barrier Reef in Australia and to the barrier reefs of the Philippines and Indian Ocean was revealed by morphological parameters, species diversity and zonal distribution. Their geomorphological status, the presence of fore reef, epi-reef and back reef complexes with their specific composition of flora and fauna, and an obligatory lagoon separating the reef from fringing inshore reefs, enabled the attribution of the surveyed reefs to the barrier type of reef.