The spatial-temporal variability and stability of Vietnamese reef communities

Abstract

During expeditions in 2010 and 2013 on the R/V Akademik Oparin the individual coral reefs of Vietnam, whose species compositions and structures of benthic communities were first studied and described in the 1980s, were surveyed. The current state of the coral reefs was studied, significant changes in the abun dances of certain hydrobionts were considered, and possible causes of these changes were discussed. It was determined that the general geomorphological zoning of the reefs, species composition, and the structure of the coral communities of the Con Dao, Lý Són (Cú Lao Ré), and Thu islands have not changed significantly. However, negative changes have occurred in reefs of the Namsu (Gulf of Thailand) and Hon Mieu (Nha Trang Bay) islands as a result of increasing anthropogenic impacts. In reefs of the Cu Lao Cham and Tho Chau islands, which were almost completely destroyed or badly damaged by powerful typhoons in 2006 and 2009, signs of gradual recovery of the surviving coral and the formation of new coral populations were recorded.

Sponges and Their Microbiomes Show Similar Community Metrics Across Impacted and Well-Preserved Reefs

“…Nha Trang bay is located in central Vietnam and harbors one of the highest coral diversities in the area (Latypov, 2011). Unfortunately, the health of the local ecosystems is being threatened by an increase of human activities leading to an alarming degradation of the bay in some zones (Latypov, 2015). The islands located closer to the city and the port of Nha Trang show a higher degree of anthropogenic impact, with higher sedimentation fluxes and lower water transparency compared to the ones located farther from the coast line (Latypov, 2006; Tkachenko et al, 2016).…”

Results of Thirty Years of Research on Corals and Reefs of Vietnam

“…Central Vietnam and Gulf of Tonkin and Gulf of Siam reefs have some special aspects. Due to the excessive eutrophication and shallowness in these regions branchy Acropora and encrusted Montipora were substituted for massive Porites and various alcyonarian in some reefs, they became predominant [23]- [35].…”

“…All drugs and chemicals from aquaculture floats and ground of construction process are streamed. One-time prosperous reef in the south and south-east practically had been dying during last 5 years, and now its population is only about macrophytes spots and some dozens of declining reef colonies [26] [32] [35] [43]. Widening of living communities and daily seafood harvesting with up-to-date techniques happen in the island along coast of Gulf of Siam.…”

“…At the same time reefs guarded by reservation conditions and located 10 -20 kilometers far from Nha Trang city and port are in the optimal conditions even with daily tourist excursions (Mun Island) and dozens of divers among them. Also reefs located in inaccessible places due to their farness (Bach Long Vi, Spartly islands) or complete defense lands (east reefs of Con Dao islands, Figure 3(b)) are in almost perfect condition of both corals and reef communities in whole [31] [35].…”

“…Since the beginning of this century all reef-building zones of Vietnam from north line of Gulf of Tonkin to south line of Gulf of Siam and Spartly islands in the South China Sea (their country affiliation is still a disputable theme) including all any large islands and banks were investigated [21]- [38]. All types of reefs and more than 350 species of reef-building corals were monographic ally described; their field guides were published [26] [29] [33] [35]. The demand arose for summarizing all volume of information received about the coral composition and classification, specifics about reef formation in Vietnam and their connection with Indo-Pacific reef ecosystem.…”