The latest research results of the Institute of Ecology and Evolution – Russian Academy of Sciences, Vietnam – Russia Tropical Center in Nha Trang and Institute of Oceanography in the journal Marine and Freshwater Research (March 2021) recorded 90% of coral in Nha Trang Bay has disappeared compared to the 1980s. In which, the current period has the strongest and alarming decline.
The coral disappears? The team led by Professor Konstantin Tkachenko and his colleagues conducted a coral survey at 10 points for about 3 years (2016 – 2019). Average coral cover decreased 64.4%, of which the strongest reduction was two corals Acropora and Montipora, which are the main components of coral reefs in Nha Trang Bay, decreased by 80, respectively. 6% and 82.3%. The level of coral degradation in the above survey points is serious. On Hon Mot island, this coral has lost completely or its coverage decreased by 4-8 times. Collecting coral samples on Nha Trang Bay. Observation results, collecting analytical samples at 20 fixed points (2013 – 2019), combining the tools of mapping reefs and analyzing GIS geographic information systems for comparison with 4 decades ago show that , the total area of rich and healthy coral reefs in Nha Trang Bay has decreased from 6.65km 2 before 1980 down to 0.74 km 2 in 2019. That shows, Nha Trang has lost 90% of its corals in less than 40 years. The remaining 10% of the coral communities are in two states: Some remain stable and some continue to decline, coverage ranges from 13 to 50% and species diversity is also significantly reduced. . According to Dr. Hoang Xuan Ben – Deputy Director of Nha Trang Institute of Oceanography, the results of recent research and publication (2015, 2017, 2019 and 2020) of the Institute of Oceanography on the current situation and trend of change The coral reefs in Nha Trang Bay Reserve also showed that the average coverage of hard corals in Nha Trang Bay was 22.8%. The cover of coral reefs in Nha Trang Bay can be divided into 3 groups: The group with high coverage is Hon Mun area reaching level 4 (coverage 51 – 75%); the average coverage group is Bai Bang, Hon Chong, Hon Vung and Hon Tam with the value of level 2 (10-30%) and the group with low coverage are the remaining points with the value of level 1 (less than 10%). . The assessment results at the fixed monitoring points in Nha Trang Bay showed that the monitoring points located in the strictly protected area all had a high value of hard coral coverage and remained stable over time from 2002 – 2015. Meanwhile, most of the monitoring points outside the strictly protected area have fluctuations in a downward trend. Compared with the results in 1994 (over 25 years), the average coverage of Nha Trang Bay corals is about 30%, the current coral coverage is 7.2%. The area of coral reefs decreased from 754ha to 636.6ha (down 117.4ha, equivalent to 13.5%). 9 species of hard corals that are resilient Dr. Hoang Xuan Ben said that the decline of coral reefs in the bay has many causes such as: Exploiting destruction by explosives, cyanide (currently no longer available); environmental pollution (tourism activities, waste discharge, aquaculture …) altering living conditions, appearing diseased corals, outbreak of coral-eating organisms (starfishes) and local eutrophication; coral bleaching phenomenon and natural disasters (storms, floods) … However, the biggest loss of coral reefs is due to the leveling process, construction of tourism infrastructure and people in the coastal and island areas. The leveling not only loses the area of the coral reef but also sends sediment into the sea, causing deposition on the reef surface, causing the coral to die. Over the past time, the Institute of Oceanography has experimented with restoring corals in Nha Trang Bay, has identified 9 recoverable hard corals with a survival rate of over 60%, the average growth rate from 0. , 4 – 6.5mm / month. This result brings certain effects, contributing to minimizing adverse impacts on coral reefs, improving reefs by increasing coral cover, increasing sustainable attachment prices for corals. To restore and create a stable environment for the development of the reef biome. However, compared with other recovery areas in Vietnamese waters such as Ly Son, Binh Dinh, and Con Dao, the survival rate of the recovered corals in Nha Trang Bay is not high. Some of the causes are identified such as: coral damage, competition between species, environmental quality changes due to indirect activities from humans and other factors such as dynamic mode, coral. wounded at the cuts. Therefore, the province needs a comprehensive assessment to have a solution to this problem. VL
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