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

The coral reefs in Con Dao waters have been recovered after the “catastrophe”. RECOVERY 7 TYPES OF MARRIES Con Dao sea area is considered to be the place with the highest marine biodiversity in Vietnam with coral reefs playing an important role. However, since 1997, the coral in Con Dao sea has developed slowly, in many places, the coral has died and bleached. Therefore, the Provincial People’s Committee “ordered” Con Dao National Park and Institute of Oceanography project “Selection of applied models of hard coral restoration in ramsar area of ​​Con Dao National Park”. Associate Professor – Dr. Vo Si Tuan, Former Director of Institute of Oceanography (Nha Trang City, Khanh Hoa Province) – project manager, said that the coral reef restoration was done in 3 areas: Dat Doc, Southwest of Hon Tai (recovered on natural bottoms) and Bai Cat (restored on artificial bottoms). Rehabilitation activities include: assessment of current conditions, removal and fixation of corals, and monitoring of survival and growth (conducted 5 turns over a 2 year period). Accordingly, there are 7 types of corals belonging to 3 varieties: Acopora, Montipora and Pocillopora selected to be restored in the waters of Con Dao. In addition, some types with beautiful shapes and colors such as Echinophyllia echinoporoides, Oxypora glabra, Echinophyllia cehinoporoides were also tested to create diverse habitats for ecotourism. In the coral restoration area on the artificial bottom, the scientists split the pieces and then fixed the corals to 150 dome-shaped concrete tanks. In areas with natural bottoms to ensure good coral growth, scientists make direct fixings on dead corals by wire or drawstring. To make sure, the group used a 35cm iron pole or 10cm steel nail mounted on the dead coral foundation as a support. Talking about the project implementation process, Associate Professor, Dr. Vo Si Tuan said that the project team of up to 20 people (including scientists from Nha Trang, Con Dao National Park staff and fishermen) is not concerned. day and night, wind waves to work both on the sea and under the ocean. In particular, the hardest thing is to bring 150 dome-shaped concrete tanks of 100x60cm size to the sea. After being manufactured in Con Dao, these 150 tanks were implemented by the team implementing the project to rent a crane to Ben Dam port. From here, it takes 25 more boat trips to transport these concrete tanks to Hon Bay Canh. Dozens of healthy fishermen were mobilized to bring the concrete tub to Cat Lon beach (Hon Bay Canh) and put it in the right position (distance from 0.5-1m). According to Mr. Tran Dinh Hue, Deputy Director of Con Dao National Park, the agency in charge of the project, said that he has accompanied the scientists of the Institute of Oceanography during 2 years of implementing the project. The project is carried out entirely on the sea, under the ocean, so it is very difficult, depends a lot on weather factors. “Sometimes, when we are implementing the work, the weather is unfavorable, the waves are strong, the wind is strong, we have to stay 10 days before we can continue to deploy”, Mr. Hue said. SIGNIFICANT IMPROVEMENT After 2 years (from October 2018 to September 2020), implementing an experimental coral restoration in Con Dao waters showed that corals have recovered well. Specifically, according to a detailed assessment of the current status of the bottom of the coral restoration area in September 2020, it shows that the amount of coral has been significantly improved through the coverage data of living corals. Accordingly, in Bai Cat Lon area, the coverage of hard corals varies from 0-13.1%. Hon Tai area The coverage of hard corals increased from 3.8% to 13.1%. Similarly for the Dat Doc area the coverage of hard corals increased from 0.6% to 10%. Thus, after 2 years of restoring corals, coverage of average hard corals at the three recovery points increased from 1.5 to 12% with the number of more than 4,400 coral groups restored on the natural bottom and 1,600 coral groups have been restored on the man-made reef. Mr. Nguyen Cong Danh, Director of the Department of Science and Technology, said the project “Selecting an application model for recovery of hard corals in the ramsar area of ​​Con Dao National Park” is an experimental project of great significance to the province and country. In particular, coral rehabilitation and development for the Con Dao ramsar area has achieved the main goal of improving coral reefs by increasing coral cover, increasing the cost of sustainable attachment for corals. restore and create a stable environment for the development of the coral reef biomes. From there, contributing to biodiversity conservation and restoration of natural resources, improving the quality of the ecosystem.