A dead wetland forest in Ben Tre province (Source: VNA) Hanoi (VNA) – The loss and degradation of wetland areas are occurring more rapidlythan in any other ecosystem due to large-scale land use changes, infrastructuredevelopment, altered water flow, and the impact of climate change.
The shrinking of naturalwetlands and their ecosystems has accelerated over recent years, said Assoc.Prof., PhD. Nguyen Thu Ha from the Hanoi University of Science at the VietnamNational University (VNU-HUS), citing the decline in sea grass as a keyexample. About 40-50 percent of Vietnam’s sea grass meadows have been destroyeddue to human activities – such as marine navigation, destructive fishing,tourism, and aquaculture – she said, adding that natural disasters, unusualwater flow, and increased sediment loads along rivers during rainy season posea further threat to the national sea grass coverage.
Over the last fiveyears, 30 percent of sea grass coverage in waters off the coast of Khanh Hoa havebeen lost, while sea grass meadows along the shores of Quang Ninh and Hai Phonghave completely disappeared as a consequence of human development projects, Hanoted.
A survey of more than200 near-shore coral reefs conducted by the Institute of Oceanography in NhaTrang shows that coral cover, which measures the proportion of reef surfacecovered by live stony coral instead of sponges or algae, is in alarming declinewith only 1 percent of coral reefs recorded with high cover, while reefs withlow coral cover account for up to 31 percent. Extensive use of explosives andpoisonous chemicals like cyanide to catch fish has played a large part in theloss of many coral reefs off the islands of Co To, Bach Long Vi, and Con Dao.
Other experts alsovoiced great concern over changing hydrological conditions of wetlands causedby mass water discharge for irrigation projects, land reclamation, andexploitation of groundwater. When the water level drops, trees and plants diebecause they are deprived of their life-sustaining supplies, resulting inbiodiversity loss in freshwater and saline wetlands and brackish marshes. Atthe same time, these human activities have also led to expanded saline waterintrusion into farming lands.
Pollution in wetlandsis another growing concern. Drainage and runoff from fertilised crops andpesticides in agriculture, pollutants from aquaculture, discharge of industrialwaste, and the overexploitation of natural resources are among the main reasonsbehind the draining of wetlands.
According to a reportby the Ministry of Environment and Natural Resources, export processing zonesand industrial parks in the southern localities dispose of over 111,600 cu.m ofwastewater – including 15 tonnes of suspended solids, 20 tonnes of BOD5, 1.6tonnes of nitrogen, and 500 kg of phosphorus – into the Dong Nai and Sai Gon riverseach day. The amount of lindane in river-bed sediment in the basin of the tworivers reached around 6-32ug per kg. In the Red River Delta where pesticidesare widely used in agriculture, the level of residual pesticides detected inthe Red River estuaries during rainy season was often 23-28 times higher thanthe accepted limit.
This caused numerousmass fish die-offs along coastal areas and rivers in recent years, costing tensof billions of VND to farmers each year.
At the same time, alarge area of natural forest, particularly mangrove forests, cajuput forests,and protection forests, has been cut down to be converted for other purposes,putting further pressure on preserving the wetland ecosystem.
Climate change is alsotaking its toll. According to Prof., PhD. Truong Quang Hoc from the VNU’sCentral Institute for Natural Resources and Environmental Studies, climatechange impacts the wetland ecosystem in different ways. Increases intemperature affect the growth of temperature-sensitive plants and animals,while rainfall decline reduces the area of inundated wetlands through droughtand fuels higher greenhouse gas emissions due to the decomposition of organicmatters like peat, cited Professor Hoc as an example.
In addition, therelease of toxic chemicals into the ocean triggers a phenomenon called “redtide”, caused by algal blooms that are harmful to wildlife in the wetlands. Thephenomenon often occurs along the shores of Binh Thuan, Khanh Hoa, and othercentral provinces, resulting in large fish die-offs and negatively affectingthe environment and tourism.
However, most of theseprovinces face shortages in funding for projects to preserve and manage thewetlands and as such, very little action has been taken to ensure the long-termmonitoring, data collection, and assessment of wetland biodiversity. –VNA
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