Scientists investigate possible "red tide" as cause of mass fish deaths in Quang Binh

By Hoang Tao, Hoang Phuong   May 5, 2016 | 11:31 am GMT+7
Scientists investigate possible "red tide" as cause of mass fish deaths in Quang Binh
The seawater turns red. Photo by QH

Seawater along a 1.5-kilometer stretch of coast in Quang Binh province was reported to have turned red on May 4, possibly signaling a "red tide" and the reason behind the mass fish deaths that have blighted coastal provinces in recent weeks.

The strange phenomenon was first seen off the coast of Nhan Trach commune in Bo Trach district during the morning of May 4, but faded away in the afternoon, according to Phan Thanh Hien, chairman of Nhan Trach's People’s Committee. More dead fish also washed ashore in the commune, Hien said, adding that authorities are keeping an eye on the situation.

Quang Binh’s Department of Natural Resources and Environment has asked local people to avoid swimming or using water from the area until further notice. Scientists from the ministry and foreign colleagues have arrived at the site to investigate. The Institute of Oceanography in Nha Trang has also sent experts to the area to take samples of the seawater and new dead fish for analysis.

“Although I have not seen a seawater sample yet, I guess it might be the phenomenon known as "red tide", when dangerous algae bloom at an abnormal rate and produces toxins. We will have to wait for the test results before we know what exactly species of algae it is,” said Professor Nguyen Ngoc Lam from the institute, who has spent 20 years researching toxic algae. He added that seawater samples taken from Vung Ang in the central province of Ha Tinh on April 27 showed there is a presence of algae known as Heterosigma cf. akashiwo with a density of about 300 million cells per liter. “With this density, the micro-algae can kill fish and harm other aquatic creatures,” he added.

Since early April, about 70 tons of fish have washed up dead in the central coastal provinces of Ha Tinh, Quang Binh, Quang Tri and Thua Thien - Hue. On April 27, the Ministry of Natural Resources and Environment said there are two possible reasons for the mass fish deaths.

One is toxic chemicals released by human activities. The other is an abnormal natural phenomenon that causes algae in the water to bloom at an accelerated rate, commonly known as a “red tide”.