Here’s why Visakhapatnam beaches are glowing a shimmering blue

Visakhapatnam beaches are glowing due to a phenomenon called bioluminescence. Marine biologists throw light on this spectacle

On a moonless night earlier this week, a group of MTech students noticed something unusual while riding along the coast of Visakhapatnam. They saw waves of blue light ebb and flow by the shore. With every wave that kissed the shore, the waters turned a shimmering neon blue like a magic guarding the secrets of the mysterious marine world.

The images and videos went viral after they were shared on social media by Visakhapatnam-based blogger Sai Kiran Suri, popularly known as Vizag Weatherman. The phenomenon, visible at night, has been attracting visitors to the beaches along Visakhapatnam, including photographers, marine researchers and Nature enthusiasts. This was more pronounced in longer patches along the shore at Bhimli, about 45 kilometres from Visakhapatnam.

So what exactly is this phenomenon? Known as bioluminescence, the glow of the waves is caused by tiny marine organisms called phytoplankton, which emit light on the ocean surface at night. It is best experienced during a moonless night.

“Bioluminescent is widespread among deep sea animals in general. Many marine creatures like sponges, jellyfish, worms, species of fish, anthropods, echinoderms and unicellular alga exhibit bioluminescence to either evade predators, attract prey or during mating. In Visakhapanam, this phenomenon is most likely the result of an algal bloom (significant accumulation) of the dinoflagellate species of noctiluca and ceratium. These emit light when disturbed by breaking waves,” says M Ram Murthy, a marine biologist. This occurs when the luciferase enzyme reacts with luciferin compound in the presence of oxygen to produce a cold light.

“Bioluminescence is widespread in lagoons and sometimes breakwaters and is particularly visible during warm weather conditions. The dinoflagellates follow a circadian cycle (24-hour cycle) and as a result this phenomenon occurs during the night which is visible in low light conditions,” says Vinod Malayilethu, associate director, marine conservation programme, WWF-India. This unique phenomenon has been visible in some other beaches in India including Havelock Island in the Andamans, Thiruvanmiyur beach in Chennai, Mattu beach in Karnataka and Bangaram Island in Lakshadweep.

According to Ram Murthy, bioluminescence is not new to Visakhapatnam and has occurred on several occasions in the past. “It was observed in small patches near Tenneti Park as well. However, what makes the recent experience different is the scale, making it a visual spectacle,” he adds.

While phytoplankton blooms that results in bioluminescence are not rare and are widely reported across coasts worldwide and in India, marine biologists say that it is a likely indication of environmental changes in seawater in the region of its occurrence. “It may not be harmful to humans. But any kind of algal bloom can affect the marine ecosystem as phytoplanktons are consumed by fish,” says Vinod and adds: “In Kerala’s Kumbalangi, the toxic red tides reported in the past were a result of harmful algal blooms and caused mass mortality of fish species. The impact of these noctiluca blooms off Visakhapatnam coast on marine species is less reported and explored and needs to be studied.”