Bioluminescent Glow in Chennai Beaches Linked to Water Pollution
The recent ‘blue glow’ or bioluminescent glow spotted along the beaches of South Chennai has captivated the public’s attention. However, scientists from the National Centre for Coastal Research (NCCR) have cautioned that this spectacle might not be a positive sign. It suggests declining water quality caused by pollution and other environmental factors.
What is ‘Sea Sparkle’?
The dazzling blue glow was caused by Noctiluca scintillans, commonly known as ‘sea sparkle.’ These micro-plankton exhibit bioluminescence when disturbed, creating the glowing effect seen at night. While the glow may seem magical, it indicates an ecological imbalance.
NCCR scientists collected and studied water samples, confirming that millions of Noctiluca scintillans were responsible for the phenomenon. Though these organisms add beauty to the water, their presence often signals pollution.
Environmental Factors Supporting the Bloom
The life span of these micro-plankton can vary, typically lasting only a few hours or days, depending on factors like oxygen levels, temperature, and minerals in the water. According to a 2014 study cited by the NCCR, oxygen-depleted water rising to the surface can trigger such blooms, particularly in polluted or nutrient-rich waters.
Dr. Pravakar Mishra, a scientist at NCCR, explained that while Noctiluca scintillans are invisible to the naked eye, they can be observed under lab conditions as tiny circular structures measuring around 300 micrometres in size.
The organism thrives when rain or polluted water mixes with seawater, bringing in nutrients and minerals. Cloudy weather, temperatures between 18-27°C, and specific salinity levels create an ideal environment for these microorganisms to multiply.
Potential Dangers of Sea Sparkle
Noctiluca scintillans are mixotrophic organisms, meaning they can photosynthesise or consume smaller organisms like plankton and diatoms. When feeding, they release mucous that can potentially clog fish gills, leading to fish deaths. Additionally, as the organisms die, they release ammonia, which can be toxic and cause irritation.
Fortunately, no reports of mass fish deaths have emerged from Chennai beaches so far. Scientists believe the mucous and ammonia released by these microorganisms may dilute in the seawater under the right conditions, minimising harm for now.
