Algal Blooms...

There was a sudden green algal blooms at Padubidri (13.1384° N, 74.7708° E) and Kaup (13.2316° N, 74.7425° E) along Karnataka coast during first week of January 2019. Algal blooms are natural phenomenon in the marine ecosystems. Accumulation of nutrients due to currents, sudden influx of high amount of potash, nitrogen and phosphorous compounds support the growth of cyanobacteria. Any one or two species of the plankton of that region will dominate in the population. when their density goes beyond 10000/ml, the water changes its tint. When the density goes beyond 1 lakh cell/ml, the water looks green/red depending on the dominating species. All the nutrients will be used up soon and the algae start dying after a week. Their lifespan is 15-21 days. The bloom subsides if there is no further influx of nutrients. Or they get distributed and diluted with time.

            When I met Mr Pradeep, fishermen at Padubidri on 9 Dec, they said that water was oily, reflecting like a glass in the night. Some claim that it is because of the industrial discharge. They operate a shallow water gill net for catching anchovies. They said that the number of fishes reduced from 1400 to 300 during the high algal bloom period. They said that they were consuming the fish caught in that region and there were no cases of health issues. I brought some mackerel and ate it. Nothing happened. However, it is not safe to consume the fishes form the excessive algal bloom area. Because some of the algae known to produce neurotoxins. Excessive ingestion of some algae might cause giddiness, diarrhoea, vomiting and in extreme case even death. Fortunately no such cases recorded in the region. However, scuba diver Ms Ankita said there was little hitching of skin during bloom period. I have suggested the scuba team to educate the tourists on algal blooms.

            College of Fisheries, Mangalore has collected water samples from both regions and further investigating to find out the causative agents. Fishermen are advised not to catch fish using rampani (Shore net) or gill net in the algal bloom area. People should be aware of the natural/unnatural phenomenon and the health issues relating to it.