Octopuses were recently spotted in the serene backwaters of Kochi. The octopuses may not drag you down to the ocean depths with their long tentacles and fearsome suckers as depicted in some horror movies. But they have sent marine experts racking their brains with their unusual appearances in Kochi waters.
Scientists strongly believe that the increased salinity of the Kochi coastal waters would have invited them from the Arabian Sea. They also cautioned about the possible presence of more such organisms in the district’s waterbodies, thanks to the increased salinity in the backwaters.
Octopuses have made sudden appearances in the water bodies of Champakkara, Panangad and Kumbalanghi in the district. Fishermen have netted a few octopuses from the coastal waters. Some anglers too succeeded in getting the unusual catch. However, they continue to elude scientists who are eager to learn about them. K. Sunilkumar Muhammad, Head of the Molluscan Fisheries Division of the Central Marine Fisheries Research Institute, Kochi, said octopuses had not been reported from Kochi in the recent past. He identified one netted animal as Amphioctopus neglectus.
“The presence of the marine species in coastal waters is due to the increased salinity of the area, which would be similar to the marine environment. The level of salinity would have reached 35 ppt (parts per thousand) by now, equivalent to seawater. Sardines, another marine fish, were earlier reported from Champakkara,” said Dr. Sunilkumar.
B. Madhusoodana Kurup, the Vice-Chancellor of the Kerala University of Fisheries and Ocean Studies, Panangad, said the salinity of the Kochi backwaters could be on par with Arabian Sea these days. Strong tidal action, absence of rain and freshwater influx results in increased salinity and the environment would be transformed into one similar to the sea. Salinity is one of the crucial factors that trigger migration in aquatic animals. However the migration of octopuses was something unheard of in Kerala, Dr. Kurup said.
Mr. Sunilkumar also felt that a possible increase in the population of octopuses in sea and increased competition for food too might have forced the expedition. Such a possibility can be confirmed by conducting stomach content analysis, he said.
According to Dr. Kurup, the backwaters are excellent feeding grounds for marine organisms when compared to the sea.
Usually, the salinity variation in water between high and low tides deter marine organisms from coming to backwaters for feeding. The changed situation would invite more marine organisms hitherto unreported from here during the rest of summer months, he said.
Source:The Hindu, 7 March 2013