In the last week of October, 58-year-old Thambi, a resident of Kadavur in Kollam, was returning from work when he found several dead fish floating on the banks of Ashtamudi lake.
At first, they thought they were the remains of fishing laced with explosives and poison, locally known as ‘Thotta’ and ‘Nanchu’, illegal practices still prevalent in many parts of the 5,700-hectare lake. Are. It was designated as a Wetland of International Importance in 2002 by the Union Ministry of Environment, Forest and Climate Change (MoEFCC) under the Ramsar Convention.
As Thambi took a closer look at the reservoir, he saw species like pearl spot and tilapia scattered around. This set off alarm bells. “I felt a sense of foreboding because it was nothing like the sporadic deaths we have seen in the last few years,” says Thambi.
By the next morning, the Kuthirkadavu area of the lake was covered with a thick carpet of dead fish, emitting a strong stench in the air. While visuals of the fish kill went viral on social media and experts rushed to collect samples, people living near the reservoir had no doubts about the cause. “They can no longer fool us with scientific nonsense because we know very well what is causing mass deaths of fish. Due to continuous discharge of waste material into the lake, its water has become poisonous,” said resident and housewife R. Girija says. Her neighbor Rajni also agrees with her sentiment and says, “Everything including septage and plastic waste ends up in the lake. If you have any doubts, check the parts where the water is so thin and the color is almost black.
According to a preliminary report presented by the Kerala University of Fisheries and Ocean Studies (KUFOS), the mass die-off was caused by algal blooms, a phenomenon caused by an excess of nutrients. Due to the spread of algae, there is lack of oxygen in the water due to which aquatic organisms suffocate. The study also found presence of streptococci and E. coli in the water, pointing to sewage pollution in Ashtamudi.
While there is continuous dumping of plastic, poultry waste and slaughterhouse waste, sewage lines from many houses also open into the lake. In July 2024, the Kerala High Court had directed the Kollam district administration to take immediate steps to remove illegal encroachments in and around the reservoir and prevent waste and effluents from polluting the Ramsar site. “Now is the time that we need to secure it Kyle Poramboke for future generations and also ensure free flow of water in the Ashtamudi lake,” the court had said.
A study by the Department of Aquatic Biology and Fisheries, University of Kerala has revealed alarming levels of microplastic pollution in the aquatic ecosystem of Ashtamudi Lake. The presence of microplastics was found in fish, shellfish, sediment and water samples, with the highest percentages found in macrofauna at 60.6%, fish at 19.6% and shellfish at 40.9%. While fibers, fragments and films were found to be MP (microplastic) types, the study also identified the presence of several types of polymers, including nylon and polypropylene.
Dead fish floating on Ashtamudi lake in Kadavur, Kollam. , Photo Courtesy: Sureshkumar C
The analysis found five polymers from shellfish, five from fish gut, four in sediment and four in water samples. According to the study, the existence of these plastic polymers and heavy metals, including barium and iron, in the samples pose a threat to the vulnerable biota.
“This investigation of MPs in Ashtamudi Lake highlights the sensitivity of the system to plastic pollution and the bioavailability of small MPs to aquatic organisms,” the study said. The lake shores are used as dumping grounds for municipal solid waste, a primary source of plastic pollution in the aquatic ecosystem. Major sources of microplastics in the lake include fishing and aquaculture activities, untreated sewage, unscientific solid waste management in the lake’s watersheds, and unsustainable tourism practices. The National Green Tribunal (NGT) had taken suo motu cognizance of microplastic pollution in Ashtamudi lake based on the study.
Later, the Central Pollution Control Board (CPCB) reported that water quality data at four locations in the lake did not conform to the primary water quality criteria for bathing notified under the Environment (Protection) Rules, 1986. This is a natural phenomenon but anthropogenic stresses, especially land-based activities, can significantly increase their frequency and intensity. The presence of harmful substances such as heavy metals in fish tissues can affect public health through consumption. Additionally, neurotoxins in harmful algal blooms can have effects on animal and human health. Therefore, implementing proper waste management measures and sustainable practices is integral to protect water bodies like Ashtamudi Lake and prevent future fish kills,” said A, Professor and Head of Department, Department of Aquatic Biology and Fisheries, University of Kerala. Bijukumar says.
An earlier survey conducted by the Kerala State Pollution Control Board (PCB) had indicated that the lake was under pollution stress due to indiscriminate discharge of sewage and dumping of solid waste from households and establishments. It was also revealed that several drainage drains filled with waste fall into the lake at the southern end. The survey was conducted in Kollam Corporation and gram panchayats of Perinad, West Kallada, East Kallada, Munro Thuruth, Panyam, Kundara, Thrikkaruva, Thevalakkara, Thekkumbhagam, Chavara and Neendkara.
According to the survey, 65% of residents dispose of their sewage through septic tanks and soak pits, 15% of residents use latrine pits, and 18% of residents dispose directly into the lake. Yards and houseboat operators operating illegally, those who do notNot following responsible waste management practices also increases the problem.
Following the intervention of the Environment Committee of the Kerala Legislative Assembly, panchayats around the lake borders were asked to prepare projects on a war footing to ensure proper waste management. The concerned local self-government institutions were asked to construct sewage plants to treat waste and ensure septic tanks in all houses near the lake. It was recommended to install floating septic tanks in Munro Thuruthu, a group of inland islands, with the help of modern technology and strengthen monitoring measures to prevent septage, slaughterhouse and houseboat waste from reaching the lake.
A view of Ashtamudi Lake in Kollam. , Photo Courtesy: Sureshkumar C
“Though instructions and guidelines have been issued several times, discharge of septage waste continues in many parts. Although biotoilets were approved in some houses, there are still many houses that lack proper septage management facilities,” says a senior official of the fisheries department.
While the Kollam Corporation had initiated several programs to protect the Ramsar site and restore its biodiversity, including the ambitious ‘Jeevananu Ashtamudi Jeevikanam Ashtamudi’ (Ashthamudi is life, Ashtamudi must live), they failed in the absence of consistent follow-up. All became useless. ,
“We had made allocations for removing all outlets from houses to Ashtamudi lake and providing free biodigester toilets to BPL families. Scientists say that the recent death of fish in Ashtamudi Lake is a natural phenomenon. Although the pollution levels are much lower than before, the corporation is committed to keeping the lake clean. Since the launch of ‘Jeevananu Ashtamudi Jeevikanam Ashtamudi’, 160 tonnes of plastic has been removed from the lake, of which 120 tonnes has already been handed over to Clean Kerala Company Limited. Additionally, a sewage treatment plant (STP) that can process 500 tanks of sewage waste a day has been completed, although the connecting pipelines have not been installed yet,” says Mayor Prasanna Ernest.
Meanwhile, inland fishermen, who have been at the forefront of aquatic pollution, say they have been noticing changes in the estuary ecosystem for some time. “There are about 17 canals and channels from the estuary, but right now, they are filled with sediment and debris. The lack of flow has affected the ecosystem, and many stretches require dredging. About 15 years ago, freshwater prawns from Ashtamudi contributed 12% to the total exports from the state. Now it has reduced to less than 5% while many species have become extinct. “Sediment build-up is a serious issue affecting the health of the reservoir and the livelihood of thousands of fishermen,” says Henry, a fisherman.
At the same time, fishermen in the Dalvapuram area are facing another challenge as water hyacinth is spreading in the area and making it impossible to cast their nets in areas covered with the invasive aquatic plant. “This fast-spreading plant limits our fishing area and often damages our gear,” says clam collector Babu. They say the algal blooms had a devastating impact on their livelihoods and many cage farmers also suffered huge losses.
“There was no one to buy fish for many days and even now regular customers are refusing to buy from us. Cage farmers lost thousands of fish ready for harvest in a single day,” he says.
Xavi, a fisherman from Thekkumbhagam, says the authorities are doing nothing for the long-term health of the lake. “We have seen many species disappearing from the backwaters and the size of some varieties, including the Kanjirod pearl spot, which is considered the most picturesque, is shrinking. Random cleaning drives will not suffice, as we need sustained efforts,” he says.
While fishermen have been complaining of low yields over the years, scientific studies point to habitat degradation and increasing anthropogenic disturbances. “The septic tanks and waste water pipes of most of the houses located on the coast open towards the lake and this is no secret. Encroachments are also common and a trip through the backwaters will prove that these are not mere allegations. Look at the amount of garbage dumped next to the Kollam KSRTC stand in the heart of the city. If this continues, the lake will very soon be beyond salvation,” says Jackson Neendkara, district secretary of Matsyathozhilali Congress.
published – November 21, 2024 08:03 PM IST
