Ecological Degradation in Veli-Akkulam Lake

September 13, 2024

A recent study presented by researchers from the University of Kerala at the ECSA 60 conference in Hangzhou has uncovered a significant ecological decline in Veli-Akkulam Lake. Over the past 30 years, the lake’s ecosystem has been deeply affected by the invasion of non-native species, which has changed its trophic status (how nutrients move through the food chain) and disrupted the natural food web.

Study Overview

The researchers used the Ecopath Model to analyze how efficiently the lake’s ecosystem functions and to map the structure of its food web. The study found a major decline in native species, while invasive species (species not originally from the lake) have increased dramatically.

Historical Background

In the 1990s, a scientist named C.M. Aravindan first studied the Veli-Akkulam ecosystem. At that time, the lake was home to a rich variety of native species like prawns, cichlids, barbs, and catfish. These species helped maintain a healthy ecosystem. However, recent studies show that many of these native species have drastically declined.

Species Decline

Prawns: In the past, there were about 57.60 tonnes per square kilometer of prawns. Now, that number has dropped to just 0.110 tonnes per square kilometer.

Indigenous Cichlids: The population of native cichlids fell from 41.6 tonnes per square kilometer to 0.350 tonnes per square kilometer.

Rise of Invasive Species

By the 2000s, many native species were replaced by invasive species, which are species introduced from other regions that compete with local wildlife. Some of the main invasive species in the lake are:

Nile Tilapia (Oreochromis niloticus)
Mozambique Tilapia (Oreochromis mossambicus)

Other invasive species include the Amazon African catfish (Clarias gariepinus) and the Amazon sailfin catfish (Pterygoplichthys pardalis). These species have spread rapidly, taking over the lake and disrupting the natural balance.

Invasion Meltdown

Professor Biju Kumar described this situation as an “invasion meltdown.” This term refers to the worsening effects that happen when multiple non-native species invade an ecosystem, further damaging the local environment.

The changes in the lake’s ecosystem have had a direct impact on the people who depend on it for their livelihood. In the 1990s, over 100 local fishers relied on the lake for their income. Today, fewer than 20 remain, as the collapse of native fish populations has made it difficult for them to continue fishing.

About Veli-Akkulam Lake

Veli-Akkulam Lake is a beautiful freshwater lake in Kerala, India. It covers about 20 acres and is fed by the Veli River. The lake is known for its scenic views and is a popular spot for boating and kayaking, drawing tourists and locals alike. It connects to the Arabian Sea through a narrow channel and is home to various species, including migratory birds.

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