The Veli-Akkulam lake.
Recent research has unveiled alarming ecological degradation in the Veli-Akkulam lake, primarily attributed to bioinvasion.
Conducted by University of Kerala researchers and presented at a prominent International Conference on Coastal Resilience in Hangzhou, China, the study highlights significant shifts in the lake’s trophic status and food web over the past thirty years.
Utilizing the Ecopath Model to examine ecological efficiency and food web dynamics, the research indicates a troubling decline in the lake’s indigenous aquatic species alongside a rise in invasive species.
Initial mapping of the ecosystem in the 1990s revealed a diverse array of native species, such as prawns, indigenous cichlids, barbs, and catfishes. However, the latest findings demonstrate a stark decrease in these populations. For instance, the biomass of prawns plummeted from 57.60 tonnes per sq km to just 0.110 t/sq. km, while indigenous cichlids fell from 41.6 tonnes per sq km to 0.350 tonnes.
Invasive Species Threat
By the 2000s, native species faced replacement by the invasive Mozambique tilapia (Oreochromis mossambicus), which has since been outpaced by the Nile tilapia (Oreochromis niloticus). The ecosystem is further challenged by additional invasive species, including the Amazonian African catfish (Clarias gariepinus) and the Amazon sailfin catfish (Pterygoplichthys pardalis).
Lead researcher Biju Kumar characterized this situation as “invasion meltdown,” where multiple non-native species not only proliferate but also intensify the adverse effects on native organisms. The presence of the invasive water hyacinth was also noted as part of the study.
Impact on Local Livelihoods
The researchers pointed out the substantial impact on the livelihoods of local fishers due to these ecological shifts. The number of fishers reliant on the lake has sharply declined from over 100 in the early 1990s to fewer than 20 today.
To combat these challenges, the study advocates for immediate implementation of ecosystem-based management and ecological restoration strategies to conserve the lake. Emphasizing the importance of controlling invasive species, the researchers propose introducing indigenous species with high ecological conversion efficiency, including benthic molluscs, cichlids, mullets, and native crustaceans, as a means to restore ecological balance.
Published – September 12, 2024 09:57 pm IST
