Prelims: Current events of national and international importance | Environment & Ecology
Why in News?
Recently, a University of Kerala study revealed severe ecological decline in the Veli–Akkulam estuary due to invasive species and environmental stressors.
- It is a shallow, bar-built, seasonally closed estuary connected periodically to the Lakshadweep Sea.
- Location – Northwest of Thiruvananthapuram, Kerala, along the southwest coast of India.
- The Arabian Sea lies to the west of the lake system.
- Structure – Separated from the sea by an elongated sandbar.
- Partially divided by an embankment (bund) into –
- Veli Lake (west, near sea)
- Akkulam Lake (east, inland)
- Both are connected by a narrow channel.
- Hydrology – Inflow – Precipitation is the main inflow.
- Akkulam receives water from Kannamoola stream, while Veli receives inflow from Kulathur stream and T.S. Canal.
- Outflow and Stagnation – Outflow is episodic due to sandbar closure, with the lake mouth opening only a few times annually, causing prolonged water stagnation.
- Connectivity – Connected to Kadinamkulam and Poonthura estuaries via T.S. Canal.
- Concern – Sandbar-induced closure and water stagnation promote eutrophication, invasive species proliferation, and deterioration of water quality.
- Key Findings – Ecological Decline – Clear trajectory of ecological degradation over three decades.
- Ecosystem Shift – Transition from a moderately organised to an invasion-dominated ecosystem with invasive Species such as
- Exotic species – Mozambique tilapia (Oreochromis mossambicus), Nile tilapia (Oreochromis niloticus),
- New exotic species – Amazon suckermouth catfish (Pterygoplichthys pardalis), North African catfish (Clarias gariepinus).
- Earlier invasion by water hyacinth.
- Food Web Alteration – Restructured trophic dynamics with weakened top-down control.
- It leads to a detritus-driven system with low energy transfer efficiency and loss of native species (e.g., Karimeen) with the rise of detritivores.
- Recommendations – Adaptive wetland management includes invasive species control, native species reintroduction, wastewater treatment, ecosystem restoration and long-term monitoring.
Reference
TH | Veli–Akkulam Estuary Degradation Study
