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Study on Wetland Decline
Context:
A study conducted by researchers in Kerala between 2010 and 2019 found a significant decline in the population of wading birds, such as herons and egrets, which are key indicators of wetland health.
More on News:
- The decline in wader numbers is linked to changes in primary productivity and fish stock availability within the wetlands, which have been negatively affected by long-term anthropogenic (human-driven) environmental changes.
- The researchers conducted bird counts at 27 sites along the coast of Kerala, which included estuaries, beaches, mudflats, mangroves, and agroecosystems.
Key Findings:
- Densities of all species decreased significantly from 2010 to 2019, with variations based on seasons and habitats.
Wader Species Monitored
- Great Egret (Ardea alba)
- Median Egret (Ardea intermedia)
- Little Egret (Egretta garzetta)
- Indian Pond Heron (Ardeola grayii)
- Western Reef Egret (Egretta gularis)
- Black Headed Ibis (Threskiornis melanocephalus)
- Agroecosystems and estuaries had the highest densities of species like the Little Egret and Median Egret, while mudflats had the lowest densities.
- The Western Reef Heron and Black Headed Ibis had the highest densities in beaches and agroecosystems, respectively.
- Post-monsoon seasons saw the highest densities and monsoon seasons had the lowest densities for all species.
Environmental Factors Affecting Waders:
- Environmental variables such as rainfall, organic carbon, water temperature, salinity, phosphate, and nitrate were linked to the abundance of large wading birds.
- Changes in nutrient discharge, salinity, pH, and temperature on the western coastline were noted, with significant increases in salinity, water temperature, pH, and phosphate, while organic carbon and nitrogen decreased.
- The decline in fish stocks, caused by alterations in environmental variables, contributed to the drop in wading bird populations.
Concerns and Urgency for Conservation:
- The study concludes that the decline in wader populations signals a consistent decline in the ecosystem health of wetlands in southern India.
- The researchers urge the formulation of strategies to mitigate these declines and restore ecosystem health in order to protect the biodiversity that depends on these wetlands.
