Is Sand Bar Formation a Major Threat to Mangrove Ecosystems?

Mangroves are the most fragile ecosystems in the intertidal zones of tropical and subtropical areas, supporting a rich diversity of flora and fauna on regional and global scales. Mangrove ecosystems are prone to die back owing to diverse climatic and anthropogenic effects. The present study is focused on the various climatic and anthropogenic effects experienced by the Kadalundi- Vallikkunnu community reserve mangrove (11?07?33. '76 N and 75?49'49.40 E), located in North Kerala, India. This site forms the State's first community reserve, lying very close to the Arabian Sea and being home to various migratory birds. Results of field observations and Google Earth image analysis in the above mangrove ecosystem revealed remarkable changes in the land cover, owing to the formation of sand bars, along the edges of the river mouth. The sand bar formation at the site has resulted in the massive die-back of the mangrove vegetation, especially that of Avicennia marina. Apart from these, dumping of waste materials in the site, often completely masking the mangrove vegetation also severely affected the growth of A. marina. During the summer season, owing to heavy infestation by a Lepidopteran caterpillar, the plant was found susceptible to canopy defoliation also. The findings made during the present study recall the urgent measures to be adopted from the authorities to ensure community participation for restoration of the community reserve.