Impact of climate change on mangrove forests along the south west coast: A case study from Kasargod, Kerala, India

Abstract

Mangrove habitats are an important constituent of coastal wetlands. They are unique and located between sea and land, influenced by tidal and fresh water regimes, and hence are fragile in nature. The impact of sea level rise on mangrove community has been reported to be a serious issue in some of the Southeast Asian countries (Aksorakaoe and Paphavasit, 1993). Considering constant increase in global warming, the mangroves from Kasargod Taluka (Kerala, India), were evaluated for their structure, composition and likely impacts of predicted climate variation. The mangrove cover in Kerala, though sparse, is relatively better represented in the Kasargad Taluka. Patchy and fringing type of vegetation could be attributed to the microtidal nature, relatively steep topography of the coast. About -0.45 km sup(2) of mangrove area was estimated from the study region. The flora was represented by seven spp and dominated by Avicennia officinalis. The stand density varied from 276-583 nos. ha sup(-1) with relatively high (720 nos. ha sup(-1)) towards the upstream regions of kayals and backwaters. Substratum mainly composed of sand (37.7-95.9%) with rich (0.41-2.48%) organic carbon. Benthic faunal density ranged from 130-396 nos 10 cm sup(-2) and was dominated by polychaetes and nematodes. The mangrove exist approx. greater than 1 m above present low water level. Increased sea level may drastically impact mangrove habitats by altering the hydrological features and related processes. The vertical rise in the water column due to sea level rise and the limitations of landward margins may result in water logging, ultimately killing mangroves and associated fauna. The present observations and discussion below would help in the long term monitoring of the impact of climate change on mangrove habitats of India