Mangrove ecosystems are prone to die due to both anthropogenic and natural effects. The present study is a case study of how the formation of sand bars affects the natural mangrove ecosystem and becoming a threat to its rich biodiversity of flora and fauna. The Kadalundi – Vallikkunnu Community Reserve located in Kozhikode and Malappuram Districts in Kerala State is the first community reserve of Kerala, declared in 2007 which spread across 1.5 sq. km. andthis area includes Kadalundi bird sanctuary, mangroves and estuarine. These area mainly affected by numerous biotic interferences like over fishing, collection of oyster and mussels, mining of sand and lime and also retting of coconut. The formation of sand bars at the mouth of the river has resulted in the massive die back of the mangrove vegetation, especially that of Avicennia Marina which is one of the five species of mangroves found in the Kadalundi – Vallikunnu community reserve. The illegal utilization of land for coconut plantation, urbanization and dumping of urban waste near the mouth of the river had made the problem highly complicated. The present study highlights the need for urgent measures to be adopted from the authorities to ensure community participation for restoration of community reserve.