Abiotic stress tolerance in mangroves with a special reference to salinity

Abstract

Since mangroves are found near extremely transitional ecosystems, they face a lot of physico-chemical perturbations. As mangroves possess a unique ecotone, they experience many abiotic stressors viz. salinity, metal, oil, humidity temperature, nutrient and a wide range of biotic interactions. Amongst all, salinity is the most important factor affecting mangrove physiology and biochemistry, and thereby regulating the organic matter contribution to the consumers underneath. Exploitation by human, being a dominant biotic interference, is above the rate at which natural replacement of mangrove vegetation occur. Mal-nutrition is a limiting factor in growth and reproduction of many mangroves whereas nutrient replenishment reduces the phytotoxicity of heavy metals. Different environmental pollutants including heavy metals, recalcitrant, cosmetics, petroleum oil and endocrine disrupters have reported impact on various mangroves and associated biota. Stress tolerance in mangroves involves various mechanism including morphological and anatomical features, osmoregulation, water use efficiency, salt secretion, salt exclusion and salt accumulation and molecular regulations. Various aspects of salt tolerance strategies of mangroves related to their growth, biochemical anatomy and physiology were reported by many researchers.