Ecological observations of major Salicornia beds from highly saline coastal wetlands of India

Abstract

Extensive Salicornia beds along the Gulf of Kutchchh (northwest) and Tamilnadu (southeast) coasts were investigated with respect to vegetative structure and ambient environmental conditions. The width of the beds varied from approximately 5 m to 1000 m depending upon the topography and tidal influence. The most extensive and healthy stands occurred in the regularly (20-50 tides month sup(-1)) inundated intertidal zones. The width of Salicornia beds in the Gulf of Kutchchh was greater than those along the Tamilnadu coast due to greater (0.83-7.2 m) tidal amplitude and flat topography. The sediments from beds of the Gulf of Kutchchh were rich (4.9-16.9% dry weight) in organic matter. The salt content in the sediments from Tamilnadu was relatively very low (0.08-0.1% dry weight) compared to sediments from the Gulf of Kutchchh (0.48-0.78% dry weight). Plant biomass, density, height, and frequency of occurrence in the more frequently inundated regions were greater than in the poorly or less frequently inundated intertidal regions. The average total biomass varied from 0.2 to 4.5 kg (dry weight) sup(-2) and was mostly comprised of aboveground components. Peak biomass values of Salicornia were observed during September to February in the Gulf of Kutchchh, while along the southeast coast, they were observed during December to March. The growth of the S. brachiata seemed to be influenced primarily by the frequency of inundation, duration of atmospheric exposure at ebb tide, rainfall, and salinity and salt content of the ambient water and sediments, respectively. Average carbon and nitrogen content in the plants were estimated to be 21.7 plus or minus 1.9% and 0.8 plus or minus 0.17% (dry weight), respectively. The carbon content increased with increasing age of the plant, while protein content decreased. Constantly increasing anthropogenic pressures on coastal wetlands warrant immediate protection of S. brachiata and other obligate halophytes, which are either threatened / vulnerable or endangered