Biogeochemical fluxes of nutrients and carbon from vembanad lake southwest coast of India

Abstract

Coastal ecosystems play a pivotal role in marine primary newlineproductivity and encompass rich biodiversity which include mangroves salt newlinemarshes estuaries and lagoons These ecosystems provide services like newlinecoastal protection fish resources habitat linkages and medicinalgenetic newlineresources Nutrient and carbon cycling in these ecosystems is important in newlinedetermining food production climate regulation and overall stability and newlinehealth of the ecosystem In recent decades these areas have been newlinecharacterised by increasing population density and intense anthropogenic newlineactivities These in turn have enhanced the loading of nutrients carbon and newlinetrace metals and also spiked sedimentation rate in coastal ecosystems Recent newlinestudies have found that these altered environmental conditions affect the newlinenormal biogeochemical processes and the releasesequestration of nutrients newlineand carbon CO and CH newlineIn this study the focus is on understanding the fluxes of nutrients newlineand carbon in an anthropogenic stressed coastal ecosystem Vembanad Lake newlinesituated in the southwest coast of India The lake consists of two arms with newlinevarying dimensions bathymetry and drainage area Six perennial rivers join at newlinedifferent parts of the lake during its travel to the ocean and the two openings newlineto the sea makes it a complex system Since the climate regime in this region newlineis controlled by the seasonal monsoon studies were carried out over two newlineyears 2008 and 2009 and two sampling seasons a year in addition sediment newlinecores were studied to provide past information Widely tested LOICZ budget newlinemodel was used to calculate the fluxes of nutrients and carbon Further the newlinelake status was assessed using Pollution Load Index from the sediments newlineSurface water of the lake displayed spatial heterogeneity and high newlineseasonal variability for the physicochemical parameters as well as nutrients newlineIn the DIN pool nitrate was the dominant form during wet season newlinetransforming to ammonia indicated by increased ammonium levels during the newlinedry season DIP distribution showed an internal source in the lake whe