Impact of shrimp farming on the soil characteristics of Vellar Coleroon estuary complex, Tamil Nadu.

Abstract

Assessment of changes in soil caharacteristics in and around shrimp farms will be helpful to evaluate the impact of aquaculture on the surrounding environment. Satellite data of IRS-IC, LISS III of 2003 were used to estimate the area extent and spatial distribution of aquaculture farms in the Vellar Coleroon estuary complex based on satellite image processing softwares such as ERDAS Image and ARC VIEW. Sampling stations were fixed based on the spatial distribution of aquaculture farms using GlobalPositioning system (GPS). Soil samples were collected in and around the farms at various depths and analyzed. Electrical conductivity which varied from 5.75 to 5.81 ds/m before and during the culture period respectively, indicated the increase in salinity by 46-58% in shrimp ponds. Soil salinity decreased as the distance from the farm increased up to 100m. Soil ph (7.85 to 8.37) and organic carbon (0.88 to 1.46%) registered higher values in the shrimp ponds, than surroundings. Shrimp culture did not influence porosity, water retention capacity and texture. There was no significant difference in soil properties of the surrounding environment before and during culture. Surface soil had higher PH, electrical conductivity, organic carbon and porosity than the sub surface oil. The water reaction capacity and clay content increased with the depth of soil. The present study has shown that the development of aquaculture in Vellar Coleroon estuary did not have any adverse impact on the soil quality of the nearby environment.