Status and monitoring the health of coral reef using multi-temporal remote sensing - a case study of Pirotan Coral Reef Island, Marine National Park, Gulf of Kachchh, Gujarat, India

Abstract

The health status for Pirotan reef (22^o 60' N, 70^o 40'E) located in the Gulf of Kachchh, India, has been assessed using health indicators. Indicators of Pirotan Reef health are temperature rise, increase in macro-algae, over-fishing, high sedimentation rate, human influences, and deposition of mud over reef. Field data was carried out on the reef to collect information about the status and to map benthic cover using the line transect method. Indian Remote Sensing Satellite LISS III sensor data of periods 1998, 2000 and 2005 were analysed to zone the eco-morphological zones of the reef into nine classes with an accuracy of 89% to 92% at 90% confidence level. NOAA AVHRR average monthly SST data was analyzed from 1998 to 2005 (March, April, May and June) to identify the effect of temperature rise on coral reef bleaching. Depositions of sand and mud have increased owing to the high sedimentation rate, sand mining and cutting of mangroves. Coral bleaching and stress have resulted in increased macro-algal growth. The Pirotan reef is under severe degradation as is apparent from the indicators of health. Integrated data of multi-temporal and spectral remote sensing data, SST and field data are important to asses the health of Pirotan coral reef. Although not all deleterious processes can be measured directly (e.g. overfishing), many environmental and ecological coral properties can be measured using remote sensing.