Methodology

Three spatially distinct areas in each of the 3 islands were selected to record the coral percent coverage and diversity and sampling was conducted using SCUBA on the outer reef crest using Line Intercept Transects (LIT) at depths ranging from 4 to 10m. LIT was used to calculate the percent coverage of both living and non-living benthos. Each spot (<2km2) at each island was considered as a site and two spatially distinct areas were surveyed in each spot. At each site, at least two 45 min LIT was conducted. Data suggested that 2 surveys in three different spots in each islands would be adequate for determining the abundance of the most common species within the desired precision (20%). Four transects of 20m were placed parallel to depth contour at each site. To account for intra-site variation, transects were laid in representative areas of the substrate at a distance separated by 10-30m, such that surveys were distributed over approximately 150m to 250m of each reef.

The intercepts of all underlying coral species, typology of dead and live coral (massive/submassive/branching/digitate, mushroom and foliose), soft coral, sponge, macro algae and sand were recorded to the nearest 1cm along each transect. The Project Officer examined the bottom underneath points each 25 cm along the line, giving a total of 100 possible points per transect. The percent coverage was calculated as the total number of points for each benthic category divided by 100.

Almost all studies in India on coral reefs are evaluated according to a linear scale of coral cover such that only those reefs with >75% live coral cover are considered to be in excellent condition. Reefs with 50-70% live coral are considered in ‘good’ condition; reefs with 25-50% live coral cover in ‘fair’ condition; and reefs with <25% live coral cover in poor condition (Kulkarni and Saxena, 2000). This use of coral cover to define the condition of reefs ignores the roles of disturbance, competition and stress in regulating coral species diversity (Huston 1994). Definitions and detailed descriptions of categories can be found in English et al (1997).

Click to know more:

• Project Abstract
• Oil Spillage
• Pollution
• Coral bleaching
• Highlights of the findings achieved in the project
• Detailed report of work done on the project
• Description of the study areas
• Recommendation including remedial measures
• Impacts of the work on the scientific potential of our country