Spatial analysis of geophysical and environmental factors characterize distinct coral reef habitats around Sri Lanka; implications for management

Abstract

Spatial distribution patterns of coral reefs are maintained by a magnitude of chemical, physical and biological factors. Being a small continental island in the Indian Ocean, the extent of coral reef habitats around Sri Lanka has been limited and patchy showing unique, regional distribution patterns owing to these factors. However, the available data on these factors are sparse and outdated hindering proper management implications of these coral reefs. Here, we use remote sensing data on coral reefs in providing a framework to formulate hypotheses about the ecological processes governing these spatial and temporal patterns of coral reef distribution around the country. The results explained that the coral reef habitats around Sri Lanka are mostly shaped by the variation in nutrient levels (phosphate, nitrate and silicate), annual variance in sea surface salinity, mean current velocity and bathymetric shape. The study identified four unique coral reef areas around the island owing to variations of these factors; east coast reefs, south coast reefs, west coast reefs and north/northwestern reefs around Jaffna peninsula and Gulf of Mannar. The predicted Maximum entropy distribution models for the coral reef habitats of Sri Lanka revealed a significant amount of coral reef cover around the island (~2739 km2) which might deplete by ~4% in another 30 years due to changes in these factors. The highest amount of loss will be in the west coast (~17.76%) and least amount of loss will be in the east coast (~5.54%). The current research aids in understanding the reef ecology around Sri Lanka and provides implications for marine ecosystem management and conservation planning.