Species diversity in fished taxa along the southeast coast of India and the effect of the Asian Tsunami of 2004

Abstract

Based on geographic features, the Tamil Nadu coast along the southeast coast of India can be divided into three systems, namely the Coromandel Coast, Palk Bay and Gulf of Mannar. Data on landed catches of all marine species, routinely recorded on a monthly basis from a total of 352 landing centres over the period 1995–2007, were examined for differences in species composition and numbers between the three regions and, specifically, for detectable effects of the Asian Tsunami of 2004. The average taxonomic distinctness (DELTA+) measure showed that the Coromandel Coast has distinct features with regard to taxonomic structure compared with the other two regions. However, neither this nor the variation in taxonomic distinctness (LAMBDA+) index were sensitive enough to reveal the effect of a natural disturbance such as the Tsunami. Simple measures of alpha, beta and gamma diversity were also not significantly different between the pre-Tsunami and post-Tsunami periods. In contrast, nonmetric multi-dimensional scaling (MDS) ordinations displayed differences in species composition among the three regions and also some change in the years after the Tsunami. The latter was confirmed by analysis of similarities (ANOSIM) tests, with the clearest and strongest effects seen on the Coromandel Coast. It is inferred that the Sri Lankan land mass on the eastern side of the Gulf of Mannar and Palk Bay may have offered these regions a degree of protection from the Tsunami waves.