Contemporary and historic patterns of intraspecific diversity in Indian anchovy, Stolephorus indicus, from Indian peninsular waters.

We analyzed intraspecific diversity of Indian anchovy, Stolephorus indicus, a commercially and ecologically important species, using mitochondrial DNA markers so as to derive insights into population structuring and historical demography. Analyses were carried out on 128 and 138 individuals collected from 5 locations along the range of distribution using mitochondrial ATPase (843 bp) and COI (663 bp) sequences respectively. Significant connectivity and gene flow was detected among fishes collected from all the geographic locations as indicated by lack of structuring in Bayesian clustering analysis along with insignificant ΦST values. Oceanographic features of the Bay of Bengal, Arabian Sea and Andaman Sea may be favorable for the dispersal of anchovy larvae and subsequent gene flow. Historical demographic analyses indicated a demographic and spatial expansion taken place approximately during 125,000 years before present, the Pleistocene epoch. Indian Ocean witnessed emergence of upwelling events and consequent increase in productivity during the Pleistocene epoch causing a demographic and spatial expansion of anchovies. Management measures for this species should be devised considering it as a single stock along its entire range of distribution.

Bacterial bioluminescence response to long-term exposure to reverse osmosis treated effluents from dye industries.

The bacterial bioluminescence assay is one of the novel means for toxicity detection. The bioluminescence response of 2 marine bioluminescent bacteria was tested upon their long-term exposure to 9 different reverse osmosis (RO) rejects with varying chemical composition sampled from various dye industries. Bioluminescent bacteria were cultured in the RO reject samples, at different concentrations, and their growth rate and luminescence was measured for 24 h. The RO reject samples caused sublethal effects upon exposure and retarded the growth of bacteria, confirming their toxic nature. Further, continuation of the exposure showed that the initial luminescence, though reduced, recovered and increased beyond the control cultures irrespective of cell density, and finally decreased once again. The present study emphasizes the need of evolving a long-term exposure assay and shows that the method followed in this study is suitable to evaluate the toxicants that exert delayed toxicity, using lower concentrations of toxicants as well as coloured samples.