Hydrography and biogeochemistry of the north western Bay of Bengal and the north eastern Arabian Sea during winter monsoon

The north eastern Arabian Sea and the north western Bay of Bengal within the Indian exclusive economic zone were explored for their environmental characteristics during the winter monsoons of 2000 and 2001 respectively. The two regions were found to respond paradoxically to comparable intensities of the atmospheric forcing. There is an asymmetry in the net heat exchange of these two basins with atmosphere because of the varying thickness of barrier layer. During winter, the convective mixing in the Arabian Sea is driven by net heat loss from the ocean, whereas the Bay of Bengal does not contribute to such large heat loss to the atmosphere. It appears that the subduction of high saline Arabian Sea water mass is the mechanism behind the formation of a barrier layer in the northeast Arabian Sea; whereas that in the Bay of Bengal and the southeast Arabian Sea are already established as due to low saline water mass. The weak barrier layer in the Arabian Sea yields to the predominance of convective mixing to bring in nitrate-rich waters from the deeper layers to the surface, thereby supporting enhanced biological production. On the other hand, the river discharge into the Bay of Bengal during this period results in the formation of a thick and stable barrier layer, which insulates vertical mixing and provide oligotrophic condition in the Bay

The roles of endolithic fungi in bioerosion and disease in marine ecosystems. II. Potential facultatively parasitic anamorphic ascomycetes can cause disease in corals and molluscs

Anamorphic ascomycetes have been implicated as causative agents of diseases in tissues and skeletons of hard corals, in tissues of soft corals (sea fans) and in tissues and shells of molluscs. Opportunist marine fungal pathogens, such as Aspergillus sydowii, are important components of marine mycoplankton and are ubiquitous in the open oceans, intertidal zones and marine sediments. These fungi can cause infection in or at least can be associated with animals which live in these ecosystems. A. sydowii can produce toxins which inhibit photosynthesis in and the growth of coral zooxanthellae. The prevalence of many documented infections has increased in frequency and severity in recent decades with the changing impacts of physical and chemical factors, such as temperature, acidity and eutrophication. Changes in these factors are thought to cause significant loss of biodiversity in marine ecosystems on a global scale in general, and especially in coral reefs and shallow bays

Production and use of two marine zooplanktons, Tigriopus japonicus and Diaphanosoma celebensis, as live food for red sea bream Pagrus major larvae

We evaluated the effectiveness of two representative marine zooplankton, the harpacticoid copepod Tigriopus japonicus and the euryhaline cladoceran Diaphanosoma celebensis, as live food for red sea bream Pagrus major larvae. Chicken-dropping extract (CDE) was applied to both zooplankton cultures to improve population growth. Population growth of both zooplankton was significantly enhanced by CDE supplementation (at 1 or 2 ml/l). The highest amount of docosahexaenoic acid (DHA) and higher DHA/eicosapentaenoic acid ratio were detected in T. japonicus, whereas D. celebensis showed similar values to that of Artemia. Effectiveness of both animals as live food was tested by rearing red sea bream larvae on them for 28 days and comparing the results with those for Artemia. There were no significant differences in total length (8.6 ± 1.1?8.7 ± 0.7 mm) or wet weight (8.2 ± 0.3?9.4 ± 0.1 mg) among fish larvae feeding on the three different zooplankton. Survival rate was significantly higher with T. japonicus (39.4 ± 3.1 %) than with D. celebensis (20.8 ± 3.8 %) and Artemia (16.7 ± 9.8 %). Viability was significantly higher in fish fed with T. japonicus (60.0 ± 27.8 %) and D. celebensis (60.0 ± 32.2 %) than in those fed with Artemia (44.4 ± 12.3 %). Fish fed with T. japonicus contained higher n-3 highly unsaturated fatty acids than those fed with D. celebensis and Artemia. It is concluded that T. japonicus and D. celebensis have high potential as live food in marine fish larviculture