Nutrient dynamics and seasonal variation of phytoplankton assemblages in the coastal waters of southwest Bay of Bengal.

In order to understand the phytoplankton community structure and its relationship with the environmental variables in the near shore waters of Kalpakkam, east coast of India, observations were carried out during 2008-2009. Phytoplankton population was comprised of 219 species, and the density was higher during the southwest monsoon (SWM) and inter-monsoon seasons than that of north east monsoon (NEM) season. The nutrient status on a temporal and spatial scale indicated the impact of point sources carrying anthropogenic runoff. Comparison of ambient nutrient ratios with the Redfield ratio (N/P/Si = 16:1:16) showed a clear temporal variation in the factors that regulate the phytoplankton growth. SWM and inter-monsoon season was evident to have an acute N-limitation of algal growth (~76%) whereas P-limitation was encountered during the NEM season (~75%). Interestingly, a sizable population of cyanobacteria (Trichodesmium erythraeum) were noticed during NEM season when there was an exponential increase in nitrogen concentration, probably due to nitrogen fixation. No significant impact of temperature on phytoplankton proliferation was observed in situ during the study period.

A new species of the genus Scolopsis Cuvier, 1830 (Perciformes: Nemipteridae) from southern India and Sri Lanka.

Scolopsis igcarensis, a new species of monocle bream (family Nemipteridae) from the coastal waters of southern India and Sri Lanka is described. The species is distinguished from other species of the genus Scolopsis by a combination of the following characters: scales on top of head reaching forward to between anterior nostril and snout tip; lower margin of eye below the line from snout tip to upper pectoral fin base; a bony ridge below eye; a white band from behind eye to level of end of dorsal fin base.

Heavy metals concentration in edible fishes from coastal region of Kalpakkam, southeastern part of India.

Concentrations of Cu, Mn, Zn, Fe, Cr, and Pb were estimated using ICP-MS in nine commercially important and locally consumed fish species (Sarda orientalis, Scomberomorus commerson, Rastrelliger kanagurta, Sardinella longiceps, Paraplagusia bilineata, Cynoglossus lida, Cynoglossus macrostomus, Lepturacanthus savala, and Siganus javus) collected from coastal waters of Kalpakkam, eastern part of India. Their concentration (µg g(-1)) in the examined fish species ranged as follows: Cu (0.8-6.5), Zn (14.3-27.9), Mn (0.5-8.8), Fe (17.6-117.0), Cr (0.24-1.78), and Pb (0.18-2.29). Concentrations of most of the metals in the fish species studied were found to be safe for human consumption barring Mn.

Impact of temperature on heat shock protein expression of Bombyx mori cross-breed and effect on commercial traits.

The present study investigated the effect of increasing temperature stress on the thermotolerance of B. mori cross-breed PM x CSR2 and tissue specific differential expression of heat shock proteins at IVth and Vth instars. The larvae reared at 25 +/-1 degrees C and 70 +/- 5% relative humidity were treated as control. Larvae were subjected to heat shock temperatures of 34, 38 and 42 degrees C for 3 hr followed by 3 hr recovery. Expression of Heat shock protein 72 were analyzed by SDS-PAGE and confirmed by western blotting analysis. The impact of heat shock on commercial traits of cocoons was analyzed by following different strategies in terms of acquired thermotolerance over control. Resistance to heat shock was increased as larval development proceeds and increased thermotolerance is achieved with the induction of Heat shock protein 72 in the Vth instar larval haemolymph. Relative influence of heat shock temperatures on commercial traits corresponding to the generation of heat shock protein 72 was significantly improved over control. In PM x CSR2, cocoon and shell weight significantly increased to 9.90 and 11.90% over control respectively.

Zinc induced histological changes in brain and liver of Labeo rohita (Ham.).

Labeo rohita fingerlings were exposed to zinc metal toxicity (5 and 10 ppm) for duration of 5 and 15 days. The histological changes were studied in brain and liver of the treated fish. The brain tissues showed enlarged pyramidal cells with extensive vacoulation while severe necrosis, haemorrhage and degeneration of hepatocytes were witnessed in the liver tissues.

Impact of cadmium on food utilization of the Indian major carp, Catla catla (Ham).

Catla catla, under the sublethal stress of cadmium exhibited depletion in food utilization parameters and it was concentration dependent. Heavy metal intoxication was found to exhibit reduction in biomass.

A preliminary report on effect of pulsed magnetic fields on fresh water fish (Labeo rohita) chromosomes.

Marine-life scientists around the world are already carrying out investigative trials to obtain higher yields under in-captive breeding conditions, on both edible varieties and ornamental fishes with optimal inputs. However, for such trials to succeed there is a need for genetic improvement. The idea that fish production can be enhanced by genetic manipulation is gaining acceptance, as there is a strong possibility that qualitative improvement of economically important traits can be achieved by identifying and utilizing more effective genotypes. In the present communication a tentative plan for genetic manipulation of fresh water fish using controlled, pulsed magnetic fields, is being discussed. Chromosome preparations of Labeo rohita were made using Colchicine-Methanol-Acetic acid air drying technique, using tissue from gills. The fish were exposed to Pulsed Magnetic Field (PMF)with intensity 0.2 Gauss, pulsing at 50 Hz frequency (sine wave) for 6 hours / day for a total period of 30 days inside specially designed magnetic field enclosures. The karyological investigations revealed no distinct difference between "test" and "control" groups.

The effects of monocrotophos to different tissues of freshwater fish Cirrhinus mrigala.

The histopathological effects of monocrotophos on the gill, kidney and intestine tissues of the Cirrhinus mrigala were determined by light microscopy. The changes in the gills were characterized by epithelial hyperplasia, aneurysm, epithelial necrosis, desquamation, epithelial lifting, oedema, lamellar fusion and curling of secondary lamellae. Pycnotic nuclei in tubular epithelium, hypertrophied epithelial cells of renal tubules, contraction of the glomerulus and expansion of space inside the Bowman's capsule were observed in the kidney tissues of fish after exposure to monocrotophos. In the intestine tissues of fish exposed to monocrotophos, oedema, necrosis and atrophy of epithelial cells were observed.