The qualitative analysis of the gut content of Charybdis (Charybdis) feriatus (Linnaeus) inhabiting the coastal waters of Mangalore indicates that the gut consisted of crustaceans (33.73%), fishes (19.10%), molluscs (9.35%), unidentifieable(22.42%) and sand and debris(15.4%). Crustaceans contributed upto 83.57% and it occurred in large quantities in the month of April (61.33%). This crab is detritivorous in feeding habit, at times feeding on fresh and decaying flesh of all kinds. Month wise, sex wise variation in the occurrence of prey organisms are also observd depending on its habitat.

Abstract

The maximum fluctuation in temperature, dissolved oxygen, salinity and pH were 3oC, 3.7ml./lt., 5 ppt and 0.6, which were the difference between the highest and lowest recorded during the period. The plant nutrients and chlorophyll 'a', by and large, showed higher values at shallower stations than at deeper station. Quantitative estimations of phytoplankton in terms of volume, net weight and dry weight revealed that the net phytoplankton standing crop was higher in November/December during post-monsoon season and in March/April during pre-monsoon period. Quantitative analysis showed the dominance of diatoms followed by dinoflagellates and blue green algae in the plankton community studied. Diatoms and dinoflagellates showed a decreasing trend with increasing depth, while the blue greens remained more or less same in all depths. The dominance of diatoms and dinoflagellates during the post - monsoon period at 10 and 15m was quite evident. Phytoplankton population showed significant difference between months and depths.

Key words: Hydrography, Phytoplankton, Diatom, Dinoflagellates, Blue green algae, Numerical abundance

Abstract

The present study deals with spatial and temporal changes in phosphorus contents of two estuaries, namely, Bhatye and Kalbadevi of Ratnagiri District of Maharashtra state. Characteristic features of water such as temperature, pH, electrical conductivity, salinity and phosphorus were studied. Surface water temperature along the midstream remains higher than towards the bank. No specific trend in pH is found with depth of water. The temporal variations in EC are more prominent than spatial. Summer evaporation plays important role in raising the salinity. Bottom water as well as monsoon water is rich in phosphorus. Spatial distribution of phosphorus indicates that it is more at the bottom of the estuary. The vertical distribution of total phosphorus along with horizontally selected sites gives higher values for midchannel than other two sites towards the bank.

Abstract

Growth studies were conducted with mrigal, (Cirrhinus mrigala ,Hamilton) fry to determine quantitative requirements for lysine. The experimental diets (40% crude protein) were formulated using purified ingredients, casein and gelatin supplemented with crystalline aminoacids to provide an aminoacid profile similar to that of mrigal tissue protein except for the test aminoacid. The test diets consisted of six graded levels of lysine (1.88, 2.00, 2.30, 2.60, 2.90 and 3.20% of dry diet). The diets were made isonitrogenous by decreasing the non-essential aminoacids, as the level of essential aminoacid increased. Break point in the growth curve which represent the optimum dietary concentration of lysine for fish growth was determined by the broken-line regression method. Growth data indicated that the requirement of mrigal fry for lysine is 2.65% of the dry diet, which corresponds to 6.63% of dietary protein.

Abstract

Key words : Periphytic, Rio Grande de Norte, coconut shells, Environmental impact