NISCAIR Online Periodicals Repository Community: IJMS Vol.30 [2001]

Evaluation of the Nethravathi spit complex, west coast of India: Integrated change detection study using topographic and remotely sensed data

Wed, 28 Nov 2001 22:58:59 GMT

Title: Evaluation of the Nethravathi spit complex, west coast of India: Integrated change detection study using topographic and remotely sensed data

Authors: Raghavan, B. R.; Vinod, B. T.; Dimple, K. A.; Prabhu, H. Venkatesh; Udayashankar, H. N.; Murthy, T. R. Sreedhara

Abstract: The Nethravathi spit complex of Karnataka coast consists of Mangalore spit to the north and Ullal spit to the south of Nethravathi-Gurupur river mouth. The integration of topographic sheets and satellite imageries of this area has enabled the evaluation of the migration of spits over a period of 83 years. Morphologically, Mangalore spit has shrunk by 750 m in length and 749780 m² in area. On the other hand the Ullal spit exhibits an increase in length of 800 m and an area of 111620 m². The spits show no prominent lateral migration. Shrinkage of the Mangalore spit and the growth of the Ullal spit indicates net northward migration of the estuarine mouth.

Page(s): 268-270

Control of bacterial pathogens, associated with fish diseases, by antagonistic marine actinomycetes isolated from marine sediments

Wed, 28 Nov 2001 22:58:59 GMT

Title: Control of bacterial pathogens, associated with fish diseases, by antagonistic marine actinomycetes isolated from marine sediments

Authors: Patil, R; Jeyasekaran, G; Shanmugam, S A; Shakila, R Jeya

Abstract: Actinomycetes were isolated from different marine samples collected from various stations along the Tuticorin coast. About 133 cultures of actinomycetes were isolated from 129 marine samples. Of the 104 isolates of actinomycetes screened for their inhibitory activity against the bacterial pathogens associated with fish diseases viz. Aeromonas hydrophila, A. sobria and Edwardsiella tarda, 77 isolates were found to be inhibitory to at least one of the pathogens. The highest incidence of inhibitory isolates was from the sediment samples. All the isolates of antagonistic marine actinomycetes were identified to be Streptomyces. The findings suggest that the antagonistic marine Streptomyces isolates or the antibacterial substances produced by them could be used as antibiotics, which might have a future application in aquaculture systems.

Page(s): 264-267

Length- weight relationship and morphometric study on the squid Loligo duvauceli (d’Orbigny)(Mollusca / Cephalopoda) off Mumbai (Bombay) waters,west coast of India

Wed, 28 Nov 2001 22:58:59 GMT

Title: Length- weight relationship and morphometric study on the squid Loligo duvauceli (d’Orbigny)(Mollusca / Cephalopoda) off Mumbai (Bombay) waters,west coast of India

Authors: Karnik, Nirmala S; Chakraborty, Sushant Kr

Abstract: The length- weight relationship and morphometric study on the squid, Loligo duvauceli (d’Orbigny) is reported from Mumbai waters. The regression coefficient between the sexes was found to be not significant at 1% level. The ‘b’ value differed from the ideal cube law of ‘3’as is with the case of length- weight relationship studied on this species elsewhere. The morphometric characters indicated high degree of correlation among the compared characters. The study substantiated further that the length-weight relationship of squids do not follow ideal cube law. The morphometric characters compared here would be very useful for comparison with the same species in other geographical locations.

Page(s): 261-263

Reproductive biology of the siboga squid Doryteuthis sibogae (Adam) from Thoothukkudi (Tuticorin) coast, southeast coast of India

Wed, 28 Nov 2001 22:58:59 GMT

Title: Reproductive biology of the siboga squid Doryteuthis sibogae (Adam) from Thoothukkudi (Tuticorin) coast, southeast coast of India

Authors: Neethiselvan, N; Venkataramani, V K; Srikrishnadhas, B

Abstract: Studies on the seasonal occurrence of maturity stages of Doryteuthis sibogae revealed that it is a prolonged breeder as matured and spent specimens of both the sexes were recorded almost round the year. Two peak spawning periods, one from August to September and another from December to January were observed. Matured animals were represented by a wider length range inferring non semelparous nature of the species. However, dominance of males during peak spawning season as evidenced from sex ratio studies do confirm existence of a minor degree of post spawning mortality in females. The weight of gonad and nidamental glands increased during maturation and proved as good indices of maturation. Females attained maturity earlier than males. Fecundity showed a significant correlation with dorsal mantle length. Doryteuthis sibogae form regular fishery in Thoothukkudi coast on commercial scale. Since this species is a continuous spawner as evidenced in the present study and is intensively exploited at Thoothukkudi bay, an in depth study on stock assessment of this species is an urgent need to sustain the fishery.

Page(s): 257-260