Reproductive physiology of indian species of the genus perna (family mytilidae)

This thesis deals with the reproductive physiology of the two species of Indian sea mussels, namely the brown mussel perna indica and the green mussel p viridis .The major aspects of the study include ecophysiology of reproduction linking up the animal reproductive cycle of the animals with the ecological conditions of the natural mussel beds, biochemical and histochemical changes associated with reproduction and neurosecretory cycle in synchrony with the reproductive cycle. Some basic studies on gamete morphology and certain aspects of gamete physiology have been taken up. The experimental work deals with the influence of different feeding levels on gamatogenesis and maturation and the effect of ganglia ablation on spawning. The material for the investigation on perna indica were collected from the natural mussel beds at Vizhinjam near Trivandrum and on p.viridic from Elathur, near Calicut. The period of observation extended from October 1981 to December 1982.

Studies on the reproductive physiology of lazes calcarifer (BLOCH)

At present, there is paucity of information regarding the breeding biology, especially from southeastern region, which differs in its climatic features from northeastern coastal areas, where some attempts have been made to study the biology of the fish, though not documented in detail (Jhingran and Natarajan, I969; Patnaik and Jena, 1976; Kowtal, 1977; Roy e_t _a_l_., I977). The present work, first to undertake detailed investigation into reproductive aspects of the fish from India is not only confined to biology, but extend to the study on histological as well as physiological changes in the processes associated with natural reproductive cycle. The main objective of the study is to develop a background for the standardisation of subsequent artificial propagation techniques for the Sea Dass The thesis is presented in three chapters. The first chapter; general introduction, surveys the literature pertaining to the status of research on Lates calcarifer with specific reference to reproduction and acquaculture. The second chapter entitled, materials and methods gives description regarding collection of specimens as well as samples in addition to the various analytical methodologies employed during the study.

STUDIES ON THE BIOLOGY OF THE WEDGE CLAM DONAX INCARNATUS (GMELIN) FROM THE MALIPPURAM BEACH OF KERALA

The present investigations have considerably enhanced the existing knowledge on the biology and distribution/availability pattern of D.incarnatus in the Malippuram region. The species occurs in good concentration during October - March/April, and disappears from the area during late premonsoon and monsoon months. Recolonising the area in September, it grows fast in the subsequent months. The life span of the species is estimated to be about an year. Studies on the reproductive biology of the species have revealed that there are two spawning peaks, the major peak in February - March and minor peak, in December. The salinity regime of the area influences the reproductive activity. These observations form the original contribution in the thesis. The information on variation in water content, protein,glycogen and lipid levels in relation to reproductive cycle has helped to a better understanding of the gametogenic activity and spawning of the species. Similarly, the findings on salinity tolerance and filtration rate have shown that small sized clams exhibit greater tolerance range than larger clams, and grow at a faster rate with active metabolism. It is hoped that these information would considerably add to the present knowledge of the basic facts which are relevant to the improvement and management of the clam fishery of this region.

Studies on the histological and biochemical changes during spermatogenesis in MUGIL CEPHALUS linnaeus and related species

Several studies on the biology and fisheries of mullets, particularly of M cephalus are now available. Different aspects of breeding, larval rearing, seed production, field culture and ecophysiology have also been investigated. However, information on the spermatogenesis in M cephalus as well as L parsia is scanty. Since an understanding of the reproductive strategies is an essential pre-requisite for evolving successful breeding programmes through artificial fertilization and gametic preservation, investigations on spermatogenesis in these species were taken up and the results are presented in this thesis. The thesis is presented in 9 chapters