Studies on the mangrove ecosystem

Mangrove ecosystem is one of the most specialised and productive coastal habitats in the world. Due to human interference in many ways, most of the mangrove forests are on the verge of destruction and disappearance. The main causes for the degradation of Indian mangroves are land reclamation, pollution and overexploitation of the resources. A proper understanding of this specialised ecosystem and careful implementation of the conservation measures would alone save the ecosystem from further destruction and extinction. The present account deals with the ecological aspects of the mangrove habitats covering their extent, distribution, zonation, biological assemblage, hydrography and productivity, and giving importance to their role, man-made impacts and conservation aspects with emphasis on the approaches for the sustainable use of this ecosystem to the mankind with special reference to the mangroves of India

Occurrence of giant male and female groupers with a note on sex change in groupers

Serranid fishes are popularly known as 'Groupers' or 'Rock cods' and locally 'Kalava'.In view of their importance in the capture and culture fisheries, the present account on the record of giant female groupers [Epinephelus tauuina (Forskal), Epinephelus malabaricus (Bloch and Schneider) and Promicrops lanceolatus (Bloch)] of more than two metres in total length and their sex ratio] in the natural population from the Indian coast (Table 1) deserves special attention

Mariculture in India, its potentialities and practical applications

India is passing through a very critical period of food crisis and consequentiy calling for the necessity of adopting various techniques and methods to augment the food production. Among them , mariculture is an important means of getting additional source of human food

Marine fisheries development in Tamil Nadu

Fisheries development is governed by the stock of fishery resources, the level and types of fishing effort and the use of diversified craft and gear. The growing Importance of fishery resources and the level of their exploitation are traced in this paper. The marine capture fisheries account for a substantial proportion of the total fish production in Tamil Nadu. The present level of fish landings, their seasonal variation and the major species groups are brought out. The developmental programme aimed at increasing fish production are reviewed. The need for innovations In and diversification of fishing methods is highlighted. The Impact of investment on fish production is analysed with a time frame of ten years. Basic needs of fisher folk which have a bearing on fisheries development are identified. Technological developments made over the last decade are mentioned with a note on the extent of non-adoption of new technology and the major determinants thereof are pointed out for remedying the situation. Culture practices in suitable areas along the coasts are stressed to provide employment opportunities that step up production. Developments in the preservation and processing of the sea foods are presented and the scope for the establishment of a stable Internal and external market is explored. The state of affairs of marine or coastal fisheries management and suggestions for toning up resource management are stressed. The need for sea ranching and SCUBA diving Is Indicated. The vital feature of training and the nature and areas of extension programmes are also pointed out for ushering In speedier development of the sector

Notes on the juveniles of the rock cod Epinephelus tauvina (Forsskal)

The occurrence of the very young juveniles of the rock cod Epinephelus tauvina (Forskal) in Cochin backwater during February-June is reported here with brief notes on the morphometric variations between juveniles and adults and food and feeding habits of juveniles

Some observations on primary production and plankton biomass along the continental shelf and slope off the northeast coast of India during January 1989

The present study deals with the quantitative aspects of chlorophyll pigments, primary productivity and plankton biomass from the continental shelf and slope off the northeast coast of India between 16° and 20°N latitudes towards the end of northeast monsoon season. In surface waters, the mean values of chl-a, -b, and -c were 0.249,0.275 and 0.837 mg/m^ along the shelf and 0.246,0.260 and 0.805 mg/m^ in the slope respectively while the net primary productivity values were 0.074 and 0.081 g C/m /d for the shelf and slope waters respectively. Column productivity in the upper 0-50 m water in the shelf and slope regions were 2.9 and 3.25 g C/m /d with an average production of 3.08 g C/m /d. Higher rate of production was observed around 18° and 20°N latitudes. Zooplankton biomass exhibited progressive increase in volume from 16° to 20°N. The estimated mean zooplankton biomass volume of the study area was 28.83 ml/m . The mean transfer coefficient from primary to secondary production was found to be 14% when 50% of the zooplankton biomass was considered as the daily rate of production. From the mean primary and secondary productivity values, potential tertiary production of pelagic fishery resources in the upper 0-50 m water column of the study area for the month was assessed

Influence of mangrove ecosystem on the biological resources and fishery of Kakinada

Since there are no records of detailed investigation on the ecology of the mangrove Kakinada around Kakinada and keeping in view of the vastness, fertility and biological resources of the Kakinada Bay and the adjacent sea, the Institute took initiative to conduct a study on the ecology of mangrove areas around Kakinada during 1982-'85 to understand the various ecological aspects connected to the water, soil/ sediment and mangrove-associated fauna and their influence on fisheries

Diurnal variations in the vertical distribution and abundance of zooplankton in the continental shelf waters off Cochin during April 1991

The present study is based on zooplankton samples collected by vertical hauls from 0-30, 30-60 and 60-90 m depths from a 100 m depth station in the continental shelf (09° 44' N, 75° 42*8) off Cochin for two days at three hourly interval. The mean displacement volume of zooplankton biomass at these depth zones were 6.24, 6.70 and 6.07 ml/100 m water while their numerical counts were 14490,13355 and 11290 no/100 m respectively. The overall mean volume (ml) and number per 100 m in the endre water column (0-90 m) were 6.34 and 13045 respectively and were distributed as 5.89 ml and 11715 no/100 m^ in the daytime and 6.79 ml and 14376 no/100 m^ during night hours respectively. The biomass was dominated by copepods (75.6%), decapod larvae (12.2%), chaetognaths (6.5%) and appendicularians (2.4%) in April. In general, copepods, decapod larvae and appendicularians showed increasing trend in number from the bottom (60-90 m) to the surface layer (0-30 m); chaetognaths, medusae, pteropods, heteropods, salps and doliolids were distributed more in the middle zone (30-60 m); while ostracods and planktonic polychaetes were more in the bottom zone (60-90 m). Distribution of amphipods and ostracods indicated significant diurnal vertical migration. The phenomenon of mid- night sinking was noticed in the case of copepods, chaetognaths, appendicularians, medusae, siphonophores, salps and doliolids

Dial variations in temperature, salinity and dissolved oxygen from the neritic waters off Cochin during April (peak summer)

Dial variations of important hydrographic parameters were studied continuously for 7 days at a 100 m depth station off Cochin. The frequency of observations varied from 1-3 hourly intervals. In surface waters, the ranges in temperature, salinity and dissolved oxygen values recorded during 10-17 April were 30.64°-32.36°C, 34.56- 34.68 X lO''' and 4.06-4.65 ml/1 respectively. Tlie STD profiles in the diurnal study revealed clearly the premonsoon warming (30°-31°C) in the upper 0-30 m depth zone. In the water column up to 50 m depth, mean salinity values ranged from 34.6 to 35 X 10 while dissolved oxygen values were above 4 mI/1. Time series observations on the production and utilisation of dissolved oxygen revealed wide fluctuation from hour to hour. Vertical gradients in the diurnal study indicated the existence of thermocline around 60 m depth with sharp decline in temperature and dissolved oxygen and increase in salinity below 60 m. The diurnal variation on the distribution of temperature and dissolved oxygen exhibited significant rhythmic tidal impulse of a semi-diurnal wave pattern which was more prominent in the bottom layer below 60 m

Rare Chimaeroid and Elasmobranch fishes from the continental slope off the West Coast of India

During exploratory trawling from the upper continental slope in depths between 180 and 450 metres off the West Coast of India, specimens of the Chimreroid fish Neoharriotta pinnata (Schnackenbeck) and the rare elasmobranchs Echinorhinus b"UC11S (Bonnaterrc) and Atractophorus armatus Gilchrist have been obtained. All three are new distributional records for Indian Seas and they are described and illustrate