A note on observations on cetaceans in the western Indian sector of the Southern Ocean (20-56°S and 45-57°30’E), January to March 2004

A multi-disciplinary and multi-institutional pilot expedition was organised by the National Centre for Antarctic and Ocean Research (NCAOR) to the ice-free areas of the Western Indian Ocean sector of the Southern Ocean onboard ORV Sagar Kanya during the austral summer of 2004 (January-March). This survey, conducted by the Central Marine Fisheries Research Institute (CMFRI), is the first Indian attempt to survey for cetacean diversity in the Southern Ocean. The ultimate objective is to determine distribution, relative abundance, migration patterns and critical habitat parameters. 68% of a total of 13 sightings (22 individuals) were positively identified and species observed included Antarctic minke whales (Balaenoptera bonaerensis), fin whales (B. physalus), sei whales (B. borealis) and blue whales (B. musculus). The blue whales were not identified to the sub-species level. The highest concentration of cetaceans was between 35° and 37°S (along 45°E) and between 48° and 53°S (along 45°E). Relatively small numbers of cetaceans were observed during the present cruise, possibly because most of the cetacean sighting effort was made during inclement sea conditions. Results on the sighting characteristics and occurrence patterns of the cetaceans in relation to the region and hydrographical parameters are discussed briefly vis a vis published information from the Southern Ocean

Trichodesmium erythraeum (Ehrenberg) bloom along the southwest coast of India (Arabian Sea) and its impact on trace metal concentrations in seawater

The incidence of a large scale Trichodesmium erythraeum bloom along the southwest coast of India (Arabian Sea) observed in May 2005 is reported. Around 4802 filaments of T. erythraeum ml−1 seawater was observed and a colony consisted of 3.6 × 105 cells. The bloom was predominant off Suratkal (12° 59′N and 74° 31′E) with a depth of about 47 m, covering an area of 7 km in length and 2 km width. The concentrations of Zinc, Cadmium, Lead, Copper, Nickel and Cobalt were determined in samples collected from the bloom and non-bloom sites using stripping voltammetry. The observed hydrographical and meteorological parameters were found to be favorable for the bloom. The concentrations of Zinc, Cadmium and Nickel were found to be higher at bloom stations, while the concentrations of Lead, Copper and Cobalt were found to be very low at bloom stations. Elevated concentrations of Cadmium and Cobalt were observed at Valappad mainly due to the decomposition of detrital material produced in the bloom. Statistically significant differences (P > 0.01) in metal concentrations between the bloom and non-bloom stations were not observed except for Copper. Metals such as Lead, Copper and Cobalt were removed from the seawater at all places where bloom was observed. Cadmium was found to be slowly released during the decaying process of the bloom

Influence of salinity on hatching rate, larval and early juvenile rearing of sea cucumber Holothuria scabra Jaeger

The fertilized eggs, auricularia larvae and one month old juveniles of Holothuria scabra, obtained from induced spawning were used for various experiments to assess the effect of salinity on hatching rate and larval and early juvenile growth. The experiments were conducted for two days on hatching rate of fertilized eggs, for ten days on larval survival, growth and development and for 30 days on juvenile’s growth rate. The maximum hatching of 39% at 35 ppt, followed by 32% at 33 ppt indicated the suitability of an ambient salinity of 33 to 35 ppt for effective hatching of fertilized eggs. High survival, growth rate and fastest development of auricularia were obtained at salinity between 33 and 35 ppt. The maximum growth rate in length and weight, was at 30 ppt, which may be the optimum for juvenile rearing. The one way ANOVA on differences in the hatching rate, larval growth and survival rate and juvenile growth rate at different salinities indicated high level of significance (p<0.001 )

Stock enhancement of seacucumbers - a solution for the depletion of natural stocks of Holothuria scabra along Gulf of Mannar

Sea cucumbers form a valuable source of income for the poor fisherfolk along Gulf of Mannar and Palk Bay areas of South-east-coast of India. Owing to the high demand in international market and inadequate fishery management practice, the commercial sea cucumber species have been over-exploited leading to the extinction of sea cucumber populations in several habitats. The "Convention on International Trade in Endangered species of Wild Fauna and Flora" (CITES) has recommended inclusion of sea cucumbers in the list of endangered animals and cited the reasons as limited mobility, late sexual maturity, density depended reproduction, low rates of recruitment and ease of collections for their overexploitation and subsequent resource depletion. The releasing of hatchery produced juveniles of commercial sea cucumber species to their natural habitat, a process called restoration, restocking or reseeding is gaining momentum world wide, as the only way for replenishing the depleted stock of sea cucumbers

Mangroves of India : Biodiversity, Conservation and Management

Mangroves are salt-tolerant plants of tropical and subtropical intertidal regions of the world. The specific regions where these plants occur are termed as 'mangrove ecosystem'. These are highly productive but extremely sensitive and fragile. Besides mangroves, the ecosystem also harbours other plant and animal species

Studies of planktonic Ostracoda collected from Arabian Sea and Bay of Bengal

General distribution and numerical abundance of planktonic ostracods, as a whole, in the Exclusive Economic Zone of India and nearby seas based on 1086 collections (1985-'88) are discussed. The average density of ostracods in the area investigated was estimated to be 17395/1000 m . The ostracods occurred far more abundantly in the shelf waters than in the oceanic areas. Samples collected indicated that 95% of the ostracod population occurred off the west coast of India round the year. They were found remarkably high (61168/1000 m\ 63.3%) between 10°N and 15°N off the west coast, while their abundance between 10°N and 15°N off the east coast of India was the lowest (624/1000 m , 0.65%). The abundance of ostracods was always associated with monsoon when the maximum of 31920/1000 m was obtained and this was mainly due to the swarming nature of these organisms. The minimum was observed during the premonsoon period when an average of 1508/1000 m ostracods occurred. Comparison of ostracod distribution in the EEZ of India between day and night yielded values of 30.95 and 69.05% respectively, which showed that they are more abundant during night, thereby illustrating pronounced diurnal vertical migration

Mangrove vegetation

Mangrove vegetation includes plants ranging from herbs, shrubs to tall trees. In favourable conditions the mangrove trees can form dense forests in intertidal habitats. However; only a few species form a massive canopy. The main characteristic features of these special type of plants are the tidal amplitude, defined by the species, and their ability to tolerate high salinity and stress. The majority of the plant groups have adaptations like prop and stilt roots for fixing support and the pneumatophores otherwise called the breathing roots for exchanging gases and the viviparous germination. In addition to these, the plants have leathery, dark, ever green leaves with deeply embeded stomata and aquous tissues

Assessing the impacts of climate change on marine fisheries of Karnataka and identifying regime shifts

Climate related regime shifts, namely the rapid reorganization of marine ecosystems from one relatively stable state to another, have been reported from several parts of the world, and found responsible for the fluctuations of major fisheries. Time series on ocean-atmosphere parameters together with time series on plankton and/or fish abundance has been extensively used for identifying regime shifts in the oceans from several parts of the globe