20 research outputs found
Genetic stock characterization of fish using molecular markers
Accurate Identification of genetic resources is necessary for detecting new species and
varieties for products of commercial value. Fish, as a group, apart from their economic value
from a biodiversity viewpoint, have the highest species diversity among all vertebrate taxa.
They exhibit enormous diversity in size, shape, biology and in the habitats they occupy.
In terms of habitat diversity, fishes live in almost all conceivable aquatic habitats, ranging
from Antarctic waters to desert springs. Of the 62,305 species of vertebrates recognized
world over, 34,090 (nearly 52%) are valid fish species; a great majority of them (97 %) are
bony fishes and the remaining (3 %) are cartilaginous (sharks and rays) and jawless fishes
(lampreys and hagfishes). Further, on an average, 300 new fish species are described each
year, and global surveys indicate that there could well be at least 5,000 species more to be
discovered
Concept for estimation of secondary and tertiary biomass from primary production
Fixation of inorganic carbon to organic carbon in the ocean is driven purely by phytoplankton.
Phytoplankton carbon fixation plays an important role in maintaining the quasi steady state
level of atmospheric CO2. Relative contribution of marine primary productivity to global
photosynthetic production is between 10 and 50%. Magnitude ranges from 20 to 55 Gt of
C/ year (Ryther 1969, Smith et al., 1983, Walsh 1984 and Martin 1992). Ocean-atmospheric
coupled climate models predict changes in the ocean circulation and hypothesize that
changes in the ocean circulation will stimulate phytoplankton biomass production in the
nutrient depleted areas in the open ocean (Roemmich & Wunch 1985). The effect on
atmospheric CO2 is uncertain because the relationship between the enhanced primary
production and air sea exchange of CO2 is not understood. The challenge is to study the
magnitude and variability of Primary productivity, its time scales and changes in atmospheric
forcing and upscale it into secondary and tertiary productivity
Satellite ocean colour sensors
The 70% of the earthтАЩs surface is covered by the ocean and the life inhabiting the
oceans play an important role in shaping the earthтАЩs climate. Phytoplankton, also known as
microalgae, are the single celled, autotrophic components of the plankton community and
a key part of oceans, seas and freshwater basin ecosystems. They are significant factor in
the ocean carbon cycle and, hence, important in all pathways of carbon in the ocean.
Phytoplankton contain chlorophyll pigments for photosynthesis, similar to terrestrial plants
and require sunlight in order to live and grow. Most of them are buoyant and float in the
upper part of the ocean, where plenty of sunlight is available. They also require inorganic
nutrients such as nitrates, phosphates, and sulphur which they convert into proteins, fats,
and carbohydrates. In a balanced ecosystem, phytoplankton are the base of the food web
and provide food for a wide range of sea creatures (NOAA). The measurement of
phytoplankton can be indexed as chlorophyll concentration and is important as they are
fundamental to understanding how the marine ecosystem responds to climate variability
and climate change
Identifying mesoscale eddies- Relevance to mud banks and fishery
The most popular fishing area during mud bank formation in Kerala is off Punnapra
coast in Alapuzha district. This place is equipped with unique crafts such as one-man operated
expanded polystyrene thermocol made gill netters, and several other traditional crafts. The
fishermen community along this coast is vigilant against any mechanized fishing during
mud bank period which falls in the southwest monsoon months when there is a ban on
mechanized crafts. There are comparable datasets, from mud bank vis-├а-vis non mud bank
in this region, which indicate that, the catch per unit effort (CPUE) do not vary significantly.
Fishing in Thrissur and Malappuram districts are not restricted by the formation of mud
banks. In these districts modified outboard crafts such as pair trawlers operating double
net and the high horse power of the out board engines are generally on a look out for nonmud
bank resources also. In Malappuram district, the occurrence of the mud bank fishery is
for limited days and generally less reported. Therefore, the analysis of data sets indicated
better production and CPUE from non-mud banks in Malappuram. In general we can say
that there is no significant increase in abundance of fishes reported from the mud bank
regions. But the calm waters generated at certain pockets of the otherwise disturbed coastal
waters act as areas for seasonal landings of fish
Satellite Data Products for Marine Ecosystem Studies
Satellite Data Products for Marine Ecosystem Studie
El-Nino and its impacts on coral reef ecosystem in 289 the eastern Indian Ocean
The coral reef bleaching associated with the elevated Ocean temperature has been
widely reported in the last three decades from different regions of the world. The rising
temperature and acidification of Oceans makes a big challenge for the survival of reefs in
the world. The other important stresses for the reefs include increased UV radiation, sea
level variations, suspended sediments and increased turbidity of water. There are different
studies which relate bleaching events with global warming and climate change. However,
the increased frequency of mass bleaching events could not be sufficiently explained with
current warming rates of the Ocean. Stone et al., (1999) put forward a new theory that
recent increases in mass bleaching events were in response to the relative increase in El
Ni├▒o experienced over the last two decades
Upwelling over the eastern Arabian Sea
Upwelling is a vital oceanographic phenomena determining the biological productivity
of the coastal oceanic provinces in a greater extent. The annual pelagic fisheries of coastal
rim countries, adjacent to the eastern boundary of the Ocean, over the trade wind zone are
greatly dependent on upwelling. Over the North India Ocean (NIO), west coast of India,
adjacent to the eastern Arabian Sea is well known for its seasonal occurrence of upwelling
and downwelling annually. Over the past, several authors have studied upwelling along the
west coast of India (Banse 1959, 1968; Sharma 1978; Johannessen et al., 1987
Satellite Remote Sensing Applications in Mariculture Activities
During the last two decades the marine fisheries sector in India has undergone considerable change. The
fishing fleet became larger and more energy-intensive, and the catch and trade of marine fishes increased
substantially. Concern arising from the increasing fishing effort and the potential for overexploitation in Indian
waters, led to scientific assessment of the status of several fish stocks. Consequently, attempts were made to
shift from open to regulated access fisheries through Marine Fishing Regulation Acts (MFRAs). However, conflicts
in sharing the limited resources intensified within and with other sectors and this, in turn, had high economic,
social and environmental costs (Vision 2050, CMFRI). Thus, in recent years, the sector recognized the need for
effective management for sustainable fisheries and a healthy marine environment through ecosystem approach
and habitat restoration. Success has been achieved in mariculture, raising hopes of producing a plentiful supply
of fish in future by farming marine fis
Spatial variability in sea surface temperature and wind-driven coastal upwelling along the southwest coast of India
The coastal environment along the southwest coast of India is influenced by seasonal wind-driven coastal upwelling. The trend of upwelling index (UI) and sea surface temperature (SST) along the southwest coast of India during 1988-2015 were analysed in this study. In order to understand the spatial variation in SST and UI, the entire southwest coast of India was divided into three strata viz. stratum_1 (ST_1, southern part), stratum_2 (ST_2, middle part) and stratum_3 (ST_3, northern part). Temporal analyses of these parameters were carried out for three seasons such as monsoon (June-September), post-monsoon (OctoberJanuary) and pre-monsoon (February-May). In addition to seasonal changes in upwelling, large-scale latitudinal differences in upwelling were observed during this study, which is associated with spatial differences in coastal topography. The upwelling index along stratum_3 has increased after 1995 compared to previous period. Both SST and UI exhibited spatial variation along southwest coast of India. Eventhough, UI is higher during the summer monsoon compared to other seasons, a declining trend in UI during the summer monsoon was found from
1988 to 2015
Holistic Approach to Upwelling and Downwelling along the South-West Coast of India
An attempt has been made to develop a holistic understanding
of upwelling and downwelling along the south-west coast
of India. The main objective was to elucidate the roles of different
forcings involved in the vertical motion along this coast.
The south-west coast of India was characterized by upwelling
during the south-west monsoon (May to September) and by
downwelling during the north-east monsoon and winter
(November to February). The average vertical velocity calculated
along the south-west coast from the vertical shift of the
26 я┐╜C isotherm is 0.57 m/day during upwelling and 0.698 m/
day during downwelling. It was concluded that upwelling
along the south-west coast of India is driven by offshore
Ekman transport due to the alongshore wind, Ekman pumping,
horizontal divergence of currents and by the propagation
of coastally trapped waves. Whereas downwelling along the
coast is driven only by convergence of currents and the
propagation of coastally trapped Kelvin waves. Along the west
coast of India, the downwelling-favorable Kelvin waves come
from the equator and upwelling-favorable waves come from
the Gulf of Mannar region