248 research outputs found
Breeding of endemic catfish, Horabagrus brachysoma in captive conditions
Asian seabass or barramundi (Lates calcarifer) is an important food fish with commercial
value and a wide geographic distribution. Though some reports based on molecular and/or
morphological data exist, a comprehensive effort to establish species identity across its
range is lacking. In order to address this issue and especially to ascertain whether the
wide-spread distribution has resulted in bifurcation of the species, we collected Asian
seabass samples from various locations representing the Western and Eastern Coastline
of India, Andaman and Nicobar Islands, Bangladesh and Australia. Samples from Malaysia,
Indonesia, Thailand and Singapore were collected as part of a previous study. DNA
sequence variations, including cytochrome c oxidase subunit 1 (COI), 16S rDNA and the
highly variable D-loop (or control region), were examined to establish species delineation.
Data from all the sequences analyzed concordantly point to the existence of at least two
distinct species—one representing the Indian subcontinent plus Myanmar, and a second,
representing Southeast Asia (Singapore, Malaysia, Thailand and Indonesia) plus Northern
Australia. These data are useful for conservation ecology, aquaculture management,
for establishing the extent of genetic diversity in the Asian seabass and implementing
selective breeding programs for members of this species complex
Unusual mass shoreward movement of bivalve (Mollusca) Donax scortum Linnaeus along the coastal waters off Calicut - South Eastern Arabian Sea
67-72Eutrophication and oxygen depletion are the major factors influencing the responses of benthic organisms in coastal ecosystems. Along the coastal waters of South Eastern Arabian Sea a mass shoreward movement of bivalve Donax scortum (locally referred as “eranthu”) occurred during end phase of summer monsoon upwelling. Possible reasons for this shoreward movement points to the low dissolved oxygen (0.25 ml L-1) in the bottom waters. Intense blooms of large dinoflagellate species, Noctiluca scintillans were observed a week prior to this event along these coastal waters and the crashing related decaying might have resulted in lower DO values in the region. The study discuss on the deleterious effects of hypoxic conditions caused by summer monsoon algal blooms on benthic fauna of South Eastern Arabian Sea
Spatio-temporal variation of microphytoplankton in the upwelling system of the south-eastern Arabian Sea during the summer monsoon of 2009**This investigation was conducted under the Marine Living Resources Programme funded by the Ministry of Earth Sciences, Government of India, New Delhi.
AbstractThe phytoplankton standing crop was assessed in detail along the South Eastern Arabian Sea (SEAS) during the different phases of coastal upwelling in 2009. During phase 1 intense upwelling was observed along the southern transects (8°N and 8.5°N). The maximum chlorophyll a concentration (22.7mgm −3) was observed in the coastal waters off Thiruvananthapuram (8.5°N). Further north there was no signature of upwelling, with extensive Trichodesmium erythraeum blooms. Diatoms dominated in these upwelling regions with the centric diatom Chaetoceros curvisetus being the dominant species along the 8°N transect. Along the 8.5°N transect pennate diatoms like Nitzschia seriata and Pseudo-nitzschia sp. dominated. During phase 2, upwelling of varying intensity was observed throughout the study area with maximum chlorophyll a concentrations along the 9°N transect (25mgm−3) with Chaetoceros curvisetus as the dominant phytoplankton. Along the 8.5°N transect pennate diatoms during phase 1 were replaced by centric diatoms like Chaetoceros sp. The presence of solitary pennate diatoms Amphora sp. and Navicula sp. were significant in the waters off Kochi. Upwelling was waning during phase 3 and was confined to the coastal waters of the southern transects with the highest chlorophyll a concentration of 11.2mgm−3. Along with diatoms, dinoflagellate cell densities increased in phases 2 and 3. In the northern transects (9°N and 10°N) the proportion of dinoflagellates was comparatively higher and was represented mainly by Protoperidinium spp., Ceratium spp. and Dinophysis spp
Successful transportation of wild stock of endangered "Thooli" (Labeo dussumieri) spawners without anaesthetics
Several problems are encountered during transportation of fishes from wild to
captivity. The note describes successful transportation of wild caught endangered
Labeo dussumieri spawners over distances below 100 km without anesthesia or
sophisticated transporting devices which is of immense help in the gene banking
programme of endangered species
Variabilities in the community structure of phytoplankton in the upwelled and non-upwelled waters of southeastern Arabian Sea during the early summer monsoon
542-549The community structure of microphytoplankton was assessed along the southeastern Arabian Sea during the early phase of the summer monsoon. The study records an intense coastal upwelling along the southernmost region (off Thiruvananthapuram), which decreased further north. High chlorophyll-a (10.8 mg m-3) and nutrient concentration was recorded in the coastal waters of Thiruvananthapuram. Even though off Mangalore (12° N) and off Goa (15° N) where upwelling was confined to narrow coastal zone, also showed high chlorophyll-a concentration, 3.98 mg m-3 and 6.31 mg m-3, respectively. The upwelled waters were dominated by centric diatoms (Thalassiosira sp.) and the non-upwelled waters (12° N and 15° N) were dominated by dinoflagellates. Microphytoplankton cell density was the highest along off Thiruvananthapuram (4.8×104 cells L-1), with maximum cell density along the coastal waters (1.4×104 cells L-1). Phytoplankton community of upwelled and non-upwelled waters showed significant variations with 60 % similarity between phytoplankton communities of upwelled waters
Ecosystem Responses in the Distribution of Black Clam (Villorita cyprinoides) Beds in Vembanad Estuary during Environmental Changes Using GIS and RS
The biomass and distribution of black clam (Villorita cyprinoides) in Vembanad,
a tropical estuary located along the southwest coast of India varied significantly.
Sampling was done in freshwater-dominated zone in the south
(distal) and brackish water zone in the north (proximal), during pre and post
monsoon seasons. Clam biomass was estimated from samples, collected from
different stations during the study period. Water transparency and temperature
were measured at the sample sites. Water samples were collected and
analysed for salinity, dissolved oxygen (DO), pH and hardness. There was a
significant difference in the clam biomass during the two seasons in the distal
zone, and those collected from the distal and proximal zones during premonsoon
season. The data were further analysed to determine the factors affecting
the clam biomass distribution in the two zones and seasons. Factor
analyses, comparing the distal zone during two seasons and zonal variations
were similar to earlier observations. Step wise regression analyses found that
dissolved oxygen (adjusted R2 = 0.3) is the only variable affecting clam survival
during pre-monsoon period in the distal and proximal zones. A geographic
map of the region obtained from the Indian satellite sensor LISS
(Linear Image Self Scanner) was used along with in situ data to map the results
using inverse distance weightage model
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