Reproductive and feeding biology of unicorn leatherjacket, Aluterus monoceros from the Bay of Bengal, Northern Indian Ocean

2021 ◽  
pp. 1-13
Author(s):  
Shubhadeep Ghosh ◽  
Manas Munivenkatappa Hoshalli ◽  
Satishkumar Mamidi ◽  
Prathibha Rohit ◽  
Gopalakrishnan Achamveetil
Keyword(s):  
Indian Ocean ◽  
Bay Of Bengal ◽  
Feeding Activity ◽  
Northern Indian Ocean ◽  
Feeding Intensity ◽  
Comprehensive Information ◽  
Significant Difference ◽  
Size At Sexual Maturity ◽  
Western Bay Of Bengal ◽  
Prey Items

Abstract No prior comprehensive information on the reproductive biology and trophodynamics of Aluterus monoceros was globally available. The present study was performed on 1036 individuals landed along the western Bay of Bengal during 2017 to 2019. Length ranged between 25.3–64.4 cm in females (mean at 48.34 cm) and from 21.5–64.1 cm in males (mean at 47.83 cm). Growth was negatively allometric with no significant difference between sexes. Sex ratio (F:M) was 1.03 with variations based on sizes and months. Size at sexual maturity for females and males was 40.85 and 41.60 cm, respectively. The species spawned throughout the year with major and minor peaks during February to May and October and November. Absolute fecundity increased linearly with length and weight and ranged from 33,640 eggs to 12,39,202 eggs. Stomachs were empty or with trace amounts of food in 59.17%, part-full in 34.07% and full in 6.76% of the fishes. Stomach vacuity and fullness and predator–prey weight ratios varied with an increase in body size, implying higher feeding intensity in large-sized fishes. Feeding activity was more intense during June–August and less during the peak spawning months. The species is omnivorous and a bottom feeder. Teleosts contributed the most to the prey items (43.23% by Index of Preponderance) implying preference for carnivory. Ontogenetic shifts and seasonal variations in prey items were observed. The present study provides paramount information that can significantly contribute to the management and conservation of monacanthid stocks in northern Indian Ocean.

scholarly journals Wind-Driven Response of the Northern Indian Ocean to Climate Extremes*

2007 ◽  
Vol 20 (13) ◽  
pp. 2978-2993 ◽  
Author(s):  
Tommy G. Jensen
Keyword(s):  
Indian Ocean ◽  
Ocean Circulation ◽  
Bay Of Bengal ◽  
El Niño ◽  
Arabian Sea ◽  
El Nino ◽  
Ocean Model ◽  
La Niña ◽  
Northern Indian Ocean ◽  
La Nina

Abstract Composites of Florida State University winds (1970–99) for four different climate scenarios are used to force an Indian Ocean model. In addition to the mean climatology, the cases include La Niña, El Niño, and the Indian Ocean dipole (IOD). The differences in upper-ocean water mass exchanges between the Arabian Sea and the Bay of Bengal are investigated and show that, during El Niño and IOD years, the average clockwise Indian Ocean circulation is intensified, while it is weakened during La Niña years. As a consequence, high-salinity water export from the Arabian Sea into the Bay of Bengal is enhanced during El Niño and IOD years, while transport of low-salinity waters from the Bay of Bengal into the Arabian Sea is enhanced during La Niña years. This provides a venue for interannual salinity variations in the northern Indian Ocean.

scholarly journals Reviews and syntheses: Present, past, and future of the oxygen minimum zone in the northern Indian Ocean

2020 ◽  
Vol 17 (23) ◽  
pp. 6051-6080
Author(s):  
Tim Rixen ◽  
Greg Cowie ◽  
Birgit Gaye ◽  
Joaquim Goes ◽  
Helga do Rosário Gomes ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Indian Ocean ◽  
Nitrogen Cycle ◽  
Bay Of Bengal ◽  
Arabian Sea ◽  
Oxygen Supply ◽  
Northern Indian Ocean ◽  
Minimum Zone ◽  
Oxygen Minimum ◽  
Oxygen Concentrations

Abstract. Decreasing concentrations of dissolved oxygen in the ocean are considered one of the main threats to marine ecosystems as they jeopardize the growth of higher organisms. They also alter the marine nitrogen cycle, which is strongly bound to the carbon cycle and climate. While higher organisms in general start to suffer from oxygen concentrations < ∼ 63 µM (hypoxia), the marine nitrogen cycle responds to oxygen concentration below a threshold of about 20 µM (microbial hypoxia), whereas anoxic processes dominate the nitrogen cycle at oxygen concentrations of < ∼ 0.05 µM (functional anoxia). The Arabian Sea and the Bay of Bengal are home to approximately 21 % of the total volume of ocean waters revealing microbial hypoxia. While in the Arabian Sea this oxygen minimum zone (OMZ) is also functionally anoxic, the Bay of Bengal OMZ seems to be on the verge of becoming so. Even though there are a few isolated reports on the occurrence of anoxia prior to 1960, anoxic events have so far not been reported from the open northern Indian Ocean (i.e., other than on shelves) during the last 60 years. Maintenance of functional anoxia in the Arabian Sea OMZ with oxygen concentrations ranging between > 0 and ∼ 0.05 µM is highly extraordinary considering that the monsoon reverses the surface ocean circulation twice a year and turns vast areas of the Arabian Sea from an oligotrophic oceanic desert into one of the most productive regions of the oceans within a few weeks. Thus, the comparably low variability of oxygen concentration in the OMZ implies stable balances between the physical oxygen supply and the biological oxygen consumption, which includes negative feedback mechanisms such as reducing oxygen consumption at decreasing oxygen concentrations (e.g., reduced respiration). Lower biological oxygen consumption is also assumed to be responsible for a less intense OMZ in the Bay of Bengal. According to numerical model results, a decreasing physical oxygen supply via the inflow of water masses from the south intensified the Arabian Sea OMZ during the last 6000 years, whereas a reduced oxygen supply via the inflow of Persian Gulf Water from the north intensifies the OMZ today in response to global warming. The first is supported by data derived from the sedimentary records, and the latter concurs with observations of decreasing oxygen concentrations and a spreading of functional anoxia during the last decades in the Arabian Sea. In the Arabian Sea decreasing oxygen concentrations seem to have initiated a regime shift within the pelagic ecosystem structure, and this trend is also seen in benthic ecosystems. Consequences for biogeochemical cycles are as yet unknown, which, in addition to the poor representation of mesoscale features in global Earth system models, reduces the reliability of estimates of the future OMZ development in the northern Indian Ocean.

Description of Rhinobatos ranongensis sp. nov. (Rhinopristiformes: Rhinobatidae) from the Andaman Sea and Bay of Bengal with a review of its northern Indian Ocean congeners

Zootaxa ◽  
2019 ◽  
Vol 4576 (2) ◽  
pp. 257
Author(s):  
PETER R. LAST ◽  
BERNARD SÉRET ◽  
GAVIN J.P. NAYLOR
Keyword(s):  
Indian Ocean ◽  
Bay Of Bengal ◽  
Intraspecific Variability ◽  
Andaman Sea ◽  
Nominal Species ◽  
Northern Indian Ocean ◽  
Additional Material ◽  
Tissue Samples ◽  
New Material ◽  
Colour Morphs

A new species of guitarfish, Rhinobatos ranongensis sp. nov., is described from 5 preserved specimens, and images and tissue samples of additional material, collected from the Andaman Sea and Bay of Bengal. This species co-occurs in the eastern sector of the northern Indian Ocean with two poorly defined congeners, R. annandalei Norman and R. lionotus Norman, which have been misidentified and confused with Indo-Pacific congeners since they were first described in 1926. Norman’s species are rediagnosed based on limited new material and a re-examination of the types. In the western sector of the northern Indian Ocean, Rhinobatos annandalei has been confused in recent literature with the sympatric R. punctifer Compagno and Randall, which is represented by four primary colour morphs, including a white-spotted colour morph resembling R. annandalei. Rhinobatos punctifer also displays strong intraspecific variability and sexual dimorphism in some body dimensions. These four species of Rhinobatos have unique MtDna sequences and belong to a clade of Indo-West Pacific species that are morphologically similar. Despite the relatively small numbers of specimens available for investigation, these species exhibit some clear differences in body proportions, meristics and squamation. Rhinobatos ranongensis sp. nov. differs from its northern Indian Ocean congeners through a combination of a relatively narrow disc and mouth, high vertebral count, long snout, low dorsal fins, and being largely plain coloured. A new lectotype and a paralectotype are designated for the syntypes of R. annandalei, and the four primary colour forms of R. punctifer, the plain, white-spotted and ocellated morphs, are described and the three nominal species rediagnosed. A key is provided to the four known members of the genus in the northern Indian Ocean. 

A report on epibionts and new record of two ciliates Ephelota plana and Ephelota gigantea in the coastal waters of Bay of Bengal, Northern Indian Ocean

Symbiosis ◽  
2019 ◽  
Vol 80 (2) ◽  
pp. 217-230 ◽  
Author(s):  
Jasmine Purushothaman ◽  
Aishee Bhowal ◽  
Alfisa Siddique ◽  
Sanu V. Francis ◽  
Chelladurai Raghunathan
Keyword(s):  
Indian Ocean ◽  
Bay Of Bengal ◽  
Coastal Waters ◽  
New Record ◽  
Northern Indian Ocean

scholarly journals ΔR Correction Values for the Northern Indian Ocean

Radiocarbon ◽  
2001 ◽  
Vol 43 (2A) ◽  
pp. 483-488 ◽  
Author(s):  
Koushik Dutta ◽  
Ravi Bhushan ◽  
B L K Somayajulu
Keyword(s):  
Indian Ocean ◽  
Bay Of Bengal ◽  
Arabian Sea ◽  
Andaman Sea ◽  
Northern Indian Ocean ◽  
Northern Arabian Sea ◽  
Ocean Region ◽  
Thermocline Ventilation ◽  
Ventilation Rates ◽  
Made In

Apparent marine radiocarbon ages are reported for the northern Indian Ocean region for the pre-nuclear period, based on measurements made in seven mollusk shells collected between 1930 and 1954. The conventional 14C ages of these shells range from 693 ± 44 to 434 ± 51 BP in the Arabian Sea and 511 ± 34 to 408 ± 51 BP in the Bay of Bengal. These ages correspond to mean ΔR correction values of 163 ± 30 yr for the northern Arabian Sea, 11 ± 35 yr for the eastern Bay of Bengal (Andaman Sea) and 32 ± 20 yr for the southern Bay of Bengal. Contrasting reservoir ages for these two basins are most likely due to differences in their thermocline ventilation rates.

scholarly journals High-throughput screening of sediment bacterial communities from Oxygen Minimum Zones of the northern Indian Ocean

2019 ◽  
Author(s):  
Jovitha Lincy ◽  
Cathrine Manohar
Keyword(s):  
Indian Ocean ◽  
Bacterial Diversity ◽  
Bay Of Bengal ◽  
High Throughput Screening ◽  
Arabian Sea ◽  
Northern Indian Ocean ◽  
Oxygen Minimum Zones ◽  
Sediment Biogeochemistry ◽  
Generation Sequencing ◽  
Oxygen Minimum

Abstract. The Northern Indian Ocean host two recognized Oxygen Minimum Zones (OMZ): one in the Arabian Sea and the other in the Bay of Bengal region. The next-generation sequencing technique was used to understand the total bacterial diversity from the surface sediment of off Goa within the OMZ of Arabian Sea, and from off Paradip within the OMZ of Bay of Bengal. The dominant phyla identified include Firmicutes (33.06 %) and Proteobacteria (32.44 %) from the Arabian Sea, and Proteobacteria (52.51 %) and Planctomycetes (8.63 %) from the Bay of Bengal. Statistical analysis indicates that bacterial diversity from sediments of the Bay of Bengal OMZ is ~ 48 % higher than the Arabian Sea OMZ. Diverse candidate bacterial clades were also detected, whose function is unknown, but many of these were reported from other OMZs as well, suggesting their putative role in sediment biogeochemistry. Bacterial diversity from the present study reveals that the off Paradip site of Bay of Bengal OMZ is highly diverse and unexplored in comparison to the off Goa site of the Arabian Sea OMZ. Functional diversity analysis indicates that the relative percentage distribution of genes involved in methane, nitrogen, sulfur and many unclassified energy metabolisms is almost the same in both sites, reflecting a similar ecological role, irrespective of the differences in phylotypic diversity.

The impact of northern Indian Ocean rivers on the Bay of Bengal using NEMO global ocean model

2020 ◽  
Vol 39 (3) ◽  
pp. 45-55
Author(s):  
Atul Srivastava ◽  
Anitha Gera ◽  
Imran M. Momin ◽  
Ashis Kumar Mitra ◽  
Ankur Gupta
Keyword(s):  
Indian Ocean ◽  
Bay Of Bengal ◽  
Ocean Model ◽  
Global Ocean ◽  
Northern Indian Ocean ◽  
The Impact

scholarly journals Export fluxes of dissolved inorganic carbon to the northern Indian Ocean from the Indian monsoonal rivers

2019 ◽  
Vol 16 (2) ◽  
pp. 505-519 ◽  
Author(s):  
Moturi S. Krishna ◽  
Rongali Viswanadham ◽  
Mamidala H. K. Prasad ◽  
Vuravakonda R. Kumari ◽  
Vedula V. S. S. Sarma
Keyword(s):  
Indian Ocean ◽  
Spatial Variability ◽  
Bay Of Bengal ◽  
Arabian Sea ◽  
Chemical Weathering ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Precipitation Pattern ◽  
Freshwater Flux ◽  
Northern Indian Ocean

Abstract. Rivers are an important source of dissolved inorganic carbon (DIC) to the adjacent coastal waters. In order to examine the spatial variability in the distribution and major sources of DIC in the Indian monsoonal rivers and to quantify their export flux to the northern Indian Ocean, 27 major and medium-sized rivers were sampled during the discharge period. Significant spatial variability in concentrations of DIC (3.4–73.6 mg L−1) was observed, and it is attributed to spatial variations in the precipitation pattern, the size of rivers, pollution and lithology of the catchments. The stable isotopic composition of DIC (δ13CDIC) also showed strong spatial variability (−13.0 ‰ to −1.4 ‰) in the Indian monsoonal rivers with relatively depleted δ13CDIC values in rivers of the northwest of India (-11.1±2.3 ‰) and enriched values in the southeast of India (-3.5±2.3 ‰). Results of the linear least-squares regression models of Keeling and Miller–Tan's plots indicated that the chemical weathering of carbonate and silicate minerals by soil CO2 is the major source of DIC in the Indian monsoonal rivers. Spatial variability in the deviation of δ13CDIC from the approximated δ13C of the source may probably be due to dominant autotrophic production in rivers of the southeastern region, whereas heterotrophic decomposition of organic matter largely influences the other Indian monsoonal rivers. It is estimated that the Indian monsoonal rivers annually export ∼10.3 Tg of DIC to the northern Indian Ocean, of which the major fraction (75 %) enters into the Bay of Bengal, and the remaining fraction reaches to the Arabian Sea. This is consistent with the freshwater flux, which is 3 times higher for the Bay of Bengal (∼378 km3 yr−1) than for the Arabian Sea (122 km3 yr−1). Despite discharge from the Indian monsoonal rivers accounting for only 1.3 % of the global freshwater discharge, they disproportionately export 2.5 % of the total DIC exported by the world's major rivers. Despite rivers from the region in the southwest (SW) of India exporting DIC that is an order of magnitude lower (0.3 Tg yr−1) than the rivers from other regions of India, the highest yield of DIC was found in the rivers of the SW region of India. It is attributed to intense precipitation (∼3000 mm), favorable natural vegetation of tropical moist deciduous and tropical wet evergreen and semi-evergreen forests, tropical wet climate, high soil organic carbon, and the dominance of red loamy soils in catchments of the rivers of the SW region.

Observations on feeding habits of the common dolphinfish, Coryphaena hippurus (Linnaeus 1758) from the western Bay of Bengal

2021 ◽  
Vol 34 ◽  
pp. 24
Author(s):  
Shubhadeep Ghosh ◽  
Satishkumar Mamidi ◽  
Manas Hoshalli Munivenkatappa ◽  
Prathibha Rohit ◽  
Abdussamad Eruppakkottil Median ◽  
...  
Keyword(s):  
Bay Of Bengal ◽  
Prey Species ◽  
Niche Breadth ◽  
Feeding Habits ◽  
Weight Ratio ◽  
Primary Study ◽  
Feeding Intensity ◽  
Coryphaena Hippurus ◽  
Dietary Niche ◽  
Western Bay Of Bengal

Coryphaena hippurus is a large pelagic species and constitutes an important by-catch in drift gillnet, trolling and long-line fishing gears operated along the Bay of Bengal, northeastern Indian Ocean. The present study, first from the region, is aimed at deciphering the feeding dynamics from 1150 individuals collected from 2017 to 2019. 32.17% of the fishes had empty stomachs or was with food traces, 45.57% had partially-full stomachs and 22.26% had full stomachs. The feeding intensity was inferred through stomach filling and predator-prey weight ratio, which was higher in May and lower in January, and increasing as increase in the fish size. Coryphaena hippurus is considered a piscivorous pelagic predator as pelagic teleosts contribute more than half of the prey species. Major prey species were big-eye scad (27.3%), squid (10.3%), crabs (9.3%), Indian mackerel (7.2%), Indian scad (5.9%), whitebaits (5.7%) and sardines (5.4%). Scads and crabs were abundantly preyed during summer and winter, while clupeids and engraulids in monsoon; however, no significant variations were observed in prey composition between sizes. Trophic Level was 4.22 ± 0.15 and Levins Standardized Niche Breadth Index was 0.30. Dietary niche breadth was higher during summer (0.48) and monsoon (0.33) and in fishes measuring 60.0–74.9 cm (0.51) and below 45.0 cm (0.48) indicating generalised feeding. This primary study from Bay of Bengal is the first comprehensive report on trophodynamics for the species and would contribute to its management using trophic interactions.

Pseudanthias vizagensis, a junior synonym of Pseudanthias pillai Heemstra & Akhilesh, 2012 (Perciformes: Serranidae)

Zootaxa ◽  
2020 ◽  
Vol 4890 (1) ◽  
pp. 135-147
Author(s):  
K.V. AKHILESH ◽  
T.G. KISHORE ◽  
M. MUKTHA ◽  
M.W. LISHER ◽  
GOP P. AMBARISH ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Bay Of Bengal ◽  
Andhra Pradesh ◽  
Arabian Sea ◽  
Original Description ◽  
Junior Synonym ◽  
Andaman Sea ◽  
Northern Indian Ocean ◽  
Additional Material ◽  
Bay Of Bengal Coast

Pseudanthias vizagensis Krishna, Rao and Venu, 2017 was described from 44 specimens, collected from Visakhapatnam (Andhra Pradesh), on the Bay of Bengal coast of India, but without clear designation of a holotype. The characters used for differentiating the species from its nearest congener Pseudanthias pillai Heemstra & Akhilesh, 2012, a species currently known only from the northern Indian Ocean, were limited, poor and substantially overlapping. Examination of additional material of P. pillai from the Arabian Sea, Bay of Bengal, Andaman Sea, and comparison with the original description and images of P. vizagensis revealed that the latter is a junior synonym of P. pillai. Diagnostic characters are reviewed, additional morphological details and fresh colouration, including sexual dimorphic characters not covered in previous works are provided. 

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