Dynamics of Andaman Sea circulation and its role in connecting the equatorial Indian Ocean to the Bay of Bengal

Abhisek Chatterjee; D. Shankar; J. P. McCreary; P. N. Vinayachandran; A. Mukherjee

doi:10.1002/2016jc012300

STOMACH CONTENT OF THREE TUNA SPECIES IN THE EASTERN INDIAN OCEAN

Indonesian Fisheries Research Journal ◽

10.15578/ifrj.18.2.2012.57-62 ◽

2012 ◽

Vol 18 (2) ◽

pp. 57 ◽

Cited By ~ 1

Author(s):

Bram Setyadji ◽

Andi Bahtiar ◽

Dian Novianto

Keyword(s):

Indian Ocean ◽

Stomach Content ◽

Equatorial Indian Ocean ◽

Yellowfin Tuna ◽

Feeding Habit ◽

Andaman Sea ◽

Eastern Indian Ocean ◽

Skipjack Tuna ◽

Bigeye Tuna ◽

Fish Prey

Feeding habit of tuna in Indian Ocean has been described around Sri Lanka, Indian Waters, Andaman Sea, western Indian Ocean (Seychelles Islands), western equatorial Indian Ocean whereas the tunas feeding habit study in Eastern Indian Oceanis merely in existence. The purpose of this study is to investigate the stomach content of three tuna species (bigeye tuna, yellowfin tuna, and skipjack tuna), apex predator in the southern part of Eastern Indian Ocean. The study was conducted in March – April, 2010 on the basis of catches of commercial tuna longline vessel based in Port of Benoa. A total of 53 individual fishes were collected, consisting of bigeye tuna (Thunnus obesus), yellowfin tuna (Thunnus albacores), and skipjack tuna (Katsuwonus pelamis). Stomach specimens were collected and analyzed.Analysis was conducted on the basis of index of preponderance method. The diet of the three tuna species showed fishes as the main diet (56–82%), followed by cephalopods (squids) as the complementary diet (0–8%), and crustaceans (shrimps) as the additional diet (2–4%). Fish prey composed of 6 families i.e. Alepisauridae, Bramidae, Carangidae, Clupeidae, Engraulidae, and Scombridae.

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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 ◽

10.11646/zootaxa.4576.2.3 ◽

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.

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ΔR Correction Values for the Northern Indian Ocean

Radiocarbon ◽

10.1017/s0033822200038376 ◽

2001 ◽

Vol 43 (2A) ◽

pp. 483-488 ◽

Cited By ~ 89

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.

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Importance of wind variations and intersecting waveguides near Sri Lanka for the intraseasonal sea level variability along the west coast of India

10.5194/egusphere-egu2020-19919 ◽

2020 ◽

Author(s):

Iyyappan Suresh ◽

Jerome Vialard ◽

Matthieu Lengaigne ◽

Takeshi Izumo ◽

Muraleedharan Pillathu Moolayil

Keyword(s):

Sri Lanka ◽

Indian Ocean ◽

Sea Level ◽

Bay Of Bengal ◽

West Coast ◽

Equatorial Indian Ocean ◽

Direct Connection ◽

Local Wind ◽

The West ◽

Eastern Equatorial Indian Ocean

Remote wind forcing plays a strong role in the Northern Indian Ocean, where oceanic anomalies can travel long distances within the coastal waveguide. Previous studies for instance emphasized that remote equatorial forcing is the main driver of the sea level and currents intraseasonal variability along the west coast of India (WCI). Until now, the main pathway for this connection between the equatorial and coastal waveguides was thought to occur in the eastern equatorial Indian Ocean, through coastal Kelvin waves that propagate around the Bay of Bengal rim and then around Sri Lanka to the WCI. Using a linear, continuously stratified ocean model, the present study demonstrates that two other mechanisms in fact dominate. First, the equatorial waveguide also intersects the coastal waveguide at the southern tip of India and Sri Lanka, creating a direct connection between the equator and WCI. Rossby waves reflected from the eastern equatorial Indian Ocean boundary indeed have a sufficiently wide meridional scale to induce a pressure signal at the Sri Lankan coast, which eventually propagates to the WCI as a coastal Kelvin wave. Second, local wind variations in the vicinity of Sri Lanka generate strong intraseasonal signals, which also propagate to the WCI along the same path. Sensitivity experiments indicate that these two new mechanisms (direct equatorial connection and local wind variations near Sri Lanka) dominate the WCI intraseasonal sea level variability, with the &#8220;classical&#8221; pathway around the Bay of Bengal only coming next. Other contributions (Bay of Bengal forcing, local WCI forcing) are much weaker.We further show that the direct connection between the equatorial waveguide and WCI is negligible at seasonal timescale, but not at interannual timescales where it contributes to the occurrence of anoxic events. By providing an improved understanding of the mechanisms that control the WCI thermocline and oxycline variability, our results could have socio-economic implications for regional fisheries and ecosystems.

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Deoxygenation in Marginal Seas of the Indian Ocean

Frontiers in Marine Science ◽

10.3389/fmars.2021.624322 ◽

2021 ◽

Vol 8 ◽

Author(s):

S. Wajih A. Naqvi

Keyword(s):

Indian Ocean ◽

Oxygen Content ◽

Red Sea ◽

Bay Of Bengal ◽

Persian Gulf ◽

Oxygen Demand ◽

Andaman Sea ◽

Marginal Seas ◽

The Indian Ocean ◽

Oxygen Minimum

This article describes oxygen distributions and recent deoxygenation trends in three marginal seas – Persian Gulf and Red Sea in the Northwestern Indian Ocean (NWIO) and Andaman Sea in the Northeastern Indian Ocean (NEIO). Vertically mixed water column in the shallow Persian Gulf is generally well-oxygenated, especially in winter. Biogeochemistry and ecosystems of Persian Gulf are being subjected to enormous anthropogenic stresses including large loading of nutrients and organic matter, enhancing oxygen demand and causing hypoxia (oxygen < 1.4 ml l–1) in central and southern Gulf in summer. The larger and deeper Red Sea is relatively less affected by human activities. Despite its deep water having remarkably uniform thermohaline characteristics, the central and southern Red Sea has a well-developed perennial oxygen minimum at mid-depths. The available data point to ongoing deoxygenation in the northern Red Sea. Model simulations show that an amplified warming in the marginal seas of the NWIO may cause an intensification of the Arabian Sea oxygen minimum zone (OMZ). Increases in particulate organic carbon and decreases in oxygen contents of the outflows may also have a similar effect. In the Andaman Sea, waters above the sill depth (∼1.4 km) have characteristics similar to those in the Bay of Bengal, including an intense OMZ. As in the case of the Bay of Bengal, oxygen concentrations within the Andaman Sea OMZ appear to have declined slightly but significantly between early 1960s and 1995. The exceedingly isothermal and isohaline water that fills the deep Andaman Basin is also remarkably homogenous in terms of its oxygen content. A very slight but statistically significant decrease in oxygen content of this water also seems to have occurred over three decades preceding 1995. New information is badly needed to assess the extent of further change that may have occurred over the past 25 years. There have been some reports of coastal “dead zones” having developed in the Indian Ocean marginal seas, but they are probably under-reported and the effects of hypoxia on the rich and diverse tropical ecosystems – coral reefs, seagrasses, and mangroves – in these seas remain to be investigated.

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Seasonal prediction of cyclonic disturbances over the Bay of Bengal during summer monsoon season : Identification of potential predictors

MAUSAM ◽

10.54302/mausam.v61i4.883 ◽

2021 ◽

Vol 61 (4) ◽

pp. 469-486

Author(s):

M. MOHAPATRA ◽

S. ADHIKARY

Keyword(s):

Indian Ocean ◽

Bay Of Bengal ◽

Large Scale ◽

Monsoon Season ◽

Equatorial Indian Ocean ◽

Seasonal Prediction ◽

Reanalysis Data ◽

Scale Field ◽

Large Scale Field ◽

Cyclonic Disturbances

The cyclonic disturbances (CD) over the Bay of Bengal during monsoon season have significant impact on rainfall over India. On many occasions, they cause flood leading to loss of lives and properties. Hence, any early information about the frequency of occurrence of such disturbances will help immensely the disaster managers and planners. However, the studies are limited on the seasonal prediction of CD over the Bay of Bengal unlike other Ocean basins of the world. Hence, a study has been undertaken to find out the potential predictors during the months of April and May for prediction of frequency of cyclonic disturbances over the Bay of Bengal during monsoon season (June – September). For this purpose, best track data of India Meteorological Department and large scale field parameters based on NCEP/NCAR reanalysis data have been analyzed for the period of 1948 – 2007. The linear correlation analysis has been applied between frequency of CD and large scale field parameters based on NCEP/NCAR reanalysis data to find out the potential predictors. The large scale field parameters over the equatorial Indian Ocean, especially over west equatorial Indian Ocean and adjoining Arabian Sea (up to 15° N) should be favourable in April and May with lower mean sea level pressure (MSLP), lower geopotential heights and stronger southerlies in lower and middle levels, along with stronger northerly components at upper level for higher frequency of CD during subsequent monsoon season. Consequently, there should be increase in relative humidity (RH) and precipitable water content and decrease in outgoing longwave radiation (OLR) and temperature at lower levels over this region during April and May for higher frequency of CD during subsequent monsoon season. Comparing the area of significant correlation between frequency of CD and large scale field parameters and its stability from April to September, MSLP and geopotential heights are most influencing parameters followed by OLR, sea surface temperature, air temperature and RH at 850 hPa level.

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Cloud climatology of the Indian Ocean based on ship observations

MAUSAM ◽

10.54302/mausam.v52i3.1722 ◽

2022 ◽

Vol 52 (3) ◽

pp. 527-540

Author(s):

M. RAJEEVAN ◽

R. K. PRASAD ◽

U. S. DE

Keyword(s):

Indian Ocean ◽

Bay Of Bengal ◽

Cloud Cover ◽

Monsoon Season ◽

Equatorial Indian Ocean ◽

Enso Events ◽

Decadal Scale ◽

Low Cloud ◽

The Indian Ocean ◽

Low Cloud Cover

Surface cloud data based on synoptic observations made by Voluntary Observing Ships (VOS) during the period 1951-98 were used to prepare the seasonal and annual cloud climatology of the Indian Ocean. The analysis has been carried out by separating the long-term trends, decadal and inter-annual components from the monthly cloud anomaly time series at each 5° × 5° grids. Maximum zone of total and low cloud cover shifts from equator to northern parts of India during the monsoon season. During the monsoon season (June-September), maximum total cloud cover exceeding 70% and low cloud cover exceeding 50% are observed over north Bay of Bengal. Maximum standard deviation of total and low cloud cover is observed near the equator and in the southern hemisphere. Both total and low cloud cover over Arabian Sea and the equatorial Indian Ocean are observed to decrease during the ENSO events. However, cloud cover over Bay of Bengal is not modulated by the ENSO events. On inter-decadal scale, low cloud cover shifted from a "low regime" to a "high regime" after 1980 which may be associated with the corresponding inter-decadal changes of sea surface temperatures over north Indian Ocean observed during the late 1970s.

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Review of the Indian Ocean spikefish genus Mephisto (Tetraodontiformes: Triacanthodidae)

Zootaxa ◽

10.11646/zootaxa.4802.1.5 ◽

2020 ◽

Vol 4802 (1) ◽

pp. 82-98

Author(s):

KATHERINE E. BEMIS ◽

JAMES C. TYLER ◽

PETER N. PSOMADAKIS ◽

LAUREN NEWELL FERRIS ◽

APPUKUTTANNAIR BIJU KUMAR

Keyword(s):

Indian Ocean ◽

Bay Of Bengal ◽

East Coast ◽

Andaman Sea ◽

Micro Ct ◽

Tooth Replacement ◽

Color Photograph ◽

Replacement Pattern ◽

The Indian Ocean ◽

Ct Data

We redescribe the triacanthodid spikefish Mephisto fraserbrunneri Tyler 1966 based upon eight specimens (five newly reported herein) and the first color photographs of freshly collected specimens; these data are compared with that of the single specimen of the recently described M. albomaculosus Matsuura, Psomadakis, and Mya Than Tun 2018. Both species are found in the Indian Ocean, with M. fraserbrunneri known from the Arabian Sea off the east coast of Africa to the eastern Bay of Bengal, and M. albomaculosus confirmed only from the type locality in the Andaman Sea (a color photograph of an individual M. cf. albomaculosus from the Bay of Bengal that was not retained is also presented). We describe and diagnose the genus Mephisto and provide a key to the two species based upon all available specimens. We also provide a distribution map for both species and summarize literature records. Using micro-CT data, we show that Mephisto fraserbrunneri replaces teeth intraosseously, which suggests this tooth replacement pattern is plesiomorphic for Tetraodontiformes.

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

Zootaxa ◽

10.11646/zootaxa.4890.1.9 ◽

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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