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. 

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. 

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 Impact of Climate Change on Past Indian Monsoon and Circulation: A Perspective Based on Radiogenic and Trace Metal Geochemistry

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 330
Author(s):  
Harunur Rashid ◽  
Yang Wang ◽  
Alexandra T. Gourlan
Keyword(s):  
Indian Ocean ◽  
Bay Of Bengal ◽  
Indian Subcontinent ◽  
North Indian Ocean ◽  
Sea Surface ◽  
Andaman Sea ◽  
Northern Indian Ocean ◽  
Hafnium Isotopes ◽  
Neodymium Isotopes ◽  
The Last Glacial

The Indian summer monsoon (ISM), one of the dramatic illustrations of seasonal hydrological variability in the climate system, affects billions of lives. The ISM dominantly controls the northern Indian Ocean sea-surface salinity, mostly in the Bay of Bengal and the Andaman Sea, by the Ganga-Brahmaputra-Meghna and Irrawaddy-Salween rivers outflow and direct rainfall. In the past decade, numerous studies have used radiogenic neodymium (εNd) isotopes of seawater to link Indian subcontinent erosion and the ensuing increase in discharge that results in changes in the north Indian Ocean sea surface. Here we synthesized the state of the ISM and ocean circulation using the neodymium and hafnium isotopes from north Indian Ocean deep-sea sediments. Our data suggest that the Bay of Bengal and north Indian Ocean sea-surface conditions were most likely modulated by changes in the ISM strength during the last glacial-interglacial cycle. These findings contrast to the hypothesis that suggests that the bottom water neodymium isotopes of the northern Indian Ocean were modulated by switching between two distant sources, namely North Atlantic Deep Water and Antarctic bottom water. Furthermore, the consistency between the neodymium and hafnium isotopes during the last glacial maximum and Holocene suggests a weak and dry ISM and strong and wet conditions, respectively. These data also indicate that the primary source of these isotopes was the Himalayas. Our results support the previously published paleo-proxy records, indicating weak and strong monsoons for the same periods. Moreover, our data further support the hypothesis that the northern Indian Ocean neodymium isotopes were decoupled from the global ocean neodymium budget due to the greater regional influence by the great Ganga-Brahmaputra-Meghna and Irrawaddy-Salween discharge draining the Indian subcontinent to the Bay of Bengal and the Andaman Sea.

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.

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 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.

scholarly journals Deoxygenation in Marginal Seas of the Indian Ocean

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 &lt; 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.

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

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

Zootaxa ◽  
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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