Population structure, phylogeography and demographic history of Tenualosa ilisha populations in the Indian Ocean region inferred from mitochondrial DNA sequence variation

Maritime security is a broad and vague area, though it could be defined as the security dealing with the prevention of illicit activities in the maritime domain. Indian Ocean has become multifaceted and dynamic. Indian Ocean regional maritime security has become a key factor as the Indian Ocean Region transitions from an international backwater, a mere route for maritime trade, to a major global nexus of resource, human, economic and environmental issues. The Indian Ocean Region contains a large proportion of the world's failed and failing states, including 11 of the 20 states listed in Foreign Policy Journal 's 2009 article 'The Failed State Index'. 2 The non-traditional threats to security comprise threat of non-state actors. The trafficking of narcotics, weapons and people continues to be a great concern. The likelihood of terrorist attack has become a major concern. Although terrorist attacks on shipping remain relatively low, the threat of terrorism must be viewed as credible. Any major attack can easily disrupt global economy. Maritime security concerns in the Indian Ocean continue to be dominated by piracy and armed robbery at sea, especially hijacking of merchant vessels. Therefore, maritime security in the Indian Ocean Region is an apt model of Buzan and Weaver's 'regional security complex', that is, a group of states united by common security problems of the region. 3Geographically, the Indian Ocean is the third-largest ocean in the world, covering 68.556 million sq. km or 20 per cent of the earth's water surface. 4 Broadly, it has been bounded by India in its north; Africa in its west; Thailand, the Malay Peninsula, Indonesia, Malaysiaand Australia in its east; and Antarctica in its south. The Indian Ocean also embraces many seas like Arabian Sea, Bay of Bengal, Andaman Sea, the Gulf of Mannar and the Gulf of Oman. The major ports in the Indian Ocean are Chennai, Colombo, Durban, Jakarta, Kolkata, Melbourne, Mumbai and Richards Bay. 5 There are several choke points in the Indian Ocean such as the Mozambique Channel, the Bab-elMandeb, the Suez Canal, the Strait of Hormuz, the Malacca Strait and the Lombok Strait. 6 According to Michel and Sticklor, 38 states have influence over the Indian Ocean Region. Some of the 38 states are Australia, Bahrain, Bangladesh, Comoros, Maldives, Mauritius, Mozambique, Myanmar, Oman, Pakistan, Qatar, Sri Lanka, Sudan, Tanzania, Thailand, United Arab Emirates and Yemen. France and United Kingdom are also included because of their island territories. 7 These countries draw 40 per cent of the world's total coastlines. In 2010, the population of Indian Ocean Region comprises almost onethird, that is 35.70 per cent, of the world's total population while the average Human Development Index of this region is only 0.597 in comparison to the world average of 0.682. Looking at the brief history of the Indian Ocean, one can say that the Indian Ocean has been a significant route, making it accessible for traders from the worldwide. The western Indian Ocean was dominated by the Persians from the third century to the seventh century while the Arabs dominated the northeastern part of the Indian Ocean from seventh century to the fourteenth century. The Arabs occupied the coastline of East Africa, the north-western coastline of India and Southeast Asia. Rais is of the view that the neglect of the naval strategy by the Arabs led European traders to enter the Indian Ocean. 8The Portuguese came with the aim to monopolize over the Asian trade, especially in spices. The Portuguese occupied Colombo, Socotra, Goa and Melaka, but by the end of the sixteenth century, the Dutch started occupying most of the Portuguese domains. The Dutch formed the United East India Company in 1602 to promote the eastern trade. It is said that Spain's occupation of Portugal in 1580 and religious intolerance and lack of commercial associations in Portugal led to weaken Portugal, while newly discovered Brazil diverted its focus from the Indian Ocean. Because of the lack of resources, the Dutch failed in effectively controlling the region. The war with England and alteration in Dutch colonial policies led Dutch to lose their domination to the British and the French in the seventeenth century. The English established the East India Company in 1601, while the French East India Company was established in 1604. The Indian Ocean has been called 'British Lake'. 9By the end of the Second World War, almost all the countries of Indian Ocean area got independence from the colonial domination. However, following the Cold War between the two superpowers, the United States and the USSR, the Indian Ocean occupied centre stage in the foreign policies of the super power because of their strategic and economic interest in the region. Chomsky argued that the United States is interested in the region because of its oil reserves. However, the Cold War reached the Indian Ocean in the 1960s and 1970s. Both the United States and the USSR tried to install their naval bases and submarines in the Indian Ocean. The United Nations declared the Indian Ocean as the zone of peace in 1971. Bouchard and Crumplin argued that the India-Pakistan war of 1971, Israel-Palestine war of 1973, Gulf oil crisis in 1973 and 1979, the Indian nuclear test in 1974, the invasion of Afghanistan by the Soviet and the Iran-Iraq war in 1980s gave Indian Ocean a geostrategic importance. After the end of Cold War, the United States intervened in Iraq-Kuwait war in 1991. The US invasion of Afghanistan in 2001 and the military intervention in Iraq in 2003 brought instability to the region. The war between the Sri Lankan government and the Liberation Tigers of Tamil Eelam (LTTE) from 1983 to 2009 also brought turmoil to the region. It is argued that India is a great power in the Indian Ocean Region while China is also gradually proving its presence in the region. 10Maritime rights of the nations are enshrined in the United Nations Convention on the Law of the Sea (UNCLOS), but these rights are sometimes in conflict with their strategic interests. The Indian Ocean Region has now turned into a multidimensional and dynamic region; however, it was neglected for a long time. Venkatshamy is of the view that Indian Ocean has an increasingly important role to play in the geopolitics in the coming times. Forty-eight out of 63 ports in Asia are located in the Indian Ocean Region. By 2013, it has become the pivot of trade and energy as the region has 61 per cent of total global container traffic besides 70 per cent of the petroleum products transportation. 11 The Malacca Strait is the major shipping route between the Indian Ocean and the Pacific Ocean, connecting Asia, Middle East and Europe. The 550-mile strait is a vital choke point in the Indian Ocean as more than 50,000 merchant ships travel by the waterways every year. 12 'If Straits get blocked, almost half of the world's fleet would need to reroute through the Sunda or Lombok Straits.' 13 The strategic importance of the Indian Ocean Region has made many extra-regionalstates to keep a naval presence in the Indian Ocean. 14 It is said that most of the armed conflicts are located in the Indian Ocean Region. According to Venkatshamy, 45 per cent of the world's conflicts (such as Palestine and Israel, Iraq, Iran and Afghanistan) and 75 per cent of the world natural disasters occur in the Indian Ocean Region. 15The region is said to be very rich in the natural resources like gold, tin, uranium, cobalt, nickel, aluminium and cadmium. It is estimated that the region contains almost 55 per cent of recognized oil reserves and around 40 per cent of gas reserves. According to Berlin, in 2011, 40 per cent of trade in oil transports passed through the Strait of Hormuz, 35 per cent through the Strait of Malacca and 8 per cent through Bab-el-Mandeb Strait. Most of the energy exports from the five major world oil producers pass the narrow route of the Indian Ocean. 16 It is argued that the growing interest of the Gulf Cooperation countries in the Indian Ocean is because of the gradual increase in the consumption of energy by India and China. It is argued that countries like the United States, China, India and Japan are increasingly depending on energy supplied by Saudi Arabia, Russia, Qatar, Kuwait and Iran, making Indian Ocean Region more and more important in the coming decades or rather century. 17Besides its economic importance, Indian Ocean Region also has military significance. The island of Diego Garcia has been a major airnaval base of the United States in the Indian Ocean. The United States has also installed some major naval task forces such as Combined Task Force 152 and Combined Task Force 150, while France has its naval bases installed in Djibouti, Reunion and Abu Dhabi. China has commercial ports at Hambantota in Sri Lanka and Gwadar in Pakistan. Port construction by the Chinese is also under way in Myanmar and Bangladesh. It is argued that Marao Atoll in Maldives is among potential Chinese military bases.

In this study, we analyzed mitochondrial COI gene sequences to reveal genetic diversity, population structure and demographic history of two Bangladeshi (BD) populations (SB and CK) of the orange mud crab Scylla olivacea of the Northern Bay of Bengal (BoB), and compared these two with other four populations in the Northern Indian Ocean region (Arabian Sea, Andaman Sea and Malacca strait) and South China Sea. For all of the populations, nucleotide diversities were low (0.005–0.01) while the haplotype diversities were as high as 0.70–0.96, indicating that the S. olivacea has undergone a recent population expansion after experiencing bottleneck. The pairwise population statistics (FST) revealed that no genetic variation was made between SB and CK populations of BD in BoB. However, these two BoB populations showed separate genetic structure with each of the Andaman Sea (Myanmar coast, MM) and Malacca strait (West coast of Malaysia, MS) populations. On the other hand, two BoB populations did not form separate genetic structure from the population of Arabian Sea (AS). Larval dispersal-based migration by the East and West India coastal currents probably caused this genetic homogeneity between BoB and AS populations.The MM population had separate genetic structure from all of the populations studied in the present study. The Hierarchical analysis of molecular variance (AMOVA) revealed four large population groups of S. olivacea within its distribution range in the Indo-west Pacific region namely, Arabian Sea, Bay of Bengal, Andaman Sea and South China Sea groups. Some geographical barriers (e.g. Indian peninsula, Andaman and Nicobar Islands) along with seasonally formed marine gyres in the Andaman Sea are responsible for separate genetic structure among different populations and also for establishing four population groups. Star-shaped patterns of haplotype network and neutrality test corroboratethe recent population expansion of all populations except MM and CK. Mismatch distribution analysis reveals that the demographic expansion of the species started during the late Pleistocene period approximately 125,000 to 365,000 years ago. These results will help to establish the conservation and management strategy for orange mud crab in the Northern Indian Ocean region including the Bay of Bengal.
 J. of Sci. and Tech. Res. 4(1): 101-118, 2022

The NOAA Geophysical Fluid Dynamics Laboratory three‐dimensional Global Chemical Transport Model (GFDL GCTM) is used to examine the winter‐spring evolution of pollution (fossil fuel combustion and biomass burning) from South and Southeast Asia with special focus on the Indian Ocean region. We find that during the monsoonal winter‐spring outflow, pollution over the Indian Ocean north of the ITCZ is concentrated in the maritime boundary layer and originates from both regions. South Asian emissions dominate over the Arabian Sea and the Western Indian Ocean, while the Southeast Asian emissions have the greatest impact over the Bay of Bengal and Eastern Indian Ocean. Over these oceanic regions, CO pollution in both source regions, most of which is from biomass burning, accounts for 30–50% of the boundary layer CO. It is transported equatorward from South and Southeast Asian source regions and episodically lofted into the upper troposphere by tropical convection events. This transport path has a noticable impact (10–20%) on total CO at 300 mb and produces a maximum in a tropical belt over and north of the ITCZ. Another free troposphere transport path, primarily open to Southeast Asian emissions, carries CO from that region out over the North Pacific and around the Northern Hemisphere. O3 production is driven by NOx, which, unlike CO, comes almost equally from biomass burning and fossil fuel combustion in this region and has a chemical lifetime of a few days or less. The resulting NOx distributions, while qualitatively similar to CO, have much steeper gradients, are transported much less widely, have a much lower background, and over the Indian and Pacific Oceans, are strongly dominated by pollution. O3 resulting from these anthropogenic sources generally exhibits patterns similar to those found for CO and NOx. Pollution accounts for 20–50% of the near‐surface O3 and 5–10% of the O3 in the upper troposphere. South and Southeast Asian emissions only produce 25% of the boundary layer O3 in the continental source regions. The maximum impact of the emissions occurs over the Indian Ocean (25–40%) with comparable contributions from O3 produced in the continental emission regions and O3 produced over the ocean by transported precursors. Convective lifting of the transported pollution O3 supplies ∼10% of the O3 in the tropical upper troposphere. While both emission regions have modest impacts on O3 (5–10%) outside of the Indian Ocean region, Southeast Asian pollution impacts free troposphere O3 in a midlatitude belt across the North Pacific, similar to NOx.

ABSTRACTThis study investigates inter‐dependency between various wave parameters. It includes the mean wave direction (MWD), swell MWD, wind direction, maximum significant wave height (MSWH), resultant of wind direction and swell MWD, mean wave period (MWP), and peak wave period (PWP) using daily data from altimeter measurements, European Centre for Medium‐Range Weather Forecasts (ECMWF) Re‐Analysis Interim (ERA‐Interim), and ERA‐20C datasets in a changing climate for the past two decades in Indian Ocean region. It also examined the variability in monthly anomalies using linear circular correlation maps. The analysis used quality checked and well calibrated altimeter data from eight satellite missions for MSWH, and WAM (wave model) output from ERA‐Interim and ERA‐20C datasets for other variables. Spatial variability of correlation coefficient maps explained their inter‐dependency. Directional statistics methods explain the directional wave characteristics. Correlation maps signify that regions over the western sectors of Indian Ocean and Bay of Bengal are swell dominant. Over these regions the swell MWD clearly dominated the total MWD (combined effects from wind‐sea and swells). For regions in Arabian Sea, the resultant of wind direction and swell MWD contributed about 91%, whereas contribution from swell MWD alone is about 86%. The variability in monthly anomaly MSWH exhibited a specific pattern that resembles the movement of synoptic systems from Southern Ocean propagating north‐eastwards reaching various destinations in the Bay of Bengal basin, having a strong positive correlation with MWD and swell MWD. Over the tropical South Indian Ocean (TSIO) region, the obtained feature correlates with the surface current pattern of Agulhas retroflection. These patterns are distinctly visible in the correlation maps between MSWH and resultant of wind direction and swell MWD as well wind direction monthly anomaly maps. For the North Indian Ocean an out of phase relation exists between the variability of MWSH with PWP monthly anomalies.

Are Indian mackerel (Rastrelliger kanagurta) populations in the eastern Indian Ocean truly homogeneous? Insights from geometric morphometric analysis

Griffin, D. J. G. Spider Crabs (Crustacea: Brachyura: Majidae) from the International Indian Ocean Expedition, 1963-1964. Smithsonian Contributions to Zoology, number 182, 35 pages, 8 figures, 6 tables, 1974.—Spider crabs were collected by the RV Anton Bruun from 52 stations in the Andaman Sea, Bay of Bengal, Arabian Sea, and western Indian Ocean from Natal to the Gulf of Aden. Specimens from seven stations worked by the Te Vega in the Andaman Sea, Indonesia, and western Pacific, and shore collections made at Madagascar and the islands to the north and at Cocos (Keeling) Island in the eastern Indian Ocean are also dealt with. A total of 56 species belonging to 30 genera are reported on. Fifty-two of the species were collected by the Anton Bruun and the 32 species collected at 28 stations in the western Indian Ocean represent just over one-third of the total number of majid spider crabs from that area. The collections were taken mainly on the upper part of the continental shelf, but six species were collected at depths exceeding 200 meters. Basic references, descriptive notes, and a summary of the geographic distribution are given for each species. Achaeus curvirostris (A. Milne Edwards), new combination, and Hyastenus ovatus (Dana) are shown to be senior synonyms of A. fissifrons (Haswell) and Hyastenus tenuicornis Pocock, respectively, and Naxia mamillata Ortmann, a junior synonym of Naxioides rohillardi Miers. In addition, Doclea tetraptera Walker is confirmed as a junior synonym of D. calcitrapa White, Eurynome longimana Stimpson of E. aspera (Pennant) and PseudocoUodes complectens Rathbun of Inachus dorsettensis (Pennant). Barnard's Macropodia formosa var is identified as M. intermedia Bouvier. These last three species, previously known from the east Atlantic and South Africa, are recorded from east Africa for the first time. Chlorinoides tosaensis Sakai and Majella hrevipes Ortmann, previously known from Japan, and Oncinopus neptunus Adams & White ( = O. aranea auct. in part) and Simocarcinus obtusirostris Miers from the western Pacific are recorded from the Indian Ocean for the first time. The majority of the species collected are widely distributed Indo-West Pacific ones. OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. SI PRESS NUMBER 5136. SERIES COVER DESIGN: The coral Montastrea cavernosa (Linnaeus). Library of Congress Cataloging in Publication Data Griffin, D. J. G. Spider crabs (Crustacea: Brachyura: Majidae) from the International Indian Ocean Expedition, 1963-1964. (Smithsonian contributions to zoology, no. 182) Supt. of Docs.: SI 1.27: 182. 1. Majidae. 2. International Indian Ocean Expedition, 19623. Crustacea—Indian Ocean. I. International Indian Ocean Expedition, 1962II. Title. III. Series: Smithsonian Institution. Smithsonian contributions to zoology, no. 182. QL1.S54 no. 182 [QL444.M33] 591'.08s [595'.3842] 74-6395 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 • Price 85 cents, GPO Bookstore

Climate Change and Tropical Cyclone Activity.- A Climatology of Intense Tropical Cyclones in the North Indian Ocean Over the Past Three Decades (1980-2008).- Tropical Cyclones in a Hieararchy of Climate Models of Increasing Resolution.- Modeling Climate Change: Perspective and Applications in the Context of Bangladesh.- Changes in Tropical Cyclone Precipitation Over China.- Toward Improved Projection of the Future Tropical Cyclone Changes.- Global Warming and Tropical Cyclone Activity in the Western North Pacific.- Tropical Cyclones and Climate Change: An Indian Ocean Perspective.- Recent Trends in Tropical Cyclone Activity in the North Indian Ocean.- Progress on Tropical Cyclogenesis.- Generating Synthetic Tropical Cyclone Databases for Input to Modeling of Extreme Winds, Waves, and Storm Surges.- Numerical Simulation of the Genesis of Cyclone Nargis Using a Global Cloud-System Resolving Model, NICAM.- Simulation of the North Indian Ocean Tropical Cyclones Using the Regional Environment Simulator: Application to Cyclone Nargis in 2008.- Simulation of Track and Intensity of Gonu and Sidr with WRF-NMM Modeling System.- Operational Tropical Cyclone Forecasting & Warning Systems.- Monitoring and Prediction of Cyclonic Disturbances Over North Indian Ocean by Regional Specialised Meteorological Centre, New Delhi (India): Problems and Prospective.- Evaluation of the WRF and Quasi-Lagrangian Model (QLM) for Cyclone Track Prediction Over Bay of Bengal and Arabian Sea.- Simulation of Tropical Cyclones Over Indian Seas: Data Impact Study Using WRF-Var Assimilation System.- Impact of Rain-Affected SSM/I Data Assimilation on the Analyses and Forecasts of Tropical Cyclones, and Study of Flow-Dependent Ensemble Background Errors, Over the Southwest Indian Ocean.- Statistical Forecasting of Tropical Cyclones for Bangladesh.- THORPEX and Its Application for Nargis by Ensemble Prediction.- Cyclone Gonu: The Most Intense Tropical Cyclone on Record in the Arabian Sea.- Real-Time Prediction of Cyclone Over Bay of Bengal Using High-Resolution Mesoscale Models.- Performance Evaluation of DGMANs NWP Models During Gonu.- Capabilities of Using Remote Sensing and GIS for Tropical Cyclones Forecasting, Monitoring, and Damage Assessment.- Assessment of Risk and Vulnerability from Tropical Cyclones, Including Construction, Archival and Retrieval of Best-Track and Historic Data Sets.- On Developing a Tropical Cyclone Archive and Climatology for the South Indian and South Pacific Oceans.- Improving the Australian Tropical Cyclone Database: Extension of the GMS Satellite Digital Image Archive.- Coastal Vulnerability Assessment Based on Historic Tropical Cyclones in the Arabian Sea.- The International Best Track Archive for Climate Stewardship (IBTrACS) Project: Overview of Methods and Indian Ocean Statistics.- Remote Sensing Imagery Assessment of Areas Severely Affected by Cyclone Gonu in Muscat, Sultanate of Oman.- Urban Sprawl and City Vulnerability: Where Does Muscat Stand?.- Flood Studies in Oman and the Difficulties in Using Rainfall-Runoff Analysis.- Disaster Preparedness, Management and Reduction.- Cyclone Gonu Storm Surge in the Gulf of Oman.- How the National Forecasting Centre in Oman Dealt with Tropical Cyclone Gonu.- Cyclone Disaster Management: A Case Study of MODES Experience with Cyclone Gonu.- Recent High Impact Tropical Cyclone Events in the Indian Ocean: Nargis, SIDR, Gonu and Other Events.- The Impact of Cyclone Gonu on Selected Coral Rich Areas of the Gulf of Oman Including Indications of Recovery at the Daymanyiat Islands.- Cyclone Nargis Storm Surge Flooding in Myanmar's Ayeyarwady River Delta.- The First Ever Super Cyclonic Storm GONU over the Arabian Sea During 1-7 June 2007: A Case Study.- Characteristics of Very Severe Cyclonic Storm NARGIS over the Bay of Bengal During 27 April to 3 May 2008.- Characteristics of Very Severe Cyclonic Storm SIDR over the Bay of Bengal During 11-16 November 2007.- Influence of a Tropical Cyclone Gonu on Phytoplankton Biomass (Chlorophyll a) in the Arabian Sea.- Recent Outbreaks of Harmful Algal Blooms Along the Coast of Oman: Possible Response to Climate Change?.- Understanding the Tropical Cyclone Gonu.

The TRMM Microwave Imager (TMI) is relatively unaffected by the presence of clouds, so the TMI provides excellent data sets for sea surface temperature (SST), sea surface wind speed (SWS) and total precipitable water vapour (TWV) over the Indian Ocean basin during the summer monsoon regime. We show here that rainfall peak in the month of July during the Indian summer monsoon is related to the unexpected inter‐annual and intra‐seasonal variability of SST over the Arabian Sea (AS) and South Central Indian Ocean in the months of April and May. There was a shift of mean convective heat source (SST>30°C) from the Western Indian Ocean (WIO) to the Central Equatorial Indian Ocean in April during deficient rainfall years (2002 and 2004). In May this convective source moved north to the Arabian Sea in 2003, (AS)/Bay of Bengal (BB) in 1998, whereas it moved to the Bay of Bengal in 2002 and 2004. The years 2002 and 2004 were below normal monsoon years (drought) with total seasonal rainfall being 71 cm and 76 cm respectively, whereas 1998 and 2003 were above normal monsoon years with total seasonal rainfall being 92 cm and 90 cm respectively. The gradual onset of monsoon (early start, slow growth to full strength), as in the case of 2004 or multiple onset (early start, then a lull and resumption to full strength) as in the case of 2002 (Simon et al.2006), especially in the beginning of May and subsequent upwelling, led to Arabian Sea cooling. This also resulted in reducing the convection in subsequent months and influenced the overall circulation patterns over the Indian subcontinent. The vertical winds (NCEP) averaged over the Arabian Sea in May show there is convection and cooling instead of the normal subsidence (0.5 Pa/s) for the years 2002 and 2004. The wind circulation at 200 hPa in May 2002 and 2004 shows a shift of its ridge position from its normal position of 50° E to 60° E (10° longitude) in 2002 and 2004. This may be a response to the shift in the convective heat source, resulting in reduced movement of depression from the Bay of Bengal. The shifting of the convective source would have resulted in shifting of the Walker circulation pattern 10° east of its normal position.

A relationship between sea surface temperature (SST) and surface nitrate concentrations has been obtained for the first time based on in situ datasets retrieved from U.S. JGOFS (1991–96) and Indian cruises (2000–2006) in the Arabian Sea, Bay of Bengal and Indian Ocean region around the southern Indian tip. The dataset includes 1537 points. A sigmoid relationship obtained with value 0.912. NOAA-AVHRR pathfinder satellite monthly averaged SST data retrieved from the PODAAC/JPL/NASA archive during July 1999–June 2004. The datasets imported in the ERDAS-Imagine software and SST images generated on monthly and seasonal scales, for latitudes 5–12°N and longitudes 75–85°E. The ocean surface nitrate images retrieved based on the established sigmoid relationship with SST. The nitrate concentrations ranged between 0.01–3.0 μM and categorized into five ranges. The significant seasonal upwelling zone around the southwest coast of India (Kerala coast, Latitude 80.10–9.30°N and Longitude 75.60–76.20°E) was identified during July–September 1999–2004 with very high nitrate concentration (~1.00 μM). Low nitrate and nitrate-depleted zones observed during summer (March–May). In the Arabian Sea and northern Indian Ocean, high nitrate concentration (~0.50 μM) observed during the southwest monsoon (SWM), whereas the Bay of Bengal was marked with high nitrate (~0.50 μM) during the northeast monsoon (NEM). SST was high (~29°C) in the Bay of Bengal and low (~26°C) in the Arabian Sea and northern Indian Ocean during SWM and vice versa during the NEM. There is a clear inverse relationship between nitrate and SST in the study area during July 1999–June 2004.

Aerosol chemical, microphysical, and optical data collected from an island station and a ship during the first field phase of the Indian Ocean Experiment provided a unique opportunity to develop models for retrieving aerosol optical depth from the advanced very high resolution radiometer (AVHRR) onboard NOAA14 during January–March 1998. Columnar aerosol optical depth (AOD) over Arabian Sea, Bay of Bengal, and Indian Ocean was derived for the 630 nm wavelength from the radiance in channel 1 (580–680 nm) of AVHRR. The satellite retrieval model for AOD accounts for several aerosol species (sulfates, nitrates, sea salt, soot, dust, and organics), the in situ measured value of single scattering albedo, and the wind speed dependence of sea surface albedo. Satellite‐retrieved AOD is in good agreement with surface measurements of AOD taken from the Indian Ocean island of Kaashidhoo (4.96°N, 73.46°E) in the Maldives and from the R/V Sagar Kanya cruising between 20°N and 20°S. The success of our model is most likely due to the use of observed single scattering albedo, the use of phase function derived from in situ data, and the limitation of the analysis to the antisolar side of the satellite scan. However, the model relies on atmospheric column data and surface measurements, which need future verification with in situ aircraft data. Regional maps reveal that the entire northern Indian Ocean has large 0.15 AOD with monthly mean values exceeding 0.2 for latitudes north of ∼5°N, for all 3 months. AOD increases northward, reaching values as high as 0.35 toward the coast in the Bay of Bengal and the Arabian Sea. The non‐sea‐salt component of AOD is inferred to be more than 3 times that of the estimated wind‐dependent sea salt component. In the western Indian Ocean and Arabian Sea the high concentration of non‐sea‐salt aerosols are due to transport from the Indian subcontinent and Arabia. The eastern Indian Ocean is influenced by the transport from the Indian subcontinent and southeast Asia, particularly from Indonesia. The 1998 El Niño‐related forest fires from Indonesia resulted in high AOD values (0.25–0.35) in the eastern equatorial Indian Ocean. Minimum AOD is observed between the equator and 10°S, which is the location of the Intertropical Convergence Zone (ITCZ) during the observation period. AOD is generally found to increase to the south of ITCZ and reach a maximum around 20°S.

Two deep-sea roughies, Hoplostethus (Leiogaster) rubellopterus Kotlyar, 1980 and H. (L.) melanopus (Weber, 1913), are re-described based on several specimens collected from the Arabian Sea, Bay of Bengal and Andaman Sea. Some notes on the taxonomic status of these two species are also included, and their distributional ranges are updated. Hoplostethus (L.) rubellopterus is a commonly occurring species in the deep-sea catches from the upper continental slope (160–800 m) of this region, which is often misidentified and reported as H. mediterraneus Cuvier, 1829. Previous reports of H. mediterraneus from Indian waters were found to be misidentifications, and should be referred to H. (L.) rubellopterus. Hoplostethus (L.) melanopus is found to be distributed in much deeper waters at bathyal depths (>900 m) of the Arabian Sea and Andaman Sea.

In terms of geographical location and natural endowments, Indian Ocean and the coastal areas naturally have the gene to become a stage for the game of world powers and a key region for the competition of interests; the Indian Ocean Region today is experiencing not only the gradual change of international architecture but also the reconstruction of maritime order in the Indian and Pacific oceans. In the twenty-first century, the Indian Ocean Region becomes increasingly important in its strategic position but it is still not the “center stage” or “strategic center” in global politics and economics; in recent years, China’s ambition towards the Indian Ocean has been growing, but that ambition is still a subordinate direction of its geo-strategy (maritime strategy). We shall have rational understanding about the geographical environment in the Indian Ocean Region and the geographical risks in China’s the Belt and Road Initiative in the Indian Ocean; the principal geographical risk for China in the Indian Ocean Region is not the security of Indian Ocean sea routes but two others: first, regionalization of structural contradictions between big powers; second, complicated and fragile geopolitical ecology in relevant Indian Ocean areas. From the perspective of geostrategic adjustments by big powers, the rise of the “Indo-Pacific” concept indicates the competition between big powers in the Indian Ocean Region becomes increasingly complicated. The US’s Indo-Pacific strategy, in particular, makes the Indian Ocean a major geo-direction in containing China, while the India’s “Maritime Doctrine” also strengthens vigilance against China’s growing presence in the Indian Ocean Region. Therefore, the geopolitical competition between big powers including the US and India are major challenges and geographical risks for China in this region. From the perspective of regional geopolitical ecology, issues like cultural conflicts, resource disputes, poverty, turbulence, territorial disputes and terrorism in the shatter belt make geopolitics in the Indian Ocean Rim complex and fragile, and geographical risks and security in this region have significant spillover effect; local turmoil and political risks with instability in relevant regions have become another main geographical risk for China. Adverse impacts of the two on China’s maintaining and expanding its strategic interests in the Indian Ocean Region go far beyond the security of Indian Ocean sea routes and unconventional security threats like the Indian Ocean pirates and regional terrorismKeywordsIndian OceanGeo-environmentGeographical risksIndo-Pacific strategyChina’s Indian Ocean strategy

With the implementation of trade protectionism by western countries dominated by the US and EU, particularly the redefinition of trade rules by the Trump administration based on the “America First” policy, over the past two years, China’s foreign trade and investment will expand into the Indian Ocean region at a faster pace, and China will become an increasingly important economic and security stakeholder in the region. Moreover, the US is shifting its strategic focus from anti-terrorism to checking “strategic rivals”, hoping the countries within the Indian Ocean region like India and Australia will assume more security responsibilities. That causes new changes to the international environment in the Indian Ocean region, and the strategic competition among powers in the Indian Ocean region is increasingly intensified. Meanwhile, instead of being eased, the instability of the security situation across the Indian Ocean shows a sign of further deterioration. In the future, the US will still be the biggest variable that affects the international environment in the Indian Ocean region, and India, as a power within the region, will become a main variable that affects the international environment in the region. Amid the changing international environment across the Indian Ocean region, China will have fast growing demand for security in the region, which will prompt China to include the Indian Ocean into its strategic vision to meet its rising economic interests and security demand in the region and ease the pressure from the strategic competition among powers. According to this report, although China is not a country in the Indian Ocean, it’s a country close to the Indian Ocean. That is to say, China is the power outside but closest to the Indian Ocean. As the economic relations between China and the countries along the Indian Ocean coast has become increasingly closer in recent years, both traditional and non-traditional security challenges are growing in the region; in particular, given the strategic importance of the Eastern Indian Ocean, which is adjacent to South China Sea, to China’s peripheral environment, actively creating the political, economic and security environment favorable to China in the Indian Ocean region will be a choice for China’s foreign strategy in the next decade or even a longer period of time. In the Indian Ocean region, China has been, is, and will always be a builder that promotes economic prosperity, a participant that develops international rules and a contributor that safeguards common security. The main objective of China’s Indian Ocean strategy is to safeguard its freedom of navigation in the Indian Ocean and ensure its security of maritime transport, and to have the capability to expand its economic interest in the Indian Ocean region. This requires China to have corresponding military defense and projection capabilities, and to play a constructive role that matches its own capabilities in the field of security governance in the Indian Ocean.KeywordsIndian Ocean strategyInternational EnvironmentStrategic GameBelt and Road Initiative

The intermediate water circulation and ventilation of the Indian Ocean is somewhat unique among the world oceans (in terms of the source waters). This has been studied with historical and recently obtained hydrographic data including potential temperature, salinity, dissolved oxygen, phosphate and silicate in a mixing model of applying optimum multiparameter analysis (OMP). The mixing model comprises three source water masses, Antarctic Intermediate Water (AAIW) (applied the transformed AAIW north of the Antarctic frontal zone and central South Indian Ocean), Indonesian Intermediate Water (IIW) and Red Sea Intermediate Water (RSIW) (including the influence of Persian Gulf Intermediate Water). A possible source from south of Australia has also been considered and accommodated into the water type definition of AAIW. This study was performed on six closely spaced neutral density surfaces which encompass the intermediate layer of the Indian Ocean from 500 m (in the northern Indian Ocean) to 1500 m (in the subtropical latitudes) with a distance of about 100-150 m between a pair of surfaces. Water-mass mixing contributions were plotted on the neutral surfaces and in three cross sections, the western Indian Ocean along 60E, the eastern Indian Ocean along 90E, and a zonal section along 10S. The intermediate water circulation and ventilation of the Indian Ocean can thus be inferred from the spreading paths and mixing patterns of these source water masses. A schematic intermediate water circulation of the Indian Ocean therefore emerges from the water-mass and dynamical information. The latter is derived from the acceleration potential (10 m 2 s -2 ) mapped on the neutral surfaces. The equatorward AAIW enters the Indian Ocean from the mid-ocean of the southern Indian Ocean, is advected with the subtropical gyre and transits to the north through the western boundary. In the western equatorial Indian Ocean, AAIW flows northeastward to eastward. At about 80E, AAIW bifurcates into northward and southward flows. The former continues into the Bay of Bengal through the western boundary (east of Sri Lanka) with up to 10% of the contribution. It returns southward in the eastern Bay of Bengal and along the Sumatra and Java Islands, zonally westward with IIW. The latter recirculates southward and then westward, forming a cyclonic gyre. The AAIW then turns southward into the Agulhas Current system through either side of Madagascar. AAIW contributes about 10-20% of its water into the equatorial Indian Ocean. Its northward flow in the western Indian Ocean is limited to 5N. IIW flows zonally westward and bifurcates into a northward and a southward flow in the western Indian Ocean. The direction of the latter is southward into the Agulhas Current system through either side of Madagascar. The former lows northward by the way of AAIW. Although AAIW does not flow into the Arabian Sea, IIW is found flowing into the Arabian Sea via the west coast of India. The main flow path of IIW into the Bay of Bengal is through the south of Sri Lanka. IIW largely contributes about 50-60% of its water into the Bay of Bengal. The northward flow of IIW is interrupted at the central equatorial region by the eastward AAIW. These circulations form two cyclonic gyres in the western and eastern equatorial Indian Ocean.

We present high-resolution sustained, persistent observations of the ocean around Sri Lanka from autonomous gliders collected over several years, a region with complex, variable circulation patterns connecting the Bay of Bengal and the Arabian Sea to each other and the rest of the Indian Ocean. The Seaglider surveys resolve seasonal to interannual variability in vertical and horizontal structure, allowing quantification of volume, heat, and freshwater fluxes, as well as the transformations and transports of key water mass classes across sections normal to the east (2014–15) and south (2016–19) coasts of Sri Lanka. The resulting transports point to the importance of both surface and subsurface flows and show that the direct pathway along the Sri Lankan coast plays a significant role in the exchanges of waters between the Arabian Sea and the Bay of Bengal. Significant section-to-section variability highlights the need for sustained, long-term observations to quantify the circulation pathways and dynamics associated with exchange between the Bay of Bengal and Arabian Sea and provides context for interpreting observations collected as “snapshots” of more limited duration. Significance Statement The strong seasonal variations of the wind in the Indian Ocean create large and rapid changes in the ocean’s properties near Sri Lanka. This variable and poorly observed circulation is very important for how temperature and salinity are distributed across the northern Indian Ocean, both at the surface and at depths. Long-term and repeated surveys from autonomous Seagliders allow us to understand how freshwater inflow, atmospheric forcing, and underlying ocean variability act to produce observed contrasts (spatial and seasonal) in upper-ocean structure of the Bay of Bengal and Arabian Sea.