Indian Exclusive Economic Zone Research Articles

Offshore wind energy potential along the Indian Coast considering ecological safeguards

This study focuses on assessing the offshore wind energy potential along the Indian Coast over a 10-year period (2005–2014) using high-resolution data from the simulation of the Weather Research and Forecasting (WRF) model. The predicted wind fields are utilized to identify potential sites, estimate offshore wind technical potential at different depths (ranging from 30 to 200 meters), and develop wind energy blocks within the Indian Exclusive Economic Zone. To ensure environmental protection, environmentally sensitive areas have been excluded from the offshore wind potential sites. The gross technical offshore wind potential was estimated to be 3941 GW within depths of 30–200 meters, excluding environmentally sensitive areas within the 0 to 30-m depth range. High-potential sites have been identified in the coastal states of Gujarat, Maharashtra, Kerala, and Tamil Nadu. The environmental offshore wind potential across these identified sites (feasible OWE sites) along the Indian coast is estimated at 432.34 GW within the 30 to 200-m depth range (at 140 m AGL).According to the report by the Central Electricity Authority (CEA), the predicted offshore wind power has the potential to significantly contribute to the country's total electrical power requirement for 2020–21. This study encourages exploration of offshore wind energy possibilities along the Indian coast and highlights the management challenges at suitable sites, including addressing potential conflicts between offshore wind energy development and other marine uses. The findings of this study can assist in the assessment of offshore wind resources and provide decision-makers with scientific evidence for the development of offshore wind energy in India, while also considering the management and conservation of marine ecosystems.

First Record of the Rarely Known Squat Lobster, Allomunida Magnicheles Baba, 1988 (Decapoda: Anomura: Galatheoidea: Galatheidae) from the Bay of Bengal, Northern Indian Ocean

The present study reports the rarely recorded species of the family Galatheidae, Allomunida magnicheles Baba 1988, based on material from the Indian Exclusive Economic Zone. The specimens attached to an unidentified soft coral of the genus Dendronephthya Kükenthal, 1905, were collected using a Smith McIntyre grab from the depth of 52 m in the southwestern Bay of Bengal. Previous records showed that Allomunida magnicheles was known only from the Philippines, Papua New Guinea, and New Caledonia; the present specimens greatly extend the distribution range of the species westwards to the Indian Ocean. Morphological description and intraspecific variations of A. magnicheles are provided.

Evidence of Coral Diseases, Phase Shift, and Stressors in the Atolls of Lakshadweep Islands, Arabian Sea—With Geographical Notes on Their Occurrence within the Indian EEZ and Contiguous International Waters

Photographic evidence of some important coral diseases (black band disease, black disease/Terpios hoshinota, white syndrome, pink line syndrome, pink spots, invertebrate galls, skeletal growth anomalies, tissue loss), coral competing sponges, and coral–algal phase shifts (competitive overgrowth of the seaweed Caulerpa spp. over corals and competitive scleractinian interactions such as with Halimeda spp.) have been collected during field observations in a few atolls within the Lakshadweep archipelago, Arabian Sea. Further, earlier reports of similar diseases and other stressors within the Indian Exclusive Economic Zone (EEZ) and its contiguous international waters, including the reefs of the Maldives and Sri Lanka, are highlighted and their distributional ranges are shown.

Squat lobsters of the genera Raymunida Macpherson & Machordom, 2000 and Munidopsis Whiteaves, 1874 (Decapoda: Anomura: Galatheoidea) from the Indian Exclusive Economic Zone, with descriptions of three new species

ABSTRACT We report four squat lobster species of the genera Raymunida Macpherson and Machordom, 2000 (Munididae) and Munidopsis Whiteaves, 1874 (Munidopsidae) from the Indian Exclusive Economic Zone. The genus Raymunida is recorded for the first time from Indian waters, including a new species R. shraddhanandi sp. nov. and R. vittata Macpherson, 2009 based on material from the Andaman Sea. Raymunida shraddhanandi sp. nov. differs from its closest congener R. formasanus Lin, Chan and Chu, 2004 in the armatures of the anterior branchial carapace region, antennal peduncle and third maxilliped merus, and the length of the fourth pereopod. Two new species of the genus Munidopsis, referred to the Anoplonotus group, are described from the south-western Bay of Bengal and the south-eastern Arabian Sea. Munidopsis bengala sp. nov. and M. kadal sp. nov. are distinguished from all of their allies – M. bruta Macpherson, 2007, M. shulerae Vázquez-Bader, Gracia and Lemaitre, 2014, and M. truculenta Macpherson and Segonzac, 2005 – by the unarmed dorsodistal margin of the third maxilliped merus and the relative length of the antennal peduncle, respectively. http://www.zoobank.org/urn:lsid:zoobank.org:pub:5C724556-6532-41F2-9A6E-8424CAE0F2C6

Two axiidean ghost shrimps (Crustacea: Decapoda) from India, Guyanacaris keralam sp. nov. (Axiidae) and Paragourretia galathea (K. Sakai, 2017) (Ctenochelidae).

Ghost shrimps collected from the Indian Exclusive Economic Zone by the Fishery Oceanographic Research Vessel Sagar Sampada during two cruises in the eastern (105 metres depth) and southeastern Arabian Sea (101 and 326 metres depth) were studied. One male, identified as Guyanacaris keralam sp. nov. of the Axiidae, differs from its congeners in the unique armature of the rostrum, gastric region of carapace, pleonal pleural margins, dorsal margins of cheliped fingers, ventral margin of second pereopod merus, and lateral margins of telson; the presence of corneous spines on the propodi and dactyli of third and fourth pereopods, and the relative sizes of the ocular peduncles, antennular peduncle, scaphocerite and cheliped fingers. Guyanacaris K. Sakai, 2011 is re-diagnosed based on the presence of short supraocular spine and post-cervical carina on carapace, dentate margins of first two pleonal pleura, third to fifth pleura with angular to straight posterior margins, antennal scaphocerite with mesial spine at base, and presence of male first pleopod 1. Bruceaxius thailandensis K. Sakai, 2015 is tentatively retained in Bruceaxius K. Sakai, 2011, owing to absence of mesial spine at the base of scaphocerite, tuberculate upper margins of carpus, propodus and dactylus of major cheliped, and tri-segmented appendix masculina on male second pleopod. In addition, two males, diagnosed herein as Paragourretia galathea (K. Sakai, 2017) of the Ctenochelidae, differ from the holotype female only in the relative length of the terminal antennular article and the presence of a distomedian spinule on the telson, of all the features.

Oxygen minimum zone along the eastern Arabian Sea: Intra-annual variation and dynamics based on ship-borne studies

The oxygen minimum zone (OMZ) in the eastern Arabian Sea (EAS, ∼6° to 21°N), within Indian Exclusive Economic Zone (EEZ), is mapped, for the first time, for one year through ten repeated ship-based observations between December 2017 and January 2019 at seven to ten stations along the 2000 m depth contour. On an annual basis, the OMZ (<20 µM oxygen) in the EAS varied between 60 and 1350 m; its thickness decreased from north to south. During the winter monsoon, the upper boundary of the OMZ in the north and south was deeper (150–160 m) than the central EAS (∼110 m). Consequent to the summer monsoon upwelling and resultant Ekman transport, this upper boundary shoaled to 50–70 m in the south and central EAS. In contrast, relatively weaker upwelling in the north restricted the shoaling to ∼ 110 m. The core-OMZ (<5 µM oxygen), representing the core-denitrifying zone, has been found to have a perennial southern boundary in the central EAS at ∼ 15°N, which was thinner (150–750 m) than in the north (190–1000 m). The restriction of perennial core-OMZ to the central EAS is augmented by the relatively stronger upwelling south of it during the summer monsoon; the resultant upliftment of the water column has facilitated the progression of poleward undercurrent that ventilates this region. The aeration due to this poleward undercurrent enhanced the oxygen levels of OMZ (150 to 500 m) by ∼ 5 µM between 6.5°N and 13°N, and further north it increased by ∼ 2.5 µM up to ∼ 15°N. But this core-OMZ was extended to the south up to 12°N when a weak equatorward undercurrent acted in the region during the non-monsoon seasons. The study affirms the importance of sustained ship-based studies on OMZ in the EEZs, where no autonomous observatories like Bio-Argo floats are available, as such studies are critical to assess not only the future changes in the extent and behaviour of OMZ (core-OMZ) and its consequent advection onto the western continental shelf of India developing severe hypoxic to anoxic conditions but also its implications in modifying their biogeochemistry and food chain.

Occurrence of a rare lambridiform fish, Desmodema polystictum (Ogilby, 1898) from Andaman coast of India

The present study reveals the first documented distribution record of Desmodema polystictum (Ogilby, 1898) from the Andaman coast, eastern Indian Ocean. The species is rare in nature and the knowledge regarding the taxonomy, ecology and distribution is still limited. Only few records have been come from the Indian Ocean. The study is based on a single specimen (34 cm total length) collected from the northeastern region of Andaman Islands, India. The present record of D. polystictum from Andaman waters provides greater latitude and depth distribution than previously acknowledged from the Indian Exclusive Economic zone. Along with the comparative morphometric and meristic data from previous reports, description of present specimen as well as distributional information are also provided and discussed.

First records of two species of reef-associated mantis shrimps (Crustacea: Stomatopoda) from India.

The coastal marine environments in the Indian Exclusive Economic Zone harbour a rich diversity of mantis shrimps. However, several regions have not been adequately surveyed for their stomatopod faunal composition. In this paper, we report the first records of two species, Gonodactylopsis drepanophora (de Man, 1902) and Cloridina malaccensis (Manning, 1968) from Indian waters. Samples were collected using a chain dredge deployed by the Fishery Oceanographic Research Vessel Sagar Sampada on the shallow reefs (5356 m depths) of the Andaman Sea and Bay of Bengal during AugustNovember 2019. Gonodactylopsis drepanophora was previously known only from Indonesia, and Cloridina malaccensis from Southeast Asia, New Caledonia and Madagascar.

Rare deep-water crabs (Crustacea: Decapoda) from Indian waters, with description of one new species

Deep-water brachyuran crabs collected from the Indian Exclusive Economic Zone by the Fishery Oceanographic Research Vessel “Sagar Sampada” in the southeastern Arabian Sea (50 m depth), southwestern Bay of Bengal (307 m depth), and in the vicinity of the Andaman and Nicobar Archipelagos (271-535 m depth) were studied. They are referred to Sphaerodromia kendalli (Alcock and Anderson, 1894) and Sphaerodromia nux Alcock, 1900 (family Dromiidae), Intesius brevipes sp. nov. (family Mathildellidae), Tunepugettia corbariae B.Y. Lee, Richer de Forges and P.K.L. Ng, 2019 (family Epialtidae), Cyrtomaia suhmii Miers, 1885 (family Inachidae), Chaceon alcocki Ghosh and Manning, 1993 (family Geryonidae), and Sphenomerides trapezioides (Wood-Mason, 1891) (family Trapeziidae). Sphaerodromia nux and T. corbariae are new records from Indian waters. The first male specimen of C. alcocki is reported, with a description of the male first gonopod. Intesius brevipes sp. nov. is the fifth species of the genus, differing from the four known congeners in the form and setation of the carapace, distinctly curved and granular anterolateral margins, and shorter pereopods with much slender merus and carpus articles.

Misidentification and notes on Plesionika semilaevis, Spence Bate, 1888 (Crustacean: Decapoda: Caridea) from the southern coast of India.

The commercial deep-sea caridean shrimp Plesionika martia (Milne-Edwards 1883) has long been recorded from India and constitutes an important species of deep-sea shrimp catches in the southern coast of India. However, the present study revealed that all the previous records of "Plesionika martia" is actually a misidentification of the closely related species P. semilaevis, which was recently obtained from Indian waters. The specimens were collected from three fish landing harbours (Sakthikulangara, Kalamuku, and Tuticorin) fished from the depth of about 150-250 m along the southern coast of India during 2014 to 2017. The level of interspecies genetic divergence between 16S rDNA (16.8-18.6%) and COI (26.1%) sequences of the Indian P. semilaevis and P. martia sequence retrieved from NCBI were found to be comparatively high. The current work illustrates the detailed morphological characters with color photographs of the species, P. semilaevis off the Indian Exclusive Economic Zone (EEZ).

The First Record of the Rearfin Flying Fish, Cypselurus opisthopus (Exocoetidae), from the Waters of South India, with the Assessment of Flying Fish Species Occurring in the Indian Exclusive Economic Zone

The present study reports the first record of the rearfin flying fish, Cypselurus opisthopus (Bleeker, 1865), in the south-eastern Arabian Sea based on a single specimen caught by a commercial trawler off the Kerala coast. Hitherto unknown in the waters off Indian coast, this is the first occurrence of this species in the Indian EEZ, suggesting the extension of distributional range of the species in the Indian Ocean. Detailed information on the morphometric and meristic characters are given and discussed. Molecular confirmation of the species identification was carried out using partial mitochondrial cytochrome oxidase sub-unit I gene. A map of the geographical distribution of C. opisthopus in the Indian Ocean based on published data and a list of flying fishes occurring in the Indian waters (within EEZ) is provided. Up to now, 24 species from 6 genera of flying fishes are recorded from the Indian waters.

Further report of Bariaka alopiae Cressey, 1966 (Copepoda, Siphonostomatoida) from the Indian Ocean with new host and geographic record.

A copepod parasite, Bariaka alopiae Wilson, 1932 (Eudactylinidae) infested on thresher sharks caught from the Indian Exclusive Economic Zone off Andaman and Nicobar archipelago, eastern Indian Ocean is further reported. Adult females of B. alopiae were collected from the gill filaments of two host species, Alopias pelagicus Nakamura and A. superciliosus Lowe. The species B. alopiae can be easily distinguished from other species within the genus by the following characteristic features: cylindrical body devoid of spines, eighteen segmented antennules and four segmented abdomen. In the Indian Ocean, this parasite was known only from its original description 51years ago, based on materials from western Indian Ocean off Madagascar. Further the present study reports, A. pelagicus as a new host for this parasite.

Population variations of Opal fish, Bembrops caudimacula Steindachner, 1876 from Arabian Sea and Andaman Sea: Evidence from otolith morphometry

Bembrops caudimacula dominates the deep-sea trawl catch in the exploratory surveys and as bycatch in the commercial trawling targeting deep-sea shrimps, in the Indian Exclusive Economic Zone. The intra-species variability in the bathy-demersal fish Bembrops caudimacula collected from two different ecosystems in the Indian Ocean were studied using otolith morphometric analysis. Five otolith size parameters (ferret length, ferret width, area, perimeter and weight), and five shape indices (roundness, rectangularity, ellipticity, form factor and circularity) were taken from forty-seven otoliths collected from two regions. Principal component analysis (PCA) and non-parametric PERMANOVA successfully differentiate the fishes from two regions based on the otolith morphometry. PCA indicated that ellipticity and otolith weight were the major factor responsible for the variation. The study indicated that otoliths of the fishes collected from Andaman Sea (part of Bay of Bengal) were more elliptic and massy compared to those collected from the Arabian Sea. This is the first work on the differentiation of B. caudimacula population from these two unique ecosystems, using otolith morphometry which is highly imperative to understand its population structure. Our study confirmed the suitability of otolith morphometric studies as an easiest and inexpensive method for differentiating the fish populations.

Seismology in India

The controlled source seismology (CSS), where artificial sources are used and near-vertical reflections, refractions and wide-angle reflections are recorded, has been a powerful tool for delineating shallow/deep crustal structures and subsurface features. Significant results, brought out from the vintage and new CSS data in the 21st century, include geological/tectonic aspects of the Dharwar craton, Delhi-Aravalli fold belt, Central Indian Tectonic Zone, Southern Granulite Terrain, Proterozoic Cuddapah basin, Kangra fold-thrust belt, Hazara syntaxis in NW Himalaya, Chambal-valley Vindhya basin, Mahanadi delta and Bengal basins. These studies also provide useful inputs in understanding the genesis of 1997 Jabalpur and 2001 Bhuj earthquakes. Imaging sub-volcanic Mesozoic sediments, in which more than 50% of global oil is found, has been a challenge by routine geophysical methods. This problem has been alleviated by CSS experiments, and Mesozoic sediments below the Deccan volcanic rocks have been delineated in the Saurashtra peninsula, Kutch peninsula, Tapti-graben and Kerala-Konkan offshore regions, and Gondwana sediments below the Rajmahal Traps have been mapped in the Mahanadi and Bengal basin. Several approaches have been proposed for the detection, characterization and assessment of gashydrates from shallow seismic data. These have been applied to field data that has resulted into identifying gas-hydrates, a major future energy resource of India, in the Krishna-Godavari, Mahanadi and Andaman offshore regions. Gas-hydrates have been subsequently recovered by drilling & coring under India National Gas Hydrates Program. The prognosticated amount of methane stored as gas-hydrates within Indian Exclusive Economic Zone is so huge that only 10% production may suffice our vast energy requirement for the next 100 years.

Anisakis infections in lantern fish (Myctophidae) from the Arabian Sea: A dual role for lantern fish in the life cycle of Anisakis brevispiculata?

Data on geographic distribution and life cycles of parasitic nematodes of the genus Anisakis in tropical oceanic regions are extremely scarce. Myctophids (lantern fishes) are a key component of mesopelagic trophic webs and could play a significant role in the transmission of Anisakis spp. in these regions. We examined Anisakis infections in a sample of 160 myctophids collected in three localities from the Indian Exclusive Economic Zone (Arabian Sea) in 2015–16. Due to the poor condition of fish, a combination of morphological data and molecular barcoding was used to identify myctophids. Of the 104 specimens that could be identified at least to genus level, 75 (72.1%) were assigned to Diaphus spp. A total of 131 Anisakis larvae were collected from the fish sample (prevalence: 52.5%). One larva was identified as type I, 114 as type II, and 16 larvae could not be assigned to either type. The morphology of all type II larvae conformed to the recent diagnosis of Anisakis brevispiculata. DNA could be obtained only from four larvae, and phylogenetic analyses based on mtDNAcox2 confirmed the identification. Anisakis brevispiculata is specific to dwarf and pygmy sperm whales (Kogiidae), which feed on mesopelagic cephalopods and marginally on myctophids. Therefore, myctophids could play a dual role in the transmission of A. brevispiculata, as direct prey of kogiids and/or as prey of cephalopods that consume myctophids. The prevalence of A. brevispiculata varied significantly in myctophid samples that were just ~ 265 km apart, suggesting potential local effects on transmission rates.

GIS-based approach for the evaluation of offshore wind power potential for Gujarat

In the current global scenario, India is increasing its focus towards the methods to enrich the benefits of non-renewable energy sources as much as possible due to their key advantage of having low carbon footprint. India has already emerged as a key global player in on-shore wind energy and to achieve its annual wind energy production demand of 50 GWh, avenues other than current options have been researched on. Offshore wind energy has experienced remarkable growth worldwide but has not yet been harnessed sufficiently in India, despite addressing many of environmental and economic concerns. The present study focuses on offshore wind resource assessment on Indian exclusive economic zone (EEZ) around Gujarat region. The geographical information system (GIS) methodology has been used to develop maps of wind speed, power density and capacity factor maps. Further, careful consideration has been accorded for expulsion of marine protected areas, shipping transportation lines, fishing zones, and migratory bird movements. The resultant available area has been considered for annual energy production considering data from Siemens Wind Turbine 3.6. The results obtained shows that offshore wind energy can offset twice the annual energy demand of entire country with a potential energy production of more than 2580 TWh.

Estimation of potential zones for offshore mariculture in the Indian Sea using geographical information system as a management tool

Coastal mariculture is now facing tremendous pressures, especially from the anthropogenic activities, variable environment, and multi-user conflict. Hence, offshore mariculture is envisioned to enhance the production by promoting the commercial farming (floating cages) of cobia (Rachycentron canadum) and other fin fishes. Essential environmental parameters for mariculture have been selected and converted into thematic layers using Geographical Information System (GIS) tool. Weights of relative importance were assigned to each layer and integrated together through overlay analysis to provide a final model suggesting possible offshore floating marine fish cage deployment sites. In the present study, it is estimated that from 368,009 km2 area within 100 m depth of Indian Exclusive Economic Zone available for mariculture activities, about 161,188 km2 area is appropriate for deploying cages. There are 76,396 km2 of highly suitable and approximately 84,792 km2 of suitable areas available for mariculture in India including Andaman & Nicobar and Lakshadweep Islands. Analysis of variance (ANOVA-one way) showed significant (p < 0.05) spatial variation for sea surface current, total suspended matter, and chlorophyll-a. This study is an attempt to integrate the weighing criteria and GIS to derive a suitable criterion for deployment of floating cages in the offshore environment, which could serve as a model for similar cases, particularly in the maritime nations for sustainable mariculture.

Application of reanalysis data to estimate offshore wind potential in EEZ of India based on marine ecosystem considerations

India is striving hard to develop new and renewable energy resources on a vast scale, to meet its future energy demands. To fulfill the need of renewable energy resources, utilization of wind energy is a good option to avoid several issues of pollution and climate change caused by the consumption of fossil fuels. The present study aims to provide a summary of offshore wind energy potential available in the exclusive economic zone (EEZ) of India, by utilizing reanalysis wind dataset (ERA-Interim) for 14 years (2001–2014) along with corresponding data of bathymetry and cumulative human impact on marine ecosystem. Geographic Information System (GIS) environment is used to develop maps of wind speed and power density at a hub height of 80 m. Annual energy production (AEP) capacity in Indian EEZ was observed to be about ten and six times of the present (Financial year 2015–16) and anticipated future (Financial year 2021–22) energy demand while considering 5 MW turbine. Outcomes of the present study seem to be useful for developers, planners and decision makers in realizing about available offshore wind power potential at the coasts of India.

Petroleum Exploration in India - A perspective and Endeavours

Indian oil industry has come a long way since the first oil discovery at Digboi in 1889 through concerted exploratory efforts. Production of oil from a 5 barrels per day level from a single field in Assam has grown to more than 750000 barrels per day from over 50 major oil and gas in seven sedimentary Basins and is projected to attain 1 million barrels per day mark in near future. After Independence, oil and gas exploration was accorded high priority and was taken up by National, Private and International oil companies across the 26 sedimentary Basins covering an area of about 3.14 million sq. kms. Of the 26 sedimentary Basins, 7 Basins are producing oil and gas today. Sedimentary Basins of India are categorised into four categories based on their degree of hydrocarbon prospectivity as presently known. At present India’s estimated hydrocarbon resource is of the order of 28 billion tonnes of oil equivalent (BTOE) and an Initial In-place volume of about 11.18 billion tonnes of oil equivalent (BTOE). A project for re-assessment of the resource potential of Indian Sedimentary Basins has been initiated by Government of India with active participation of ONGC, OIL and DGH in view of extensive availability of new data from all the Sedimentary Basins. Currentefforts are to enhance the production from category–I Basins with a focus on upgrading the Category-II Basins to Category-I Basins. Present paper outlines the endeavours during last few years through opening up of new areas, especially frontier areas of Proterozoic Basins of Vindhyan and Satpura, Deep offshore Basins of Bay of Bengal and Arabian Sea within Indian exclusive economic zone, Andaman fore-arc and back-arc Basins, unconventional sources of hydrocarbons such as Basement exploration, CBM (Coal Bed Methane), shale oil and gas, gas hydrates and leveraging the technology advances in Petroleum exploration.

Feeding ecology and consumption rates of yellowfin tuna (Thunnus albacares) in the eastern Arabian Sea

Diet composition, predator-prey relationships and consumption rates of yellowfin tuna Thunnus albacares in the western Indian Exclusive Economic Zone (eastern Arabian Sea) were studied by stomach content analysis. Stomachs of 406 specimens in the fork length range of 48 to 165.5 cm caught during exploratory longlining conducted in the eastern Arabian Sea during 2006 to 2009 were examined, of which, 15.52% were empty. Purple back flying squid ( Sthenoteuthis oualaniensis ) was the dominant prey species, followed by the swimming crab ( Charybdis smithii ), bigeye cigarfish ( Cubiceps pauciradiatus ) and flyingfishes (family Exocoetidae). Diet breadth index and the modified Costello diagram showed dominance of few prey species which are available in high densities in the Arabian Sea, indicating opportunistic feeding nature of this apex predator. Diet did not significantly differ between sexes and size groups. Higher food intake during premonsoon and winter monsoon indicated a seasonal variation in diet. A steady increase in the abundance of C. smithii and a decrease in the proportion of S. oualaniensis in the diet were observed from premonsoon to winter monsoon seasons. Yellowfin tuna in the Arabian Sea consume an average of 545.65 g of food in a day and require daily ration of 1.95% body weight per day.