Coast Of India Research Articles

Balancing Nets and Lives: A Socio-Ecological Analysis of Sustainable Fisheries on the Indian Coast of the Gulf of Mannar

Balancing Nets and Lives: A Socio-Ecological Analysis of Sustainable Fisheries on the Indian Coast of the Gulf of Mannar

Morphometry and active tectonics of the Konkan coast, western India

The Indian western coast is petroliferous drawing attention from academicians and industrial experts. In this work, geomorphic indices have been calculated to decode neotectonics of the Konkan onshore region on India’s west coast. Earthquake and Bouguer anomaly data have been used along with the present-day stress data from the World Stress Map project. Gravity modeling was performed in order to gain seismotectonic insights. The b-values were determined using Z-MAP 7.1 (2021). Morphometric analysis at both linear and spatial scales were performed using the digital elevation model from the data derived from the Shuttle Radar Topography Mission, analysed with ArcGIS 10.3 (2014) software. Maps depicting slopes, aspects, and reliefs were created. NW-SE trending lineaments in the Konkan plain guided the major stream courses. Two of the five watersheds, watersheds 4 and 5, reveal high tectonic activity, are landslide-prone and host hot springs. Interestingly, watersheds 4 and 5 show high b-values (except near the rivers’ sources), low Bouguer anomalies, and higher Hypsometric integral values (0.18523 and 0.16698) than the other watersheds. A low b-value in watershed 3 indicates stress accumulation. Over a larger area, the gravity trend varies from ∼ -80 to 30 mGal. The lineaments diagram deduced from the first vertical derivative technique shows that the structural fabrics mostly trend ∼ NW-SE at the west of the Western Ghat Escarpment (WGE) while it is NE-SW at the east. The tilt derivative ratio technique reveals a major NE-SW trend to the west of the WGE and an E-W trend to the east. Structural interpretations based on drill-cores around Koyna combined with geophysical studies for deep crust will be required are required for a better understanding of the blind (active) structures in the region.

Fishery and stock dynamics of ribbonfish Trichiurus lepturus (Linnaeus, 1758) in the Indian Exclusive Economic Zone

The fishery and stock dynamics of Trichiurus lepturus (Linnaeus, 1758) were studied in the Indian Exclusive Economic Zone (EEZ) for the period 2014-2019. The average annual landing was 2,09,285 t and varied from 1,77,259 to 2,39,355 t. Trawl nets were the majorgear, contributing more than 85% with an average annual catch rate of 4.56 kg h-1. The annual catch rate decreased over the years from 5.40 to 3.85 kg h-1. Landings (23,155-40,354 t) and catch rates (4.24-8.67 kg h-1) were highest during the post-monsoon months (September-December). Around 63% of the landings (1,32,072 t) were from the north-west coast, with Gujarat alone contributing three-fourth (98,296 t) of it, followed by the south-west coast (17%, 36,017 t), the south-east coast (12%, 25,322 t) and the north-east coast (8%, 15,875 t). The von Bertalanffy’s growth equation was Lt = 143.8 [1-e–0.48 (t + 0.03285)]. Natural mortality, Exploitation ratio and Maximum Sustainable Yield (MSY) were 0.76; 0.65 and 1,59,504 t respectively. Recruitment was substantial throughout the year with a single modal peak during June-October. With lower lengths at first capture and recruitment and with exploitation above the maximum permissible level and landings higher than MSY; the species appears to be overexploited along the Indian coasts. The present study is the first holistic report on the population parameters and stock status of T. lepturus from the Indian EEZ. Keywords: Cutlass fishes, Management, Recruitment, Stock dynamics

High-resolution numerical modelling of seasonal volume, freshwater, and heat transport along the Indian coast

Abstract. Seasonal reversal of winds and equatorial remote forcing influences the circulation of the Arabian Sea (AS) and Bay of Bengal (BoB) basins in the northern Indian Ocean. In this study, we numerically modelled the physical characteristics of the AS and BoB, using the Massachusetts Institute of Technology general circulation model (MITgcm) at a high spatial resolution of 1/20° forced with climatological initial and boundary conditions. The simulated temperature, salinity, and flow fields were validated with satellite and in situ datasets. We then studied the exchange of coastal waters by evaluating transports computed from the model simulations. The alongshore volume transport on the eastern coast is stronger with high seasonal variability due to the poleward-flowing western boundary current and equatorward-flowing East Indian Coastal Current. West coast transport is influenced by large intraseasonal oscillations. The alongshore freshwater transport is an order less than the alongshore volume transport. Out of the net volume transport, freshwater accounts for a maximum of 6.03 % during the southwestern monsoon season, followed by 4.85 % in the post-monsoon season. We observe an inverse relationship between alongshore freshwater and volume transport on the western coast and a direct relationship on the eastern coast. The contribution of eddy-induced heat and freshwater transport was also examined. The relation between net heat transport and net heat flux illustrates the role of coastal currents and equatorial forcing in dissipating heat within the coastal waters. We observed that meridional heat transport over the AS is stronger than over the BoB. Both basins act as a heat source during the summer monsoon and heat sink during the winter. This high-resolution model setup simulates all the important physical climatological patterns, leading to a better understanding of the state of the northern Indian Ocean.

Impact of river discharge and suspended sediments on the nearshore benthic environment along the Indian southwest coast

River discharge into the sea and its implications on the environmental setting and fauna in the nearshore represent the intricate interactions among the atmosphere, hydrosphere, lithosphere, and biosphere. This study, based on in-situ and satellite data, presents how spatially varying river discharge laden with suspended sediments structure the hydrography and the nearshore benthic environment over a 590 km southwest (Kerala) coast of India. The 41 rivers that discharge along the Kerala coast are monsoon-driven; they are small but swift and cumulatively supply huge amounts of freshwater and suspended sediments into the Southeastern Arabian Sea (SEAS) during the Southwest Monsoon (SWM) when around 70 % (1925 mm) of the yearly rainfall occurs. These rivers are distributed unevenly along the coastline, with twenty-four of them discharging in the northern region (10.9–12.5°N), nine in the central (9.2–10.9°N), and eight in the south (8–9.2°N). During the SWM, plumes of low salinity (<32) with high clay content were widespread in the northern and central regions of the study area due to heavy river discharge and the presence of crystalline rocks and laterite deposits. In contrast, the low salinity plumes and suspended sediments were markedly low in the southern region due to limited river discharge and a predominance of sedimentary rocks and coastal alluvium that supported sandy sediments. This resulted in a spatial change in benthic sediment texture as well, with the central and northern regions more silty or clayey, while the south was sandy. Interestingly, the sandy south section had a noticeably higher faunal abundance than the rest of the region with an increased abundance of sensitive fauna of molluscs and echinoderms. This is a clear case of how spatially varying river discharge and sediment flux impact the nearshore environment and fauna.

High heat tolerance and thermal safety margins in mangroves from the southwestern coast of India

Mangroves are key components of productive ecosystems that provide a multitude of ecosystem goods and services. How these species will respond to future climates with more frequent and severe extreme temperatures has not received much attention. To understand how vulnerable mangroves are to future warming, we quantified photosynthetic heat tolerance and estimated thermal safety margins for thirteen mangrove species from the southwestern Indian coast. We quantified heat tolerance as temperatures that resulted in a 5 % (T5) and 50 % (T50) decline in photosystem II function, and thermal safety margins (TSM) as the difference between T50 and maximum leaf temperatures. T50 ranged from 48.9 °C in Avicennia Marina to 55.3 °C in Bruguiera gymnorhiza, with a mean of 53.3 °C for the thirteen species. Heat tolerance was higher for species with bigger leaves which experience higher leaf temperatures, but was not related to the other leaf traits examined. Heat tolerance was exceptionally high in these mangroves compared to other woody species. With their high tolerance and large safety margins these mangroves may be relatively less vulnerable to future climates with higher temperatures.

Anopheles jamesii Supports Plasmodium vivax Sporogony under Laboratory Conditions.

Anopheles jamesii, considered to be a non-malaria vector, is an abundant mosquito species found in coastal India and several countries in Asia. In Goa, western India, An. jamesii is the dominant anopheline species by numbers, and in recent epidemiological surveys, they have tested positive for Plasmodium carriage. To assess An. jamesii's capacity as a malaria vector, we carried out six controlled membrane feeding assays with the F1 generation of field-caught An. jamesii and Plasmodium vivax-infected patient blood samples. As a control, the established local vector, Anopheles stephensi, was fed in parallel to compare the oocyst and sporozoite loads. The average oocyst load of An. jamesii was 3.29, while for An. stephensi it was 10.23. Furthermore, An. jamesii's blood feeding rate (21.7% versus 85%), oocyst positivity rate (60% versus 90.6%), and sporozoite positivity (45.16% versus 83%) were significantly lower (P <0.05, unpaired t test) than those of An. stephensi, suggesting a recent adaptation to support Plasmodium sporogony.

A Lankan invasion? An intriguing case of the presence of a Sri Lankan endemic skink on the southwestern Indian Coast

The biota of the Indian subcontinent is a result of Gondwanan vicariance to some extent but largely through multiple faunal exchanges between neighbouring regions. However, in recent times, humans have influenced regional biotas through the human-mediated transport of many generalist species. In this study, we report populations of Lankascincus fallax, a skink species supposedly endemic to Sri Lanka, from the west coast of Kerala in India. We conducted morphological and genetic analysis to ascertain the identity of this species and to check whether the Indian population is monophyletic. We then performed a divergence dating analysis to test whether the presence of this population is a result of ancient dispersal into India or a result of more recent events. Additionally, we used species distribution modelling to test whether the Indian L. fallax is a result of natural dispersal into India during the past (mid-Pliocene to the last glacial maximum) when there were possible land bridges between India and Sri Lanka. We find that the Indian population is nested within the Sri Lankan L. fallax and that this population diverged from the Sri Lankan population very recently, during the Pleistocene. We do not find climatic suitability between the Indian west coast and Sri Lanka under current climatic conditions, or during the past suggesting no suitable dispersal corridors between India and Sri Lanka. Overall, we hypothesize that the Indian populations of L. fallax are likely a result of human-mediated transport into India and subsequent dispersal across the west coast of Kerala.

Computational Modelling of 2004 Off West Coast of Sumatra Earthquake-Tsunami Wave Propagation Using Two-Dimensional Cellular Automata in the Eastern Indian Coast

ABSTRACT The ability to detect destructive tsunamis and spare lives from serious harm has made the computation of tsunami wave dynamics increasingly important. The tremendous loss of life and property brought on by the 26th of December, 2004 tsunami has raised the demand for accurate and timely propagation of tsunami wave simulations. These days, a variety of early warning technologies and models are utilized to predict tsunami waves. The propagation phase of a tsunami wave is simulated using two-dimensional cellular automata of rectangular lattices in eight directions from this research. Modelling of the Sumatra-Andaman earthquake in 2004 to simulate the propagation of tsunami waves to strike the northern coasts of India. The earliest tsunami arrival time, travel time, and wave spread rate are determined from this study, and the results are verified using historical data.

Correction: Exploring phenolic compound extraction from marine seaweeds of south coast India: in vitro antioxidant and antimicrobial evaluation

Correction: Exploring phenolic compound extraction from marine seaweeds of south coast India: in vitro antioxidant and antimicrobial evaluation

Addressing maritime security challenges through maritime domain awareness: a study of the role of the Information Fusion Centre-Indian Ocean Region

ABSTRACT In recent years, many non-traditional maritime safety and security threats viz. piracy, armed robberies at sea, maritime terrorism, human trafficking, drugs trafficking, illicit trafficking in wildlife, illegal deals in weapons, IUU fishing, dilapidation of ocean health and illegal exploitation of sea resources, etc. have emerged as real and serious challenges not only to the commercial shipping but also to the national security. A comprehensive response from the worldwide seafaring community is the need of the hour to tackle these maritime threats, both natural and man-made. India’s initiative of establishing the Information Fusion Centre-Indian Ocean Region (IFC-IOR) in the year 2018 can be regarded as a significant step in dealing with the variety of maritime security challenges. Jointly managed and run by the Indian Navy and Coast Guard, the IFC-IOR fulfils the purpose of creating Maritime Domain Awareness on the issues pertaining to maritime safety and security. Protecting maritime interests and augmenting security in the Indian Ocean Region (IOR) is indispensable for maintaining free navigation and overflight, unconstrained commerce and a free, open and UNCLOS-based regime in the IOR.

Description and Assessment of an Antimicrobial Substance from Marine Actinobacteria

Streptomyces is thought to be the primary source of bacteria for the synthesis of bioactive substances, such as naturally occurring antibiotics. Finding and identifying the actinomycetes exhibiting antagonistic activity was the primary goal of the current investigation. A strain of actinomycetes that was isolated from marine sand samples that were collected off the Indian coast of Vedharanyam exhibited antimicrobial activity against a number of microbial pathogens. The nutritional requirements and cultural conditions for maximal growth and yield of bioactive compounds have been optimized under shake flask condition. Analyze the compound characterization of the sample such as UV, FT-IR, GC-MS and sequencing 16S rRNA for species identification. The actinomycetes isolates which are isolated from sediment sample can be further used as antimicrobial activity agents against bacterial and fungal pathogens and their compound characterization.

Navigating mortality prediction in severe malaria: risk stratification models from the emergency department of coastal India

Navigating mortality prediction in severe malaria: risk stratification models from the emergency department of coastal India

Dissolved organic carbon (DOC) and labile organic compounds' spatial and temporal variations in coastal Indian groundwater: their bioavailability and transfer to neighboring coastal waters of India.

Submarine groundwater drainage (SGD) changes the elemental composition of the neighboring coastal ocean and impacts the biogeochemical cycles. To examine the seasonal and spatial variability in dissolved organic carbon (DOC) and labile organic compound biochemical compounds like dissolved carbohydrates (TDCHO), dissolved proteins (TDPRO), and dissolved free amino acid (TDFAA) concentrations during the dry and wet periods, groundwater samples were taken at 90 locations (180 samples) along the Indian coast. The mean DOC contents in Indian coastal groundwaters were more significant than the global mean values. DOC, TDCHO, TDPRO, and TDFAA concentrations are higher during wet than dry periods. The DOC and labile organic compound showed a substantial positive association with soil organic carbon, and respective labile compounds in soil, population, and land usage and poor relation with woodland territories, implying that soil organic compounds leaching is a source of DOC and other labile organic compounds into the groundwater. DOC and other labile compounds concentrations were linearly associated with population density, land usage, and sewage production, demonstrating that anthropogenic activities tightly regulate the formation of DOC in groundwater. During the wet and dry periods, total labile organic compounds (TDCHO, TDFAA, and TDPRO) constituted 21% and 10.5% of DOC, respectively. Compared to the wet time, more aromatic compounds accumulated during the dry season but were less bioavailable. SGD DOC flux contributed 2-7% of riverine DOC flux to the coastal ocean. The SGD flux from the Indian subcontinent to the nearby northern Indian Ocean accounts for approximately 2% of the worldwide SGD flux. The effect of DOC flux via SGD on coastal bacterial activity, the plankton food web, and the oxygen minimum zone must be studied.

Assessing climate change vulnerability: A village level analysis of the Indian west coast

The Indian west coast is under constant threat from climate change-induced hazards. Various social, economic, and infrastructural disparities along the coast cause significant variations in climate vulnerability. Current literature assesses vulnerability either over (1) a large area with poor spatial resolution or (2) a local area with better spatial resolution. The former assessments provide more comprehensive and broad insights into large spatial trends of vulnerability, while the latter provide more accurate and specific inputs needed by the local governments for effective intervention. However, there is a lack of studies that assess vulnerability simultaneously at a high-resolution and over a large geographic area, due to inadequacies in existing methodologies and difficulty in data management and analysis. This is a key gap that we address in our paper. We assess climate vulnerability of the entire Indian west coast at the village level, and propose a novel machine-learning based methodology tailored for high-resolution assessment over large geographic areas. This helped us produce the first high-resolution (i.e. village-level) climate vulnerability map of the entire Indian west coast. We found that the state of Maharashtra has the highest number of vulnerable villages and the state of Kerala has the least number of vulnerable villages. We collate and utilize a large dataset of 112 indicators describing socioeconomic characteristics, infrastructure and availability of financial services, among other aspects, to obtain a comprehensive picture of vulnerability. We analyze geospatial trends and attribute high vulnerability to specific indicators, which will help in effective decision-making at the village level.

Nuclear and Radiological Material Smuggling in the Indian Ocean: Implications for India’s Coastal Security

Incidents of nuclear and radiological smuggling in the Indian Ocean are a matter of concern. Attempts to smuggle nuclear material within India have also been reported as recently as 2021. Indian security agencies previously have also seized natural uranium in coastal states such as Gujarat, Maharashtra and Bengal indicating how vulnerable the Indian coast is to radiological and nuclear smuggling. The Nuclear Security Index has also consistently ranked India below China and Pakistan despite their poor record on nuclear non-proliferation. These facts highlight concerns regarding the possible misuse of nuclear and radiological material by criminal and terrorist networks. Since India is targeted by terrorist groups and lies in the vicinity of countries and routes that see frequent nuclear and radiological trafficking, there are inevitable implications for the Indian coastal security system. This article identifies and analyses these security implications and argues for a beefing up of India’s coastal security.

First record of two species of brachyuran crab (Crustacea: Decapoda) Austruca albimana (Kossmann, 1877) and Tirmilyra concinnus (Ghani and Tirmizi, 1995) from India

This study reports the first record of two brachyuran crab species, Austruca albimana Kossmann, [21] and Tirmilyra concinnus Ghani and Tirmizi [18], from the western Indian coast. Their identification, taxonomic observations, and geographic distribution are provided. The species belong to the families Ocypodidae and Leucosiidae, respectively. This is the first report from Indian waters, as the species are so far reported from Oman, Iran and Persian Gulf. These records emphasize the need for research and conservation efforts in the region to explore the diversity and distribution of brachyuran crabs in Indian waters.

Wind-driven sediment exchange between the Indian marginal seas over the last 18 000 years

The Indian Coastal Current is the only channel for material exchange between the two largest marginal seas in the northern Indian Ocean: the Bay of Bengal and the Arabian Sea. However, its past history is poorly known, limiting accurate predictions of its future changes. Here, we present a new clay mineral record from south of India supported by interpretations of model simulations to trace its variability over the last 18 000 years. Decreased smectite/(illite + chlorite) ratios during the cold intervals suggest that a stronger northeasterly wind led to a mean southward flow of the Indian Coastal Current in the Bay of Bengal. In contrast, increased smectite/(illite + chlorite) ratios during the warm intervals suggest the opposite scenario. Combining the proxy record with model simulations, we infer that atmospheric circulation changes were the main driver of the changes. Moreover, a possible link is observed between a positive Indian Ocean Dipole (IOD) and weakened southward flow of the Indian Coastal Current in the Bay of Bengal during the Holocene. These findings imply that future warming scenarios, if associated with more intense positive IOD events as proposed, may lead to a reduction in fresh water transport from the Bay of Bengal to the Arabian Sea.

Diversity of Foraminifera from the Indian Coast

Foraminifera, members of the class Granuloreticulosa, are marine protozoans distributed across both pelagic and benthic zones of the ocean. After the death of these microscopic organisms, their shells are washed along the intertidal sandy shores along with sand granules. This organism's shell is called a test which is composed of calcium carbonate, silica, or agglutinated materials that characterize the genera of Foraminifera. In the present study, the sand samples were collected along the different sites of the Indian coastline viz. Juhu Beach (Mumbai), Alibaug Beach (Raigad), Palolem Beach (Goa), Kanyakumari Beach (Tamil Nadu), and Puri Beach (Odisha). In this study, samples from Juhu Beach showed the highest foraminiferan diversity (24%) followed by Alibaug (21%) &gt; Kanyakumari = Puri (19%) &gt; Goa (17%). Across all selected study sites, the prevalence of specimens from the Globothalamea class was notable, comprising 39% of the total foraminiferans. This was followed by Monothalamae (26%), Fusulinata (13%), Tubothalamea (11%), and Nodosariata (11%). 13 extinct genera were also documented in the study.

Bacillus Paralicheniformis: A potential candidate for natural antibacterial agents from marine macro-algae associated bacteria.

Antibiotic resistance poses a major global health threat, necessitating new approaches to treat bacterial infections. We isolated bacteria from the brown macroalgae Sargassum swartzii collected along the Indian coast. Of 279 isolates, 47.6% showed antibacterial activity against Staphylococcus aureus and Vibrio parahaemolyticus when screened. Ten potent isolates underwent analysis of biosynthetic gene clusters and 16S rRNA sequencing. Isolate MP-99 carried polyketide synthase (pks) and non-ribosomal peptide synthetase (nrps) genes and exhibited antibacterial effects.