Indian Journal of Geo-Marine Sciences (IJMS)

Insights into the rare Viperine sea snake, Hydrophis viperinus (Schmidt, 1852): Addressing research gaps along the Indian coastline

2024-06-13T18:58:16+0530

The Viperine sea snake (Hydrophis viperinus), occasionally called the Grey Sea Snake, is an elapid sea snake found in tropical and subtropical reefs and coasts of the Indo-Pacific waters. The species has been reported in limited numbers along the Indian coast, either as bycatch or stranded. Given its naturally rare occurrence, there is a considerable lack of information about its research history in India. This review assembles all available information on species (n = 112) through various search engines and databases, ranging from 1852 to 2024. The literature was then analysed to determine areas where further research is required. Despite recognising that India has listed H. viperinus as a scheduled species, it remains vital to understand how anthropogenic activities affect the species' habitats to conduct vulnerability assessments and prevent exploitation. This article reviews the ecology, population dynamics, and threats while highlighting research gaps concerning the species in its Indian distribution.

Underwater bloom of toxic cyanobacterium Lyngbya majuscula Harvey ex Gomont, 1892 on coral reefs in Hare Island, Gulf of Mannar Marine Biosphere Reserve

2024-12-10T11:24:18+0530

Tuft blooms of toxic cyanobacterium Lyngbya majuscula Harvey ex Gomont, 1892 prevalence was documented from coral reefs of southern Hare Island in Gulf of Mannar region, south east coast of Tamil Nadu. Lyngbya majuscula was observed to be overgrowing and dominating dead coral reefs, rubble, rocks, and other floral substrates. The persistence of L. majuscula blooms on dead reefs in southern Hare Island appears to inhibit coral recruitment, as evidenced by the presence of coral recruits in bloom-free areas and their absence in areas with blooms. Further, long-term monitoring and seasonal studies are needed to understand the impact of L. majuscula blooms on reef structure and communities.

A new host record of pea crab, Arcotheres placunae (Hornell & Southwell, 1909) (Brachyura: Pinnotheridae), in Placuna quadrangula (Philipsson, 1788) (Bivalvia: Placunidae), from the southeastern coast of India

2024-07-10T19:51:32+0530

Previously, the pea crab Arcotheres placunae (Hornell & Southwell, 1909) was only recorded from the known host bivalve species, Placuna placenta (Linnaeus, 1758). This study presents the first report on the host association between A. placunae and Placuna quadrangula (Philipsson, 1788) based on specimens found in the Vellar estuary, southeastern coast of India. During regular fishing survey along the Vellar estuary, observed a single male and female specimen of A. placunae in the mantle cavity of a live windowpane oyster, P. quadrangula. The association observed here remarks that the pea crab has a commensal relationship with the host, P. quadrangula. The present study provides the details of morphological features and association of new host of the species herein.

First occurrence report of the hermit crab Dardanus setifer (H. Milne Edwards, 1836) (Crustacea: Decapoda: Anomura) from the Odisha coast, India

2024-12-13T10:31:20+0530

The Hermit crabs belonging to the Diogenidae family are represented by 483 species under 22 genera and are mainly found in the Indo-Pacific region. Hermit crab species Dardanus setifer (H. Milne-Edwards, 1836) is documented for the first time from the Odisha coast based on specimens collected from Paradeep harbour and Bahuda estuary situated on the coast of Odisha state, India. The species has been documented across a range extending from South Africa to Australia. In India, it has been reported from Karnataka, Kerala, Tamil Nadu, Andhra Pradesh and Andamans. The current record claims the range extension of this species to the coastal water of Odisha, reporting northward extension in the distributional range of the species in the Bay of Bengal.

First record of Gossamer blenny, Omobranchus ferox (Herre, 1927) from the mussel farming sites of Kavvayi estuarine wetland system, Southwest coast of India

2024-08-16T14:53:47+0530

The gossamer blenny, Omobranchus ferox (Herre, 1927), a member of the family Blenniidae (Order Blenniiformes), is documented for the first time in the Kavvayi estuarine wetland system. This record is established based on the examination of four specimens collected from the Kavvayi estuary, marking the initial occurrence of this species on the southwest coast of India.

Design and performance assessment of a hydrographic unmanned surface vessel for enhanced autonomous bathymetry operations in shallow water areas

2024-08-16T15:01:26+0530

This paper details the development and performance evaluation of an Unmanned Surface Vessel (USV) designed for enhanced autonomous bathymetry in shallow water areas. Through significant technological enhancements, including the integration of a CXSense controller, M1G2 GNSS receiver, KVH C100 magnetic compass, and SBG System INS, the USV demonstrated exceptional operational capabilities. Performance metrics revealed a cross-track error of 0.92 to 2.39 meters, surpassing the International Hydrographic Organization's Category 2 standards. The study outlines the comprehensive upgrades undertaken on the USV’s propulsion, GNSS positioning, course control, and data transmission systems, which collectively facilitated robust automated operations. The successful deployment of low-cost multi-GNSS receivers illustrates a shift toward more economical hydrographic survey methods, challenging the need for expensive professional-grade equipment. The findings underscore the potential of USVs in revolutionising hydrographic surveying, offering substantial improvements in cost-efficiency, operational flexibility, and data accuracy, thereby enhancing marine research and commercial maritime operations.

Exploring the biomass and carbon stock of mangrove vegetation in Palk Bay's dugong conservation reserve

2024-09-20T14:46:08+0530

Mangroves are crucial tropical carbon sinks, yet the carbon reserves in Indian mangrove ecosystems, particularly in Palk Bay, remain under-researched. This study evaluates the carbon stock of mangroves in the Dugong Conservation Reserve, Palk Bay, covering 15 zones and 47 transects. Four true mangrove species: Avicennia marina, Rhizophora mucronata, Excoecaria agallocha, and Lumnitzera racemosa, were identified with Avicennia marina contributing most to the biomass and carbon stock. The mean total biomass obtained was 40.09±26.64 mg/ha, with above-ground biomass of 25.31±18.86 mg/ha and below-ground biomass of 14.77±7.93 mg/ha. Zone 2 exhibited the highest mean biomass per unit area (89.03 mg/ha) and vegetation carbon stock (38.87 mg-C/ha), followed by Zone 10. Relatively low biomass and carbon stock values observed in this study can be attributed to the low diversity and abundance of mangrove species in the region. These results underscore the significant carbon storage capacity of the Dugong Conservation Reserve's mangroves and highlight the need for targeted conservation and management efforts to enhance carbon sequestration. This study also emphasises the interconnectedness of mangroves and seagrass ecosystems, which support species like dugongs, reinforcing the reserve's ecological importance.

Growth and biochemical changes in response to salinity stress in Gayralia oxysperma (Kützing) K.L. Vinogradova ex Scagel et al. 1989 (Chlorophyceae)

2025-01-30T16:39:08+0530

Gayralia oxysperma (Kützing) K.L. Vinogradova ex Scagel et al. 1989, Doty, (Monostromataceae, Ulvales) possesses exceptional nutritional, antioxidant, and medicinal properties, thriving in fluctuating saline environments and demonstrating resilience against salt stress due to its rich composition of nutrients and phytochemicals. This is an estuarine form of seaweed and is subjected to intense salinity regimes, particularly during the monsoon period (June – September). Therefore, the present study was undertaken to investigate the changes in growth and some cellular biochemical constituents of G. oxysperma following exposure to selected salinities viz. l.6 ‰, 4.8 ‰, 8 ‰, 16 ‰, and 32 ‰ in the laboratory culture. The growth of fronds increased with increasing salinity and showed an optimum growth of 2.5-fold increase over initial biomass in 1.6 ‰ on day 15. The microscopic observation of fronds from lower salinity showed unevenly distributed elongated cells with low density and large intercellular spaces. In contrast, at a higher range (> 8 ‰), cells were more compact and evenly distributed all over the thallus. The chlorophyll content increased to 2.8-fold in 32 ‰ over the initial salinity of 1.6 ‰. Proline content of fronds cultured in 32 ‰ showed 9.5-fold increase compared to 1.6 ‰ salinity. Similarly, glycinebetaine also increased with salinity (32 ‰) and showed 2.3-fold increases over values obtained for 1.6 ‰. These findings suggest that G. oxysperma thalli accumulate a high amount of osmolytes like proline and glycinebetaine to sustain during adverse salinity stress conditions.

First occurrence of Metanophrys sinensis Song & Wilbert, 2000 (Protozoa: Ciliophora: Scuticociliatida) outbreak in a marine ornamental fish: Morphological and phylogenetic analysis

2025-02-17T12:36:12+0530

A scuticociliatosis outbreak with high mortality was recorded in the clownfish breeding facility of the ICAR-NBFGR, Maharashtra, India. Moribund fish juveniles showed abnormal swimming and high mucus secretion with energy loss. Microscopic investigation found that all moribund juveniles had dense parasites on their gills, fins, and almost the whole-body surface. Thin to elongated oval-shaped ciliates Metanophrys sp. with pointy anterior end (25-50 × 10-20 µm) were detected and collected for further observation. The causative parasite was characterised by 18 SSU rRNA gene sequencing method using universal and specific primers. The causative ciliate was confirmed as Metanophrys sinensis Song & Wilbert, 2000, based on 97 % gene similarity in BLAST analysis results. The accession codes OM055651.1 (universal primer) and ON329185.1 (specific primer) were acquired after gene sequences were uploaded to GenBank. On the basis of available literature, this is the first occurrence record of scuticociliatosis outbreak caused by Metanophrys sinensis in the marine ornamental fish hatchery in India and elsewhere.

Research on the characteristics of earthquake ruptures and infrasound anomalies based on percolation theory

2024-12-16T16:33:48+0530

Compared with other precursors, infrasound has exceptional earthquake sensitivity; but it lacks relevant quantitative simulation of the dynamics of main faults and the mechanism of infrasound anomalies generated by earthquakes. Nevertheless, it is impossible to understand information on fracture source development based on these characteristics, which poses a challenge to applying this method to earthquake prediction. This paper uses the concept of percolation theory to establish the scale and loading variation in earthquakes from microfractures to large fractures. In an elastic medium model with several cracks, a theoretical analysis is done to understand the formation of acoustic emission and seismic activity. A dynamic study of the solid material in the initial microfracture during the extensive fracture process is carried out based on the dynamic method. The physical principles of solid mechanical fracture prediction are discussed, the characteristic mechanism of acoustic anomalies is revealed, and the applicability of the infrasound anomaly principle to the prediction of ground fracturing is discussed. Through the conclusions obtained from these theories, an analysis of the physical process of acoustic signal formation during fracture generation is carried out, the existing records are analyzed, the characteristics of phenomena are explained, and the causes of phenomena are partially revealed to verify the effectiveness of infrasound anomalies as precursors and to explore the method of predicting earthquakes through acoustic signal recording.