Trace metal concentrations were monitored in the yellow clam (Paphia malabarica), green mussel (Perna viridis) and edible oyster (Crassostrea madrasensis) from growing areas in the Ashtamudi and Vembanad estuaries, Kerala. Samples of shellfish (clams n=26, mussels n=18, oysters n=36) and environmental parameters (salinity, temperature, pH and rainfall) were measured in these growing areas from July 2012 to December 2014. Ranges of mean annual concentrations (mg/kg) were Ni (0.46–0.65); Co (2.87–3.49); Fe (80.0–119.4); Mn (3.88–9.38); Zn (40.8–76.2); Pb (1.28–2.00); and Cu (1.59–4.38). In Ashtamudi, clams had higher mean concentrations of Ni, Co, Fe, Mn and Pb than oysters. Mean concentrations of Ni, Pb (in all species), Zn (in clams and mussels) and Cu (in mussels) did not exceed maximum permissible limits mandated by the Food Safety and Standards Authority of India. Mean Mn concentrations exceeded the World Health Organization guideline (1 mg/kg) in the three species while mean Fe concentrations in clams and oysters did not exceed the guideline (100 mg/kg).
The study reports massive and dense Blue coral Heliopora coerulea (Pallas, 1766) population in Chetlat atoll, one of the northernmost atolls in the Lakshadweep Archipelago. Globally, there are only a few instances of the occurrence of such massive blue coral populations, mostly from Japan. Underwater survey shows that about 60 % of the entire reef area is occupied by the Blue coral. In addition, this atoll was observed to have lesser cover of different species of Acropora as compared to the reports from other Lakshadweep atolls. Both Acropora and Heliopora are described to be mutually competitive and Heliopora are comparatively more resilient to climatic stressors. The knowledge about the occurrence of such a large swathe of the Blue corals is important in the current scenario of the widespread deterioration of the coral reefs due to changing climate.
Appearance of drug-resistant microorganisms prompted researchers to unravel new environments for development of novel antimicrobial agents. Culture-supported analysis of heterotrophic bacteria associated with seaweeds yielded 152 strains, in that larger share of the isolates was embodied by Bacillus atrophaeus SHB2097 (54%), B. velezensis SHB2098 (24%), B. subtilis SHB2099 (12%), and B. amyloliquefaciens SHB20910 (10%). One of the most active strains characterized as B. atrophaeus SHB2097 (MW821482) with an inhibition zone more than 30 mm on spot-over-lawn experiment, was isolated from a seaweed Sargassum wightii, was selected for bioprospecting studies. Signifcant antibacterial potential was displayed by bacterial organic extract against vancomycin-resistant Enterococcus faecalis, Pseudomonas aeruginosa, methicillinresistant Staphylococcus aureus, and Klebsiella pneumonia with minimum inhibitory concentration 6.25 µg/mL and comparable to the antibiotics ampicillin and chloramphenicol.
This study presents the linkage between recurrent (repeat) Potential Fishing Zones (PFZ) and seasonal hydrographic conditions along India’s Southwest (Kerala) coast in the Southeastern Arabian Sea (SEAS). The PFZ advisories released by the Indian National Centre for Ocean Information Services (INCOIS), Hyderabad, India are based on the fact that ocean processes that enhance biological production leave imprints on surface ocean parameters that can be tracked using satellite remote sensing techniques and used to forecast fish availability. Sea surface temperature and chlorophyll-a features of satellite remote sensing data sets usually coincide in regions and situations where physical processes and biological responses are closely coupled, which is used by INCOIS to create PFZ advisories. Nonetheless, it is unknown how PFZ frequency varies seasonally or how the recurrent PFZs are related to the region’s predominant seasonal hydrographic settings, which have been addressed here based on a retrospective analysis of PFZs disseminated by INCOIS in advisories distributed over five years (2008–2012). For the current investigation, 432 PFZ advisories over five years were analysed, and the regions of repeat PFZs were demarcated every month along the Kerala coast in the SEAS. This study found that almost all of the very prominent repeat PFZs are formed within the 50 m depth contour and the most frequent and pronounced repeat PFZs were observed across the entire SEAS during the Northeast Monsoon in December, January, and February. On the other hand, the lowest repeat PFZs were discovered in April and May, during the Pre-monsoon season.
Restoration of Rhizophora mucronata stand in the Gurupura Estuary resulted in improved water and sediment quality parameters. Monthly monitoring from 2011 to 2016 indicates that the restored mangroves grew to a height of 61.49 ± 5.76 cm. Principal component analysis (PCA) showed that increased duration of salinity in the estuary aided the growth of barnacles in planted mangroves which reduced survival by 10%. The United States Environmental Protection Agency ratings revealed that natural mangrove site in Shambavi River exhibit the maximum good water quality rating though dissolved inorganic phosphorous was rated highest due to non-point pollution sources. The pH, salinity, dissolved oxygen, silicate, phosphate, ammonia, and rainfall demonstrated significant seasonal differences (P < 0.001). Mangrove roots and biomes aided in accumulation of clay and significant difference (P < 0.001) was observed yearly. Land use management, efficient waste disposal system along with restoration of diverse mangroves can improve the water quality of estuarine ecosystem.
In this study, we measured the impacts of an effective fishing regulation on the sustainability of fisheries in Zuari estuary, a tropical estuary situated along western coast of India through an Ecosim approach. Ecosystem indicators for 2016 and 2031 (for each Ecosim scenario) were measured to compare and contrast the decadal changes in the status of the ecosystem between these two periods. Four different hypothetical fishing patterns were simulated to explore the best suited management scenario. The ecosystem indices of 2031 ecosystem were compared with that obtained for 2016 to evaluate the possible effects of fishing regulations. The functional groups showed a decline in their biomass when no fishing regulations are implemented (S1). The direct fishing effort reductions of all the fleets (S4) and ban/reduction of indiscriminate fishing fleets (S2-immediate ban and S3-gradual reduction) showed a more or less similar trend for recovery of fish stocks through diverse fisheries policies. A complete ban of indiscriminate fishing seems to slightly more advantageous than the direct reductions in the fishing effort for all the fleets in terms of stock recovery (130%), Q statistic (1.15), Shannon diversity (1.43), mean trophic level of ecosystem (2.98), mean trophic level of the catch (2.91) and fish catch in the gillnet fleet (200%). The simulations have also suggested that a complete control for mechanized fishing fleets will be the best possible management strategy for the recovery of fish stocks in the ecosystem.