Distribution of luminescent Vibrio harveyi and their bacteriophages in a commercial shrimp hatchery in South India

Luminescent Vibrio harveyi is a natural microflora of marine and coastal water bodies and is associated with mortality of larval shrimp in penaeid shrimp hatcheries. It is also known that the bacteriophages occur virtually in all places where their hosts exist. In this study, distribution of luminescent V. harveyi and the bacteriophages affecting these hosts was examined in a commercial Penaeus monodon hatchery during three shrimp larval production cycles, including a cycle affected by luminescent bacterial (LB) disease outbreak

Is the Scyphozoan jellyfish Lychnorhiza malayensis symbiotically associated with the crucifix crab Charybdis feriatus?

Scyphozoan jellyfish (Medusae), the gelatinous invertebrate group, plays a vital role in the global oceanic and coastal ecosystems. By virtue of their floating nature, and horizontal and vertical spread in the water column, they are known to have varied associations with other invertebrates and teleosts, which make them an integral part of the marine ecosystem

Role of Clams in Regulating Biogeochemical Processes of Ashtamudi Lake

Role of Clams in Regulating Biogeochemical Processes of Ashtamudi Lak

Microbial dissolution of a low grade Indian chalcopyrite ore using mixed culture of Mesophiles

An enriched culture of mesophiles namely, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans derived from mine water of Malanjhkhand Copper Project (MCP), India in the ratio of 4:1, and adapted on 5%(w/v) ore at 35oC was used for the bioleaching of a low grade chalcopyrite ore (0.27% Cu). Optimum copper recovery of 91% was achieved at 1.5pH and 10% (w/v) pulp density in 30days using <50μm particles. Copper recovery decreased to 82% when pH was raised to 2.5 under similar conditions. Higher copper recovery at pH 1.5 may be attributed to the improved bacterial activity (7.0x108 cells/mL), higher redox potential (666mV) and formation of minimum amount of hydronium jarosite, which was prominent at higher pH. Copper recovery was 41.2% in sterile control leaching conditions at 1.5pH. However, unadapted bacterial consortium yielded copper recovery of 69.4% only in 30 days at pH 1.5 under the above conditions. Higher metal recovery with adapted mixed culture may be attributed to increased rate of iron bio-oxidation. The biorecovery of copper from the MCP lean grade ore appeared to follow direct as well as indirect mechanism

Assessment of provisional ecosystem services in Vypin Island, Cochin Backwater and payment for coastal ecosystem services

Assessment of provisional ecosystem services in Vypin Island, Cochin Backwater and payment for coastal ecosystem service

Assessment of biogeochemical processes of Ashtamudi Lake ecosystem in relation to clam fishery

The Ashtamudi Lake ecosystem in Kerala (southwest coast of India) is well known for its clam resources. This estuarine system contributes approximately 80% of the total clam export trade of India besides providing livelihoods for at least 3,000 local people. Among bivalves, clams are an important source of meat for human consumption while its shells are used in the cement industry

Copper biodissolution from a low grade chalcopyrite ore by unadapted/adapted acidithiobacillus ferrooxidans

The depletion of high-grade deposit of copper around the world has drawn attention for the utilisation of low-grade reserves . Malanjkhand Copper Project (MCP) in India is a low-grade ore containing -0.3% Cu in which copper metal is found to be present as chalcopyrite associated with pyrite in quartz veins and granitic rocks. In order to extract copper from this material , an alternate processing option such as bioleaching has been followed. Bench scale bioleaching experiments were carried out using Acidithiobacillus ferrooxidans (Ac. Ti) isolated from mine water. On using unadapted Ac. Tf isolate directly at pH 2.0 and 35°C, the optimum leaching conditions in shake flask were found to be 5% pulp density (PD), 2.OpH , 35°C temperature for <50p .m particles , yielding 72% Cu biorecovery in 35days. The Tf isolate when adapted to the ore and employed for the bioleaching of the ore at 5% PD (w/v), 2.OpH and 25 °C with three particle sizes viz.150 -76μm, 76-5011m and <50μm, resulted in recovery of 38 .31%, 29.68% and 47.5% Cu respectively with a rise in Eh from 530 to 654 mV in 35 days. Under similar conditions , the unadapted strain gave maximum recovery of 44.0 % for <50pm ore size with rise in Eh from 525 to 650mV . Copper biorecovery increased to 75.3% with the adapted isolates at 35°C for the finer particles of <50gm at 2.OpH with a rise in cell count from lx l 07 cells/mL to 1.13x109 cells/mL in 35 days. The biodissolution of copper from chalcopyrite with the involvement of adapted Ac. Tf species resulted in the improvement of iron oxidation rate (Fe2+ to Fe'`) and consequently higher redox potential

Some observations on the beaked sea snake Enhydrina schistosa (Daudin, 1803) in the mudbank area, off Alapuzha, Kerala, southwest coast of India

Hook-nosed sea snake or beaked snake, Enhydrina schistosa were caught during experimental fishing operations in the mudbank region along central Kerala Coast at depths ranging from 6 to 12 m. The sea snakes were found to form aggregations of 5 to 6 numbers and were able to tolerate highly turbid waters. The catfish Arius jella and the puffer fish Lagocephalus inermis were the dominant prey items. mudbanks are unusually calm areas which form along the Kerala coast during the monsoon. The inshore waters including the mudbanks are intense fishing areas of non mechanized crafts during the monsoon. The presence of venomous sea snakes is precarious and there is a need to give awareness programme for the fishers about this danger

Assessment of marine debris in the stake net fisheries of Vembanad Lake, Kerala, India

The stake net fishery of Panambukad in the main channel area of Vemband Lake, Kerala was studied during the first fortnight of August 2014. The observations indicated that the average catch including the marine debris ranged from 1.04 to 2.04 kg net-1 day-1 with an average of 1.34 kg net-1 day-1. The percentage of marine debris in the stake nets ranged from 42.68 to 73.4%. Plastic items formed 97% by weight and 99% by number of the total marine litter. The observed litter stuff was categorized as per UNEP system of classification of marine litter where, they are first identified based on their material composition (litter codeeg. PL) and then by their form (RL classes). Items found in the collection included plastic covers (PL07, RL15), metal cap (ME02, RL01), plastic bottle (PL02, RL02), fishing net (PL20, RL05), plastic cup and food containers (PL06, RL09), thermocol (FP 04, RL13), rubber sheet (RB05, RL28), plastic sacks (PL24, RL23), diaper (OT02, RL18) etc. Among them, plastic covers were most dominant and their average number and weight net-1 day-1 was 28 nos and 985 g respectively. The study also showed positive signs of decline in plastic bottles as a major litter item due to its targeted collection by recycling industry within a span of three years. In a survey conducted among the stake net fishers, there was consensus on the view that plastic litter in Vembanad Lake has increased during the last 10 years and this has affected the resources and the fishery. The stakeholders also expressed their willingness to pay for restoration of the fishery resources of the lake. The study recommends the need to establish proper solid waste management systems in coastal villages, to reduce the use of plastics, and provide facilities for disposal of litter which gets collected in stake nets and to increase the awareness among the public about the impacts of marine debris on ecosystem and resources

Effects of residual stresses on interlaminar radial strength of Glass-Epoxy L-bend composite laminates

The built-in heterogeneity of the composite laminates has been exploited to tailor the stiffness and strength requirements of modern structures to meet the specific functional demands. However, the non-homogeneity in these composites is the root cause for most of their failures. One of the undesirable consequences of the inherited heterogeneity is the development of cure-induced stresses during composite manufacturing. This work aims to investigate the influence of process-induced stresses on interlaminar radial strength in curved composite laminates. Glass-Epoxy (GE) laminates of two different thicknesses were prepared by hand lamination technique using V-shaped tooling and cured under room temperature. The state of residual stresses in GE laminates is varied by post-curing these laminates at different temperatures. Curved bending strength (CBS) and corresponding interlaminar radial stress for delamination of L-bend laminates were evaluated experimentally using four points bending test. The residual stress profile in each GE laminate is experimentally characterized by employing the Slitting method. The results indicate that the residual stresses have a negligible effect on the critical stress for initial delamination in GE laminates. But, the critical stress for delamination was found to be independent of the laminate thickness and increased with higher curing temperatures. The delaminated surfaces of L-bend laminates were studied using a scanning electronic microscope (SEM). The enhancement in the critical stress due to post-curing can be attributed to the improved fiber-matrix interfacial bonding with higher curing temperature