Abatement of mercury pollution in aquatic systems: A biotechnological approach

Mercury has been in use since time immemorial for medicinal, agricultural and industrial purposes. It is widely used in the manufacture of thennometers, fungicides, insecticides, batteries, caustic soda, pulp and paper, urethane plastics and many other purposes. During 1953to 1961,43 people ilied and about 113 were affected with mercury poisoning after consuming mercury contaminated fish in Minamata, Japan. In 1960, in Sweden, methyl mercury accumulation in fish and decrease in the population of birds was noticed. This was attributed to the use of methyl mercury dicyanide

Cardiac myxosporiosis of pearl-spot, Etroplus suratensis (Bloch), due to Myxobolus etropli sp. nov.

A new myxosporea, Myxobolus etropli sp. now, was found to infect the bulbus arteriosus of Etroplus suratensis from brackishwarer lasoons of Muaulkadu. Chenna

Transgenic fish

Transgenic animal is defined as an animal that has been become transformed following the introduction of a novel gene in to its DNA. Gordon et al (1980) were the first to produce transgenic animals leased on the microinjection of cloned DNA into pronucleus of the fertilized eggs at the arc cell stage. Palmitev et al (1982) INTRODUCED GH gene into mice and achieve dramatic increase in growth of the animals and the successful transgenic animal has been produced

Fish health management in cage aquaculture

Finfish is the primary source of animal protein for humans in many parts of the world and per capita consumption of fish has been increasing from an average of 9.9 kg in the 1960s to 19.2 kg in 2012 (FAO, 2014). Growing global population, dwindling natural fish stocks, and the increasing demand are the major drivers for increasing fish production. Aquaculture remains the only option to meet these demands and globally, the share of aquaculture is projected to rise to 62% of the total fish production by 2030. However, considering the limitations of the traditional aquaculture systems due to environmental issues, carrying capacities etc., it has been recognized that cage culture, especially mariculture has many advantages. Over the years, cage culture has become one of the economically viable methods of large-scale production of high-value food fishes

Incidence of white muscle disease, a viral like disease associated with mortalities in hatchery reared postlarvae of the giant freshwater prawn Macrobrachium rosenbergii (De Man) from the south east coast of India

Incidence of post-larval mortalities of 30- 100% was reported from commercial freshwater prawn Macrobrachium rosenbergii (De Man) hatcheries in Andhra Pradesh and Tamil Nadu (south-eastern states of India) since 2001. Infec ted postlarvae (PL) exhibited clinical symptoms with lethargy, anorexia and whitening of abdominal muscles and the disease was identified as white muscle disease (WMD)

Volatilization of inorganic mercury by Isochrysis galbana Parke from aquatic system

The loss of mercury added cxtraneously as an inorganic source to the algal cultures (Jsochrysis sp.) and to the seawatcr containing in situ phytoplankton populations off Cochin was determined quantitatively. Such loss of mercury was attributed to uptake as well as volatilisation of mercury (Hg") by the activity of phytoplankton and micro - organisms. The rate of removal of mercury in the culture system was 54% per day and that by in situ phytoplankton was 38

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

Effect of temperature and salinity on the infectivity pattern of white spot syndrome virus (WSSV) in giant tiger shrimp Penaeus monodon (Fabricius, 1837)

White spot disease (WSD) caused by the lethal white spot syndrome virus (WSSV) continues to be the major cause of mortality among farmed tiger shrimp in India and elsewhere, resulting in an annual loss of about 4-6 billion US$. Among the environmental variables, temperature and salinity of the rearing water are considered to be major triggering factors for white spot disease outbreak. In order to characterise the effect of salinity and temperature on the pathogenecity of WSSV infection in giant tiger shrimp Penaeus monodon, a laboratory challenge study was conducted at different levels of temperature (16, 25, 27, 28, 30, 32 and 36 ºC) and salinity (0.5, 5, 10, 15, 30 and 45 g l-1) with virulent white spot syndrome virus. Significant influence of temperature (p<0.05) on the percentage mortality and time until death of shrimp affected by the virus was observed, whereas salinity did not show any effect. Significantly higher survival rate was recorded in animals exposed at 32 ºC (37%) and 36 ºC (14%), 21 days post-challenge (dpc). All the shrimp challenged at other temperature levels, however, died after 21 dpc. These results demonstrated preference of WSSV for lower temperatures and higher survival in temperature ranges of 32 ºC to 36 ºC. The present observation may help to develop a management option to control the WSSV inflicted mortalities by selecting favorable hyperthermic rearing conditions for the shrimp

Histopathology of Y-organ in Indian white shrimp Fenneropenaeus indicus, experimentally infected with white spot syndrome virus

Histopathology of Y-organ (moulting gland) in Indian white shrimp Fenneropenaeus indicus was studied after challenging the shrimp with virulent white spot syndrome virus (WSSV). Histopathological investigation on the Y-organ collected from moribund shrimps revealed the presence of intranuclear basophilic inclusions, characteristic of WSSV. More than 70% of the Y-organ cells were infected, suggesting the degenerated state of the organ. The cellular integrity of the Y-organ was completely destroyed by the WSSV. Further, Y-organ tissue samples collected from all the 16 experimental shrimp were positive by one-step polymerase chain reaction (PCR), confirming severe WSSV infection. The infected Y-organ in F. indicus with majority of the organ cells observed in the lysed condition suggests a physiological dysfunction of the organ. In uninfected and healthy controls, the lobulated Y-organ showed closely packed normal cells with prominent nuclei and sparse cytoplasm. Physiological implication of a degenerated Y-organ in the moulting and reproduction of the penaeid shrimp is discussed

Variation in fish catches from the continental shelf between Quilon and Gulf of Mannar and its relation to oceanographic conditions during the southwest monsoon period

The present paper is based on the fishing results of FORV Sagar Sampada during July-August, 1987 along the southwest coast of India. The fish fauna of the Quilon Bank and Wadge Bank has a dominant nemipterid element and the Gulf of Mannar area has a dominant population of barracudas. Nemipterids constituted 88.2 and 64.4% of the total trawl catch from the Quilon Bank and Wadge Bank respectively