Assessment of soft bottom polychaete diversity in Thondi, Palk bay, India.

Polychaete assemblages are relatively poorly known in comparison to other components from Indian waters. In the present study, the spatial and seasonal distributions of polychaetes were investigated in the Thondi coastal area. Polychaete assemblage structure seems to be influenced by environmental parameters, such as temperature, salinity, pH, dissolved oxygen and total organic carbon. A total of 34 polychaete species were found, of which 26 species were in station I while 22 species in station II. There was a pronounced variation in diversity of polychaetes between the studied sites. Among the families maximum percentage of species constituted by Glyceridae (12%) and minimum Owenidae (4%) at station I and in station II, the Eunicidae (14%) was maximum and Pisinidae as (4 %) minimum. The population density varied from 1456 to 2456 no m-2 in station I; 2120 to 4424 in station II and diversity index varied from 1.96 to 2.48 in station I; 2.01 to 2.53 in station II. Species richness varied from 1.21 to 1.65 in station I; 1.36 to 1.69 in station II and evenness index varied from 0.9 to 0.97 in station I; 0.91 to 0.98 in station II. BIO-ENV analysis showed that salinity, TOC and temperature as the key variables in influencing the faunal distribution.

Observation on an isopod parasitizing the edible fish Parastromateus niger in the Parangipettai coast of India.

Cymothoidae are big parasites on fishes and often they are host specific. This study reports that in India, the Black pomfret (Parastromateus niger), a highly edible marine fish belonging to the family Carangidae, is the type host of Cymothoa eremita (Isopoda, Cymothoidae). Among one hundred and sixty fish examined from April to July, 2010 in Parangipettai coastal waters, only three female specimens were infested in June, 2010. It seems that such parasitism depends particularly on the season and on the host sex.

Molecular interactions and excess thermodynamic properties of mixed solutions of zinc sulphate and zinc nitrate at 303K by ultrasonic method.

The ultrasonic velocity, density and viscosity were measured in aqueous mixtures of zinc sulphate (Heptahydrate) and zinc nitrate (Hexahydrate) at 308 K. Acoustic parameters, such as specific acoustic impedance, free length, isotropic compressibility, molar compressibility, molar sound velocity, free volume, available volume, relaxation time, excess parameters and the deviation from the experimental values has been evaluated. The value of ultrasonic velocity decreases and comes to a minimum and then increases as the mole fraction of zinc nitrate increases in the mixed salt solution. The excess adiabatic compressibility of zinc sulphate and zinc nitrate mixed solution with water was positive at all concentrations, while it is negative at a mole fraction of 0.7945. Variation of these parameters with concentration indicates the non-linear behavior. This non-linear variation of velocity with increase in concentration indicates the complex formation between the constituents of mixture. The results were interpreted as per the intermolecular interactions.

Identification of Parapenaeopsis stylifera, a new host for Epipenaeon ingens.

Epipenaeon ingens (Isopoda: Bopyridae) is reported for the first time from Parapenaeopsis stylifera (Decapoda: Penaeidae) in South India. According to the month the parasitic prevalence ranged from 0.0 to 2.9%. A characteristic bulge of the branchial chamber, growth retardation and degenerated sex organs were observed in the infested shrimp.