Effect of Environmental Factors on the Intensity of Nematode Infection in Marine Fishes of Visakhapatnam, A.P, India

Abstract

| Environmental factors are of critical significance influencing the parasitic infection in fish and the subsequent expression of pathogenic potential. It has been seen that the nematode infection relates to the environmental factors like temperature and salinity. These two important parameters evidently influence the intensity of nematode infection in the marine fish community. Twenty-eight nematode parasites were recorded during the study in 112 marine fish species examined. Hundred and ninety-eight fish (8% of total sample) were infected with nematodes among 2500 fish specimens examined. The prevalence of nematode parasites was high in summer season followed by rainy season and winter season in all the three years (January 2007-December 2009). Based on the data given by the National Institute of Oceanography (N I O), Visakhapatnam, that the marine climate particularly of the coastal regions there are two peaks of high temperatures in every year recorded from 2007 to 2009. The intensity of nematode infections was also recorded high in these peak periods. This is an indication that the high temperature of the coastal marine environment plays an important role for the intensity of nematode infection to the marine fish, whereas during this period (Jan 2007 to Dec 2009) there was not much variation in salinity in the horizontal depth stratification ranging from 5 to 90 meters depth. The purpose of this study was to find out the effect of temperature and salinity on the intensity of nematode infection in edible marine fishes of Visakhapatnam.