Physico-chemical studies of River Pumba and distribution of prawn, Macrobrachium rosenbergii.

Physico-chemical factors of river Pumba, Kerala has been analyzed to understand its relationship with the distribution of Giant river prawn, Macrobrachium rosenbergii in the water body. Water samples were taken from two sites on the basis of presence and absence of juveniles. Analysis of temperature, pH, turbidity, dissolved oxygen, dissolved carbon dioxide and salinity of the water samples revealed that except salinity all the other parameters were identical in both the regions. Salinity was high i.e., 5-8 per thousand in lower Kuttanad region, where juveniles were seen. In upper Kuttanad region, where only adults were located, the salinity was of freshwater pattern i.e., 2.1-2.9 per thousand. The gut content analysis of M. rosenbergii in both the regions showed similar food pattern. The study reveals the significance of a water body with high saline region for breeding purpose and low saline region i.e., freshwater pattern for adult prawns in the life cycle of M. rosenbergii.