Effect of environmental factors and sex difference on physiological responses of the exotic red swamp crayfish, Procambarus clarkii, in Egypt.

Abstract

ABSTRACThe current study was conducted to investigate the effect of environmental factors and sex difference on the physiological status of the exotic red swamp crayfish (Procambarus clarkii) in Egypt along four successive seasons during the period from 2005 to 2006. Animals were collected from El-Mansourya canal at Giza governorate . Water and sediments were collected from three different aquatic habitats in order to determine the least polluted water quality region for collecting specimens used in the current study . These sites were: El-Mansourya canal (site I), El-Mouhit drain (site II) and Bany Magdoul canal (site III). During the four seasons, measurements of physicochemical characteristics of water and sediments revealed elevated annual concentrations for ammonia, nitrates, nitrites, in addition to high chlorosity in site II and heavy contamination with iron, copper, manganese, zinc and aluminum in site III; whereas site I was the least polluted and possesses the most transparent water with lowest electrical conductivity than the other sites. Lowest water temperature was recorded during winter and the highest one was during summer; while at the same season no wide difference has been found among the three habitats. Biochemical analysis of the main edible parts of crayfish inhabiting El-Mansourya canal (site I) revealed that males showed little rise in their muscle water content but females exhibited significant higher lipid content almost the year round. No marked changes were observed in the protein content in both sexes. Females also showed more glycogen accumulation in their abdominal muscles but lack statistical significance except during spring . In both sexes, highest levels for water content were reported during winter and for lipid during spring while for glycogen were during autumn . The lowest content for lipid was during autumn and for glycogen during winter for both sexes. The results indicate that seasonal changes in biochemical composition of edible parts of both sexes could reflect different physiological processes related to sex difference as an expression of animal adaptive response, an ecophysiological adaptation, to habitat quality and environmental conditions along the four successive seasons in Egypt.