The stress resulted from fluccuative of changing environmental gradiants generally effects on aquatic organisms and body compositions. The benthic macroinvertebrates are the aquatic organisms that show the changing environment conditons properly. In this research, the content of trehalose and glycerol were investigated in two amphypod species of Gammarus pseudosyriacus and Gammarus bakhteyaricus from Khersonak and kalicheh during different seasons for One-year study period. The species were collected seasonally from the beginning of autumn 2015 to summer 2016 from two defined sampeling stations. The sample were dried, extracted and then injected to high performance liquid chromatography (HPLC) for determination of trehalose and glycerol content. Results showed that trehalose were 0.76, 0.08, 0.78, 0.26 µg/mg wet weight for G. pseudosyriacus during spring, summer, autumn and winter, respectively, and for were Gammarus bakhteyaricus were 0.08, 0.21, 0.53, 0.03 µg/mg wet weight. The trehalose contents showed significant difference (P 0.05) among different seasons. In spring and autumn while had not significant difference in other seasons. Glycerol content were 91.69, 3.72, 29, 24.28 µg/mg wet weight for G. pseudosyriacus during spring, summer, autumn and winter, respectively, and for were Gammarus bakhteyaricus were 28.86, 9.57, 40.81, 2.81 µg/mg wet weight. The glycerol contents showed significant difference (P 0.05) among different seasons. In spring and autumn while had significant difference in other seasons. In summer these components were in lower amount. The reason could be attributed to various environment parameters. Such as gradual fluccuations in water/air temperature. Another reason may be assocated with rate of trehalose/glycerol consumption in these two examined amphypods. In winter, the storaged glycerol was used for prevention from freezing while in the autumn. The glycerol was consumed follow by lowest amounts n cold/winter season. This study showed that the amphypods are suitable organisms for monitoring of aquatic environments by measuring of biochemical components, especially trehalose/glycerol. Key words: G. pseudosyriacus,G. pseudosyriacus, Gammarus, trehalose, glycerol, seasonal changes.
