The hydroxyproline content in Crangon crangon tissues from the Gulf of Gdansk (southern Baltic) was determined in males, non-ovigerous females and ovigerous females, depending on the individual body length, the study area (two profiles: Gdynia and Sopot) and the depth of occurrence. Individuals were collected and analyzed from April to August 2008. The research on the migratory species C. crangon indicates that the area and depth of its occurrence do not significantly affect the level of hydroxyproline in the tissues of this animal (p > 0.05). However, certain trends have been observed. Hydroxyproline participates in various life processes of C. crangon and its level in the tissues is significantly correlated with the sex of animals (p < 0.05). In males, hydroxyproline plays a major role in the body growth. Moreover, water temperature significantly affects the hydroxyproline content in males of different body sizes. Ovigerous females use hydroxyproline in the reproductive process. In non-ovigerous females, hydroxyproline participates both in the growth of organisms and in the reproductive period. Hydroxyproline can be an indicator of the collagen level, as well as an important factor in physiological processes.
