Physiological and Reproductive Disorders of Baltic Amphipods Gmelinoides fasciatus Exposed to 4-tert-Octylphenol

Alkylphenols, which are industrial chemicals, are xenoestrogens; however, their sublethal effects on aquatic animals are poorly studied. The aim of this work is to study possible metabolic and reproductive disorders in amphipods using the example of Gmelinoides fasciatus from the Gulf of Finland (Baltic Sea) after experimental exposure to 4-tert-octylphenol (4t-OP) from the group of alkylphenols. The mortality of G. fasciatus amphipods in 4t-OP concentration ranges from 0.5 to 1000 μg/L after 96 h and 7 days increases with increasing concentration. At 4t-OP concentrations of 0.5 and 5 μg/L, the mortality of G. fasciatus has not been observed. At a concentration of 20 μg/L, after 7 days, the mortality of crustaceans is 20%; at a concentration of 100 μg/L, it is 60%. Exposure to sublethal concentrations of 4t-OP (0.5 μg/L) resulted in a decrease in sexual activity of these amphipods after 1 week: only 25% of amphipods retain precopulatory pairs versus 100% in control. Under chronic exposure (28 days) to the lowest concentration, males show signs of demasculinization (a decrease in the width of the gnatopods and an increase in the depth of the coxal plates); females show a decrease in the overall fecundity and irreversible disturbances in the state of embryos (a high proportion (>50%) of embryos stop their development at different stages of organogenesis). The study shows significant functional disorders of metabolic processes and reproduction in crustaceans even when exposed to nonlethal concentrations of octylphenol. These results confirm the high toxicity of this industrial pollutant, the presence of which in the aquatic environment can lead to irreversible changes in the biota.