Marine Debris and Trace Metal (Cu, Cd, Pb, and Zn) Pollution in the Stranded Green Sea Turtles (Chelonia mydas).

Marine debris and trace metals are among the common environmental contaminants known to affect marine organisms. In this study, the quantitative and qualitative aspects of marine debris levels and bioaccumulation of trace metals (Cadmium: Cd; Copper: Cu; Lead: Pb; and Zinc: Zn) were investigated in 42 green sea turtles (Chelonia mydas) stranded on the northern coast of the Sea of Oman. The greatest quantity of debris was found in the intestine, stomach, and esophagus of the animals, respectively. Results of a Marine Strategy Framework Directive (MSFD) subcategory analysis of the ingested debris showed that sheet and thread-like plastics were the most frequently detected debris followed by various rubbish. The results revealed that white-colored debris were the most common debris, followed by black > green > blue > transparent > and brown ones. The results suggested that the rope monofilament was the main source of the ingested debris by the green sea turtles. Concentrations of the trace metals in the liver, kidney, and muscle ranged between 0.66-33.43, 0.36-15.12, and 0.33-7.47 µg/g (ww), respectively. The results of this study suggest that ingested marine debris and tissue concentrations of trace metals are present at levels that may cause sublethal effects on green sea turtles (C. mydas) through potentially affecting the physiological processes and making the turtles susceptible to other natural or human threats. Results indicated that the green sea turtles from the northern coast of the Sea of Oman have high interaction with the marine debris. These factors are considered as a serious threat to the existence and survival of the green sea turtles (C. mydas) living on the northern coast of the Sea of Oman.

Biochemical and histological changes in fish, spotted scat (Scatophagus argus) exposed to diazinon.

Pesticide accumulates in aquatic ecosystems and exerts toxic effects on aquatic animals. In this study, stress parameters and tissue histopathology under acute diazinon exposure were investigated in fish, scat (Scatophagus argus). Spotted scat was exposed to different diazinon concentrations (0, 10, 20, 30 µg L(-1)) for 24, 48, 72, 96 h. Cortisol and glucose levels showed a significant increase after exposure to different diazinon concentration with increase in exposure time. The electrolytes (K(+), Cl(-), Ca(2+), Na(+)) and glucose were differentially affected during the exposure to diazinon. Gill and kidney tissues showed many histopathological changes in diazinon-exposed fish. These results suggest that the release of spotted scat (S. argus) into the diazinon-contaminated regions may alter their physiology and jeopardize their survival.

Impact of a short-term diazinon exposure on the osmoregulation potentiality of Caspian roach (Rutilus rutilus) fingerlings.

The stocks of Caspian roach (Rutilus rutilus), an economically important species in the Caspian Sea, are depleting. Each year millions of artificially produced fingerlings of this species are restocked in the mouth of rivers of the Southern Caspian Sea (e.g. Qare Soo River), where they are exposed to pesticides originating from regional rice and orchard fields. This early exposure to pesticides could affect the hypo-osmoregulatory ability of juvenile fish. Thus, in this study, Caspian roach fingerlings were exposed to environmentally-relevant concentrations of the organophosphate insecticide diazinon for 96 h in fresh water and then transferred to diazinon-free brackish water (BW) for another 96 h. We report that cortisol and glucose levels were significantly increased in all diazinon treatments at all sampling time points in comparison to the control group. Moreover, the thyroid hormone levels of TSH, T4, and T3 significantly decreased in diazinon-exposed fish even after the transfer to BW. The electrolytes were differentially affected during the exposure to diazinon and after the transfer to BW. The number of chloride cells in the gill tissue was significantly increased during diazinon exposure at the higher concentrations and decreased to control levels after transfer to BW. Finally, gill and kidney tissues showed many histopathological changes in diazinon-exposed fish even after 240 h in BW. These results suggest that the release of Caspian roach fingerlings into the diazinon-contaminated Caspian Sea regions may alter their physiology and jeopardize their survival, which could lead to a failure in rebuilding the Caspian roach stocks in the Caspian Sea.