Trace elements and high sulfur levels in the blood of rehabilitated eastern Mediterranean Sea green sea turtles (Chelonia mydas)

The Eastern Mediterranean Sea (EMS) exhibits high temperature and salinity, low levels of biologic production and is considered oligotrophic. Nonetheless, it is also a hotspot of biodiversity, with several important endangered flagship species, including several species of sea turtles. These turtles serve as bioindicators for the health of their ecologic systems, due to changes in diet, habitat and migration patterns that characterize different stages in their lives. This study covered 100 blood samples taken between 2008 and 2019 from 72 green sea turtles (Chelonia mydas) tested for 67 elements, some of which carry toxic potential. The turtles were treated at the Israeli Sea Turtle Rescue Center (ISTRC) after being rescued from sea, exhibiting a variety of health conditions and Injuries. The data were compared to similar studies worldwide and serve as a basis for monitoring the health status of the green sea turtles' EMS populations. The results of all animals presented noticeably high levels of sulfur – an order of magnitude higher than sea turtles from other locations around the world. This paper discusses the possible origins of this element, as well as its potential effects, while raising the question regarding the ability of these sea turtles to endure such sulfur levels.