Effects of heavy metals on the sperm quality and the larvae survival of sea urchins

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Context of the study

Paracentrotus lividus, the dominant sea urchin in the Mediterranean, is highly sensitive to various chemicals. Therefore it is used to asses the environmental impacts and toxic effects of numerous pollutants. In the Mediterranean several sites have been reported to be contaminated by heavy metals. In order to fully understand its toxicity it's important to know the different effects of different doses of the contaminant.[1]

Content of the study

The study aims to determine the toxicity of 4 heavy metals (mercury Hg, copper Cu, silver Ag, and cadmium Cd) on the fertilization and the early development of this sea urchin.

Main results of the study

Exposure of the sea urchin sperm to high concentrations of the 4 heavy metals affected their fertility. Lower concentrations of Hg (10-7M) were necessary to cause the same results than from Ag or Cu (both 10-6M). Even higher concentrations of Cd (10-5M) to affect the sea urchin's sperm cells. However, the offspring that did develop out of exposed sperm cells didn't display any abnormalities. These concentrations are much higher then those commonly reported from the North Sea, but they occur in heavily polluted area's in the Mediterranean. However, the sperm cells were exposed for periods of 30 min, while in natural conditions they are only for 5 minutes in free water before fertilization. Therefore, this experiment doesn't allow conclusions for natural conditions.

The lowest concentrations that proved toxic for the larvae were 100 times lower for Hg, Ag and Cu (10-7M, 2.5*10-7M and 5*10-7M respectively) than for Cd (10-5M). Each metal showed also different development defects. The severity of the development defect depended on the exposed concentration of the heavy metal. Since these concentrations occur in heavily polluted area's, or could occur after accidental major spills, heavy metals could in some area's impair the development of this sea urchin. [1]


References