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

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.

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 are concentrations which occur in heavily poluted 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.