Overview of the effects of heavy metals on the reproductive health of males in the genus Mytilus spp.

This review examines the reprotoxic effects of key heavy metals, specifically nickel, chromium, zinc, copper, mercury and cadmium, on the reproductive health of bivalve molluscs of the genus Mytilus spp. which serve as important bioindicators in marine ecosystems. Exposure to even sub-lethal concentrations of these metals induces oxidative stress, DNA damage and changes in chromatin structure, which are thought to affect fertility. These metals, known for their persistence and bioaccumulation, interfere with critical reproductive processes by also altering the functions of protamine-like proteins (PLs), the main nuclear basic proteins of sperm chromatin of these organisms. Moreover, Seasonal variations influence the toxicity of these metals, coinciding with critical phases of gametogenesis and amplifying their detrimental effects during reproductive cycles. The study highlights the urgent need for comprehensive biomonitoring programmes, as the sensitivity of Mytilus spp. to environmental contaminants provides valuable insights into the health of marine ecosystems. Given their economic importance and ecological role as filter feeders, the impact of heavy metal pollution on these bivalve molluscs goes beyond increased environmental pollution and threatens biodiversity and seafood safety. To mitigate these risks, strict pollution controls and further research into molecular toxicology are essential. Understanding this will help to develop effective strategies to conserve marine life and maintain the ecosystem benefits provided by these sentinel species.