Ecotoxicological effects of heavy metals on marine mammals:A systematic review

Abstract

Heavy metal pollution originates from mining, agricultural,
and domestic activities, significantly impacting water
resources. It has been reported that between 75% and
96% of the world’s seas are contaminated, exposing marine
mammals to ecotoxicological effects, with about 60%
affected. The data sources used for this research include Scopus, ScienceDirect, Springer, ResearchGate, and the Journal
of Wildlife Diseases. Additionally, the PRISMA methodology was
employed for a systematic review, analyzing 60 articles. The results
indicate that most studies are from the United States, with the
Delphinidae family being the most frequently studied. Furthermore,
93% of the studies focus on chronic effects related to bioaccumulation
in the liver and kidneys. There is a positive correlation between
exposure time and concentration differences according to diving
depth. High concentrations of arsenic have been shown to weaken
the immune system, making animals more susceptible to infectious
diseases, while high levels of cadmium can cause chronic kidney
damage. The remaining 7% of studies address acute effects,
revealing that elevated concentrations of mercury and cadmium
are associated with significant damage to cellular organelles and the
immune system. Consequently, heavy metal pollution in marine
mammals constitutes a significant problem due to its persistence,
bioaccumulation, and biomagnification. These animals, positioned
at the top of the food chain, face various exposure pathways, with
dietary intake being the most significant.