Fish Parasites as Biological Indicators of Metals Pollution in the Aquatic Environments

Abstract

This review focused on comparing the capability of different helminthic taxa infecting fish to accumulate heavy metals in their bodies, as well as the conditions that influenced such accumulation. Fish-parasite models, fish habitat, elements accumulated, and host tissues analyzed were considered in the present article. The papers published between 2010 and 2022, concerned with helminthic fish parasites, which were used as biological indicators of metal contamination in aquatic environments were retrieved using specific inclusion and exclusion criteria. Four taxa of helminthic parasites were assessed to be bioindicators: acanthocephalan, nematodes, cestodes and trematodes. Fish parasites can accumulate heavy metals at levels of magnitude orders higher levels than their fish hosts' tissues, and can give helpful information on the chemical status of their environment. Compared to helminths that have a gastrointestinal tract; gutless helminths are better sentinels for metal pollution. Factors that impacted the metal accumulation in both fish and their parasites were investigated in a number of retrieved studies. There are various benefits to using fish parasites as bioindicators of heavy metal contamination, but three stand out: protecting fish health as an important element of the ecosystem, monitoring pollution levels in the environment, and safeguarding human health by determining the suitability of fish for human consumption in terms of the accumulation of heavy elements in it. In addition, researchers in the field of ecotoxicology who use fish as bioindicators must keep in mind that parasites reduce heavy metal bioaccumulation in the tissues of their hosts.