Benefits of Parasitism in Polluted Environments: A Review and Perspectives

Abstract

The frequency and strength of biotic interactions are thought to be shaped by environmental conditions. In this study, we reviewed and discussed the potential effects of toxic chemicals in driving shifts along the parasite-mutualist continuum. Some parasites have the astonishing capacity to accumulate trace metals and organic pollutants from various taxa within freshwater, marine, and terrestrial ecosystems. Recent studies have provided evidence of clear benefits for the host: when exposed to contaminants, infected organisms exhibited reduced contamination levels, less severe oxidative stress, and histological alterations, as well as higher body condition and survival rate compared with their uninfected conspecifics. Such effects might arise when the costs of parasitism are lower than their benefits in specific environmental conditions. Assessing the potential outcomes for parasites exploiting contaminated hosts is a crucial but neglected issue, since ecotoxicological effects on parasites may alter interspecific relationships. We identified possible avenues for future research using innovative tools and long-term experimental manipulations of both parasitism and pollution to better understand how toxic chemicals can modulate the strength and direction of host-parasite interactions.

Do Organochlorine Contaminants Modulate the Parasitic Infection Degree in Mediterranean Trout (Salmo trutta)?

“…This scenario indicates the possibility that a shift from parasitism to mutualism occurs. If concentration levels of the contaminant are high, they could induce damage to both host and parasites changing their relationships (see [ 71 ] and references therein).…”

Comparative Biodepurative Potentials of Metadavinae Cestodes and Strongyloides Nematodes on Trace Metals in the Intestine of whe-bellied Pangolin (Phataginus tricuspis)

“…Excessive bioaccumulation of manganese in the parasite may lead to a condition known as manganism, a neurodegenerative disorder that causes dopaminergic neuronal death (Avila et al, 2013), which may impair the parasitological effects on the host. This trend may thus protect the pangolin in the polluted environment in a more sustainable manner than conventional bioremediation methods (Sharma Agrawal, 2005;Zanvo et al, 2021;Goutte and Molbert, 2022). Notably, nematodes have been previously recommended as sentinel bioindicators of trace metals in aquatic and terrestrial ecosystems (Yen et al, 2013;Akinsanya et al, 2020;Isibor et al, 2020), sharing more burden of environmental pollutants than the initially exposed host.…”

“…Certain parasites exhibit symbiotic relationship by accumulating contaminants such as heavy metals and organic pollutants from their hosts into their own tissues (Akinsanya et al, 2020). Goutte and Molbert (2022) reported reduced contamination levels, oxidative stress, histological alterations, improved survival rates, and better body condition in infected individuals compared to non-infected counterparts of the same species.…”

Assessments and Identification of Selected Fish-Borne Zoonotic Parasites in Nile Tilapia and African Catfish Species in Lakes of Haramaya District, Ethiopia

“…The safety of food is affected by the health of animals, plants, and the environment within which it is produced [13]. Environmental change can affect parasite and host individuals directly by changing the ecological settings in which the interaction takes place [88,89]. It can negatively affect fish host via altering its ability to manage the parasite; the parasite via effects on virulence, transmission, or reproduction; invertebrate host via increasing reproduction; and human host via increasing aquatic-derived zoonoses [88,90].…”