Potential Benefits of Acanthocephalan Parasites for Chub Hosts in Polluted Environments

Abstract

Some parasites are expected to have beneficial impacts on wild populations in polluted environments because of their bioaccumulation potential of pollutants from their hosts. The fate of organic micropollutants in host–parasite systems and the combined effect of parasitism and pollution were investigated in chub Squalius cephalus, a freshwater fish, infected (n = 73) or uninfected (n = 45) by acanthocephalan parasites Pomphorhynchus sp. from differently contaminated riverine sites. Several ubiquitous pollutants (polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl-ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), phthalates, insecticides, pyrethroids, and N,N-diethyl-meta-toluamide (DEET)) and some of their metabolites were characterized for the first time in parasites and various fish matrices (muscle, liver, and stomach content). Most organic pollutants reached higher levels in parasites than in chub matrices. In contrast, metabolite levels were lower in parasite tissues compared to fish matrices. Infected and uninfected chub exhibited no significant differences in their pollutant load. Body condition, organo-somatic indices, and immunity were not affected by parasitism, and few correlations were found with chemical pollution. Interestingly, infected chub exhibited lower oxidative damage compared to uninfected fish, irrespective of their pollutant load. In light of these results, this correlative study supports the hypothesis that acanthocephalan parasites could bring benefits to their hosts to cope with organic pollution.

Trophic Transfer of Micropollutants and Their Metabolites in an Urban Riverine Food Web

“…46 At last, individual traits, such as age and sex, may also explain the bioaccumulation of persistent organic pollutants in terrestrial 47 and aquatic 48 vertebrates but not levels of PAH, phthalates, and their metabolites in fish. 49,50 Trophic Transfer of Metabolites. A novel aspect of this study is its consideration of the fate of metabolites across the food web, as this has been previously recommended 45 but poorly conducted.…”

Fish from urban rivers and with high pollutant levels have shorter telomeres

“…Among the wide range of analysed contaminants, the levels of phthalate metabolites were more prone to explain differences in our data than parent pollutants. In a previous study using the same dataset, metabolites of organic pollutants were negatively correlated to antioxidant capacity and peroxidase activity in chub plasma [31]. Organic pollutants may therefore produce oxidative stress by disrupting the pro-oxidant/antioxidant balance, which is a potential pathway of telomere shortening [11].…”

“…Physico-chemical and hydrological parameters of each sampling site are presented in the electronic supplementary material (electronic supplementary material, appendix A, table S2). Left pelvic fins were consistently sampled for DNA extraction and scales were removed for age determination (see [31], for details). Muscle samples (n = 118) were used for the quantification of parent organic contaminants and metabolites of pollutants were analysed in the liver (n = 93), as the primary organ of xenobiotic biotransformation.…”

The potential use of Octolasmis spp. parasites in mud crabs Scylla spp. as a bioindicator for mercury pollution

“…This confirms earlier studies using parasites as bioindicators, that have also reported higher heavy metal concentrations in the parasite relative to the host. This can be assumed to (i) the influence of the parasites on the host's capacity to detoxify pollutants (Gismondi et al 2012;Molbert et al 2020), or heavy metal load (Sures et al 2017), (ii) the effect of pollutants on the prevalence and intensity of parasites (Ugokwe and Awobode 2015;Borkovcovaet al 2020;Nur et al 2020); and (iii) the adult life stage of Octolasmis and associated exposure to Hg.…”

“…However, the use of certain fish endoparasites have also been identified as particularly useful bioindicators of heavy metal pollution (Al-Hasawi 2019; Mehana et al 2020) due to their capacity for bioconcentration (Brázová et al 2012). For example, an early study of acanthocephalan parasites ('thorny-headed worms') indicated significantly greater concentrations of heavy metals than in the host body, providing the role parasites could play as environmental quality indicators (Sures et al 2017;Mehana et al 2020;Molbert et al 2020). Tellez and Merchant (2015) also found that trematode parasites in the intestine of American alligator, Alligator mississippiensis, are preferable magnifiers of heavy metal, while Hassan et al (2016) found similar in nematode helminths in the muscles of koshar fish, Epinephelus summana.…”