Effects of a Chemically Polluted Discharge on the Relationship Between Fecundity and Parasitic Infections in the Chub (Leuciscus cephalus) from a River in Southern England

Abstract

In fish there is a close association between endocrine and immune function that during seasonal changes in reproductive status can affect the fishes susceptibility to parasitic infection. The effects of endocrine-disrupting pollution on this association are not known. The present study investigates the effects of a chemically polluted (ammoniacal nitrogen, zinc, bromide) discharge in Cranleigh Waters, a river in southern England, on the fecundity and parasitism of chub, Leuciscus cephalus, over an 18-month period. In the polluted site, the gonado-somatic index (GSI) of fish was lower in females and higher in males compared to an unpolluted upstream site, indicating an androgenic effect on reproduction. Parasite species richness, especially the intestinal helminths Proteocephalus torulosus and Pomphorynchus laevis, was increased in fish in the polluted site. However, the occurrence of the two most common parasite species in the river-Myxobulus sp. 1, a gill myxozoan, and Diplostomum sp., a trematode found in the eye-was unchanged between polluted and unpolluted river sites. Nevertheless, there was a significant relationship between GSI and the prevalence of these two parasite species in the unpolluted site but not the polluted site suggesting that endocrine disruption of reproduction did not lead to an increase in host susceptibility. The reasons for this are discussed.

Pharmaceutical contamination and biotic factors affecting parasitism in common carp ( Cyprinus carpio )

“…Mikl, unpublished data). Similar results were found in polluted ecosystems using cyprinid (Morley et al, 2010) or cichlid (Madanire-Moyo et al, 2012) fish.…”

“…These organisms can tolerate organic pollution (Sibley et al, 2000), being in accordance with our finding of ten‐times higher density of oligochaetes at polluted compared with control site (L. Mikl, unpublished data). Similar results were found in polluted ecosystems using cyprinid (Morley et al, 2010) or cichlid (Madanire‐Moyo et al, 2012) fish.…”

Preliminary evaluation of some aspects of the ecology (growth pattern, condition factor and reproductive biology) of African pike, Hepsetus odoe (Bloch 1794), in Lake Eleiyele, Ibadan, Nigeria

“…Louiz et al (2009) were of the opinion that a low GSI in fish has often been linked to gonad disturbance in polluted sites which could be probably due to atresic oocytes and disintegration of cytoplasm that are often found in their ovaries. Morley et al (2010) reported a low GSI for fish investigated in polluted water of Cranleigh Waters but were in good condition (with K > 1).…”

Hatchability and survival of oncomiracidia of Paradiplozoon ichthyoxanthon (Monogenea: Diplozoidae) exposed to aqueous aluminium

“…Monogeneans are particularly sensitive toward heavy metals in the environment [ 7 ]. The responses of diplozoids toward pollution, like other monogeneans, varies with the type of pollutant present [ 10 , 14 , 27 , 28 ]. The present study highlighted the effect of varying nominal concentrations of aluminium on the hatchability of eggs and survival of oncomiracidia of Paradiplozoon ichthyoxanthon which has not been investigated previously.…”