Correlations between pathological changes and chemical contamination in American eels, Anguilla rostrata, from the St. Lawrence River

Abstract

American eel (Anguilla rostrata) from the St. Lawrence River are heavily contaminated with chemicals that may be associated with increased incidence of diseases and reproductive impairment. The relationship between tissue mirex concentration and body mass was used to separate eels into two groups: the proportion of eels migrating from contaminated areas (Lake Ontario and upper St. Lawrence River) increased as the migration season progressed. Vertebral malformations and basophilic foci in the liver (preneoplastic lesions) were more frequent at the end of the migratory season, when the eels were more heavily contaminated with organochlorine compounds. In contrast, mesenteric nematodes were more common in the first week of the season, when eels were less contaminated. Diameters and percentages of different stages of oocytes, and density and surface area of pigmented macrophage aggregates in the spleen, did not vary among weeks. While basophilic foci are specific biomarkers of exposure to environmental contaminants, vertebral malformations may be caused by a variety of other anthropogenic or natural factors.\b Further studies are needed to confirm the observed associations between chemical contamination and pathological changes.

Plasma non‐esterified fatty acid profiles and 17β‐oestradiol levels of juvenile immature and maturing adult American eels in the St Lawrence River

“…The I G values observed in Quebec City and Kamouraska eels agree well with other studies on American eels in the St Lawrence River (Couillard et al, 1997) and other systems (Wenner & Musick, 1974) and the two-to three-fold increase in I G supports the notion that the eels from Quebec City and Kamouraska are more sexually mature than most eels found in Lake St Lawrence. The gonad sections from the eels collected in Quebec City and Kamouraska had a very high proportion of vitellogenic oocytes (stage 4) with diameters comparable with those published elsewhere (Wenner & Musick, 1974;Couillard et al, 1997). Only the small group of eels classified as Lake St Lawrence-Mature, collected from the upstream study area, had comparable ovarian development with intermediate I G values [ Fig.…”

“…Sections were cut at a thickness of 6 m. The diameters of 100 randomly selected oocytes in which the nucleus was visible were measured along the longest axis. Additionally, the stage of development of each of these oocytes was determined using the criteria described by Couillard et al (1997) which assesses the maturity of an oocyte based on vacuole development. Stage 1 is the most immature stage and contains no or few cytoplasmic vacuoles; stage 2 contains a small number of relatively large vacuoles; a stage 3 oocyte contains a large number of vacuoles which form a complete ring around the circumference of the developing oocyte, but cover <50% of the oocyte area; stage 4, which is the most advanced stage, in which both large and small vacuoles cover >50% of the cytoplasm.…”

Utilisation des poissons pour évaluer les effets biologiques des contaminants dans l’estuaire du Saint-Laurent et le fjord du Saguenay

“…Des lésions pré-néoplasiques au foie et des foyers basophiles ont été observés chez les anguilles argentées capturées à Kamouraska en 1990 et indiquent que ces poissons ont été exposés à des HAP cancérigènes ( Figure 1, Tableau 2; COUILLARD et al, 1997). Quoique aucun HAP n'ait été détecté dans les tissus des anguilles (HODSON et al, 1992), on considère que ces composés sont rapidement éliminés par les poissons même s'ils laissent des changements tissulaires irréversibles.…”

“…Ainsi, le Mirex, un pesticide dont l'utilisation et la production ont été restreintes à la région des Grands Lacs de 1959 à 1976, a été utilisé pour reconnaître les anguilles argentées provenant du secteur du lac Ontario (DUTIL et al, 1985). Les lésions pré-néoplasiques au foie étaient plus fréquentes en fin de migration chez les anguilles les plus fortement contaminées au Mirex et provenant vraisemblablement du lac Ontario ou de la partie amont du fleuve Saint-Laurent ( Figure 5, COUILLARD et al, 1997). Des lésions semblables, associées à des lésions cancéreuses au foie, ont été décrites chez les meuniers noirs du Lac Ontario, dans le port d'Hamilton, fortement contaminé aux HAP (HAYES et al, 1990).…”

Chemical–environment interactions affecting the risk of impacts on aquatic organisms: A review with a Canadian perspective — interactions affecting vulnerability

“…For example, in the Great Lakes, early life stage mortality causing reproductive failure in lake trout (Salvelinus namaycush) has been attributed to organohalogen compounds (Cook et al 2003). Fish liver tumours indicative of exposure to polycyclic aromatic hydrocarbons (PAHs) have been reported in the Great Lakes, St. Lawrence River and Estuary and in Vancouver Harbour, BC (Hayes et al 1990;Couillard et al 1997;Mikaelian et al 2002;Stehr et al 2004). Fish liver tumours indicative of exposure to polycyclic aromatic hydrocarbons (PAHs) have been reported in the Great Lakes, St. Lawrence River and Estuary and in Vancouver Harbour, BC (Hayes et al 1990;Couillard et al 1997;Mikaelian et al 2002;Stehr et al 2004).…”