ABSTRACT
Brown trout (Salmo trutta) collected from a number of Danish streams impacted by sewage effluent were examined for alterations to gonadal development and induction of vitellogenin synthesis. Among fish collected in June/July 2000/2001 and November 2002 higher levels of plasma vitellogenin were found in males from six streams impacted by sewage effluent compared to males from their respective reference sites. A direct non-competitive ELISA was developed for brown trout vitellogenin in order to perform the vitellogenin measurements. Intersex in females with no apparent relation to sewage effluent exposure was observed at all sites. In one stream, male brown trout with a very high level of vitellogenin were concomitantly found to have a high degree of vacuolation of the testes and a presence of only the early spermatogenic stage, spermatogonia. The cause of these alterations to the testis structure is unclear. However, as a high level of plasma vitellogenin in these males indicated estrogenic exposure, the vacuolation might also be a result of endocrine disruption causing delayed or disrupted spermatogenesis.
Subject(s)
Fresh Water/analysis , Gonads , Salmonidae , Sewage/chemistry , Vitellogenins/metabolism , Water Pollutants, Chemical/toxicity , Animals , Denmark , Environmental Monitoring , Female , Gonads/drug effects , Gonads/metabolism , Gonads/pathology , Male , Ovary/drug effects , Ovary/metabolism , Ovary/pathology , Salmonidae/blood , Salmonidae/growth & development , Salmonidae/metabolism , Testis/drug effects , Testis/metabolism , Testis/pathology , Vitellogenins/bloodABSTRACT
Roach (Rutilus rutilus) from Danish streams that receive discharges of domestic sewage effluent were examined for the presence of alterations to gonadal development. In male roach, intersex was observed at a prevalence of 4.5-5% at reference sites and 6.7-6.5% at sewage effluent-impacted sites. A positive correlation was found between sewage effluent load and intersex frequency among male roach. The highest frequency of intersex (26.5%) was found in the stream Kristrup Landkanal, which had the highest percentage and load of sewage effluent (87,578 population equivalents). Further, a tendency to an average higher severity of the phenomenon (calculated as an intersex index value) was seen in males from streams impacted by sewage effluent compared to males from reference sites. However, this was significant only in male fish from Egaa Brook. Among roach from the Kristrup Landkanal 5.8% of male and 0.8% of female roach were infected with the parasite Pleistophora mirandellae, causing degenerative changes in testes and ovaries. No correlation was seen between the intersex condition and the presence of P. mirandellae in the gonads of roach.
