Abstract
The Uruguay river basin supports intensive agricultural and forest production, and receives municipal sewage discharge and industrial effluent. Therefore, the river receives xenobiotic compounds which can be distributed in sediments, biota, water and particulate matter. There is evidence of the ability of several of these compounds to interfere with the endocrine system and the sediments are an important source. The aim of this study was to determine whether exposure of immature Cyprinus carpio to Uruguay river sediments undergo physiological and endocrine alterations. A 30-day semi-static assay was performed using sediments from four sites along the Uruguay river and compared with an unexposed group in dechlorinated water as a negative control. The results showed that plasma vitellogenin levels increased along the river, and significant differences were found in exposed fish. Significant difference in hepatosomatic index was observed in fish exposed to sediment from an industrial site. In the histological analysis, only reproductive stage of males showed differences, where the number of primary spermatocyte accumulations was lower in exposed ones, and some exposed individuals from industrial sites presented with testis-ova. Our results suggest that the Uruguay river sediments are a source of endocrine-disrupting compounds available to the aquatic organisms.
Highlights
The endocrine system is the main regulator of important metabolic processes such as nutrition, development and reproduction
Significant differences were observed among the sediment of exposed groups with the control (Tukey’s HSD, p < 0.05); no differences were detected among the exposed groups
Several known sources of endocrine disruptors are located in the Uruguay river basin, and previous studies have detected some EDCs in sediments [27] that could be responsible for the observed alterations
Summary
The endocrine system is the main regulator of important metabolic processes such as nutrition, development and reproduction. The term endocrine disruptor defines, by both, to a compound or set of exogenous chemical compounds (natural or synthetics) that alter the normal functioning of the endocrine system through alterations in hormonal balance, causing effects on exposed organisms and including about his progeny [1, 5, 6]. A wide variety of EDC sources have been documented, including municipal sewage discharges and industrial effluents (e.g., pulp mills), as well as some pesticides and their metabolites [1, 7, 8]. Some of these compounds are persistent and lipophilic, and their concentrations are higher in sediments than in river water [9]. Several laboratories and field studies have reported that fish exposed to sediments experience significant alterations in endocrine functions [14–19]
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