Distribution of antidepressants and their metabolites in brook trout exposed to municipal wastewaters before and after ozone treatment--evidence of biological effects

This study examined the tissues distribution of selected serotonin reuptake inhibitors (SSRIs) in brook trout exposed for 3 months to continuous flow-through primary-treated effluent before and after ozone treatment. A reliable analytical method was developed for the quantification of trace amounts of antidepressants in small tissue homogenate extracts. Levels of six antidepressants and four of their N-desmethyl metabolites were determined using liquid chromatography-tandem mass spectrometry. Significant amounts of the SSRIs were found in fish tissue-in decreasing order: liver>brain>muscle. Sertraline and its metabolite desmethylsertraline were the predominant substances observed in most tissues (0.04-10.3 ng g(-1)). However, less SSRIs (0.08-1.17 ng g(-1)) were bioaccumulated in the ozonated effluent. The early molecular effects of these SSRIs on the Na/K-dependent ATPase pump activity in brain synaptosomes where also investigated in vitro and in fish exposed to the municipal effluents. With respect to their potential biological effects, in vitro exposure to selected SSRIs induced a reduction of the brain Na/K-ATPase activity in synaptosomes in a dose-dependent manner. Results showed that Na/K-ATPase activity was readily inhibited by exposure to municipal effluent before and, to a lesser extent, after ozone treatment. Moreover, the Na/K-ATPase activity was significantly and negatively correlated with brain tissue concentrations of fluoxetine (r=-0.57; p<0.03), desmethylsertraline (r=-0.84; p<0.001), and sertraline (r=-0.82; p<0.001). The present study reveals that SSRIs are readily available in fish, biologically active and corroborates previous findings on the serotonergic properties of municipal effluents to aquatic organisms.     

Potential impact of a toxic dinoflagellate (Alexandrium excavatum) bloom on survival of fish and crustacean larvae

During the last 20 yr the western half of the Dutch Wadden Sea has undergone significant eutrophication: concentrations of P and N compounds and planktonic algae have roughly doubled, as has primary production. Though oxygen levels are often low in summer, anoxic areas are small and rare due to strong tidal mixing. During the 1970 to 1990 period, macrozoobenthos was sampled annually at 15 stations at Balgzand, a 50-km² tidal-flat area in the westernmost part of the Wadden Sea. Not only did the estimates of total numbers, biomass, and production double during these two decades, but significant changes in the composition of the benthic community were observed, too: (1) the numerical proportion of polychaetes increased at the expense of molluscs and crustaceans, (2) the overall mean weight per individual of the macrozoobenthos decreased (numbers of individuals of small-sized species increased more rapidly than those of large-sized species), and (3) though absolute numbers and biomass of all feeding types increased, the share of carnivores declined and that of deposit feeders increased; the proportion of suspension feeders showed little change. This study refers to true macrobenthos only (1-mm sieve) and further excludes two taxa (Corophium spp. andHydrobia ulvae) which occasionally exercised an undue influence on numbers. Mass mortalities caused by low oxygen concentrations were of a small-scale nature only. Total number of species fluctuated without a clear trend. As a consequence of the increasing numerical densities, trends in species numbers were slightly increasing when expressed per unit of area and slightly decreasing when estimated per 100 individuals (by rarefaction).     

Evidence of coprostanol estrogenicity to the freshwater mussel Elliptio complanata

Coprostanol (5 beta (H)-cholestan-3 beta ol) is a reduced metabolite of cholesterol produced by micro-organisms found in the intestinal tract of mammals. This substance abounds in urban effluents and is accumulated by organisms living in the vicinity of municipal effluent outfalls. In an earlier study, freshwater mussels exposed to contaminated river water for 62 days accumulated large quantities of coprostanol (Cop) in their soft tissues (16 micrograms/g dry wt.). Moreover, these mussels were found to have elevated levels of vitellin in their hemolymphs, suggesting estrogenic effects. Although municipal wastewaters are known to contain other estrogenic compounds capable of inducing Vn synthesis in mussels, the estrogenic potential of coprostanol was singled out for examination. To this end, mussels were first injected with concentrations of coprostanol via the abductor muscle route, and allowed to stand in aerated water for 72 h at 15 degrees C. The levels of Vn in mussel hemolymph were assayed using the organic alkali-labile phosphate method. A competitive estradiol-binding assay was then devised to measure the ability of coprostanol to compete in the binding of fluorescein-labeled estradiol-albumin to cytosolic proteins. Coprostanol partially reversed the binding of labeled estradiol-albumin to cytosolic proteins with an EC50 of 1 mM. In addition, injections of coprostanol and estradiol-17 beta led to increased levels of vitellins in the hemolymph of treated mussels. Moreover, incubation of cop in gonad homogenate extracts in the presence of NADPH led to the formation of two compounds, as determined by high-performance thin-layer chromatography. One of these compounds appears to be the C17 oxidation product of coprostanol, whose polarity is similar to that of estradiol. The results present evidence that coprostanol is estrogenic to freshwater mussels.     

Occurrence of alkylphenol polyethoxylates in the St. Lawrence River and their bioconcentration by mussels (Elliptio complanata)

A study was conducted in 1999 to determine the occurrence of alkylphenol polyethoxylates in the St. Lawrence River and their bioconcentration by mussels (Elliptio complanata). Concentrations of selected contaminants were measured in surface water, municipal effluent, sediments and mussels. Analyses were performed on 4-tert-octylphenol (4-t-OP), 4-n-nonylphenol (4-n-NP), nonylphenol polyethoxylates (NP(1-16)EO), nonylphenol-mono and di-ethoxycarboxylic acids (NP(1)EC and NP(2)EC), and octylphenol-mono and di-ethoxycarboxylic acids (OP(1)EC and OP(2)EC). Mussels (Elliptio complanata) taken from a reference lake were placed in cages and submerged for 62 days at two sites in the St. Lawrence River, 1.5 km upstream and 5 km downstream of the outfall of a municipal wastewater treatment plant. The results showed that many of the target chemicals were present in all matrices studied: in water, at ppt and ppb levels, and reaching ppm levels in sediments and mussels. Concentrations of these contaminants were higher in matrices sampled at the downstream site than in those drawn at the site upstream of the Montreal effluent outfall, especially in sediments. Likewise, the slight, but not significant, bioconcentration of certain alkylphenol polyethoxylates (AP(n)EO) in the mussels was more noticeable at the downstream site than at the upstream site.     

Body burden of contaminants and biological effects in mussels: an integrated approach

An investigation of contaminants and biological effects in mussels from Halifax Harbour, Nova Scotia, Canada, focused on a 6 km section in the central most industrialized core of the harbour, where a site was previously identified as highly contaminated. The aim of the study was to compare the body burden of mussels in terms of polycyclic aromatic hydrocarbons (PAH), dichlorophenyltrichloroethane (DDT family), coprostanol and elements, relative to biological parameters such as condition indices, sex ratio, survival time in air, and to biochemical indicators of mussels' health analysed in gills, digestive gland and gonad tissues. These markers are total sugar and lipid content of gonads, mitochondrial electron transport activity in digestive gland and gonad tissues, lipid peroxidation in gill, digestive gland and gonad tissues, and heme oxidase activity in the digestive gland. At the north western end of the area, near a major sewage effluent, shorter survival time, higher oxidative stress and metabolism, gonad electron transport activity, levels of coporostanol, PAH, p,p'-dichlorophenyldichlo-roethylene (p,p'-DDE), Ag, Cu, Fe and P were observed. At the opposite south eastern end, longer survival time, higher lipid content, lowest condition indices and concentrations of coprostanol, PAH and p,p'-DDE, but higher concentrations of Sn and Cd, were detected. On-going improvements to sewage treatment in Halifax Harbour, including construction of sewage treatment plants that will discharge into deeper parts of the central harbour, should improve inter-tidal mussels' health in our study area.     

Application of rough sets analysis to identify polluted aquatic sites based on a battery of biomarkers: a comparison with classical methods

The evaluation of toxicological effects at the cellular and molecular levels in organisms are often used to determine sites subjected to contamination problems that pose a threat to the long-term survival of organisms. However, the integration of multiple measurements on the health status of organisms into a model for site discrimination is challenging. This study compares two discrimination methods which are based on rule inference: rough sets (RS) analysis and classification trees (CT) with classical multivariate discriminant analysis (DA). Site classification was attempted with six biomarkers of effects: metallothionein levels, lipid peroxidation, DNA damage, levels of lipophosphoproteins (i.e., vitellins), phagocytosis activity and haemocyte cell viability on clam (Mya arenaria) populations from the Saguenay River fjord (Quebec, Canada). Rule based methods have the advantage of complete independence from data distribution constraints in contrast to the classification methods from multivariate analysis that are more commonly used in ecotoxicology. Results show that RS and CT gave better classifications than DA because they do not require strong distributional assumptions. Moreover, RS provided classification rules that could identify the most important biomarker(s) for site discrimination. RS and CT were shown to be simple and efficient methods for classifying multivariable ecotoxicological data. This methodology would be especially useful when freedom from distributional assumptions is required.     

Neuroendocrine disruption and health effects in Elliptio complanata mussels exposed to aeration lagoons for wastewater treatment

The purpose of this study was to examine neuroendocrine-disrupting effects of two domestic wastewater aeration lagoons on freshwater mussels. Mussels were caged and placed in two final aeration lagoons for treating domestic wastewaters for 60 days, at a site 1km downstream of the dispersion plume on the eastern shores of the Richelieu River; the western shore served as the reference site. The mussels were analysed for gonad activity, oxidative metabolism of xenobiotics, stress biomarkers and neuroendocrine status (monoamine and arachidonic acid metabolism). The domestic wastewaters produced many different effects at all levels examined. The gonado-somatic index and vitellogenin-like proteins were significantly induced in both aeration lagoons and gonad pyrimidine synthesis (aspartate transcarbamylase activity) was significantly reduced, indicating that vitellogenin-like proteins were produced while DNA synthesis in gametes remained constant. Biomarkers of oxidative metabolism revealed that global heme oxidase (HO), glutathione S-transferase and xanthine (caffeine) oxydoreductase (XOR) activities were significantly induced in at least one of the aeration lagoons, but not downstream of the dispersion plume. The activities of 7-ethoxyresorufin (cytochrome P4501A1), dibenzoylfluorescein (cytochrome P450 3A4 and 3A5) and benzoyloxyresorurufin (cytochrome P450 3A4 and 2B6) dealkylases were readily induced by substances sharing structural similarities with coplanar polyaromatic hydrocarbons and hydroxylated or aminated aromatic or cyclic hydrocarbon compounds such as pharmaceuticals or steroids in the domestic wastewaters. Biomarkers of toxic stress revealed that exposure to aeration lagoons led to increased production of metallothioneins, lipid peroxidation and DNA strand breaks, with decreased heme oxygenase activity. LPO was significantly correlated with XOR, HO and cytochrome P4501A1 activities. Neuroendocrine effects included significant increases in dopamine and serotonin levels and in monoamine oxidase (MAO). Dopamine transport in synaptosome was significantly increased while serotonin transport activity was significantly decreased, suggesting the mussels were in a state of serotonergicity. Moreover, arachidonic acid cyclooxygenase (COX) activity was also readily increased in one aeration lagoon. Aeration lagoons for the treatment of domestic wastewaters are toxic, estrogenic and disrupt the metabolism of monoamines and COX in freshwater mussels.     

Self‐determination theory and work motivation

Cognitive evaluation theory, which explains the effects of extrinsic motivators on intrinsic motivation, received some initial attention in the organizational literature. However, the simple dichotomy between intrinsic and extrinsic motivation made the theory difficult to apply to work settings. Differentiating extrinsic motivation into types that differ in their degree of autonomy led to self‐determination theory, which has received widespread attention in the education, health care, and sport domains. This article describes self‐determination theory as a theory of work motivation and shows its relevance to theories of organizational behavior. Copyright © 2005 John Wiley & Sons, Ltd.     

Effects of a major municipal effluent on the St. Lawrence River: A case study

The St. Lawrence River (SLR) is the second largest waterway in North America. The discharge of the City of Montreal wastewater treatment plant (WWTP) represents the largest volume of treated wastewaters being released into the river. It also ranks as the largest sewage treatment plant of its kind in North America. Over the last decade, intensive multidisciplinary research has focused on assessing the impacts of Montreal wastewater effluents on the SLR. We describe the major findings of these investigations, including the determination of the fate of contaminants, bioaccumulation in fish and invertebrates, ecotoxicological measurements of aquatic animal health, evaluation of endocrine disruption, parasitism in fish, and combined effects of multiple stressors on the SLR. Impacts of the effluents from the WWTP on aquatic organisms from the SLR are both toxicological and ecological, demonstrating the need for an integrated view of the impacts of municipal effluents on aquatic ecosystems.