Sexual difference in PCB concentrations of coho salmon (Oncorhynchus kisutch)

We determined polychlorinated biphenyl (PCB) concentrations in 35 female coho salmon (Oncorhynchus kisutch) and 60 male coho salmon caught in Lake Michigan (Michigan and Wisconsin, United States) during the fall of 1994 and 1995. In addition, we determined PCB concentrations in the skin-on fillets of 26 female and 19 male Lake Michigan coho salmon caught during the fall of 2004 and 2006. All coho salmon were age-2 fish. These fish were caught prior to spawning, and therefore release of eggs could not account for sexual differences in PCB concentrations because female coho salmon spawn only once during their lifetime. To investigate whether gross growth efficiency (GGE) differed between the sexes, we applied bioenergetics modeling. Results showed that, on average, males were 19% higher in PCB concentration than females, based on the 1994-1995 dataset. Similarly, males averaged a 20% higher PCB concentration in their skin-on fillets compared with females. According to the bioenergetics modeling results, GGE of adult females was less than 1% higher than adult male GGE. Thus, bioenergetics modeling could not explain the 20% higher PCB concentration exhibited by the males. Nonetheless, a sexual difference in GGE remained a plausible explanation for the sexual difference in PCB concentrations.     

Mobilization of river transported colloidal aluminium upon mixing with seawater and subsequent deposition in fish gills

During flooding events, increased concentrations of gill-reactive aluminium (Al) have been identified in estuarine water causing high Al accumulation in fish gills. By in situ filtering and ultrafiltering river water (pH 5.5-6.4, 3-5 mg L(-1) DOC) and continually mixing the size fractioned river water with seawater (30 in salinity), Al mobilization was studied in flow-through tank systems (6 in salinity) during a six-week field experiment in Western Norway. Atlantic salmon (Salmo salar L.) kept in tanks were continuously exposed to the mixtures. Based on in situ Al fractionation of the experimental waters and sampling of gills from exposed fish, results showed that Al associated with river transported colloids, probably organic material (8 kDa) was mobilized to low molecular mass cationic Al-species (LMM Al(i)) upon contact with seawater. Mobilized Al(i)-species deposited immediately on fish gills. During high flow conditions with increased amounts of colloidal material, the concentration of mobilized LMM Al(i) and the Al accumulation in gills of fish exposed to river water-seawater mixtures increased by a factor of 5 and 10, respectively, compared to the input river water. The concentration of mobilized LMM Al(i) and the Al accumulation in fish gills decreased with time after mixing (from 1 to 30 min) and as high runoff subsided.     

The British river of the future: How climate change and human activity might affect two contrasting river ecosystems in England

The possible effects of changing climate on a southern and a north-eastern English river (the Thames and the Yorkshire Ouse, respectively) were examined in relation to water and ecological quality throughout the food web. The CLASSIC hydrological model, driven by output from the Hadley Centre climate model (HadCM3), based on IPCC low and high CO₂ emission scenarios for 2080 were used as the basis for the analysis. Compared to current conditions, the CLASSIC model predicted lower flows for both rivers, in all seasons except winter. Such an outcome would lead to longer residence times (by up to a month in the Thames), with nutrient, organic and biological contaminant concentrations elevated by 70-100% pro-rata, assuming sewage treatment effectiveness remains unchanged. Greater opportunities for phytoplankton growth will arise, and this may be significant in the Thames. Warmer winters and milder springs will favour riverine birds and increase the recruitment of many coarse fish species. However, warm, slow-flowing, shallower water would increase the incidence of fish diseases. These changing conditions would make southern UK rivers in general a less favourable habitat for some species of fish, such as the Atlantic salmon (Salmo salar). Accidental or deliberate, introductions of alien macrophytes and fish may change the range of species in the rivers. In some areas, it is possible that a concurrence of different pressures may give rise to the temporary loss of ecosystem services, such as providing acceptable quality water for humans and industry. An increasing demand for water in southern England due to an expanding population, a possibly reduced flow due to climate change, together with the Water Framework Directive obligation to maintain water quality, will put extreme pressure on river ecosystems, such as the Thames.     

Antimicrobial resistance of fecal bacteria in waters of the Seine river watershed (France)

We studied the prevalences of antimicrobial resistance (AR) and multiple antimicrobial resistance (MAR) among the fecal bacteria found in the rivers of a large watershed under strong anthropogenic pressures, the Seine river watershed (France). Two groups of fecal indicator bacteria, Escherichia coli and intestinal enterococci, were tested for their susceptibility to 16 and 10 antimicrobials respectively, using the disk diffusion method. We found that 42% of the 214 E. coli river isolates were AR (resistant to at least one antimicrobial) and 35% were MAR (resistant to at least two antimicrobials). Among the 148 intestinal enterococci isolates from rivers, 83% were AR and 49% were MAR. We also investigated the sources of AR fecal bacteria found in the rivers of the watershed. A total of 715 E. coli isolates and 476 intestinal enterococci isolates were collected in point sources (municipal and hospital wastewaters) and non-point sources (surface runoff and soil leaching waters from agricultural or forest areas). For E. coli, the prevalence of AR differed widely from source to source and ranked in this order: hospital wastewaters (71%) > municipal wastewaters (44%) > agricultural non-point sources (16%) > forest non-point sources (2%). The prevalence of MAR ranked similarly, and the same trend was observed for intestinal enterococci. The AR level of fecal bacteria in the sources was related to their expected exposure level to antimicrobials before their release into the environment. A MAR index was calculated for every source and a good discrimination between them was thus obtained. At the global scale of the Seine river watershed, domestic wastewaters seemed more likely to be the predominant source of the AR fecal bacteria found in the rivers. This was corroborated by the similarity of the MAR indices from river and municipal wastewater isolates for both fecal indicators.     

Chlorinated hydrocarbons in fish from the river PO (Italy)

Pesticides and PCBs levels have been determined in two species of fish from the river Po during 1979--1980 at five sampling stations in different seasons. Significant higher levels have been observed in most industrial areas. When expressed on the basis of fat content, river fish levels are higher than those reported for fish from the Adriatic sea. Using experimental BCF (bioconcentration factors), pesticides and PCB concentrations in water have been calculated from fish values, and compared with measured concentrations.     

Trends in organic pollutants and lipids in juvenile Snake River spring Chinook salmon with different outmigrating histories through the Lower Snake and Middle Columbia Rivers

A three-year field study was conducted from 2006 to 2008 to monitor the spatial and temporal trends of organic pollutants in migrating juvenile Snake River spring Chinook salmon (Oncorhynchus tshawytscha) sampled from the Lower Snake and Middle Columbia River Basins. Specifically, hatchery-reared juvenile salmon were monitored as they navigated the Federal Columbia River Power System (FCRPS) by either transport barge (Barged) or remained in the river (In-River) from Lower Granite Dam to a terminal collection dam, either John Day Dam or Bonneville Dam. Levels of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine (OC) pesticides were detected in the bodies of both In-River and Barged salmon during the 2006, 2007 and 2008 outmigrating season. At the terminal dam, In-River fish had greater concentrations of persistent organic pollutants POPs than Barged salmon. Of the POPs detected, dichlorodiphenyltrichloroethanes (DDTs) were found at the greatest concentrations in the salmon bodies. These elevated lipid-normalized concentrations in the In-River fish were due to lipid depletion in all years as well as increased exposure to POPs in some years as indicated by an increase in wet weight contaminant concentrations. Salmon were also exposed to polycyclic aromatic hydrocarbons (PAHs) as indicated by the phenanthrene (PHN) signal for biliary fluorescent aromatic compounds (FACs) at the hatcheries or prior to Lower Granite Dam. There were detectable levels of biliary FACs as fish migrated downstream or were barged to the terminal dam. Therefore, the potential exists for these organic pollutants and lipid levels to cause adverse effects and should be included as one of the variables to consider when examining the effects of the FCRPS on threatened and endangered juvenile salmon.     

Effect of pH on toxicity of kraft pulp and paper mill effluent to salmonid fish in fresh and seawater

In freshwater bioassays with juvenile rainbow trout (Salmo gairdneri), at initial pH values from 4 to 11, kraft mill effluents were considerably less toxic at pH 9–10 than at neutrality. When pH of test solutions was controlled throughout the bioassay period, the least toxic range was 8.5–9.5. Toxicity at typical receiving-water pH values was 50–67% greater.The acute toxicity of effluent samples to yearling coho salmon (Oncorhynchus kisutch) was identical for these effluents in seawater and freshwater respectively, provided that the pH was adjusted and held at the same value, and that test fish were previously acclimated to the dilution water for several months. Thus seawater constituents other than pH did not affect the acute toxicity of pulp and paper mill effluents appreciably.     

Acidogenic fermentation of proteinaceous sewage sludge: Effect of pH

Proteinaceous sewage sludge represents the sludge in which the protein content exceeds the carbohydrate content, accounts for a considerable part of sewage sludge. In this study, volatile fatty acids (VFA) production and synthesis pathway as well as bacterial community in acidogenic fermentation of proteinaceous sewage sludge under different pH conditions were investigated. The results indicated that the alkaline pH improved the solubilization and biodegradation of proteins in the sludge. The soluble protein concentration at pH 11.0 was 67.88% higher than that at pH 3.0. Its biodegradation efficiencies were reduced with a decrease in pH. The pH influenced not only the total VFA production yield, but also the percentage of individual VFA. The total VFA yield at pH 9.0 was 10.70 times of that at pH 3.0. The metabolic conversion pathway of proteins to VFA in acidogenic fermentation systems was investigated using a stoichiometry approach. The Stickland reaction was found to be the main pathway for the VFA accumulation from the decomposition of proteins. pH also significantly influenced the biodiversity and bacterial community in the system. The abundance of microorganisms under alkaline or acidic pH conditions was less than that under neutral pH condition, suggesting that most anaerobic fermentative microorganisms could not tolerate the hostile environment. The terminal restriction fragment length polymorphism analysis showed that, when the pH was reduced from 12.0 to 7.0 and finally to 3.0, the dominant bacterial genuses and percentage of the total microorganisms were Granulicatella genus (65%), Clostridium genus (28%) and Bacillus genus (71%), respectively.     

Sexual difference in PCB concentrations of walleyes (Sander vitreus) from a pristine lake

We determined polychlorinated biphenyl (PCB) concentrations in 15 adult female walleyes (Sander vitreus) and 15 adult male walleyes from South Manistique Lake (Michigan, United States), a relatively pristine lake with no point source inputs of PCBs. By measuring PCB concentration in gonads and in somatic tissue of the South Manistique Lake fish, we also estimated the expected change in PCB concentration due to spawning for both sexes. To determine whether gross growth efficiency differed between the sexes, we applied bioenergetics modeling. Results showed that, on average, adult males were 34% higher in PCB concentration than adult females in South Manistique Lake. Results from the PCB determinations of the gonads and somatic tissues revealed that shedding of the gametes led to 1% and 5% increases in PCB concentration for males and females, respectively. Therefore, shedding of the gametes could not explain the higher PCB concentration in adult male walleyes. Bioenergetics modeling results indicated that the sexual difference in PCB concentrations of South Manistique Lake walleyes was attributable, at least in part, to a sexual difference in gross growth efficiency (GGE). Adult female GGE was estimated to be up to 17% greater than adult male GGE.     

Effects of 17alpha-ethynylestradiol in a partial life-cycle test with zebrafish (Danio rerio): effects on growth,gonads and female reproductive success

In this study, the impact of an exposure of zebrafish embryos (Danio rerio) until 3 months post fertilization to 17alpha-ethynylestradiol (EE2: 0; 0,1; 1; 10; 25 ng/l) was evaluated for growth and development, gonad development and body vitellogenin (VTG) content. After a recovery period of 5 months, the female reproductive success was evaluated. The results demonstrated a significant reduction in total body length, body weight, whole body Ca and P content and an increase in morphological abnormalities for fish exposed to 25 ng/l EE2 as a function of exposure time. An increase in total body VTG content was observed for fish exposed for a period of 3 months down to levels of 1 ng/l EE2. At the age of 3 months, a dose-dependent increase of the number of fish with no macroscopic recognizable gonads was observed (up to 100% at 25 ng/l EE2). After a recovery period on clean tap water for 5 months, all fish had developed either ovaries or testis with a gonadosomatic index not different from control fish and the sex ratio was similar in EE2 treatment groups and controls. Nevertheless, a reduced number of spawning females and a reduced egg production were found for the female fish exposed to 10 or 25 ng/l EE2 for 3 months and which were allowed to recover for 5 months. Although the underlying mechanism could not be elucidated, these findings did indicate that the reproduction potential of fish populations might be disturbed by a long-term exposure to EE2 (> or =10 ng/l) from fertilization until sexual maturity.     

Heavy metals: confounding factors in the response of New Zealand freshwater fish assemblages to natural and anthropogenic acidity

Acidification of freshwaters is a global phenomenon, occurring both through natural leaching of organic acids and through human activities from industrial emissions and mining. The West Coast of the South Island, New Zealand, has both naturally acidic and acid mine drainage (AMD) streams enabling us to investigate the response of fish communities to a gradient of acidity in the presence and absence of additional stressors such as elevated concentrations of heavy metals. We surveyed a total of 42 streams ranging from highly acidic (pH 3.1) and high in heavy metals (10 mg L⁻¹ Fe; 38 mg L⁻¹ Al) to circum-neutral (pH 8.1) and low in metals (0.02 mg L⁻¹ Fe; 0.05 mg L⁻¹ Al). Marked differences in pH and metal tolerances were observed among the 15 species that we recorded. Five Galaxias species, Anguilla dieffenbachii and Anguillaaustralis were found in more acidic waters (pH< 5), while bluegill bullies (Gobiomorphus hubbsi) and torrentfish (Cheimarrichthys fosteri) were least tolerant of low pH (minimum pH 6.2 and 5.5, respectively). Surprisingly, the strongest physicochemical predictor of fish diversity, density and biomass was dissolved metal concentrations (Fe, Al, Zn, Mn and Ni) rather than pH. No fish were detected in streams with dissolved metal concentrations > 2.7 mg L⁻¹ and nine taxa were only found in streams with metal concentrations < 1 mg L⁻¹. The importance of heavy metals as critical drivers of fish communities has not been previously reported in New Zealand, although the mechanism of the metal effects warrants further study. Our findings indicate that any remediation of AMD streams which seeks to enable fish recolonisation should aim to improve water quality by raising pH above ≈ 4.5 and reducing concentrations of dissolved Al and Fe to < 1.0 mg L⁻¹.     

Thyroid hormones as a potential early biomarker of exposure to 4-nonylphenol in adult male shubunkins (Carassius auratus)

Nonylphenol, an estrogenic-like compound, can induce vitellogenin synthesis in males and immature Teleostean species, but little is known about its effects on thyroid hormones balance. The present study evaluated the potential effects of a single acute exposure to nonylphenol (i.p. injected) on the thyroid and reproductive axis of 250 shubunkins (Carassius auratus). Plasma levels of thyroid hormones were quantified immunoenzymatically by ELISA assay. Nonylphenol induced a significant decrease of thyroxin levels, whereas no effect on triiodothyronine concentrations was detected. No histopathological changes were detected in thyroid or testes. The toxicological data confirmed that nonylphenol exerts an estrogenic effect on male fish. In addition, nonylphenol was suspected to inhibit the thyroid hormones balance, suggesting the thyroid should be included among the other endocrine glands susceptible to endocrine disruption.     

Contamination by chlorinated hydrocarbons (DDT,PCBs) in surface sediment and macrobenthos of the river Adige (Italy)

Surface sediments and macrobenthos communities have been employed as contamination indicators for halogenated hydrocarbons (DDT and PCBs) in the river Adige and its tributaries Fibbio and Alpone in the province of Verona. Two sampling campaigns were carried out, before and after the spring-summer floods, to determine the effects of this event on the contamination of the river. The halocarbons in the sediment were found to be associated with the fine fraction (< 53 μm) and organic carbon. From the relative concentrations of contaminants determined at various sampling stations, some information has been obtained on the sources.     

Phytoplankton biomass and production in the river meuse (Belgium)

The biomass and production of the phytoplankton in a relatively unpolluted reach of the River Meuse (Belgium) were followed through two years (1983 and 1984). Chlorophyll a varied from 0.2 to about 120 mg m⁻³, and production ranged between 0.05 and 5.78 gC m⁻² d⁻¹. The mean photosynthetic quotient (PQ) was 1.25.

The parameters of the light-photosynthesis relationship (P_opt and l_k) were calculated and related to the variations of temperature and light in the water column. A simple model allowed calculations of the annual production, which was estimated to be 494 gC m⁻² yr⁻¹ in 1983 and 547 gC m⁻² yr⁻¹ in 1984.

Finally, a simple model is developed, which explains the relationship between phytoplankton development and discharge; this model shows how the effect of discharge can be described by a “dilution rate” of the plankton growing in the river water.     

Carbohydrates as trihalomethanes precursors. Influence of pH and the presence of Cl(-) and Br(-) on trihalomethane formation potential

Upon chlorination carbohydrates can give trihalomethanes (THMs). In the present work, we have studied the influence of pH, chloride or bromide concentration on the formation of THMs from carbohydrates. We have observed that THMs are not formed at acidic pH, while basic pH values only increase slightly the THM content, although the consumption of chlorine increases up to 100% with respect to pH 8. The presence of chloride in ppm increases the THM formation from carbohydrates without influence of the chlorine consumption. In the same manner, the presence of bromide ions in ppb also increases remarkably the THMs formed upon chlorination of saccharides. Even more, we have observed that at bromide concentrations below 100ppb, complete incorporation of bromide in THMs occurs. Overall, the results obtained show that saccharides widely present in natural waters can give rise to significant THM concentrations in the disinfection process by chlorine.     

Major ion chemistry and dissolved inorganic carbon cycling in a human-disturbed mountainous river (the Luodingjiang River) of the Zhujiang (Pearl River), China

Major ion chemistry and dissolved inorganic carbon system (DIC, mainly HCO₃⁻ and gaseous CO₂) in the Luodingjiang River, a mountainous tributary of the Zhujiang (Pearl River), China, were examined based on a seasonal and spatial sampling scheme in 2005. The diverse distribution of lithology and anthropogenic impacts in the river basin provided the basic idea to assess the effects of lithology vs. human activities on water chemistry and carbon biogeochemistry in river systems. Major ions showed great spatial variations, with higher concentrations of total dissolved solids (TDS) and DIC in the regions with carbonate rocks and clastic sedimentary rocks, while lower in the regions with metamorphic sandstones and schists as well as granites. pCO₂ at all sampling sites was oversaturated in June, ranging with a factor from 1.6 to 18.8 of the atmospheric concentration, reflecting the enhanced contribution from baseflow and interflow influx as well as in situ oxidation of organic matter. However, in April and December, undersaturated pCO₂ was found in some shallow, clean rivers in the upstream regions. δ¹³C of DIC has a narrow range from − 9.07 to − 13.59‰, which was more depleted in the regions with metamorphic rocks and granites than in the carbonate regions. Seasonally, it was slightly more depleted in the dry season (December) than in the wet season (June). The results suggested that lithological variability had a dominant control on spatial variations of water chemistry and carbon geochemistry in river systems. Besides, anthropogenic activities, such as agricultural and urban activities and in-stream damming, as well as river physical properties, such as water depth and transparency, also indicated their impacts. The seasonal variations likely reflected the changes of hydrological regime, as well as metabolic processes in the river.     

Octanol-water partitioning of chemical constituents in river water and treated sewage effluent

A shake-flask approach has been employed to determine the n-octanol-water partitioning of chemical constituents in various river waters and in treated sewage effluent. The bulk inorganic composition of the water samples (conductivity, pH and the concentrations of major solutes: Ca, K, Mg, Na) was unaffected by the presence of solvent. Boron, however, exhibited increasing partition with decreasing sample pH, because its dominant form in freshwaters, B(OH)₃, is neutral, covalent and acidic. Constituents having significant association with dissolved organic matter (DOM), including components of DOM itself (C, S) and trace metals that form complexes with organic ligands (Al, Cu, Fe, Pb, Zn), exhibited measurable partition into the solvent in most cases, with conditional partition coefficients, D_ow, in the region 0.03-2.5. Significant differences in the partitioning among these constituents and among the environments studied did not appear to be related to bulk sample characteristics or the degree of association of the constituent with DOM. These observations suggest that partition is sensitive to the nature of the organic matter (C, S) and the availability of specific binding ligands (trace metals). Thus, although D_ow is critical for defining the biogeochemical behaviour and potential impacts of chemical constituents in the environment, it appears to be a difficult parameter to model or predict.     

Influence of sex, maturity and reproduction on PCB and p,p′DDE concentrations and repartitions in the European hake (Merluccius merluccius, L.) from the Gulf of Lions (N.W. Mediterranean)

The main objective of this work was to establish the influence of sex, maturity and reproduction on the contamination of the demersal fish Merluccius merluccius by organochlorine compounds. Polychlorinated biphenyls (PCBs) and p,p′DDE were quantified in muscle, liver and gonads of female and male hakes collected in the Gulf of Lions in 2004 and 2005. Observed levels appeared higher than the population of the Bay of Biscay and lower than the population of the Thyrrenian Sea. Contaminant fingerprints were roughly constant whatever the studied organ and the hake biological condition. Concentrations varied significantly according to the sex and maturity of hakes. Mature specimens were more contaminated than immature, and males presented higher levels than females. This sex effect can be linked to a lower growth rate of males, and a contaminant elimination during female spawning. Gonadal contamination depends on the importance of lipid content and increases with the maturation degree. Although the main organ of energy and PCB storage is the liver, muscle appears as the main contributor to the gonad contamination.     

Organic matter transport and degradation in the river Seine (France) after a combined sewer overflow

The impact of a combined sewer overflow (CSO) upon receiving waters has been studied in the river Seine during Summers 1995 and 1996. Three main events have been monitored with special attention paid to the computation of oxygen, carbon and suspended solids budgets. Bacterial biomass and bacterial production rates have been measured to provide a more accurate understanding of the carbon cycle of the river Seine. Oxygen consumption inside the polluted water masses was totally due to the activity of large bacteria discharged into the river by the CSO, the activity of native small bacteria did not significantly increase after CSOs. Suspended solids issued from the CSO very quickly settles in this deep, slowly flowing river. However, discharged dissolved organic carbon (DOC) cannot account for the observed oxygen depletions, the additional carbon source could be phytoplankton or deflocculated/degraded particulate organic matter.     

pH dependence of steroid hormone--organic matter interactions at environmental concentrations

The interaction of estradiol, estrone, progesterone and testosterone with environmentally relevant concentrations of Aldrich humic acid, alginic acid and tannic acid was studied using solid-phase microextraction (SPME). Since bulk organic matter and certain hormones such as estradiol and estrone contain dissociable functional groups, the effect of pH on sorption was investigated as this will influence their fate and bioavailability. For humic acid and tannic acid, sorption was strongest at acidic pH when the bulk organic matter was in a non-dissociated form and decreased when they became partially negatively charged. At acidic and neutral pH the strength of partitioning was influenced by hormone functional groups content, with the strongest sorption observed for progesterone and estrone. At alkaline pH conditions, when the bulk organics were dissociated, sorption decreased considerably (up to a factor of 14), although the non-dissociated hormones testosterone and progesterone indicated greater sorption to humic acid at pH 10 compared to the partially deprotonated estradiol and estrone. This study demonstrates that SPME can be used to assess organic matter sorption behaviour of a selected range of micropollutants and at environmentally relevant organic matter concentrations.