There is increasing global recognition of the effects of large scale land disturbance by wildfire on a wide range of water and ecosystem services. In 2003, the Lost Creek wildfire burned a contiguous area of 21,000 ha on the eastern slopes of the Rocky Mountains in southern Alberta. This disturbance had a significant and prolonged impact on the water quantity and quality of downstream river reaches and reservoirs in the Oldman watershed. Previous research in this watershed demonstrates that dissolved metal concentrations in rivers draining burned landscapes were 2 to 15 times greater than in unburned reference streams (Silins et al. 2009a). Currently there is no information on the effects of wildfire on the bioaccumulation and toxicity of sediment-associated metals in fire-impacted streams in Alberta. This study was designed to evaluate the linear downstream disturbance effects of wildfire in the Crowsnest River located in southern Alberta. The toxicity and bioaccumulation of particulate-associated metals from wildfire impacted tributaries to the Crowsnest River on freshwater amphipod Hyalella azteca were evaluated. Phillips samplers were deployed to collect suspended solids in streams draining burned zone impacted by the Lost Creek wildfire and reference (unburned) zones within the area. Metal toxicity and bioaccumulation were determined in the laboratory by exposing the epi-benthic freshwater amphipod Hyalella azteca to particulates collected from the Crowsnest River. A metal effects addition model (MEAM) was used to assess the impact of metal mixtures and to predict chronic mortality (Norwood et al. 2013). Increased concentrations of Al, Ba, Co, Cr, Mn and Zn were found in the tissues of H. azteca exposed to particulates from burned watersheds in comparison to the unburned watersheds. H. azteca mean survival was similar when exposed to the particulates samples from both burned and unburned sites indicating that 9 years after this landscape disturbance, there was little impact due to the wildfire. However, at burned site (B1), the observed survival was lower than survival predicted by MEAM. The data suggests that factors other than the metals examined in this study were influencing the survival of H. azteca. The concentrations of sediment-associated metals have decreased in the nine years since the wildfire, and minimal metal toxicity was observed in H. azteca. Although metal toxicity in H. azteca was minimal 9 years after the Lost Creek Fire, the short term effects of wildfire on metal toxicity remain largely unknown. In addition, other factors such as burn severity, stream size and hydroclimatic conditions can influence the effects of wildfire on abundance and diversity of aquatic invertebrates (Minshall et al. 2001). Therefore, the influences of those factors on metal toxicity as a result of wildfire should be rigorously assessed in future studies.

The goal of this study is to establish an accurate, simple and fast method for analysis of organotin in bio-tissues and for routine analysis of organotin in pollution control. This study also conducted the field survey investigating the accumulation status of butyltin (BT) in organisms and environments for validation of analytical method and applicability in different environmental samples. Stations had been set up from the Sih-Cao fishing port to the upstream of Luermen Stream Estuary. General water quality factors were measured in situ, and water samples, suspended particles, Pacific oysters (Crassostrea gigas), green mussels (Perna viridis), and rockshells (Thais clavigera and Thais rufotincta) were collected in summer (July 2003) and winter (February 2004) seasons and the concentrations of butyltins were measured. Surface sediment samples were also collected from each sampling station and the concentrations of butyltins were measured to present pollution status of butyltins in Luermen Stream Estuary. To determine butyl- and phenyl-tins in fish muscle, a method including base digestion pretreatment, followed by an ethylation-extraction procedure together with gas chromatography-flame photometric detection (GC-FPD) analysis is outlined. Parameters that affect analyte recovery were investigated and optimized. A solution of 3 % (w/v) potassium hydroxide and 1 h digestion time at 60 ¢J were chosen in the base digestion step to ensure complete solubilization of fish muscle and the decomposition of organotins was found to be negligivle. We found that the ratio of fish muscle/reaction solution volume should not exceed 0.2 g (dry weight) per 100 mL in order to avoid the matrix effect caused by the binding of hydrolyzed fish tissue with organotin ions. Ethylation of organotins were conducted at pH 6~7 with a 1 % (w/v) sodium tetraethylborate (NaBEt4) solution for 1 h. This simple and timesaving procedure could be applied to the routine analysis of organotins in other bio-tissues. The BT content of environments and organisms reflected that the tributyltin (TBT) pollution levels were higher in Sih-Cao fishing port than in Luermen Stream. The BT content of organisms reflected more detail TBT pollution status between Sih-Cao fishing port and Luermen Stream. However, the MBT pollution status in Luermen Stream was not reflected in MBT accumulation status of organisms. The ability of TBT accumulation in oysters and mussels was higher than in rockshells. Moreover, oysters had higher TBT accumulation ability than mussels at lower TBT pollution level, but following the increase of TBT pollution level, the ability of TBT accumulation in oysters had shifted to be lower than in mussels. The results also showed that in the higher TBT pollution level, the ratios of MBT and DBT over the total butyltins had changed to higher status and the bioaccumulation factors (BAF) had changed to smaller values in oysters and rockshells. In mussels, this phenomenon was not significant. However, the organisms (oyster, mussel and rockshells) revealed smaller BAF of TBT in Luermen Stream than in the Sih-Cao fishing port entrance. For oysters and mussels, the TBT contents and the composition ratios of TBT in total butyltins were both higher in winter season. All organisms (oysters, mussels and rockshells) had higher ability to accumulate TBT according to the larger BAF observed in summer season. The ability of TBT accumulation in rockshells was lower than in oysters or mussels. Moreover, the BT accumulation status was mainly composed of MBT and DBT (the metabolites of TBT ) in rockshells and TBT in oysters and mussels. That was attributed to higher metabolic rate of TBT in rockshells.

Abstract ¡@¡@The present study was undertaken to understand the accumulation of PCBs in the marine environment of Taiwan. Samples including oyster drills, oysters, sediments and seawater were collected from the West coast of Taiwan and analyzed by GC/ECD and GC/MS. ¡@¡@The concentration of PCBs in sediments was 31.05¡ã406.38 pg/g dry wt with the highest one at Tong-Kung. The PCBs in cultural oysters from Tong-Kung was 3.80 pg/g wet wt. Concentrations of PCBs in wild oysters from Tai-Si, Chi-Ku, and Pu-Dai were 123.57 pg/g wet wt, 2.93 pg/g wet wt, and 2.08 pg/g wet wt, respectively. The concentrations of PCBs in snails were in the range of 78.24 to 796.96 pg/g wet wt with the highest one from Tong-Kung. A positive correlations between the concentrations of PCBs in seawater and sediment (r=0.78; p<0.01) and in oysters and snails were also observed(r=0.79; p<0.01). The bioaccumulation of PCBs from seawater to oysters was about 72 times, and the biomagnification of PCBs from oysters to snails was 10 times.

Reproduction de : Thèse de doctorat : Sciences : Océanologie biologique. Environnement marin : Toulon : 2005. / Titre provenant du cadre-titre. Bibliographie p. 277-301.

Polychlorinated biphenyls (PCBs) are a class of bioactive chemical once used in industrial applications, but which now contaminate the world environment. PCBs are lipophilic with few natural degadatory mechanisms, and thus they accumulate in human and animal tissues, and are passed to subsequent generations via transfer between mother and offspring. Research has shown that PCBs can interfere with brain and sexual organ development, and adult sexual behaviors and reproduction. However, previous studies produced contradictory results based on the dose and method of administration, species, and the age at exposure. The research detailed in this thesis elucidates the effects of prenatal exposure to low levels of a commercial mixture of PCBs, Aroclor (A) 1221, on female reproductive function. The studies undertaken in this dissertation focus on three areas relevant to understanding long-term effects of PCBs on reproductive physiology in female rats: (1) developmental effects in two generations, (2) sexual behaviors in the first generation, and (3) gene expression in the first generation. In the first research section of this dissertation, the sexual and somatic development of PCB-exposed animals is investigated in first (F1) and second (F2) generation females. Dose-dependent effects are observed in both generations, and a greater number of endpoints are significantly affected in the F2, including circulating hormone levels and uterine and ovarian weight. The second research section of the dissertation explores whether sexual behaviors in the first generation of exposed animals are altered by A1221, using a paced mating paradigm designed to elucidate female-typical behaviors. Several salient behaviors are affected by PCB exposure, including likelihood to mate, mating trial pacing, and stress-related vocalizations. The third research chapter discusses the results of a genomewide microarray assay performed on the preoptic area of the brain. The preoptic area is a neuroendocrine control center implicated in regulation of reproductive physiology and behavior. Taken together, these results suggest that A1221 has long lasting and trans-generational effects on the development and behavior of exposed females, accompanied by altered gene expression in a neuroendocrine region of the brain. These findings have implications for female reproductive health and reproductive success in wildlife and humans.

No description available.

There is increasing global recognition of the effects of large scale land disturbance by wildfire on a wide range of water and ecosystem services. In 2003, the Lost Creek wildfire burned a contiguous area of 21,000 ha on the eastern slopes of the Rocky Mountains in southern Alberta. This disturbance had a significant and prolonged impact on the water quantity and quality of downstream river reaches and reservoirs in the Oldman watershed. Previous research in this watershed demonstrates that dissolved metal concentrations in rivers draining burned landscapes were 2 to 15 times greater than in unburned reference streams (Silins et al. 2009a). Currently there is no information on the effects of wildfire on the bioaccumulation and toxicity of sediment-associated metals in fire-impacted streams in Alberta. This study was designed to evaluate the linear downstream disturbance effects of wildfire in the Crowsnest River located in southern Alberta. The toxicity and bioaccumulation of particulate-associated metals from wildfire impacted tributaries to the Crowsnest River on freshwater amphipod Hyalella azteca were evaluated. Phillips samplers were deployed to collect suspended solids in streams draining burned zone impacted by the Lost Creek wildfire and reference (unburned) zones within the area. Metal toxicity and bioaccumulation were determined in the laboratory by exposing the epi-benthic freshwater amphipod Hyalella azteca to particulates collected from the Crowsnest River. A metal effects addition model (MEAM) was used to assess the impact of metal mixtures and to predict chronic mortality (Norwood et al. 2013). Increased concentrations of Al, Ba, Co, Cr, Mn and Zn were found in the tissues of H. azteca exposed to particulates from burned watersheds in comparison to the unburned watersheds. H. azteca mean survival was similar when exposed to the particulates samples from both burned and unburned sites indicating that 9 years after this landscape disturbance, there was little impact due to the wildfire. However, at burned site (B1), the observed survival was lower than survival predicted by MEAM. The data suggests that factors other than the metals examined in this study were influencing the survival of H. azteca. The concentrations of sediment-associated metals have decreased in the nine years since the wildfire, and minimal metal toxicity was observed in H. azteca. Although metal toxicity in H. azteca was minimal 9 years after the Lost Creek Fire, the short term effects of wildfire on metal toxicity remain largely unknown. In addition, other factors such as burn severity, stream size and hydroclimatic conditions can influence the effects of wildfire on abundance and diversity of aquatic invertebrates (Minshall et al. 2001). Therefore, the influences of those factors on metal toxicity as a result of wildfire should be rigorously assessed in future studies.

This thesis examines broad-scale patterns in the food web structure of lake ecosystems. The unifying framework for this analysis is the concept of trophic position, which represents the energy-weighted trophic path length leading to a consumer or population. Trophic position was estimated for over 550 populations of fish (16 species) using quantitative dietary data. A method to estimate trophic position of aquatic consumers using stable isotope ratios was developed; this involved correcting for within and among-lake variation in delta15N of primary consumers (organisms used to represent the base of the food web). We report an overall correspondence between dietary and isotopic estimates of trophic position; for each species, trophic position generally ranged the equivalent of one trophic level unit among-populations. The concept of discrete trophic levels provided only a qualitative description of energy flow pathways in aquatic food webs. Among-population variation was much greater than within-population variation in trophic position of lake trout. Long-standing hypotheses about the determinants of food chain length were examined; food chain length was most closely correlated with species richness and lake area. / The trophic position approach was used to examine two separate environmental problems relevant to lakes: the bioaccumulation of persistent contaminants in food chains and the impacts of invasive species. Trophic position was the major determinant of PCB levels in lake trout; these relationships were used to characterize biomagnification factors (BMFs) for this and a number of other contaminants. Furthermore, the introduction of smelt into lakes was linked to increased levels of PCB and Hg contamination in lake trout. Stable isotopes were used to quantify the impacts of smallmouth bass and rock bass invasions on food webs leading to lake trout. Lake trout from invaded lakes exhibited reduced consumption on littoral prey fish; a food web shift that is likely to have detrimental impacts on native lake trout populations.

Methylmercury (MeHg) is a neurotoxic global pollutant that accumulates at high levels in predatory fish and marine mammals. The dietary intake of these animals is the main source of MeHg exposure in humans. At high levels, MeHg is known to damage the sensory and motor systems in both adults and children. Due to the complexity and inaccessibility of the central nervous system (CNS), early dysfunction is difficult to detect. Biochemical markers in the CNS have been used to identify MeHg neurotoxicity in animal models. Analogues of these biochemical targets are also present in peripheral blood tissue and may reflect early CNS dysfunction in human populations. The proposed peripheral biomarkers include (1) lymphocyte muscarinic acetylcholine (mACh) receptor, (2) serum cholinesterase (ChE) and (3) platelet monoamine oxidase (MAO). This thesis evaluates the effects of mercury (Hg) compounds on these CNS and peripheral biochemical markers in laboratory and epidemiological studies. In vitro studies showed that inorganic Hg (HgCl2) and MeHg inhibited mACh receptor binding in human, rat, and mouse brain tissue. Additionally, studies demonstrated that a low-level gestational exposure to MeHg reduced MAO activity in the developing embryo and in adult female offspring. Combined, these studies provide a framework for the assessment of biochemical targets of Hg compounds in humans. A cross sectional study was conducted to evaluate the association between peripheral biochemical markers and MeHg exposure in fish-eating adults (n=129) from Lac St-Pierre, Quebec. Blood-Hg concentrations were used as a marker of exposure and ranged from 0.2 to 17.0 mug/L. Multiple linear regression analysis demonstrated that both blood-Hg (p=0.011) and heavy smoking (p=0.001) were associated with reduced platelet-MAO activity. However, neither lymphocyte mACh receptor nor serum ChE was related to blood-Hg. These results suggest that exposure to MeHg may result in reduced plat

Filter-feeding macrozooplankton were collected from 24 lakes in south-central Ontario to examine relationships between environmental factors and methyl mercury accumulation. Zooplankton methyl mercury levels ranged from 19 to 448 ng$ rm cdot g sp{-1}$ dry weight in the study lakes and were highest in zooplankton from acidic brownwater lakes. Water color and lake water pH were the best predictors of methyl mercury levels in zooplankton explaining 73% of the variation. Methyl mercury concentrations were positively correlated with water color and inversely correlated with lake water pH. Water color explained a greater portion of the overall variance in methyl mercury levels, indicating that the supply of mercury from the drainage basin plays a key role in determining methyl mercury concentrations in the lacustrine biota. Zooplankton methyl mercury levels were well correlated with mercury concentrations in smallmouth bass (Micropterus dolomieui) and largemouth bass (Micropterus salmoides) from 11 of the study lakes showing zooplankton to be good indicators of the relative bioavailability of mercury at the base of the food chain.