Anthropogenic trace contaminants and their impact on environmental and human health
Session Chair: Greg Mayer, Dept. of Biochemistry, Microbiology, Molecular Biology, UMaine
Session abstracts:
Pharmaceutically derived, waterborne estrogens inhibit DNA repair processes in zebrafish
Greg Mayer
Dept. of Biochemistry and Molecular Biology, UMaine, Orono, ME
Natural phenolic steroid estrogens and the semi-synthetic pharmaceutical estrogen,
a-ethinylestradiol, have been detected in the aquatic environment in quantities sufficient to elicit altered physiological processes in fish. Pharmaceutical estrogens enter the aquatic environment primarily via wastewater treatment facilities as excretory products or after improper disposal of unused prescriptions. Numerous investigations throughout the past several years have implicated pharmaceutical estrogens in altered reproductive status of aquatic fauna including unwarranted vitellogenesis and many other reproductive abnormalities. In addition to altering reproductive endpoints, aquatic estrogens are known mutagens and tumor promoters. Currently, little to no data exists that explains the role of estrogens in neoplastic transformation. We exposed zebrafish (Danio rerio) to effluents from three wastewater treatment plants in Maine that use differing treatment types. Estrogenicity was analyzed by in vitro reporter assays (luciferase production), examined via analysis of known biomarkers of estrogen exposure in vivo (vitellogenin and CYP1A1 mRNA abundance), and these endpoints were correlated with zebrafish hepatic DNA repair parameters (nucleotide excision repair gene expression and activity) after exposure to wastewater effluent. Results of this and corollary studies suggest waterborne estrogens in wastewater effluent can hinder DNA repair capacity in exposed fish and implicate aquatic estrogens as co-factors in environmental carcinogenesis.
Evaluating spatial patterns in mercury and methyl mercury in northeastern lakes: landscape setting, chemical climate, and human influences
Sarah J. Nelson
Senator George J. Mitchell Center, UMaine, Orono, ME
Mercury (Hg) contamination of surface waters and biota is widespread in the Northeast. Although watershed processing of Hg is complex, several research projects have identified landscape factors such as wetland extent and forest type, and chemical covariates such as dissolved organic carbon, as controls on Hg in surface waters. We hypothesize that watershed characteristics control Hg concentrations in the Northeast. Specifically, we suggest that low-conductivity, wetland-dominated systems with high lake DOC concentrations will have higher Hg concentrations than high-conductivity higher trophic-level lakes affected by human development. This project is using a Geographic Information Systems (GIS) framework to link landscape statistics to a coordinated chemical data set that contains total Hg (HgT), methyl Hg (MeHg), and full ion chemistry for a statistical population of lakes in the Northeastern U.S., all sampled within a single summer index period. The overarching goal is to identify landscape types conducive to high surface water Hg levels. We will present early results of the analysis, with a focus on comparing Hg and landscape factors in Maine lakes to those in other states throughout the study region.
Preliminary study on multiple stressor effects in early life stage Atlantic salmon (Salmo salar)
Crista Straub
School of Biology and Ecology, UMaine, Orono, ME
Atlantic salmon (Salmo salar) decline has become an increasing concern with total runs depleted from half a million adults returning to all United States rivers each year in the early 1800s to approximately one thousand returning today and only to Maine rivers. The current study investigated the possible role of environmental conditions in Maine rivers contributing to salmon decline. Blueberry pesticides, including Velpar® (active ingredient hexazinone), are found at detectable levels in Down East Maine Rivers, but there has not been extensive research on the sublethal effects of these formulations. In addition, Velpar® is proposed to be replaced by Callisto® (active ingredient mesotrione). Pesticides are not the only stressors found in Maine rivers. Some potential stressors (acidity, aluminum (Al), endocrine-disrupting chemicals, organochlorines, etc.) are present in the rivers at the same time. Effects on organisms exposed to multiple stressors may differ significantly from exposure to single stressors. Our goal was to determine how blueberry pesticides, acidic water, and high Al combinations might affect resident Atlantic salmon. The experimental setup included exposing swim up fry (sensitive early life stage) to current- and proposed-use pesticides in the presence and absence of high acidity (pH = 3.9 -5.2) and elevated inorganic aluminum (254 - 573 ppb). Pesticide exposure included environmentally realistic concentrations (0.75 ppb a.i.) and concentrations ten fold higher (7.5 ppb a.i.). Fish were exposed for 5 days in a flow-through system at 14°C. Survival, prey capture, and immune function were evaluated. Pesticide treatment alone had no effect on survival when compared to controls. However, acid/aluminum treatments significantly reduced survival. Prey capture results were confounded by high variability, and immune function assays were inconclusive. In general, the results indicate that pesticide effects on prey capture and survival may increase in the presence of acid/aluminum. However, additional endpoints and replicates are needed to determine conclusive treatment effects.
