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Burlington, Canada

Schwalb A.N.,University of Lethbridge | Alexander A.C.,Canada Center for Inland Waters | Paul A.J.,Environment Canada | Cottenie K.,University of Guelph | Rasmussen J.B.,University of Lethbridge
Environmental Reviews | Year: 2015

The long-lived migratory fish in the lower Athabasca region (including the Athabasca oil sands region) are valued ecosystem components and good bio-indicators of changes in habitat condition, water quality and quantity over the entire stream network. Changes in this region may have been caused by a variety of human activities including oil sands development, forestry, urban development, and recreational activities. We reviewed existing data to examine whether community composition and health of migratory fish (such as northern pike, walleye, and suckers) in the lower Athabasca region have changed over the past 40 years and whether these could be explained by changes in hydrology or water chemistry. Declines of 53%-100% in the abundance of three migratory fish species were detected in the Muskeg watershed (15% land change). Significant changes in fish health were detected. The largest decreases in body condition of fish in the region occurred in the late 1990s and coincided with elevated levels of fin erosion, the most frequently occurring external abnormality, and with extreme discharge conditions. Fish habitat can be affected by both increases and decreases in discharge, and the most pronounced changes were increases in some watersheds of up to 20% of average discharge post-development. In contrast, decreases in discharge post-development in the Muskeg and Steepbank rivers correlated with a decrease in precipitation. Our results show that climatic events and landscape features such as wetlands are important for understanding changes in the system. Further research is needed to examine potential ecological consequences of the observed changes in hydrology for fish and to explore what caused the changes in migratory fish communities and fish health. This will require a better understanding of the trophic structure of the system and a better monitoring program for migratory fish. © 2015 Published by NRC Research Press. Source


Madenjian C.P.,U.S. Geological Survey | Keir M.J.,Environment Canada | Whittle D.M.,Canada Center for Inland Waters
Chemosphere | Year: 2011

We determined total mercury (Hg) concentrations in 50 female lake trout (Salvelinus namaycush) and 69 male lake trout from Lake Ontario (Ontario, Canada and New York, United States). Results showed that, on average, males were 8% higher in Hg concentration than females in Lake Ontario. We also used bioenergetics modeling to determine whether a sexual difference in gross growth efficiency (GGE) could explain the observed sexual difference in Hg concentrations. According to the bioenergetics modeling results, male GGE was about 3% higher than female GGE, on average. Although the bioenergetics modeling could not explain the higher Hg concentrations exhibited by the males, a sexual difference in GGE remained a plausible explanation for the sexual difference in Hg concentrations of the lake trout. In an earlier study, male lake trout from Lake Ontario were found to be 22% higher in polychlorinated biphenyl (PCB) concentration than females from Lake Ontario. Thus, although males were higher in both Hg and PCB concentrations, the degree of the sexual difference in concentration varied between the two contaminants. Further research on sexual differences in Hg excretion rates and Hg direct uptake rates may be needed to resolve the disparity in results between the two contaminants. © 2011. Source


Rochman C.M.,San Diego State University | Rochman C.M.,University of California at Davis | Manzano C.,Oregon State University | Manzano C.,Canada Center for Inland Waters | And 3 more authors.
Environmental Science and Technology | Year: 2013

Polycyclic aromatic hydrocarbons (PAHs) on virgin polystyrene (PS) and PS marine debris led us to examine PS as a source and sink for PAHs in the marine environment. At two locations in San Diego Bay, we measured sorption of PAHs to PS pellets, sampling at 0, 1, 3, 6, 9, and 12 months. We detected 25 PAHs using a new analytical method with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry. Several congeners were detected on samples before deployment. After deployment, some concentrations decreased (1,3-dimethylnaphthalene and 2,6-methylnaphthalene), while most increased [2-methylanthracene and all parent PAHs (PPAHs), except fluorene and fluoranthene], suggesting that PS debris is a source and sink for PAHs. When sorbed concentrations of PPAHs on PS are compared to the five most common polymers [polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), and polypropylene (PP)], PS sorbed greater concentrations than PP, PET, and PVC, similar to HDPE and LDPE. Most strikingly, at 0 months, PPAHs on PS ranged from 8 to 200 times greater than on PET, HDPE, PVC, LDPE, and PP. The combination of greater PAHs in virgin pellets and large sorption suggests that PS may pose a greater risk of exposure to PAHs upon ingestion. © 2013 American Chemical Society. Source


Walsh M.G.,U.S. Geological Survey | Boscarino B.T.,The Harvey School | Marty J.,St Lawrence River Institute | Johannsson O.E.,Canada Center for Inland Waters
Journal of Great Lakes Research | Year: 2012

Mysis diluviana and Hemimysis anomala are the only two species of mysid shrimps in the order Mysidacea that are present in the Laurentian Great Lakes of North America. M. diluviana has inhabited the deep, cold waters of this region since Pleistocene-era glacial retreat and is widely considered to have a central role in the functioning of offshore food webs in systems they inhabit. More recently, the Great Lakes were invaded by the Ponto-Caspian native Hemimysis, a species that inhabits warmer water and shallower depths relative to M. diluviana. Hemimysis has rapidly expanded throughout the Great Lakes region and has become integrated into nearshore food webs as both food for planktivorous fish and predators and competitors of zooplankton. This special issue is composed of 14 papers that represent the most recent advances in our understanding of the ecological importance of both species of mysids to lake and river ecosystems in the Great Lakes region of North America. Topics discussed in this special issue will inform future research in all systems influenced by mysid ecology. © 2012. Source


Long T.,Environment Canada | Wellen C.,McMaster University | Arhonditsis G.,University of Toronto | Boyd D.,Environment Canada | And 2 more authors.
Journal of Great Lakes Research | Year: 2015

Event-based sampling was conducted from July 2010 to May 2012 at four stations in the watersheds of Hamilton Harbour, Ontario, Canada, with the primary objective of estimating total phosphorus (TP) loads. Eighty-seven 24-hour, level-weighted composite samples were collected during a variety of catchment states (rain, snowmelt, baseflow), and TP concentrations were regressed against flow or precipitation in an attempt to mitigate the considerable loading estimation bias arising from event-scale hysteresis. Annual average TP loads were estimated for 2008 to 2012 and were the highest from the Desjardins Canal (17.4 kg/d to 65.6 kg/d), followed by Red Hill Creek (6.4 kg/d to 25.8 kg/d), Grindstone Creek (3.4 kg/d to 33.4 kg/d), and Indian Creek (3.0 kg/d to 7.9 kg/d). Daily TP loads varied by three orders of magnitude between wet and dry conditions, with storm events driving peak daily loads in the urban watersheds, and spring freshet in the agricultural and wetland influenced watersheds. Areal TP loads were higher from the urban relative to the agricultural watersheds. This study demonstrated that the tributaries did not meet the Hamilton Harbour Remedial Action Plan (HH RAP) initial target of 65 kg/d in 2008 to 2011 but did in 2012. Comparison of three loading methods emphasized the vital role of characterizing TP concentrations during high flow events. The higher resolution TP loads generated in this study will assist the HH RAP in forming additional remedial actions in the watersheds for delisting the Hamilton Harbour Area of Concern. © 2015 Published by Elsevier B.V. Source

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