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(1 - 3 of 3)
- Title
- Assessing mercury exposure and biomarkers in largemouth bass (Micropterus Salmoides) from a contaminated river system in California
- Description
- We evaluated mercury (Hg) exposure and two biomarkers, metallothionein (MT) gene expression and histopathological alterations in a wild fish species, largemouth bass (Micropterus salmoides), collected from the Sacramento-San Joaquin Delta, CA, a region polluted with Hg from historic mining activities. Hg is highly toxic and can disrupt multiple physiological systems in vertebrate species, including the immune system. Total mercury (THg) concentration in muscle tissue ranged from 0.12 to 0.98 ppm (wet weight) and was not related to body condition (r 2 = 0.005, p = 0.555). Using linear regression analysis, we found a positive relationship between MT gene expression (as determined using quantitative polymerase chain reaction) and copper, zinc, manganese, aluminum, and nickel (decreased to one variable by way of principal component analysis) (r 2 = 0.379, p = 0.044), a negative relationship with selenium (r 2 = 0.487, p = 0.017), and a weak, negative relationship with THg concentrations (r 2 = 0.337, p = 0.061). Juvenile largemouth bass collected from Hg-contaminated areas displayed histopathological features of immunosuppression compared with those collected from less contaminated areas as evidenced by significantly lower macrophage density in kidney and liver tissue (p = 0.018 and 0.020, respectively), greater trematode density in liver tissue (p = 0.014), and a greater number of adult trematodes. Our results suggest that largemouth bass may be experiencing sublethal effects from chronic Hg exposure. Furthermore, our findings illustrate the utility of examining multiple sublethal markers of effect to assess the impacts of contaminant exposure on physiological function in wild species. © 2012 Springer Science+Business Media New York., Fish and Fisheries, CODEN: AECTC
- Author
- Gehringer, Finkelstein, Coale, Stephenson, Geller
- Date
- 2013-01-01T00:00:00Z
- Title
- Spatial and habitat-rased variations in total and methyl mercury concentrations in surficial sediments in the San Francisco Bay-Delta,
- Description
- Recent studies indicate significant amounts of mercury (Hg) are annually transported into the San Francisco Bay-Delta (Bay-Delta) as a result of historic gold and Hg mining activities. We examined temporal and spatial variation in concentrations of total Hg (HgT) and monomethylmercury (MMHg) in surficial sediments of various ecosystem types in the Bay-Delta. We sampled surficial sediments across the Bay-Delta system and found HgT sediment concentrations in the central Delta were generally 100-200 ng g -1 and increased westward through Suisun Bay to 250-350 ng g -1. MMHg concentrations in the central Delta were between 1 and 3 ng g-1, while those in sediments in the perimeter waterways and adjacent bays were less than 1 ng g-1. Six sites were monitored monthly for over a year to identify seasonal changes in Hg sediment concentrations. Hg T sediment concentrations ranged from 48 to 382 ng g-1 and varied as a function of location not season. However, MMHg concentrations varied seasonally, increasing from 1 ng g-1 during winter months to 6 ng g-1 during spring and summer. Transects conducted at three marshes in the central Delta revealed MMHg sediment concentrations of 4-8 ng g-1at the interior and 2 ng g-1 at the exterior of the marshes. Habitat type was a major factor controlling MMHg concentration and the MMHg to HgT ratio in sediments of the Bay-Delta. MMHg was significantly correlated to HgT (r2 = 0.49) in marsh sediments. © 2007 American Chemical Society., Cited By (since 1996):24, Oceanography, CODEN: ESTHA, ,
- Author
- Heim, Coale, Stephenson, Choe, Gill, Foe
- Date
- 2007-01-01T00:00:00Z
- Title
- Recent increase in atmospheric deposition of mercury to California aquatic systems inferred from a 300-year geochronological assessment of lake sediments,
- Description
- Age-dated sediment cores from 4 remote lakes across California were analyzed for total Hg (Hg T) concentration as a function of pre- and post-industrialization. Particle size, magnetic susceptibility and organic C and N, were measured to determine if the Hg concentration in sediment cores could be related to atmospheric deposition and/or watershed processes. Results indicate that (a) for each lake modern (1970-2004) Hg T lake sediment concentrations have increased by an average factor of 5 times more than historic (pre-1850) Hg T concentrations; (b) the ratio of modern to pre-industrial lake sediment Hg T for these lakes are higher than estimated for other locations where atmospheric deposition is presumed to be the main source of Hg; (c) 2 of the 4 studied lakes demonstrated significant relationships between Hg T concentrations and percentage organic material (r 2 = 0.68 and p < 0.01; r 2 = 0.67 and p < 0.01) whereas the other two indicated no significant relationship (r 2 = 0.05 and p = 0.51; r 2 = 0.12 and p = 0.36). © 2007 Elsevier Ltd. All rights reserved., Cited By (since 1996):13, CODEN: APPGE, ,
- Author
- Sanders, Coale, Gill, Andrews, Stephenson
- Date
- 2008-01-01T00:00:00Z