Denny R. Buckler

Survival, sublethal responses, and tissue residues of Atlantic salmon exposed to acidic pH and aluminum

Abstract Early life stages of Atlantic salmon (Salmo salar) were continuously exposed to pHs ranging from 4.5 to 7.2 in one study, and to Al concentrations ranging from 33 to 264 μg/l at pH 5.5 in a second study. The tests were begun with eyed eggs and conducted until 60 d post-hatch. The exposure water contained about 3.0 mg/l calcium and was representative of acid-sensitive surface waters with low acid-neutralizing capacity. Hatching success, mortality, growth, behavior, and tissue residues of aluminum were determined during the tests. Egg hatching and the growth of larvae were reduced significantly at pH 4.5 and 5.0, and larval mortality increased at pH 4.5. Larval feeding and swimming behavior were impaired at pH 6.5 and lower. Hatching was not affected at pH 5.5 in the presence of Al; however, larvae exposed to 124 μg Al/l at pH 5.5 incurred significant increases in mortality. The inhibition of feeding observed among fish exposed to pH 5.5 was intensified at all concentrations of Al tested. At pH 5.5, reduced growth occurred among larvae exposed to 71 μg Al/l and higher. Concentrations of Al in whole-body tissue ranged from 3 μg/g for fish exposed to 33 μg Al/l to 96 μg/g for those exposed to 264 μg Al/l. At 60 d of exposure, bioconcentration factors ranged from 76 to 190 and were directly related to exposure concentration. Sublethal exposure of Atlantic salmon to acidic pH alone, and in combination with Al, may significantly reduce their fitness and may also play a significant role in recruitment failure in some acid-sensitive waters in the northeastern United States.

Environmental contaminants in prey and tissues of the peregrine falcon in the Big Bend Region, Texas, USA

Peregrine falcons (Falco peregrinus) have been recorded nesting in Big Bend National Park, Texas, USA and other areas of the Chihuahuan Desert since the early 1900s. From 1993 to 1996, peregrine falcon productivity rates were very low and coincided with periods of low rainfall. However, low productivity also was suspected to be caused by environmental contaminants. To evaluate potential impacts of contaminants on peregrine falcon populations, likely avian and bat prey species were collected during 1994 and 1997 breeding seasons in selected regions of western Texas, primarily in Big Bend National Park. Tissues of three peregrine falcons found injured or dead and feathers of one live fledgling also were analyzed. Overall, mean concentrations of DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene], a metabolite of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane], were low in all prey species except for northern rough-winged swallows (Stelgidopteryx serripennis, mean = 5.1 microg/g ww). Concentrations of mercury and selenium were elevated in some species, up to 2.5 microg/g dw, and 15 microg/g dw, respectively, which upon consumption could seriously affect reproduction of top predators. DDE levels near 5 microg/g ww were detected in carcass of one peregrine falcon found dead but the cause of death was unknown. Mercury, selenium, and DDE to some extent, may be contributing to low reproductive rates of peregrine falcons in the Big Bend region.

A comparative assessment of contaminants in fish from four resacas of the Texas, USA–Tamaulipas, Mexico border region

A recent survey of contaminant information for the Lower Rio Grande Valley (LRGV), Texas, has shown that little is known about contaminants and their impacts on biota of resacas (oxbows) along the US-Mexico border. In 1996, fish were collected from four resacas in the Texas-Tamaulipas border region to assess contaminant loadings and their impacts on fish and birds. Tissue residue concentrations in fish were analyzed and also compared to two histopathological bioindicators of unhealthy environmental conditions. Of the organochlorine insecticides measured, DDE was the most common and was present at relatively high concentrations (10 microg/g w/w) at some sites. DDE concentrations were nearly 20 times greater in fish from resacas in Texas than from resacas in Tamaulipas, although the limited sample sizes obtained precluded statistical comparisons. DDE concentrations in fish from the two Texas resacas were also greater than those reported in fish from nearby areas during the 1980s and 1990s. Most trace element concentrations were similar among resacas from Texas and Tamaulipas. Arsenic, however, was two to six times greater in fish from a downtown resaca in Matamoros than in fish from other resacas in Tamaulipas and Texas. The bioindicators, pigment accumulation, and macrophage aggregates (MAs), in general, reflected the contamination indicated by the tissue residues for each site. Overall, it appears that some resacas of the US-Mexico border region are contaminant sinks and could pose potential health or reproductive problems for fish and wildlife, and humans that consume fish from those sites.

Optimization of the Ames/Salmonella Mutagenicity Assay for Use with Extracts of Aquatic Sediments

Abstract Non-mutagenic components interfered with the ability of the standard Ames/salmonella assay to detect mutagenicity in extracts of contaminated Great Lakes sediments. The use of gel permeation chromatography (GPC) to remove these macromolecules from methylene chloride extracts prior to Ames testing enhanced the likelihood of transfer of mutagenic components into dimethyl sulf oxide (the assay solvent). Therefore, to optimize the assays sensitivity we pre-treated sediment extracts using GPC and increased metabolic activity through the use of a 30% S9 mix. Increasing the level of Aroclor 1254-induced rat liver S9, typically used to metabolically activate promutagens, had the additional beneficial effect of reducing the cytotoxicity of the extracts. As applied in this study, the Ames assay can serve as a sensitive test for screening the mutagenic potential of large numbers of uncharacterized sediment extracts.

Mutagenicity of Great Lakes Sediments

Abstract The Ames/salmonella assay optimized for use with sediment extracts was used to assess the mutagenic potential of contaminated sediments collected from the Saginaw River, the Buffalo River, and Indiana Harbor as part of the Assessment and Remediation of Contaminated Sediments Program undertaken by the Great Lakes Program Office of the U.S. Environmental Protection Agency. Ames assays were conducted with 35 organic chemical extracts prepared from sediment samples collected from a total of 29 stations in the three areas of concern. Prior to the assay extracts required pre-treatment by gel permeation chromatography, but no further fractionation was performed. Mutagenicity was detected in both grab and core sediment samples from every station. Of the four bacterial strains tested, only TA98 consistently identified mutagenicity.