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D.J. Cain

Publications and source records attributed to D.J. Cain.

15 recordsLinked to original sources
USGS2008

Aquatic insect ecophysiological traits reveal phylogenetically based differences in dissolved cadmium susceptibility

We used a phylogenetically based comparative approach to evaluate the potential for physiological studies to reveal patterns of diversity in traits related to susceptibility to an environmental stressor, the trace metal cadmium (Cd). Physiological traits related to Cd bioaccumulation, compartmentalization, and ultimately susceptibility were measured in 21 aquatic insect species representing the orders Ephemeroptera, Plecoptera, and Trichoptera. We mapped these experimentally derived physiological traits onto a phylogeny and quantified the tendency for related species to be similar (phylogenetic signal). All traits related to Cd bioaccumulation and susceptibility exhibited statistically significant phylogenetic signal, although the signal strength varied among traits. Conventional and phylogenetically based regression models were compared, revealing great variability within orders but consistent, strong differences among insect families. Uptake and elimination rate constants were positively correlated among species, but only when effects of body size and phylogeny were incorporated in the analysis. Together, uptake and elimination rates predicted dramatic Cd bioaccumulation differences among species that agreed with field-based measurements. We discovered a potential tradeoff between the ability to eliminate Cd and the ability to detoxify it across species, particularly mayflies. The best-fit regression models were driven by phylogenetic parameters (especially differences among families) rather than functional traits, suggesting that it may eventually be possible to predict a taxon's physiological performance based on its phylogenetic position, provided adequate physiological information is available for close relatives. There appears to be great potential for evolutionary physiological approaches to augment our understanding of insect responses to environmental stressors in nature. ?? 2008 by The National Academy of Sciences of the USA.

Proceedings of the National Academy of Sciences of↗
USGS2008

Cadmium biodynamics in the oligochaete Lumbriculus variegatus and its implications for trophic transfer

It has become increasingly apparent that diet can be a major source of trace metal bioaccumulation in aquatic organisms. In this study, we examined cadmium uptake, efflux, and subcellular compartmentalization dynamics in the freshwater oligochaete Lumbriculus variegatus. L. variegatus is an important component of freshwater food webs in Europe and North America and is potentially useful as a standard food source for laboratory-based trophic transfer studies. Cadmium accumulation and depuration were each followed for 10 days. Rate constants of uptake (ku) and efflux (ke) were estimated and subcellular Cd compartmentalization was followed over the course of uptake and efflux. The partitioning of Cd into operationally-defined subcellular compartments was relatively consistent throughout the 20-day experiment, with the majority of Cd accumulating in the cytosol. No major changes in Cd compartmentalization were observed over uptake or depuration, but there appeared to be some exchange between heat-stable and heat-labile cytosolic protein fractions. Cadmium accumulation from solution was strongly affected by ambient calcium concentrations, suggesting competition between Cd and Ca for uptake sites. Finally, we demonstrate the ability to manipulate the whole body calcium content of L. variegatus as a potential tool for examining calcium influences on dietary Cd dynamics. The potential for this species to be an important conduit of Cd to higher trophic levels is discussed, along with its potential as a standardized food source in metal trophic transfer studies. ?? 2007 Elsevier B.V. All rights reserved.

Aquatic Toxicology↗
USGS2007

Cadmium ecophysiology in seven stonefly (Plecoptera) species: Delineating sources and estimating susceptibility

A major challenge in ecotoxicology lies in generating data under experimental conditions that are relevant to understanding contaminant effects in nature. Biodynamic modeling combines species-specific physiological traits to make predictions of metal bioaccumulation that fare well when tested in the field. We generated biodynamic models for seven predatory stonefly (Plecoptera) species representing the families Perlidae (5) and Perlodidae (2). Each taxon was exposed to cadmium independently via diet and via solution. Species varied approximately 2.6 fold in predicted steady-state cadmium concentrations. Diet was the predominant source of accumulated cadmium in five of the seven species and averaged 53.2 ± 9.6% and 90.2 ± 3.7% of net Cd accumulation in perlids and perlodids, respectively. Differences in Cd bioaccumulation between the two families were largely driven by differences in dissolved accumulation rates, which were considerably slower in perlodids than in perlids. We further examined the subcellular compartmentalization of Cd accumulated from independent aqueous and dietary exposures. Predicted steady-state concentrations were modified to only consider Cd accumulated in metal-sensitive subcellular compartments. These values ranged 5.3 fold. We discuss this variability within a phylogenetic context and its implications for bioassessment.

Environmental Science & Technology↗
USGS2006

Influence of metal exposure history on the bioaccumulation and subcellular distribution of aqueous cadmium in the insect Hydropsyche californica

The influence of metal exposure history on rates of aqueous Cd accumulation, elimination, and subcellular distribution was examined in the aquatic insect Hydropsyche californica . Specimens were obtained from a reference site and a metal‐contaminated site and returned to the laboratory where they were continuously exposed to aqueous Cd (518 ng/L, nominal) for 6 d, followed by 9 d of depuration. Rates of Cd accumulation and elimination were similar in insects from the two sites. Efflux rate constants, k e , ranged from 0.20 to 0.24/d ( t 1/2 ≈ 3 d). Immediately following exposure, the cytosol accounted for 40% of the body burden in insects from both sites; however, 89 ± 2% of the cytosolic Cd was associated with metallothionein‐like proteins (MTLP) in insects from the contaminated site, compared to 60 ± 0% in insects from the reference site. The concentration of Cd bound to non‐MTLPs (representing potentially Cd‐sensitive proteins) was significantly greater in the insects from the reference site (134 ± 7 ng/g) than in those from the contaminated site (42 ± 2 ng/g). At the end of the depuration period, 90% of the accumulated Cd body burden had been eliminated, and Cd concentrations in MTLPs and non‐MTLPs were similar between the sites. Results suggested that differences in exposure history had no influence on the bioaccumulation of Cd, but did affect the concentrations of Cd bound to MTLP during Cd exposure in these insects.

Environmental Toxicology and Chemistry↗
USGS2003

Response of benthic invertebrate assemblages to metal exposure and bioaccumulation associated with hard-rock mining in northwestern streams, USA

Benthic macroinvertebrate assemblages, environmental variables, and associated mine density were evaluated during the summer of 2000 at 18 reference and test sites in the Coeur d'Alene and St. Regis River basins, northwestern USA as part of the US Geological Survey's National Water-Quality Assessment Program. Concentrations of Cd, Pb, and Zn in water and (or) streambed sediment at test sites in basins where production mine density was ???0.2 mines/km2 (in a 500-m stream buffer) were significantly higher than concentrations at reference sites. Zn and Pb were identified as the primary contaminants in water and streambed sediment, respectively. These metal concentrations often exceeded acute Ambient Water Quality Criteria for aquatic life and the National Oceanic and Atmospheric Administration Probable Effect Level for streambed sediment. Regression analysis identified significant correlations between production mine density in each basin and Zn concentrations in water and Pb in streambed sediment (r2 = 0.69 and 0.65, p < 0.01). Metal concentrations in caddisfly tissue, used to verify site-specific exposures of benthos, also were highest at sites downstream from intensive mining. Benthic invertebrate taxa richness and densities were lower at sites downstream than upstream of areas of intensive hard-rock mining and associated metal enrichment. Benthic invertebrate metrics that were most effective in discriminating changes in assemblage structure between reference and mining sites were total number of taxa, number of Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa, and densities of total individuals, EPT individuals, and metal-sensitive Ephemeroptera individuals.

Journal of the North American Benthological Societ↗
USGS1984

Comparison of sediments and organisms in identifying sources of biologically available trace metal contamination

Sediments and an indicator organism (Macoma balthica, a deposit-feeding bivalve) were used to assess the relative importance of secondary sewage, urban runoff, a landfill containing metal-enriched ash wastes and a yacht harbor in contributing to Ag, Cu and Zn enrichment in South San Francisco Bay. Spatial gradients in sediments and organisms showed Cu and Ag enrichment originated from sewage discharge, whereas Zn enrichment originated from both sewage and urban runoff. Elevated concentrations of Cu in the sediments of the yacht harbor resulted from a high abundance of fine particles. The biological availability of Cu, Ag and Zn did not coincide with metal enrichment in sediments. The availability of Cu and Ag was greatest nearest the sewage outfall and greater in winter and spring than in summer. The availability of Zn in urban runoff appeared to be lower than the availability of Zn associated with sewage.

Water Research↗
USGS1980

Determining the availability of sediment-bound trace metals to aquatic deposit-feeding animals

Physicochemical form affects, by as much as 1000 fold, the uptake rate by deposit-feeding clams of metals bound to sediments. The strength of metal binding to the different sedimentary binding substrates controls this effect. Statistical studies that were spatially intensive (comparing 35 stations in 17 estuaries) and temporally intensive (2 stations through 2 years time) indicate that sediments control the availability of Ag, Cd, Co, Pb, Zn, Fe, and Mn, and possibly Cu to clams and polychaete worms in nature. Metal concentrations removed from sediments by chemical extractants generally follow availability better than do total metal concentrations, but the specific extractant differs among different metals. Concentrations of binding substrates (Fe, Mn, organic carbon, humic substances) also statistically explain a proportion of the variance of metal concentrations in the animals, suggesting that metal partitioning among substrates in sediments is an important control on metal availability. The specific substrates which contribute to availability also differ among metals. Statistical assessment of metal form in sediments suggested that different substrates compete for the partitioning of metals, that each metal is partitioned among a variety of forms in an oxidized sediment, and that partitioning will vary with the physicochemical characteristics of the sediments. (USGS)

Open-File Report↗