Christopher L. Rowe

Elevated maintenance costs in an anuran (Rana catesbeiana) exposed to a mixture of trace elements during the embryonic and early larval periods.

We investigated the relationship between maintenance costs (standard metabolic rates, measured as O2 consumption at rest) in tadpoles of the bullfrog, Rana catesbeiana, and exposure to contaminants in a coal ash‐polluted habitat (characterized by a variety of trace elements). We compared metabolic rates of tadpoles collected from the polluted site with those from an unpolluted reference pond. Tadpoles collected in the polluted site had 40%–97% higher standard metabolic rates than those collected from the reference pond. We also reciprocally transplanted eggs of the bullfrog between the polluted site and another reference pond and compared standard metabolic rates of tadpoles at 25 and 80 d posthatching. Metabolic rates of tadpoles raised in the polluted site were from 39% to 175% higher than those raised in a reference pond, depending on tadpole age and temperature at which metabolic rates were measured. There were no effects of site of origin of the eggs (polluted or unpolluted) on metabolic rates. Survival to hatching did not differ between sites, although survival to the end of the experiment (80 d posthatching) was lower in the polluted area than in the reference site. Surviving tadpoles were larger in wet body mass in the polluted site than in the reference pond, possibly due to lower survival in the former, but there was no relationship between survival and metabolic rate. It is clear that some feature of the polluted habitat was responsible for causing substantial elevation of standard metabolic rates of tadpoles. We hypothesize that the mixture of trace elements present in sediment and water in the polluted site was responsible for the observed physiological differences.

Ecotoxicological Implications of Aquatic Disposal of Coal Combustion Residues In the United States: A Review

We provide an overview of research related to environmental effects of disposal of coal combustion residues (CCR) in sites in the United States. Our focus is on aspects of CCR that have the potential to negatively influence aquatic organisms and thehealth of aquatic ecosystems. We identify major issues of concern, as well as areas in need of further investigation.Intentional or accidental release of CCR into aquatic systemshas generally been associated with deleterious environmental effects. A large number of metals and trace elements are presentin CCR, some of which are rapidly accumulated to high concentrations by aquatic organisms. Moreover, a variety of biological responses have been observed in organisms following exposure to and accumulation of CCR-related contaminants. In some vertebrates and invertebrates, CCR exposure has led to numerous histopathological, behavioral, and physiological (reproductive, energetic, and endocrinological) effects. Fish kills and extirpation of some fish species have been associatedwith CCR release, as have indirect effects on survival and growth of aquatic animals mediated by changes in resource abundance or quality. Recovery of CCR-impacted sites can be extremely slow due to continued cycling of contaminants withinthe system, even in sites that only received CCR effluents forshort periods of time. The literature synthesis reveals important considerations for future investigations of CCR-impacted sites. Many studies have examined biological responses to CCR with respect to Se concentrations and accumulation because of teratogenic andreproductively toxic effects known to be associated with thiselement. However, the complex mixture of metals and traceelements characteristic of CCR suggests that biologicalassessments of many CCR-contaminated habitats should examine avariety of inorganic compounds in sediments, water, and tissuesbefore causation can be linked to individual CCR components. Most evaluations of effects of CCR in aquatic environments havefocused on lentic systems and the populations of animalsoccupying them. Much less is known about CCR effects in loticsystems, in which the contaminants may be transported downstream,diluted or concentrated in downstream areas, and accumulated bymore transient species. Although some research has examinedaccumulation and effects of contaminants on terrestrial and avianspecies that visit CCR-impacted aquatic sites, more extensiveresearch is also needed in this area. Effects in terrestrial orsemiaquatic species range from accumulation and maternal transferof elements to complete recruitment failure, suggesting that CCReffects need to be examined both within and outside of theaquatic habitats into which CCR is released. Requiring specialattention are waterfowl and amphibians that use CCR-contaminatedsites during specific seasons or life stages and are highlydependent on aquatic habitat quality during those periods.Whether accidentally discharged into natural aquatic systems or present in impoundments that attract wildlife, CCR appears topresent significant risks to aquatic and semiaquatic organisms. Effects may be as subtle as changes in physiology or as drasticas extirpation of entire populations. When examined as a whole,research on responses of aquatic organisms to CCR suggests thatreducing the use of disposal methods that include an aquaticslurry phase may alleviate some environmental risks associatedwith the waste products.

Reproduction, embryonic development, and maternal transfer of contaminants in the amphibian Gastrophryne carolinensis.

Although many amphibian populations around the world are declining at alarming rates, the cause of most declines remains unknown. Environmental contamination is one of several factors implicated in declines and may have particularly important effects on sensitive developmental stages. Despite the severe effects of maternal transfer of contaminants on early development in other vertebrate lineages, no studies have examined the effects of maternal transfer of contaminants on reproduction or development in amphibians. We examined maternal transfer of contaminants in eastern narrow-mouth toads (Gastrophryne carolinensis) collected from a reference site and near a coal-burning power plant. Adult toads inhabiting the industrial area transferred significant quantities of selenium and strontium to their eggs, but Se concentrations were most notable (up to 100 μg/g dry mass). Compared with the reference site, hatching success was reduced by 11% in clutches from the contaminated site. In surviving larvae, the frequency of developmental abnormalities and abnormal swimming was 55–58% higher in the contaminated site relative to the reference site. Craniofacial abnormalities were nearly an order of magnitude more prevalent in hatchlings from the contaminated site. When all developmental criteria were considered collectively, offspring from the contaminated site experienced 19% lower viability. Although there was no statistical relationship between the concentration of Se or Sr transferred to eggs and any measure of offspring viability, our study demonstrates that maternal transfer may be an important route of contaminant exposure in amphibians that has been overlooked.

Exposure to Coal Ash Impacts Swimming Performance and Predator Avoidance in Larval Bullfrogs (Rana catesbeiana)

WALLS, S. C., J. J. BEATTY, B. N. TISSOT, D. G. HOKIT, AND A. R. BLAUSTEIN. 1993a. Morphological variation and cannibalism in a larval salamander (Ambystoma macrodactylum columbianum). Can. J. Zool. 71:1543-1551. , S. S. BELANGER, AND A. R. BLAUSTEIN. 1993b. Morphological variation in a larval salamander: dietary induction of plasticity in head shape. Oecologia 96:162-168. WOODWARD, B. D., J. TRAVIS, AND S. MITCHELL. 1988. The effects of the mating system on progeny performance in Hyla crucifer. Evolution 42:784-794.

Metabolic costs incurred by crayfish (Procambarus acutus) in a trace element-polluted habitat: further evidence of similar responses among diverse taxonomic groups.

Recent studies of several vertebrates and an invertebrate have shown elevated standard metabolic rate (SMR) following chronic exposure to a mixture of trace elements in a contaminated habitat. In this study, we examined whether another invertebrate, a crayfish (Procambarus acutus), also experienced elevated SMR in response to the same contaminants. We compared SMR of individuals inhabiting the contaminated site with SMR of individuals from uncontaminated reference sites. We also examined SMR of individuals collected from the reference areas and exposed in the laboratory for 50 days to sediment and food derived from the contaminated site. Individuals collected from the contaminated site had elevated SMR compared to individuals collected from the unpolluted areas (25.1 vs. 19.2 J g(-1) day(-1)). Individuals exposed to contaminated sediment and food in the laboratory experienced elevations in SMR compared to controls after 27 days of exposure (35.2 vs. 29.4 J g(-1) day(-1)), but after 50 days of exposure, metabolic rate no longer differed between treatments. Growth of contaminant-exposed individuals was lower than growth of reference animals throughout the laboratory study. Elevated SMR associated with contaminant exposure may reflect energy-demanding mechanisms required to combat deleterious effects of contaminants. Our results support the prediction that increases in energy expenditure in the contaminated habitat would negatively influence production processes, such as growth. Results from this study in conjunction with observations from other species suggest that increased SMR is a common response among several taxa to the mixture of contaminants in the study site.

Oral Deformities in Tadpoles of the Bullfrog (Rana catesbeiana) Caused by Conditions in a Polluted Habitat

In this experiment, we tested for a causative relationship between the site in which bullfrogs developed during the embryonic and early larval period and presence of oral deformities. We reciprocally transplanted fresh egg masses of bullfrogs collected from the coal ash-polluted site and an unpolluted reference pond to test the main and interactive effects of the site in which tadpoles developed and the site inhabited by the parents, on the frequency of oral deformities in tadpoles.

Nondestructive indices of trace element exposure in squamate reptiles

Compared with birds, mammals, fish, and even amphibians, very little is known about the effects of contaminants on reptiles. Recent evidence that many reptile populations may be declining has stimulated demand for toxicological studies of reptiles as well as development of nondestructive sampling techniques useful for assessing and monitoring contaminant exposure. The current study experimentally evaluated the utility of shed skins, tail clips, and blood samples as nondestructive indices of trace element exposure in banded water snakes, Nerodia fasciata. For 13.5 months, snakes were either fed fish from a coal ash-contaminated site or uncontaminated food from a reference site. Snakes fed contaminated prey accumulated As, Cd, Se, Sr, and V in various organs (i.e. liver, kidney, and/or gonads). Moreover, non-parametric discriminant function analysis revealed that snakes could be placed in two groups that reliably reflected their experimental diet based upon Se, Sr, and As concentrations in tail clips, blood, and/or shed skins. We suggest that nondestructive sampling techniques, particularly analyses of blood and tail clips, may be easily applied in evaluations of contaminant exposure in the field and laboratory and may prevent excessive destructive sampling of potentially threatened reptile species.

The value of simulated pond communities in mesocosms for studies of amphibian ecology and ecotoxicology

We provide a review of literature concerning the use of artificial pond communities in static, outdoor, above-ground tanka (mesocosms) for ecological studies of amphibians. This approach has been widely used to evaluate the interaction of biotic variables, and less often biotic and abiotic variables. Although simulated pond communities offer unusually attractive properties for evaluating the effects of xenobiotics on aquatic ecosystems, this approach has received only limited attention as a potential model system for studying the effects of toxicants on amphibian communities. We provide a summary of results and experimental designs from past studies in order to illustrate the general protocols used and complex interactions between biotic and abiotic variables that can be simulated in artificial pond communities

Growth responses of an estuarine fish exposed to mixed trace elements in sediments over a full life cycle

Hatchling Cyprinodon variegatus were raised in the presence or absence of sediments contaminated with mixed trace elements to examine lethal and sublethal bioenergetic effects (metabolic rate, lipid storage, growth, reproduction) over a full life cycle (>1 year). Contaminated sediments were derived from a site receiving coal combustion residues (CCR) and were elevated in numerous trace elements including Al, As, Ba, Cd, Cu, Se, and V. Exposures were conducted at two levels of salinity (5 and 36 ppt) to examine the potential interaction of this variable with contaminants. Salinity had no effect on responses measured. Over the course of the study, fish exposed to contaminated sediment accumulated several CCR-related trace elements, including As, Cd, Se, and V. There were no differences in fish survival for contaminated sediment treatments and uncontaminated sediment treatments, nor were there differences in metabolic expenditures. However, growth, male condition factor, and storage lipid content in females were reduced due to contaminant exposure. No significant effects on fecundity or the proportion of females that were gravid at the end of the study were observed, yet females raised under control conditions produced 12% larger eggs than did females raised on contaminated sediments. During the presumably most-sensitive early life stages, individuals were not noticeably affected by contaminants, but rather the effects of exposure became apparent later in life. Because many species inhabit contaminated areas for long periods of time, often encompassing the entire life cycle, exposures focused only on specific life stages may substantially underestimate the overall responses elicited by individuals.

Maternal transfer of selenium in Alligator mississippiensis nesting downstream from a coal‐burning power plant

Selenium (Se) is embryotoxic in many oviparous vertebrates, but little is known about maternal transfer of Se and its impact in reptiles. Over a four-year period, we collected three clutches of eggs of the American alligator (Alligator mississippiensis) from a single nest at a site contaminated with Se and compared egg and hatchling Se concentrations and clutch viability from this nest to nests downstream from the contaminated site (two clutches from two nests) and at a reference site (two clutches from two nests). Eggs and hatchlings from the nest at the Se-contaminated site and downstream nests had elevated Se concentrations (2.1-7.8 ppm) and lower viability (30-54%) compared to reference nests (1.4-2.3 ppm and 67-74% viability), but Se concentrations did not exceed reproductive toxicity thresholds established for other oviparous vertebrates. Selenium concentrations were higher in chorioallantoic membranes of eggs from Se-contaminated sites, suggesting that this tissue may be useful as a nondestructive index of Se exposure for embryos of A. mississippiensis. Examination of these data suggests that further studies on uptake, accumulation, and reproductive success of crocodilian embryos exposed to excessive Se are warranted.