Search

Habitat loss, overfishing, and decline in abundance and quality of natural resources continue to threaten marine ecosystems. A common tool used to measure health and diversity within a system is genetic diversity. The purpose of this study was to determine the genetic diversity of 2 crustacean populations by sequencing the 16S rRNA mitochondrial loci. We collected Callinectes sapidus (Blue Crab) and Arenaeus cribrarius (Speckled Swimming Crab) using seines and standard crab pots from 2 study sites along the Georgia and South Carolina coasts. We extracted DNA from leg or claw tissue and used previously published primers to sequence the 16S rRNA loci of the mitochondria and record the number of mutations found from individual crabs. A total of 177 crabs (Blue Crab: n = 129; Speckled Swimming Crab: n = 48) were sequenced. Overall, the Blue Crab showed more genetic diversity relative to the Speckled Swimming Crab, but this result may due to sample size. Knowledge of the genetic diversity of an economically important species has implications for management.

Human activities have radically shaped the global landscape, affecting the structure and function of ecosystems. Habitat loss is one of the most visible changes to the landscape and a primary driver of species declines; however, anthropogenic environmental contamination also threatens population persistence, but is not as readily observed. Aquatic organisms are especially susceptible to chemical perturbations, which can negatively impact survival and fitness related traits. Some populations have evolved tolerance to chemical stressors, which could mitigate the consequences associated with contamination. Amphibians are experiencing global declines due to multiple stressors and are particularly at risk to aquatic chemical stressors due to their permeable skin and reliance on wetlands for reproduction and larval development. However, amphibians also have substantial plasticity in response to environmental variation. We designed our study to examine whether tolerance to heavy metals is greater in Southern toad (Anaxyrus terrestris) larvae from wetlands with a history of contamination. Considering many of the most common trace elements elicit acute toxicity by disrupting osmotic- and ionic-regulation, we hypothesized that alterations to these aspects of physiology resulting from multigenerational exposure to trace element mixtures would be the most likely routes by which tolerance would evolve. We used copper (Cu) as a proxy for heavy metal exposure because it is a widely distributed aquatic stressor known to cause osmotic stress that can also cause mortality at levels commonly encountered in the environment. We found considerable within and among population variation in Cu tolerance, as measured by time to death. Larvae from populations living in sites contaminated with mixtures of heavy metals associated with coal fly ash were no more tolerant to Cu than those from reference sites. However, larvae from a population inhabiting a constructed wetland complex with high Cu levels were significantly more tolerant; having half the risk of mortality as reference animals. This wetland complex was created20 years ago, thus if elevated Cu tolerance in this population is due to selection in the aquatic habitat, such adaptation may occur rapidly (i.e. ∼10 generation). Our results provide evidence that amphibians may be able to evolve tolerance in response to trace element contamination, though such tolerance may be specific to the combination of contaminants present.

Larval zebrafish (Danio rerio) are optically transparent up to fourteen days post fertilization (dpf) and have high synteny with Homo sapiens which makes them viable research models for the study of metabolic and physiological processes at a unicellular level. Preceding methods to image zebrafish larvae have been limited to single larvae and long-term imaging has been a challenge. The aim of this study is to design a micro-fluidic slide for mounting larvae that greatly extends the duration of time for in vivo imaging, while supplying selected drugs, modified/selected diets, and fresh embryo media. Fluorescently labeled material can be custom made or are commercially available. Examples are high fat diets spiked with fluorescently conjugated lipids such as BODIPY or fluorescent polystyrene beads. To improve upon our pervious chip design, we used the Zeiss Discovery V8 microscope to re-image five seven-dpf larvae in order to adjust the measurements of the chamber to properly accommodate an average seven-dpf larvae. The newest prototype slide is currently under testing to determine effectiveness and efficiency with fluorescent polystyrene beads to visualize consumption of a diet delivered while the larvae is in the microfluidic chip. We expect to record the transit of the beads through the intestine of the treated larvae. This work was supported by NIH Grant P20GM103434 to the West Virginia IDeA Network for Biomedical Research Excellence and NIH Grant P20GM103434 awarded to Bluefield State College and the McNair Scholars Program.

International audience; In the Fall of 2016 a workshop was held which brought together over 50 scientists from the ecological and radio- logical fields to discuss feasibility and challenges of reintegrating ecosystem science into radioecology. There is a growing desire to incorporate attributes of ecosystem science into radiological risk assessment and radioecological research more generally, fueled by recent advances in quantification of emergent ecosystem at- tributes and the desire to accurately reflect impacts of radiological stressors upon ecosystem function. This paper is a synthesis of the discussions and consensus of the workshop participant's responses to three primary questions, which were: 1) How can ecosystem science support radiological risk assessment? 2) What ecosystem level endpoints potentially could be used for radiological risk assessment? and 3) What inference strategies and associated methods would be most appropriate to assess the effects of radionuclides on ecosystem structure and function? The consensus of the participants was that ecosystem science can and should support radiological risk assessment through the incorporation of quantitative metrics that reflect ecosystem functions which are sensi- tive to radiological contaminants. The participants also agreed that many such endpoints exit or are thought to exit and while many are used in ecological risk assessment currently, additional data need to be collected that link the causal mechanisms of radiological exposure to these endpoints. Finally, the participants agreed that ra- diological risk assessments must be designed and informed by rigorous statistical frameworks capable of reveal- ing the causal inference tying radiological exposure to the endpoints selected for measurement.

Animals can modulate their own exposure to environmental contaminants through behavioral plasticity such as diet and habitat choice. However, it remains unclear if behavior also has cascading effects on contaminant exposure across multiple generations. In insects, oviposition site selection is an important behavior females can use to modify offspring contaminant exposure risk. In this study, we use the yellow fever mosquito, Aedes aegypti, to test how methylmercury (MeHg) affects oviposition site selection. We found that mosquito larval development rate and survival were negatively affected at MeHg concentrations ≥100 ppb. Adult females not exposed to MeHg as larvae avoided oviposition sites with high MeHg concentrations (>50 ppb), but MeHg exposure at the larval stage significantly affected this oviposition site selection. Specifically, females raised from larvae exposed to non-toxic MeHg levels (i.e., five-50 ppb) showed a significant increase in preference for oviposition sites contaminated with toxic MeHg concentrations (≥500 ppb), compared to unexposed controls. This maladaptive behavioral response could be because, when conditioned with non-toxic MeHg concentrations, MeHg-associated olfactory cues act as a “supernormal” stimulus during oviposition site selection. Importantly, however, this maladaptive behavioral response is eliminated in female mosquitoes raised from larvae exposed to toxic MeHg concentrations (i.e. 100 ppb), and these mosquitoes showed a significant increase in preference for MeHg uncontaminated oviposition sites, compared to unexposed controls. Thus, in mosquitoes, the magnitude of MeHg exposure in one generation can impact MeHg exposure in subsequent generations by altering oviposition site selection behavior. Our results have broad implications for our understanding of how contaminant-mediated behavioral modifications can feedback on contaminant exposure risk across multiple generations, and consequently how behavior can affect the evolutionary trajectory of organisms inhabiting a heterogeneously contaminated environment.