Geology topics

Dennis R. DeVries

Publications and source records attributed to Dennis R. DeVries.

4 recordsLinked to original sources

USGS2024

Using the electron transport system as an indicator of organismal thermal tolerance and respiratory exploitation

Freshwater ecosystems are undergoing rapid thermal shifts, making it increasingly important to understand species-specific responses to these changes. Traditional techniques for determining a species’ thermal tolerance are often lethal and time consuming. Using the enzyme activity associated with the electron transport system (ETS; hereafter referred to as enzyme assay) may provide a non-lethal, rapid, and efficient alternative to traditional techniques for some species. We used largemouth bass Micropterus salmoides (Lacepede, 1802) to test the efficacy of using an enzyme assay to determine thermal tolerance and respiratory exploitation in response to variable acclimation temperatures. Three tissue types were dissected from fish acclimated to 20, 25, or 30 °C and used in ETS assays at temperatures ranging from 7.5 to 40 °C. While there were significant differences among tissue types and acclimation temperatures, maximal enzyme activity occurred from 25.23 to 31.91 °C. Fish lost equilibrium at 39–42 °C in traditional CT max trials, significantly higher than the upper optimum range determined via enzyme assays. The ratio of enzyme activity to measured whole organism respiration rate decreased with increasing water temperature, with the largest changes occurring at the upper optimum thermal range determined by enzyme assays. Our results indicate that ETS analysis may prove useful for obtaining biologically relevant thermal tolerances.

Canadian Journal of Zoology↗

USGS2023

Evaluation of shoreline rotenone application to control Largemouth Bass recruitment in small impoundments

Objective Reducing Largemouth Bass Micropterus salmoides recruitment and therefore population density could benefit recreational fisheries in small impoundments by improving individual growth rates and increasing the average size and condition of Largemouth Bass. To achieve these effects, methods of controlling Largemouth Bass recruitment should avoid reducing the productivity of their primary prey species, the Bluegill Lepomis macrochirus . Methods We tested this hypothesis by evaluating the effects of shoreline rotenone application on the density of Bluegill and the density, growth, and survival of age-0 and age-1 Largemouth Bass in 15 Alabama small impoundments. Result After treatment, Largemouth Bass age-0 densities declined and mean age-1 length increased, whereas Bluegill populations were not significantly reduced. Conclusion Our study indicates that shoreline rotenone application may be a valuable method for reducing Largemouth Bass recruitment and increasing the growth of age-1 Largemouth Bass in small impoundments. However, further research is needed to understand the effects of treatment on nontarget fishes and to better assess the effects of factors such as impoundment surface area and treatment frequency and duration on the ultimate utility of the approach.

Alabama↗

USGS2015

An examination of gender differences in the American Fisheries Society peer-review process

This study investigated the possibility of gender differences in outcomes throughout the peer review process of American Fisheries Society (AFS) journals. For each manuscript submitted to four AFS journals between January 2003 and December 2010, we collated information regarding the gender and nationality of authors, gender of associate editor, gender of reviewers, reviewer recommendations, associate editor's decision, and publication status of the manuscript. We used hierarchical linear modeling to test for differences in manuscript decision outcomes associated with author, reviewer, and associate editor gender. Gender differences were present at some but not every stage of the review process and were not equal among the four journals. Although there was a small gender difference in decision outcomes, we found no evidence of bias in editors’ and reviewers’ recommendations. Our results support the conclusion that the current single-blind review system does not result in bias against female authors within AFS journals.

Fisheries↗

USGS2012

Context-dependent planktivory: interacting effects of turbidity and predation risk on adaptive foraging

By shaping species interactions, adaptive phenotypic plasticity can profoundly influence ecosystems. Predicting such outcomes has proven difficult, however, owing in part to the dependence of plasticity on the environmental context. Of particular relevance are environmental factors that affect sensory performance in organisms in ways that alter the tradeoffs associated with adaptive phenotypic responses. We explored the influence of turbidity, which simultaneously and differentially affects the sensory performance of consumers at multiple trophic levels, on the indirect effect of a top predator (piscivorous fish) on a basal prey resource (zooplankton) that is mediated through changes in the plastic foraging behavior of an intermediate consumer (zooplanktivorous fish). We first generated theoretical predictions of the adaptive foraging response of a zooplanktivore across wide gradients of turbidity and predation risk by a piscivore. Our model predicted that predation risk can change the negative relationship between intermediate consumer foraging and turbidity into a humped-shaped (unimodal) one in which foraging is low in both clear and highly turbid conditions due to foraging-related risk and visual constraints, respectively. Consequently, the positive trait-mediated indirect effect (TMIE) of the top predator on the basal resource is predicted to peak at low turbidity and decline thereafter until it reaches an asymptote of zero at intermediate turbidity levels (when foraging equals that which is predicted when the top predator is absent). We used field observations and a laboratory experiment to test our model predictions. In support, we found humped-shaped relationships between planktivory and turbidity for several zooplanktivorous fishes from diverse freshwater ecosystems with predation risk. Further, our experiment demonstrated that predation risk reduced zooplanktivory by yellow perch (Perca flavescens) at a low turbidity, but had no effect on consumption at an intermediate turbidity. Together, our theoretical and empirical findings show how the environmental context can govern the strength of TMIEs by influencing consumer sensory performance and how these effects can become realized in nature over wide environmental gradients. Additionally, our hump-shaped foraging curve represents an important departure from the conventional view of turbidity's effect on planktivorous fishes, thus potentially requiring a reconceptualization of turbidity's impact on aquatic food-web interactions.

Ecosphere↗