Contaminants in freshwater systems
Freshwater ecosystems worldwide are increasingly threatened by multiple anthropogenic contaminants, including agrochemicals, metals, pharmaceuticals, and road salts, introduced by runoff, atmospheric deposition, and improper use and disposal. In an effort to monitor how human activities are changing water quality, the United States Geological Services (USGS) and U.S. Environmental Protection Agency (USEPA) have collaborated over numerous years to standardize the collection of abiotic and biotic samples from streams and rivers across the conterminous U.S., creating numerous data repositories.
In collaboration with Dr. Jason Rohr, Dr. Samantha Rumschlag, USGS and EPA research scientists, and leading U.S. and European researchers, I am combining these publicly available datasets with climatic and land cover data to examine how contaminants, human activities, and climate interact to influence the health of U.S. stream ecosystems. Given the immense effort by USGS and EPA researchers, we are able to assess changes in aquatic species, populations, and communities across time and space using landscape-level analyses and a weight-of-evidence approach.
The Jefferson Project at Lake George
The Jefferson Project at Lake George is an interdisciplinary effort to understand not only how Lake George (NY, USA) is changing, but why it is changing. Researchers from Rensselaer Polytechnic Institute, in collaboration with International Business Machines (IBM) and the FUND for Lake George, are using cutting-edge smart technology to monitor how Lake George is changing in response to climate change, land-use practices (i.e., land development), and contamination (e.g., road salt). It is the goal of the partners to use our understanding and findings in Lake George to preserve and restore other freshwater bodies worldwide.
In collaboration with numerous researchers at RPI and the Darrin Fresh Water Institute, it is our goal to understand why Lake George is changing. To do this, the Relyea lab group will be studying the Lake George food web, requiring the lab to sample the zooplankton, macroinvertebrate, and fish populations of the lake. The Relyea lab group is studying all portions of the Lake George watershed, including the lake, stream and tributary, and wetland communities.
My research is focused on how road salt (and road salt alternatives) influence freshwater pond and wetland communities (Jones et al. 2017). The use of road salt to deice and clear areas in northern latitudes during the winter months has led to increased chloride levels in freshwater systems. Laboratory research has shown aquatic species to differ in sensitivity to chloride, but little is known how chloride (e.g., sodium chloride [road salt], magnesium chloride, calcium chloride, etc.) influences community processes, including predator-prey interactions, productivity, and trophic cascades.
Check out the Jefferson Project at Lake George Facebook page for regular updates!
Inducible chemical tolerance
Novel research has discovered increased pesticide tolerance among amphibian larvae after exposure to sublethal concentrations ealry in life. This plastic response increases acetylcholinesterase levels within exposed wood frogs, and incurs a fitness cost within gray treefrogs. Although increased pesticide tolerance may be beneficial in contaminated systems, species are rarely exposed to a single stressor.
In collaboration with Dr. Jessica Hua at Binghamton University (SUNY), Dr. Jason Hoverman at Purdue University and Dr. Rickey Cothran at Southwestern Oklahoma State University, we aimed to investigate the relationship between the magnitudes of induced pesticide tolerance and other natural stressors among 15 wood frog populations. Specifically, we aimed to investigate the relationship between the magnitude of induced pesticide tolerance and the magnitude of plastic responses to numerous natural stressors (e.g., competition, predation, and disease).
Along with conducting both laboratory and outdoor mesocosm experiments, we conducted a large field survey of each pond that wood frogs were collected from. The field survey included abiotic (i.e., pH, dissolved oxygen) and biotic (e.g., amphibian and invertebrate densities) variables. Additionally, we will be able to investigate the effects of distance to agriculture (i.e., proxy for pesticide exposure through run-off, overspray, drift and deposition) on these aquatic communities.
Amphibian populations are declining worldwide due to numerous factors, including habitat loss, pesticide-use, and disease. Chytrid fungus (Batrachochytrium dendrobatidis) has been shown to cause lethal effects in numerous amphibian species, and has been associated with the extinction of multiple amphibian species. Although this disease has been linked to worldwide declines, little is known about its ecological interactions within aquatic communities, or its interaction with other environmental stressors.
The expansion of bullfrogs (Lithobates catesbeianus) into the western United States has been associated with species declines. Not only are bullfrogs exceptional competitors, but it is believed they are a host species to the chytrid fungus. As they spread, it is believed they are carrying the disease into pristine areas and increasing the spread of the deadly fungus. We have investigated the interactive effects of Bd strain and bullfrog presence on infection occurrence of spring breeding amphibians in an attempt to confirm the role of bullfrogs as disease vectors.
Additionally, our lab is currently investigating the interactive effects of pesticides and chytrid fungus on numerous species of North American amphibians with the Blaustein laboratory at Oregon State University. We have conducted experiments investigating the effects of both the early and simultaneous exposure to pesticides and chytrid fungus on amphibian growth and survival as metamorphed individuals (Jones et al. 2017).
Division of labor in social spiders
Community dynamics are maintained through intra- and interspecific species interactions. For Stegodyphus dumicola, intraspecific interactions are dependent on individuals’ behavioral phenotypes; more specifically, their docile or aggressive behavioral types. Additionally, S. dumicola can build large web colonies, which are often invaded by inquilines. Previous work has shown social spider colonies benefit from a heterogenous mix of behavioral types, but the function of each behavioral type remains largely unknown within colony structures.
I investigated this question during a research rotation at the University of Pittsburgh working with Dr. Jonathan Pruitt, Dr. Andreas Modlmeier, and Dr. C. Nick Keiser. We measured both boldness and aggression of all individuals to determine an individual’s behavioral type, and then tested each spider colony for web repair/building and prey-capture activities. Matching individuals in each colony to specific functions will help to determine how social spider colonies set up behavioral syndromes, and how these functions are influenced by the loss of specific individuals.