RESEARCH

Developmental plasticity of the nervous system in Lithobates pipiens

The Relyea lab has looked at many instances of phenotypic plasticty in a wide variety of amphibian species. Recently, there have been a few studies on developmental plasticity, looking at how the physiology of these animals change depending on environmental stressors. This stressors can be natural or anthropogenic. In a recent collaboration with Duquesne University, we exposed leopard frog tadpoles to predator cues, reduced food availability, or sublethal concentrations of the pesticide chlorpyrifos. Our results show that brain morphology is a developmentally plastic trait responsive to ecologically relevant natural and anthropogenic factors. This has been one of the first studies to show that these stressors alter vertebrate brain morphology. Furthermore, we found that any changes to brain development were not retained after metamorphosis.

Community Ecotoxicology

I have been involved in a number of research studies that examine the effects of toxins on amphibians. These toxins are most often pesticides, with active ingredients like Chlorpyrifos and Carbaryl.

It is common practice for pesticide manufacturers to perform short-term tests on a small number of organisms. This works in a traditional lab setting, but it doesn't take into account the communities that surround these organisms.

For example, a non-lethal dose of insecticide may not directly affect a tadpole, but it may eliminate all the zooplankton in the pond the tadpole lives in. This means there is no longer anything holding back the phytoplankton in the pond. Not long after this dose of pesticide you will often see a phytoplankton bloom, which in turns blocks out most of the light that the periphyton in the pond needs to produce food. This in turn robs the tadpole of it's main food source, eventually leading to a potentially deadly environment for the tadpole. This trophic cascade clearly illustrates the connection between members of these communites, and behooves us to further understand the effects of chemicals on them.

This picture shows an example of how drastically a very small amount of pesticide can affect a community. These two pools were treated the exact same, starting with the same species and density of zooplankton. However, the pool on the right was dosed with 5 ppm of Chlorpyrifos, causing this algal bloom.

Click the link above for more information on the Relyea Lab and the Jefferson Project at Lake George