Amphibian Occupancy, Functional Connectivity, and Resilience of Rainwater Basin Wetlands

Goals

This project will seek to assess how agricultural land–use may affect resilience of a large wetland complex.

Current Status

The Rainwater Basin is a region of Nebraska characterized by shallow wetlands. Following European settlement in the mid–to–late 19th century, more than 90% of historic wetlands in the
Rainwater Basin were filled or farmed through. The remaining wetlands exist in an intensive agricultural matrix that has further isolated wetlands and may affect their function, and reduce the resilience of the Rainwater Basin. For the Nebraska Rainwater Basin, we are interested in the effects of proximity of intensive agriculture and widespread
landscape change on the remaining wetlands and the amphibian population. Specifically, we are investigating how environmentally relevant concentrations of an agricultural fungicide,
azoxystrobin, may affect development of larval anurans. We measured concentrations of a suite of agrichemicals in surface waters throughout the basins in 2016. In 2018, we collected mating
pairs of Boreal Chorus Frogs (Psuedacris maculata) and allowed them to oviposit in the lab. We then replicated previously detected levels of azoxystrobin and exposed newly hatched tadpoles.
The tadpoles were reared through metamorphosis and assessed for growth characteristics including weight and size at metamorphosis, time to metamorphosis, and mortality. Our trial did not find a significant difference between tadpoles exposed to the azoxystrobin and those in the control groups for any of the characteristics measured. Toxicity can be complex, and developing larvae are rarely exposed to a single contaminant during development, but we can conclude that the levels of azoxystrobin alone in Rainwater Basin wetlands are unlikely to affect larval development of Boreal Chorus Frogs.

An automated recording device used to sample anuran calling activity at an irrigation reuse pit. Photo: Michelle Hellman
An automated recording device used to sample anuran calling activity at an irrigation reuse pit. Photo: Michelle Hellman
Boreal Chorus tadpoles in the laboratory
Boreal Chorus tadpoles in the laboratory
Principal Investigator(s)
-Craig R. Allen
-Dan D. Snow

Graduate Student(s)
-Michelle Hellman, Ph.D.


Project Duration
April 2013 - September 2019

Funding
-National Science Foundation IGERT Program
-U.S. Environmental Protection Agency

Project Location
Rainwater Basin, Nebraska
Cooperators