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

Goals

This project seeks to assess how agricultural land-use may affect resilience of a large wetland complex. Both the quantity and overall quality of wetlands have severely declined globally. Many remaining wetlands exist in landscapes dominated by agricultural production. The Rainwater Basin is a region of Nebraska characterized by shallow wetlands located in an agricultural matrix. 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.

Current Status

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 thousands of irrigation reuse pits, now the most numerous of wetland types in the region, are utilized by breeding amphibians. Amphibians are an important taxonomic group that provide services by controlling insects, serving as food for migratory birds and other species, and integrating terrestrial and aquatic systems. Amphibians are sensitive to environmental contaminants and can be used as an indicator of water quality, system health, and resilience.

Irrigation re-use pits and restored wetlands in a large agricultural complex were sampled for Anuran presence at several crucial reproductive stages: adult advertisement, oviposition, larval hatching, and metmorph emergence. A combination of automated recording units, dip-netting, and visual encounter surveys were used to measure reproductive activity at ten sites between May 12th and July 27th. Additionally, sediment samples were collected to be analyzed for a suite of likely agricultural contaminants. With our ongoing analysis we hope to gain a better understanding of how agricultural proximity affects Anuran reproduction and what role irrigation reuse pits play in their continued persistence in the Rainwater Basin.

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
An overwintered bullfrong tadpole pulled in dipnetting used to assess Anura breeding at irrigation reuse pits. Photo: Michelle Hellman
An overwintered bullfrong tadpole pulled in dipnetting used to assess Anura breeding at irrigation reuse pits. Photo: Michelle Hellman
Principal Investigator(s)
-Craig Allen, NE CFWRU
-Dan Snow
Graduate Student(s)
-Michelle Hellman, Ph.D.
Project Duration
April 2013 - May 2017
Funding
-National Science Foundation IGERT Program
-U.S. Environmental Protection Agency
Project Location
Rainwater Basin, Nebraska