Terrestrial wildlife and legacy oil mining on National Wildlife Refuges

Science Center Objects

Amphibian surveys are being conducted on select National Wildlife Refuges with active and/or legacy oil mining to determine species relative distribution and their risk to short- and long-term effects from exposure to crude oil and its byproducts.

The Challenge: As of 2018, over 5000 oil and gas wells are localized on national wildlife refuges. Although subsurface mineral rights remain under the control of private or commercial entities, “the conservation, management, and where appropriate, restoration of the fish, wildlife and plant resources and their habitats” remain within the US Fish and Wildlife Service mandate. Among operations extracting crude oil using conventional pumpjacks, many show signs of oil leakage around the pump heads, injection wells and above-ground rusted storage tanks, while others are incompletely plugged or  remain abandoned and open. Given the continuous gaseous emissions, the sound of the pump motors, and the presence of various classes of oil due to weathering, there remains the need to determine (1) whether terrestrial wildlife such as amphibians are at risk due to long term exposure to crude oil chemicals and whether habitat restoration can be.

The Science: The overall goal of this project is to determine risk of contaminants from oil mining to amphibians residing in habitats near oil production facilities. Surveys have been started on NWR recording presence, relative distribution, species and developmental stages of amphibians observed at sites recently or historically modified by mining operations relative to unmodified reference sites.  A multitude of methods are used to include species across developmental stages located at sites near active and abandoned oil, injection sites and storage tanks as well as at  reference sites with closely matched habitats. Early findings from this survey indicate amphibians as well as reptiles, can be found close to oil sites and are therefore exposed.   

The Future: A series of crossover mesocosm studies will be conducted to obtain potential measures of adaptation and physiological cost associated with living near oil mining by comparing short and long-term responses of resident and naïve amphibian species to substrates collected from these actively mined habitats.  Findings on their responses over time and cost of adapting to exposures will aid in assessing long-term habitat remediation and management for species at risk.