Written by Torin Miller, Research Assistant
In this article, we will take a look at the impacts of shale gas drilling on wildlife populations, with a particular focus on habitat fragmentation, water consumption and contamination as well as noise, light and air pollution. Due to the relative novelty of unconventional shale gas development, particularly throughout Appalachia, only a few studies have analyzed the impacts of shale gas drilling on wildlife populations. Additionally, the youth of the unconventional industry means that more time is needed to fully witness and analyze the impacts that shale gas development will have on wildlife and ecosystems. The research on this topic that has been conducted to date is compiled here.
According to a report by the Ecological Society of America (ESA), characteristics unique to unconventional shale drilling, such as large geographic footprints and high water consumption, are significant factors potentially impacting wildlife. Additionally, the report notes that shale regions, and the Marcellus shale play in particular, “lie beneath global hotspots of species diversity.” Specifically, rare, threatened and endangered species, such as the Greater sage-grouse, freshwater mussels, Indiana Bat, and the West Virginia spring salamander, are of special concern in areas of shale gas development, according to the report. Further, the report cites that key threats to both flora and fauna resulting from shale gas drilling include: “surface and groundwater contamination; diminished stream flow; stream siltation; habitat loss and fragmentation; localized air, noise and light pollution, climate change; and cumulative impacts.”
Among threats to wildlife, habitat fragmentation has the potential to be the most impactful, and it’s often the most notable. Well pads, plus associated infrastructure (pipelines, roads, and impoundments), convert on average 2.9-3.6 ha of habitat per pad site, according to a report published in Environmental Science and Technology (EST). This report was co-authored by Margaret Brittingham of The Pennsylvania State University, who also co-authored The Wildlife Professional study cited later in this article.
Rights-of-way (ROWs) are used to test sites prior to drilling, to access well pads, and for pipeline construction and maintenance. According to the United States Fish and Wildlife Service (USFWS), “ROWs and other linear developments like transmission lines, roads, seismic lines and trails can increase human access into new areas, displace wildlife from their habitat, act as barriers to wildlife movement and affect migration routes.” The EST report suggests that increased ROWs “can alter movement patterns, species interactions and ultimately abundance” depending on the nature of the ROW and the species present on the landscape.
Although new human access and poaching are primary concerns of increased travel corridors, according to the ESA report, predators also may use new pipelines and seismic lines. This could have an impact on bird species adapted to edge habitats, a study in The Wildlife Professional states. The study found that species that are highly adapted to human intrusion, such as American robins and brown-headed cowbirds, are doing quite well in areas of developing shale gas infrastructure. The study found, however, that specialist species (those with very specific habitat needs) are being replaced by generalist species (those easily adaptable to a wide range of habitats). Even more, access roads and pipelines may result in direct mortality of individuals, especially smaller, less conspicuous species, the EST report concludes.
ROWs and other infrastructure don’t affect only terrestrial species, though. Pipelines and roads often must cross streams, rivers, and wetlands. When they do, they can create barriers for fish and other aquatic species who have no other options for dispersal than upstream or downstream of a particular water body, according to the EST report.
Water Consumption and Contamination
Unconventional shale gas wells require an average of 20 million liters of water to fracture the shale well over its lifetime, according to the ESA report. Additionally, “[t]he close proximity of well sites to freshwater sources exacerbates the risk of chemical contamination and sedimentation of aquatic ecosystems.” The report states that extraction of water from nearby sources can reduce water levels and flow rates, increase stream temperatures and concentrations of pollutants, and decrease dissolved oxygen.
According to the USFWS, “Water withdrawal may result in streams warming, changing mussel, fish and macroinvertebrate habitats. Stream warming also may change species diversity and populations over time.” According to the EST report, a change in water quantity can affect spawning fish, macroinvertebrates, and native plants, and sedimentation and siltation can cover plants and egg masses, reduce feeding efficiency, and reduce reproductive success of fish.
Although there are still a lot of uncertainties as to how contaminates infiltrate and affect local water sources and supplies, “[f]reshwater contamination may result from well blowouts, casing failures, illegal discharge, and spills during fluid transport and storage,” the ESA report notes.
Other water concerns revolve around wastewater storage ponds. “These pits or ponds may attract birds and other wildlife or they may leak, causing the fluid to flow into a nearby stream. Flowback fluid may contaminate the stream, resulting in fish kills and changes in species diversity and populations,” according to the USFWS. Notably, “[b]ats have been observed congregating and drinking from holding ponds at industrial sites,” according to a study by the Delaware Riverkeeper Network.
Noise, Light and Air Pollution
Factors such as noise, light and air pollution may go unnoticed, at least as they pertain to wildlife. Noise, light and air pollution each affect the ecosystem in a unique, but sometimes difficult to ascertain, way. Noise pollution is created in two forms: short-term construction and long-term compressors, according to the EST report. According to the USFWS, loud noises near preferred habitats (including breeding habitats) can cause wildlife to avoid those areas completely. Additionally, The Wildlife Professional study notes that loud noises, both short term and long term, may affect the pairing success of songbirds, as their mating songs are drowned out by external noises. The study also notes that unnatural noises may create the possibility of “lower abundance, changes in reproductive behavior and success, altered predator-prey interactions and altered avian communities.”
Light sources required during drilling and operation at night may also have impacts on wildlife. “Anthropogenic light and noise can negatively affect fitness across a broad group of species, including mammals, amphibians, birds, insects and aquatic invertebrates,” the ESA report states, noting that noise and light pollution should be lower research priorities than air pollution.
Air pollution resulting from unconventional shale drilling is unique. On one hand, “[s]ince shale-gas development began in Pennsylvania in 2008, there has been a marked decrease in several major air pollutants, such as sulfur, nitrogen oxides, and carbon dioxide,” the Pennsylvania Department of Conservation and Natural Resources (DCNR) noted in its Shale-Gas Monitoring Report. The decrease is the result of cleaner natural gas replacing older, dirtier fuels. The study does note that short-term sampling at some well sites have shown natural gas constituents in the air. It’s unclear what effect small amounts of air pollution near drilling operations will have on local wildlife.
While more observation and analysis is necessary to truly understand the impacts of shale gas drilling on wildlife populations, current studies do provide insight into the potential impacts of habitat fragmentation, water consumption and contamination as well as noise, light and air pollution. A subsequent Shale Law in the Spotlight article will take an in-depth look at species-specific impacts of shale gas drilling, as well as discuss policy and legislation that have resulted from these impacts.