143-10 Benthic Macroinvertebrate Community Responses to Varying Intensities of Oil and Gas Development in the Marcellus Shale Formation

Session: A Showcase of Student Research in Geoinformatics and Data Science (Posters)

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Abstract:

Improvements to drilling technology in the early 2000s—particularly horizontal drilling and hydraulic fracturing (i.e., unconventional oil and gas development, or UOGD)—led to a significant increase in domestic hydrocarbon production, as previously inaccessible reservoirs became profitable to exploit. UOGD has been especially prolific within the Marcellus Shale Formation (MSF) in the northeastern USA. Thought to be the largest unconventional reservoir in the USA, MSF activity has propelled Pennsylvania to be the second-largest producer of natural gas after Texas. In Pennsylvania, UOG wells often co-occur with conventional oil and gas (COG) wells and other hydrocarbon extraction sites like coal mines. UOGD is unique for its high water use. Hydraulic fracturing—injecting pressurized fluid into wells to encourage gas flow—produces large volumes of “produced water.” Previous literature has suggested poor handling of produced water as the most common mechanism for UOGD to contaminate surface water. Aquatic ecosystems like benthic macroinvertebrate (BMI) communities are strongly influenced by chemistry and substrate conditions. Because of this, they have increasingly been used to proxy the ecological impacts of UOGD. This study uses BMI samples collected between 1991-2015 from the Appalachian Plateau Province of Pennsylvania to assess how the presence and intensity of COGD and UOGD influences BMI community composition and structure. We hypothesize that changes in community composition and structure will reflect patterns consistent with previously observed responses to anthropogenic stress. Using linear mixed models to account for causes of natural variability, we found that taxonomic and functional indicators of BMI communities—including richness, EPT richness, index of biotic integrity (IBI), and proportions of specific functional feeding groups (FFGs)—declined with increasing oil and gas development (OGD) intensity. These declines mirror those associated with other anthropogenic stressors, such as developed land cover. Analysis of BMI co-occurrence network topology to represent community structure also showed that OGD presence is associated with altered network topology and increased proportions of pollution-tolerant taxa. These results suggest that hydrocarbon extraction is related to  measurable disruptions in aquatic ecosystems, comparable to other anthropogenic stressors.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11211

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