# The Legacy of Conventional Oil and Gas Development Outweighs Shale Gas Impacts on Stream Biodiversity

## TL;DR

This study finds that conventional oil and gas development has a greater negative impact on stream biodiversity than shale gas development in Pennsylvania.

## Contribution

The study provides a comparative analysis of ecological impacts between unconventional and conventional oil and gas development.

## Key findings

- Conventional oil and gas development (COGD) was linked to reduced stream biodiversity and biotic integrity.
- Unconventional oil and gas development (UOGD) had limited but detectable effects on stream communities.
- Both development types altered community structures, with COGD leading to more pollution-tolerant taxa and UOGD to fragmented networks.

## Abstract

Unconventional oil
and gas development (UOGD) has expanded
rapidly
across the Appalachian Basin, raising concerns about its ecological
effects. Although UOGD has been linked to water quality changes that
may affect stream biota, a generalized relationship with stream biota
remains unresolved. We evaluated how UOGD and conventional oil and
gas development (COGD) influence benthic macroinvertebrate (BMI) communities
across the Marcellus Shale region of Pennsylvania using one of the
most comprehensive statewide BMI datasets, integrating delineated
catchments, oil–gas records, and more than 6800 BMI samples.
Linear mixed-effect models and co-occurrence network analyses were
used to quantify effects on BMI taxonomy, functionality, and network
structure while controlling for confounding factors. We found no significant
association between UOGD intensity and BMI diversity metrics, whereas
COGD intensity was correlated with reduced richness, diversity, and
biotic integritycomparable to the impact of developed land
cover. Network analyses indicated altered community structures near
both development types: COGD was linked to larger, more connected
networks dominated by pollution-tolerant taxa, while UOGD was associated
with larger but more fragmented networks. Both forms of development
were tied to increases in generalist taxa and declines in specialists.
Overall, UOGD exerted limited but detectable ecological effects, whereas
COGD imposed broader stress on stream communities.