Background Readings

Biodiversity: Native Biodiversity

  • 14% of Pennsylvania's 36 amphibian species
    are extinct, endangered, or threatened.
  • 34% of Pennsylvania's 160 fish species are
    extinct, endangered, or threatened.
  • 58% of Pennsylvania's 65 mussel species are
    extinct, endangered, or threatened.
  • Source: Pennsylvania Comprehensive Wildlife Strategy, 2005.


Introduced into the watershed as bait for recreational
fishing, the invasive rusty crayfish, Orconectes rusticus,
is now widespread across the Susquehanna River
basin. Photo credit: Ron Reed.


The spotted salamander, Ambystoma maculatum, is one
of three native mole salamander species found in
Pennsylvania. They spend most of their days hiding
under mossy logs and leaves and lay their eggs in
vernal pools. Photo Credit: Tom Tyning.

Around the world, there are concerns that biodiversity may be declining as habitat is altered by human activities. This concern extends to the Susquehanna watershed. Three of its mussel species are rare or endangered, native crayfish are being displaced by invasive rusty crayfish, and the construction of dams nearly extirpated (removed from the watershed) the American shad population in the early 1900's. With the rapid expansion of Marcellus Shale drilling in the watershed, Pennsylvania's Fish and Boat Commission has suggested that biodiversity impacts should be monitored closely.

Why should we care about native biodiversity?

Aquatic life in the Susquehanna watershed provides a variety of ecosystem services that are important to people. Macroinvertebrates provide food for the fish we like to catch and eat. Aquatic plants stabilize the soil, improving water quality and clarity for fishermen and recreational boaters. Historically, high densities of freshwater mussels in the Susquehanna drainage helped clear the water and reduce the nutrient loads entering the Chesapeake Bay.

The Susquehanna watershed has more than 49,000 miles of waterways, supporting a rich mix of aquatic plants, insects, and animals. Anglers bait their hooks eagerly, hoping to catch native brook trout or smallmouth bass, among other fish species. The basin provides habitat for more than half of Pennsylvania's 15 species of crayfish and 3/4 of Pennsylvania's freshwater mussel species. The watershed is also home to a variety of reptiles and amphibians. Its vernal pools (seasonal ponds or wetlands) are essential habitats for breeding salamanders and other amphibians.

How might Marcellus Shale drilling affect native biodiversity?

Aquatic biodiversity in the Susquehanan region is tightly tied to water quantity and quality. If a drilling site is located near a stream, lake, or pond, the water quality (clarity, chemistry, or temperature) may be altered by natural gas drilling activities. For example, fragmentation of streamside forests can increase nutrient loads downstream. Elevated concentrations of nutrients such as nitrogen and phosphorus can lead to algal blooms, which can remove oxygen from the water as they begin to die off. Low oxygen levels can ultimately lead to fish kills. While some species, such as crayfish, can tolerate major changes in water quality, others, such as freshwater mussels, are highly susceptible to changing conditions. In order to protect the native biodiversity in the streams and rivers near active drilling locations, the natural gas industry works closely with the Pennsylvania Fish and Boat Commission and the Susquehanna River Basin Commission to address water quality and water quality issues as they arise.

Discussion Questions:

  1. Select one of the articles below about the northern leopard frog, spotted salamander, or brook trout, and discuss how drilling activites might affect their natural habitat and/or their ability to reproduce. For example, will construction of new roads have an impact on breeding sites? How might changes in water quality, i.e. temperature or dissolved oxygen during water withdrawals affect fish habitat?

Background Reading: (Each reading opens a separate window.)

  1. Pennsylvania Fish and Boat Commission's (PFBC) essay on Protecting Pennsylvania’s Aquatic Resources in the Marcellus Shale Region.

  2. Impacts on PA’s Environment from Marcellus Shale Drilling, Paul Zeph, (Powerpoint presentation).

  3. “Drilling Industry a Concern to Anglers, Hunters”, by Tom Venesky, May 30, 2010, Indiana Gazette.

  4. “Sudden Death of Ecosystem Ravages Long Creek”, by Don Hopey, September 20 2009, Pittsburgh Post-Gazette.

  5. “The Basics of Water Pollution in Pennsylvania”, Pennsylvania Angler and Boater, January/February 2001.

  6. “Freshwater Biodiversity in Crisis”, by Carmen Revenga and Greg Mock, World Resources Institute, 2001.

  7. “Habitat and the Brook Trout”, by Walt Dietz, Pennsylvania Angler and Boater, March/April 2000.

  8. “Water Temperature and Fish”, by Carl Richardson, Pennsylvania Angler and Boater, 2000.

  9. “Seeing Spots: The Northern Leopard Frog”, by Andrew Shiels, Pennsylvania Angler and Boater, 1999.