Benthic macroinvertebrates represent an excellent group of organisms for use in biological monitoring programs. Their varied life spans, ranging from a few months to many years, are long enough to evaluate the full effects of intermittent and continuous pollutants, yet short enough for populations to respond relatively quickly to water quality changes.

The Macroinvertebrate Section at the Patrick Center has more than a 50-year history in the bioassessment, biomonitoring, and inventorying of rivers, streams, ponds, and lakes throughout the United States.


Stefanie Kroll, Ph.D.

Acting Section Leader For Macroinvertebrates; Project Science Director for Delaware River Watershed Initiative

Dr. Kroll has a over a decade of experience working with macroinvertebrate communities of Spain and the eastern United States, using macroinvertebrates as biological indicators of human stressors on aquatic ecosystems, including specimen identification and statistical analysis.


  • Biological quantitative and qualitative surveys of macroinvertebrates in streams, rivers, lakes, ponds, and estuarine environments
  • Multimetric assessments of biotic integrity and ecosystem health
  • Quantitative and qualitative mussel surveys, including invasive species
  • Studies of the distributions and environmental requirements of endangered species
  • Rapid bioassessments of streams and wadeable rivers
  • Short- or long-term biomonitoring programs to assess water quality and/or stream health
  • Collection of macroinvertebrate taxa for chemical contamination analyses


The Macroinvertebrate Section implements a variety of quantitative and qualitative collection methods to sample benthic macroinvertebrate communities. Quantitative field sampling techniques include a variety of active methods [e.g., Hess sampler, PIBS (Portable Invertebrate Box Sampler), quadrats, Surber sampler, plankton nets, Ekman and Ponar dredges, benthic sled, etc.] and passive approaches (inverted cone traps and multiple-plate samplers and other artificial substrates, etc.) as well as a variety of techniques for semi-quantitative and qualitative collections.

Academy certified divers have conducted dive surveys for approximately 25 years employing a wide variety of techniques (e.g., SCUBA, hookah, snorkel) in qualitative and quantitative assessments.

The Section also maintains current meters (i.e., Marsh-McBirney Flo-Mate 2000 current meter and a Gurley 625 pygmy current meter) to measure stream velocities.

Laboratory equipment includes a Zeiss Stemi SV11 stereo-zoom dissecting microscope, a Zeiss Axioscope compound microscope, and two Wild M8 stereo-zoom dissecting microscopes. A large collection of taxonomic literature and identification keys are available in the laboratory as well as synoptic reference collections. In addition, the resources of the Academy's Ewell Sale Stewart Library and the vast Malacology and Entomology collections (including non-mollusc macroinvertebrates) in the Center for Systematic Biology and Evolution are within easy access.

Selected Projects

The Ecological Effects of Dam Removal on the Manatawny Creek Watershed
A Pennsylvania Growing Greener project, funded by the Pennsylvania DEP.
A Watershed-Level Assessment to Guide Restoration Planning and Maximize the Benefits of Riparian Reforestation
A Pennsylvania Growing Greener project, funded by the Pennsylvania DEP and the William Penn Foundation.
A Risk Assessment Framework for Determining the Potential Ecological Effects of Dam Removal
A Pennsylvania Growing Greener project funded by the Pennsylvania DEP.
Long-term Biological and Chemical Studies of the Guadalupe River
Texas, 1949 to present. Funded by DuPont-Victoria.
Sabine River Monitoring Studies
Funded by the Texas Eastman Company
Long-term Biological and Chemical Monitoring of Water Quality in the Savannah River
Georgia and South Carolina, 1951 to present. Funded by the Westinghouse Savannah River Company.
Riparian Reforestation in an Urbanizing Watershed: Effects of Upland Conditions on Instream Ecological Benefits
Funded by the U.S. EPA.