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Biological Monitoring and Assessment
DRBC Biomonitoring Program

The DRBC's Delaware River Biomonitoring Program began in 2001 and is responsible for the development and implementation of methodologies for assessing ecosystem health and biological water quality criteria to support evaluation of Delaware River water quality. The Biomonitoring Program's guiding body is the Biological Advisory Subcommittee (BAS) of the Water Quality Advisory Committee (WQAC) and Monitoring Advisory Committee (MAC).

DRBC Delaware River Biomonitoring Program 2014 Quality Assurance Project Plan (pdf 359 KB)

Each year, typically during August and September, commission staff collect samples at 25 riffle habitat sites from the upper 200 miles of the Delaware River, from Hancock, N.Y. to just above the head of tide at Trenton, N.J. Conditions sampled look at the diversity and health of the aquatic life community: benthic macroinvertebrates, benthic periphyton (alga), and habitat characteristics of the Delaware River.

Samples are analyzed by the Academy of Natural Sciences of Drexel University in Philadelphia, Pa.; data will be used to create an Index of Biological Integrity, a scientific tool used to identify impacts to the health of biological systems.

The Biomonitoring Program also gathers information on other significant natural resources of the Delaware River Basin, such as fisheries, aquatic plants, mussels, and invasive species (both aquatic and riparian plants and animals). We also support the member states and the U.S. EPA in their biological monitoring surveys. Recently we have begun to develop procedures and guidance for biological assessment of natural gas development impacts in the northern part of the Delaware River watershed.

Due to our small staff size, at this time, our primary area of operation is presently in non-tidal fresh water portions of the Delaware Basin. If additional resources become available, future plans include development of biological criteria and assessment of the Delaware Estuary and Bay. If you are seeking information about estuarine resources, an excellent source of information is the Partnership for the Delaware Estuary.

Biological Assemblages

Benthic Macroinvertebrates (annual indicator assemblage):

This is the main biological assemblage monitored by DRBC and most other regulatory agencies. Analysis of macroinvertebrate communities is a reliable and cost-effective approach to water quality monitoring because:

  • They are sensitive to environmental impacts
  • They are less mobile than fish, and thus cannot avoid discharges
  • They can indicate effects of spills, intermittent discharges, and lapses in waste treatment
  • They are indicators of overall, integrated water quality, including synergistic effects and substances lower than detectable limits
  • They are abundant in most streams and are relatively easy and inexpensive to sample
  • They are able to detect non-chemical impacts to the habitat, such as siltation or thermal changes
  • They are readily perceived by the public as tangible indicators of water quality
  • They can often provide an on-site estimate of water quality
  • They bioaccumulate many contaminants, so that analysis of their tissues is a good monitor of toxic substances in the aquatic food chain, and
  • They provide a suitable endpoint to water quality objectives.

The bullet list above was taken from: NYSDEC Division of Water, 2009, Standard Operating Procedure: Biological Monitoring of Surface Waters in New York State.

As mentioned above, DRBC began annual surveys of Delaware River macroinvertebrates in 2001 for development of a multi-metric index of biological integrity for aquatic life use assessment. The annual survey covers the upper 200 miles of the Delaware River from Hancock, N.Y. to Trenton, N.J.; samples are collected at 25 riffle habitat sites. 

Benthic Macroinvertebrate Use for Interim Biocriteria - 2009 Report (pdf 345 KB)

Benthic Periphyton (short term indicator assemblage):

Benthic periphyton were chosen as an additional monitoring assemblage because they are very specific indicators of short term water quality changes, capable of providing biological signals for numerous pollution and habitat modification impacts such as eutrophication, salinity, ions, pH, and sedimentation. Since the Delaware River is generally wide, shallow, clear and exposed to full sunlight, periphyton (diatoms and soft algae growing on rocks) are the dominant source of primary production in the river.  Planktonic algae found in the non-tidal part of the river are entirely benthic in origin.

DRBC began annual surveys of Delaware River benthic periphyton in a 2005 pilot study, launching full-scale periphyton monitoring in 2006. Samples are co-located with the benthic macroinvertebrate sites at 25 primary river sites and numerous special study sites on larger tributaries to the Delaware River. Methods can be found in the 2009 QAPP, above. A Periphyton IBI is under development. Anticipated uses include assessment of general short-term Delaware River water quality and nutrient pollution impacts upon aquatic life.

Pilot Study: Implementation of a Periphyton Monitoring Network for the Non-Tidal Delaware River (pdf 1.7 MB; 2007)

Nutrient Enrichment Study Data from the Upper, Middle, and Lower Sections of the Non-Tidal Delaware River – 2009

DRBC Science and Water Quality Management Staff Contacts

Robert Limbeck, Senior Aquatic Biologist - (609) 883-9500 ext. 230

Erik Silldorff, Senior Aquatic Biologist - (609) 883-9500 ext. 234