Background

Impacts to water quality are so diverse and variable in duration that chemical monitoring alone may fail to detect many of them. Effective monitoring of NCRN water resources should address several vital signs for a more comprehensive assessment than can be gained from any single measure. Stream health should reflect the health of the entire food web, not just one component, yet most assessment methods use either fish or benthic macroinvertebrates and assume that this component represents overall system condition. However, different components may not equally reflect the presence or magnitude of stressors in the system. Therefore a number of measures should be employed to obtain a more comprehensive assessment. Information on water chemistry, physical habitat, and the aquatic community indicate much about the condition of a stream and its watershed. This is the basis of monitoring techniques such as the Index of Biotic Integrity (IBI). IBIs have been very successful at assessing the condition of aquatic resources and have been developed for the region's fish and benthic macroinvertebrate assemblages to assess current ecological conditions throughout the Potomac River watershed. Resident biota (fish and benthic macroinvertebrates) are sensitive to low-level chemical, physical, and biological disturbances and therefore function as continuous monitors of system integrity. Quantitative assessment of biotic assemblages based on ecological principles is more likely to identify human impacts than chemical or physical habitat monitoring alone because aquatic organisms integrate more anthropogenic factors that potentially influence aquatic systems.

Links
NCRN Fish Monitoring Intranet
Monitoring Protocol Ver. 2.0

Reports
2005 Annual Report
2006 Annual Report

Contacts
Marian Norris
NCRN Water Resources Specialist
202.342.1443 ext. 206

Objectives

• Determine current conditions and track long-term trends in water resource condition measured by fishes.
• Determine trends in species composition and functional groups of fishes.
• Use monitoring data to detect invasions of non-native fishes.

Measures

Fish are sampled during the summer index period using two-pass electrofishing within 75-meter stream segments (Heimbuch et al. 1997). An attempt is made to thoroughly fish each segment on each pass, sampling all habitat within the entire stream segment. Captured fish from each pass are identified to species, weighed in aggregate, counted, and released. For each pass, all individuals of each gamefish species (defined as trout, bass, walleye, northern pike, chain pickerel, and striped bass) are measured for total length. For each species, unusual occurrences of visible external pathologies or anomalies are noted.

Status

NCRN has contracted out sampling based on the Maryland Biological Stream Survey (MBSS). The MBSS was developed and tested to provide estimates of the condition of non-tidal first through fourth order streams and rivers of Maryland on a watershed as well as a statewide scale. Streams will be sampled on a 6 year rotating panel of 6 streams per year.