Index of Biotic Integrity
Historically, the health of aquatic systems was monitored primarily
through chemical means. However, chemical monitoring provides only a
"snapshot" of conditions at the time of sampling and may fail to detect
acute pollution events (e.g. runoff from heavy rain, spills),
non-chemical pollution (e.g. habitat alteration) and non-point source
pollution.
In
order to address the shortcomings of chemical monitoring, the New
Jersey Department of Environmental Protection supplements chemical
monitoring with biological monitoring. Biological monitoring is based
on the premise that biological communities are shaped by the long-term
conditions of their environment and more accurately reflect the health
of an ecosystem. Currently, the Bureau of Freshwater and Biological
Monitoring (BFBM) monitors benthic macroinvertebrate assemblages (insects, worms, clams etc.) at over 760 non-tidal stream stations throughout New Jersey.
Benthic
macroinvertebrate assemblages are generally reflective of short-term
and local impairment. In order to assess environmental conditions on a
larger spatial and temporal scale, the BFBM began to supplement benthic
macroinvertebrate monitoring with an index of biotic integrity (IBI)
during the summer of 2000. An IBI is an index that measures the health
of a stream based on multiple attributes of the resident fish
assemblage. Each site sampled is scored based on its deviation from
reference conditions (i.e. what would be found in an unimpacted stream)
and classified as poor, fair, good or excellent.
Data
provided by the IBI has become another component of the DEP's suite of
environmental indicators. The data helps to measure water quality use
attainment and the Department's success in attaining the Clean Water
Act goal of "fishable" waters as elaborated in the Department's
Integrated Water Quality Monitoring & Assessment Report. IBI data
will also be used to develop biological criteria, prioritize sites for
further studies, provide biological impact assessments, and assess
status and trends of the state's freshwater fish assemblages.
In an effort to ensure sensitivity to anthropogenic stressors, the Northern Fish IBI was re-evaluated by the BFBM staff in 2005 using Round 1 data (2000-2004). This recalibration resulted in modifications in scoring criteria and species lists for several metrics. The
current IBI measures the following metrics:
The final
FIBI network will have 100 established sampling stations in northern
New Jersey. Thereafter stations will be visited once every five years
as part of the BFBM’s ambient monitoring efforts. Fish IBI reports
of results are published by the bureau annually; copies are available
from this web site. A summary of the biological and habitat ratings are
also available from this web site for Round 1 and Round 2
data. Data are currently being collected for the planned expansion of
the network to include both portions of southern New Jersey and the
state’s headwater streams with the goal of having a statewide 200
station network. If you are interested in more information about the
IBI, please contact John Vile at 609-292-0427.
