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Background & History
In 1989, an innovative biological monitoring framework was published by EPA. This strategy consisted of two separate but inter-related components:
Once biological expectations are established, the biological community and habitat at a point of interest (a “test” site) is then compared to the regional reference condition, and the relative health of the system being evaluated may be determined.
To bring the new bioassessment approach to Florida, the Department initiated two major projects in early 1991. With funding provided by the Clean Water Act's Nonpoint Source Pollution grant program (Section 319), contracts were begun to delineate Florida's areas of ecological similarity (called ecoregions) and identify reference stream sites, and to refine EPA's biological (benthic macroinvertebrate) sampling methods to reflect Florida's freshwater stream systems.
Concurrently, the Department established its Biocriteria Committee to oversee the contracts and integrate the work into the agency's management programs. The Biocriteria Committee was composed of both technical and management staff from several divisions. The committee meetings also provided a venue for training and quality assurance activities to ensure statewide consistency in the implementation of the new approach. During method development, meetings were held four to five times per year, with various task forces established to handle pilot studies and research issues on separate occasions.
In 1993, the Regionalization Project for Florida delineated 13 sub-ecoregions from 3 ecoregions as originally determined in the Ecoregions of the Conterminous United States (Omernik 1987) mapping project. Within nine of the regions, 85 stream reference sites were identified. The southernmost ecoregion, with its four subecoregions, was not included in the streams biocriteria development because the area is dominated by wetlands and canals, and natural streams are extremely rare.
After examining reference site data collected during five years of twice-yearly sampling, the nine ecoregions were collapsed into three bioregions, or areas of general homogeneity in the freshwater macrobenthic community. These bioregions split along the Panhandle, the Peninsula (excluding the Everglades Ecoregion) and Northeast Florida. Reference sites were then compared with sites receiving known pollution sources to determine differences in the macroinvertebrate community that resulted from anthropogenic pollution.
The products of this early streams bioassessment work included the seven-metric Stream Condition Index (SCI_1992, which generally scored between 7-33, depending on region and season) and the three-metric Bioreconnaissance (or BioRecon, which used a pass/fail assessment of 3 metrics). A standardized evaluation of habitat conditions is also performed at each site (Stream and River Habitat Assessment). For a complete description on the original SCI development, see Development of the Stream Condition Index (SCI) for Florida (1996). After using these indices for several years, FDEP became aware of more advanced methods to select metrics and calibrate biological indices, and embarked on a study to improve and recalibrate the early SCI and BioRecon.
In 2004, the Department re-evaluated the SCI and BioRecon metrics
against an independent measure of anthropogenic impact, the
Disturbance Gradient (HDG). Component metrics were reviewed and
rescaled, lab processes were further standardized, and this work
resulted in an improved SCI (SCI_2004, scored 0-100) and improved
BioRecon (scored 0-10). For more information, see
Stream Condition Index Report (Fore 2004). The SCI laboratory
methods were slightly adjusted again in 2007 to increase the precision
of the method. Rather than an analysis of one subsample of approximately
100 organisms, as in the SCI_2004, the SCI score is now generated as the
average score of two subsamples of 150 organisms each (SCI_2007). At
that time, the SCI was calibrated along the BioCondition Gradient, and
an impairment threshold was proposed by an expert panel.
See Stream Condition Index Report (Fore et al. 2007) for more
In 1998, Florida DEP began development of a lake bioassessment protocol to monitor and assess the biological integrity of Florida lakes using benthic macroinvertebrate communities. Lake geographic regionalization was based on topography, natural water chemistry, lake origin, lake hydrology and soils, and reference lakes were subsequently sampled in most regions. The regionalization process (described in detail in Griffth et al. 1996, Florida lake regions report. US EPA, Corvallis, OR) resulted in the delineation of 47 lake regions within Florida, although later analyses indicated that these regions could be aggregated, and that factors such as alkalinity (pH) and color were more accurate for distinguishing lake expectations. Data from 500 lakes were analyzed to examine relationships between macroinvertebrate communities, water quality parameters, and basin land use characteristics, leading to the development of the Lake Condition Index (LCI). Lake habitat assessments (recorded on the Lake Habitat Assessment Form (FD 9000-06) were performed in conjunction with LCI sampling. See Lake Condition Index Report (Tetra Tech 2000) for more information.
In 2006, the LCI was re-calibrated using the Human Disturbance Gradient (HDG) Approach. A total of 44 metrics were tested and none were significantly associated with the Landscape Development Index or habitat score. Macroinvertebrate response was overwhelmed by natural factors, such as pH and color (see Evaluation of Benthic Macroinvertebrates Assemblages as Indicators of Lake Condition, Fore 2007).
Because of the complications in assessing human disturbance in lakes
using the invertebrate community, DEP subsequently developed methods
involving the lake aquatic macrophyte community. Lake vegetation data
were collected and evaluated against the HDG and several plant metrics
were found to have a strong correlation with human disturbance. Four
metrics were selected for the Lake
Vegetation Index (LVI), a multi-metric tool which assesses lake
health based on the plant community structure. The LVI is sampled per
DEP SOP FS7320and calculated per DEP SOP LT7500. Florida DEP is
currently using the LVI to assess human disturbance in lakes in Florida.
The LVI method involves dividing a lake into 12 units and identifying
plants in 4 of the 12 units. Plants are identified in each unit by a
visual boat “drive by” and also via a transect approach. A frodus
(double-sided rake on a rope) is deployed a minimum of five times during
transect sampling to look for the presence of submersed aquatic plants.
All plants for a unit are recorded in a single column on the Lake
Vegetation Index Data Sheet (DEP form FD 9000-27) and a dominant or
co-dominant is assigned based on areal extent. Unknown plants are
brought back for expert identification and verification. The sampling
season for the LVI is May through October. Data generated on the
presence of species is used to calculate four biological metrics:
Percent Native Taxa, Percent Invasive Exotic Taxa, Percent Sensitive
Taxa, Dominant/Co-dominant Coefficient of Conservatism (C of C). For
more information about the development of the LVI, see
Lake Vegetation Index Report (Fore 2005). In 2007, a second index
validation was conducted for the LVI, and it was calibrated against the
Biological Condition Gradient. For more information, see
Lake Vegetation Index Report (Fore 2007).
Florida DEP has developed, but not fully calibrated, biological
monitoring tools for wetland ecosystems. A research team, led by Dr.
Mark Brown of the University of Florida's Center for Wetlands,
investigated potential wetland attributes for use in the development of
biocriteria for these systems. The wetland biological assessment
consists of vegetation transects, invertebrate 20 dipnet sweep sampling,
and a qualitative periphyton sample collection. The University of
Florida research team has developed a classification scheme for
Florida’s wetland types and has completed a wetlands regionalization
map. Wetland indices were developed for isolated herbaceous wetlands,
isolated forested wetlands, and forested strands and floodplain wetlands
(see documents on Bioassessment Publications. The
Wetlands Condition Index for isolated herbaceous and forested wetlands
have three components: a Wetlands Vegetative Index, a Wetland
Macroinvertebrate Index and a Wetland Diatom Index. All three indices
are strongly correlated with the LDI. For forested strands and
floodplains, only a Wetland Vegetative Index was developed. These
wetland bioassessment tools have been used to assess biological health
in wetlands receiving wastewater.
FDEP has conducted exploratory studies and workshops for the development of estuarine and marine bioassessment tools (link to History of Bioassessment, marine activities). While the previous attempts have not yielded practical results, DEP is currently planning studies for further development, potentially including an evaluation of epi-benthic taxa and fish in a variety of habitat types. Historical (1999) marine bioassessment work products include the following:
Last updated: June 30, 2015
2600 Blair Stone Road M.S. 3500
Tallahassee, Florida 32399
850-245-8336 (phone) / 850-245-8356 (fax)