Current Bioassessment Projects
Florida DEP's bioassessment program has developed
biomonitoring tools for use in a variety of aquatic
ecosystems, including streams, lakes, and wetlands. Check this
site periodically for updates on the development of these
tools.
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 (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 of its unique ecological
characteristics (typical streams do not exist, only
occasionally flowing wetland strands are found in this
area).
Data was gathered by biologists from DEP District Offices
and the Division of Resource Assessment and Management’s
Biology
Section, and analyzed by the principal contractor,
Tetra
Tech. After examining the data from five years
of twice-yearly sampling, the nine ecoregions were collapsed
into three bioregions, or
areas of general homogeneity in the freshwater stream
macrobenthic community assemblage. These bioregions split
along the Panhandle, the Peninsula (excluding the Everglades
Ecoregion) and a small portion of Northeast Florida.
The final products of the stream bioassessment work
include the ten metric Stream Condition Index (SCI)
and the six metric Bioreconnaissance (or BioRecon).
The SCI is the primary indicator of stream ecosystem health,
identifying impairment with respect to the reference
(natural) condition. A major recalibration of the SCI, using
the Human Disturbance Gradient and Biological Condition
Gradient approaches, occurred in 2007, BioRecon differs from
the SCI in that it is used as an initial watershed screening
method to determine whether or not additional resources
should be allocated to the area, such as sampling using the
SCI method. The BioRecon is thus seen as a cost-saving
procedure to make the most efficient use of monitoring
resource for the agency in a wide variety of programs. A standardized evaluation of
habitat
conditions is also performed at each site.
SCI
The SCI is a composite macroinvertebrate index for use in
flowing streams. Sampling consists of 20 dipnet sweeps of
the most productive habitats found in a 100-meter stretch
of a stream. The FDEP Standard Operating Procedure (SOP)
for Field Collection of Macroinvertebrate Sweeps
outlines the protocol to be used in
calculating an SCI for a watercourse.
Organisms collected in these sweeps are brought back to
the laboratory for processing in accordance with the FDEP
Macroinvertebrate Sample Processing SOP. Data generated on the species
and abundance of these organisms is used to calculate
ten biological metrics - each of which has been shown to
respond predictably to human disturbance. The metrics are:
- Number of total taxa
- Number of long lived taxa, those that require more
than one year to complete their life cycle,
- Number of Ephemeroptera (mayflies) taxa,
- Number of Tricoptera (caddisflies) taxa,
- Number of Florida sensitive taxa
- Number of clinger taxa
- Percent dominant taxon
- Percent Tanytarsini
- Percent very tolerant taxa,
- Percent filterers.
Once these metrics are calculated, points are assigned
for each metric based on criteria which have been
regionally
calibrated (for the three bioregions in Florida- the
panhandle, peninsula, and northeast). The points from each
of these ten biological metrics are then summed to determine
an overall score of biological health, with”, scores of
67-100 considered “exceptional”, scores from 35 to 66
considered “healthy”, and scores of 0-34 considered
“impaired.
BioRecon
BioRecon is the screening tool version of the SCI-
intended to rapidly assess a site to prioritize it for more
intensive sampling. The SOP for Performing BioRecons
varies from that for an SCI sample in that only four dipnet
sweeps of the most productive habitats are performed. A
Biorecon also differs from an SCI sampling effort in that
the organisms are sorted in the field and then identified in
the lab. Although the BioRecon protocol only dictates that
relative species abundance be recorded on the BioRecon
Field Sheet, samples of each taxa found are verified
in the laboratory. Regionally based thresholds specific to
this method have been established for each of six calculated
metrics (a subset of the ten metrics used in the SCI). The
metrics incorporated into BioRecon assessments include:
- Number of total taxa
- Number of long lived taxa, those that require more
than one year to complete their life cycle
- Number of sensitive taxa
- Number of clinger taxa
- Number of Ephemeroptera (mayflies) taxa
- Number of Tricoptera (caddisflies) taxa
After determining which
region
the site is located within, the biologist checks to see
if the site meets or exceeds the established regional
thresholds.
Stream Habitat Assessment
A habitat assessment is conducted in conjunction with all
macroinvertebrate sampling. Overall habitat quality is
determined by measuring attributes known to have potential
effects on the stream biota. FDEP bioassessment protocols
require that a field habitat assessment be performed at each
stream sampling site using the Habitat Assessment SOP.
Upon arriving at a site, the habitat assessment SOP requires
that the sampling biologist construct a site map using the
Scaled Habitat Sketch Grid Form. A site
sketch, such as this
sample
one, is then used to estimate substrate
diversity and availability. To assess the habitat of a
stream site, a biologist records a numerical value (ranging
from 1 to 20, with 20 being the highest quality) for each of
eight habitat parameters on the Field Habitat Assessment
Form. The primary habitat parameters are:
- Substrate Diversity - an indicator of the number of
diverse, productive habitats (snags, logs, tree
roots, aquatic vegetation, leaf packs (partially
decayed), undercut banks, rock, or other stable
habitat) present in a stream
- Substrate Availability - an indicator of what
percent of the stream bed is composed of productive
habitats (as listed above)
- Water Velocity - a valuation based on the
maximum observed velocity of the stream at a typical
transect, where the higher velocities receive the
highest scores
- Habitat Smothering - an indicator of the
percent of the stream bed which is covered or
"smothered" by sand or silt accumulation
The secondary habitat parameters are:
- Artificial Channelization - a visual
interpretation of the anthropogenic channelization of
a stream based on its variance from natural stream
patterns (sinuosity) and the presence of artificial
bank structures
- Bank Stability - a visual interpretation of
the stability of a stream's banks based on evidence
of erosion or bank failure
- Riparian Buffer Zone Width - a valuation based on
the estimated width of the riparian vegetative buffer
on the stream's least buffered side
- Riparian Zone Vegetation Quality - a valuation
based on: the percent of riparian surfaces which are
vegetated; the presence of native vegetation; the
presence of a variety of vegetative classes (trees,
understory shrubs, herbs); evidence of community
disruption (bare soil, mowing, vegetative harvesting)
The values assigned for each of these parameters are then
averaged and assigned a rating corresponding to one of
four categories (optimal, suboptimal, marginal and poor)
based on their total score.
Stream Physical/Chemical Assessments
Physical/chemical characterizations are also performed
with all stream assessments using the techniques
described in the FDEP Phys/chem SOP. These characterizations
require the biologist to record a variety of physical and
chemical parameters observed in the field for later
use in interpreting overall assessment results on the Phys/chem
Field Sheet. Data collected falls into two
categories (Riparian Zone/Instream Features, Sediment
Substrate) which provide a more detailed "picture of
the conditions of the stream site on the date sampled.
Parameters that compose the Riparian Zone/Instream
Features section include:
- Predominant land-use in watershed
- Local watershed erosion
- Local watershed nonpoint source pollution
- Stream depth and velocity profiles
- Elevation of high water level marks
The Sediment Substrate section parameters include:
- Types of sediment odors present (normal, sewage,
petroleum, chemical, anaerobic, etc.)
- Extent of presence of sediment oils
- Types of sediment deposition on site (sludge, sand,
silt, etc.)
- Extent of coverage of stream bed by different
substrate types (woody debris, leaf packs or mats,
aquatic vegetation, rock or shell rubble, undercut
banks/roots, sand, mud/muck/silt, etc.) and the
number of times each of these substrates was sampled
- Water quality parameters (temperature, pH,
dissolved oxygen, conductivity, salinity, Secchi
depth) at top, middle and bottom depths
- Types of water odors present (normal, sewage,
petroleum, chemical, etc.)
- Types of water surface oils present (sheen, globs,
slick, etc.)
- Water color and clarity
- Abundance of periphyton, fish, aquatic macrophytes,
and iron/sulfur bacteria
- Weather conditions
Incorporation of Stream Assessment Tools into Program
Areas
Several program areas use these new bioassessment
tools. Regulatory applications include:
- Fifth Year Inspection (FYI) Program—domestic
wastewater facilities permitting program.
- 305(b) Program—a report to EPA on the status of
Florida’s water resources, compiled every five
years.
- Total Maximum Daily Load (TMDL)
Program—prioritization of watersheds for remedial
action.
- NPDES Stormwater, Municipal Separate Storm Sewer
System Permits—identifies "hot spots" and
evaluates the effectiveness of stormwater management
programs.
Non-regulatory applications include:
- Forestry and Agricultural Best Management Practices
(BMP) Programs—assessing the effects of timber
harvesting and agriculture on small streams.
- District Mini-basin Studies—coordination of all
surface water monitoring activities on a watershed
basis.
Reports summarizing FYI, TMDL, BMP, Mitigation, and
Basin studies can be accessed through the FDEP's
Bureau
of Laboratories Library.
Future Directions
Algal Indicators
Florida DEP has begun development of two methods to
assess algal communities, one for species composition and
the other for algal coverage. Algae are diverse, sensitive,
and are found in all aquatic habitats, making them useful
early indicators of aquatic health.
The Qualitative Periphyton Sampling method is a community
composition assessment of the algal community found on
natural substrates. A total of 10 sample aliquots are
apportioned across available habitats (snags, roots, leaf
packs, vegetation and rock, excluding sediments) in a 100 m
stream reach. To perform the method, choose a seasoned
substrate and with your fingers, rub the algae from an area
approximately 9 cm in diameter into a wide-mouth jar that
has been filled with 100 mL of site water. Mix the water and
algae and before removing a 4 mL aliquot. Repeat with 9
additional aliquots for a final volume of 40 mL. FDEP plans
to use the data collected to develop an index for periphyton
similar to the Stream Condition Index and the Lake Condition
Index.
Rapid Periphyton Survey
The Rapid Periphyton Survey (RPS) quantifies the extent
and abundance of algae in a 100 m stream segment. Nine
observations are made every 10 m for a total of 99
observations (11 transects, including 0 and 100 m marks). A
canopy measurement is made at the mid-point of each transect
using a spherical densiometer. A small handful of substrate
is haphazardly collected at each transect point and is
visually examined for the presence/absence and for the type
of algae (filamentous, diatom, or other). The average
thickness is measured perpendicular to the substrate and
this noted on the Rapid Periphyton Survey benchsheet.
The results of this sampling will allow for the eventual
development of expectations for both reference sites and
those where the algae may be interfering with the designated
use of a waterbody.
Florida DEP has begun development of a lake bioassessment
protocol to monitor and assess the biological integrity of
Florida lakes. The framework for bioassessment consists of
characterizing reference conditions upon which comparisons
can be made, and identifying appropriate biological
attributes with which to measure the condition. Reference
conditions are selected to be the "best available"
conditions for a particular region or area, and are intended
to be representative of sustainable ecosystem health. They
do not necessarily represent pristine conditions
uninfluenced by human activities.
Geographic regionalization based on topography, natural
water chemistry, lake origin, lake hydrology and soils
identified unique regions within which reference sites can
be established. This 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. Ongoing research
contracted with Tetra Tech has identified 500 potential
lakes with complete data sets for Secchi, Chlorophyll, TN,
TP, Color, and pH to examine relationships between
macroinvertebrate communities, water quality parameters, and
basin land use characteristics in Florida's lakes. Leska
Fore was contracted to analyze and recalibrate the LCI using
the Human Disturbance Gradient (HDG) Approach in 2006 and
2007. 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.
Because of the complications in assessing human
disturbance in lakes using the invertebrate community, DEP
develop methods involving the lake aquatic macrophyte
community. Subsequently, these data were 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., Florida DEP is currently using
the LVI to assess human disturbance in lakes in Florida. The
Lake Vegetation Index (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 is deployed a
minimum of five times during the transect to look for the
presence of submerged aquatic plants. All plants for a unit
are recoded in a single column on the Lake Vegetation Index
Data Sheet 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. Variability exercises have been
conducted several biocriteria meetings. Data generated on
the presence of species is used to calculate four biological
metrics - each of which has been shown to respond to human
disturbance. The metrics are:
- Native Taxa
- Invasive Taxa
- Sensitive Taxa
- Dominant Coefficient of Conservatism (C of C)
Habitat assessments are performed and are recorded on the
Lake Habitat Assessment Form.
Florida DEP has concluded the development of 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.
Wetlands biocriteria differ substantially from those
established for streams and lakes. The wetland biological
assessment tools consists of vegetation transects,
invertebrate 20 dipnet sweeps, and a qualitative periphyton
sample collection. The University of Florida research team
has developed a classification scheme for Florida’s wetland
types and have also completed a wetlands regionalization
map.. The Wetlands Condition Index has three components: a
Wetlands Vegetative Index, a Wetland Macroinvertebrate Index
and a Wetland Diatom Index. All three indices are strongly
correlated to the LDI. Updates
on the progress of research into the potential use of
biological assessments in wetlands are
included in the proceedings of the meetings of FDEP's
biocriteria committee.
The Florida estuarine and marine ecological assessment
and monitoring program is presently in the planning
stage. More information on the
development
of biocriteria for marine and estuarine systems is
available through the FDEP Bureau of Laboratories Biology
section. The FDEP Coastal and Aquatic Management Areas (CAMA)
program will take the lead in future marine bioassessment
tool development.
For
more information please contact Devan Cobb at 850/245-8542 or
devan.r.cobb@dep.state.fl.us.
