Environmental Engineering Reference
In-Depth Information
T
able 10.6
Five tiers of the rapid bioassessment protocols (after Plafkin et al., 1989)
Level
or tier
Organism
group
Level of taxonomy/
where performed
Level of expertise
required
Relative level of effort
Benthic
invertebrates
Low; 1-2 hr per site (no
standardized sampling)
One highly-trained
biologist
Ē
Order, family/field
Intermediate; 1.5-2.5 hr per site
(all taxonomy performed in the
field)
One highly-trained
biologist and one
technician
Benthic
invertebrates
ē
Family/field
Most rigorous; 3-5 hr per site
(2-3 hr of total are for lab
taxonomy)
One highly-trained
biologist and one
technician
Benthic
invertebrates
Genus or species/
laboratory
Ĕ
Low; 1-3 hr per site (no
fieldwork involved
One highly-trained
biologist
Ė
Fish
Not applicable
One highly-trained
biologist and 1-2
technicians
Most rigorous; 2-7 hr per site
(1-2 hr are for data analysis)
ė
Fish
Species /field
10.3.3.2
Comparison Standard
With stream restoration activities, it is important to select a desired end condition for the proposed
management action. A predetermined standard of comparison provides a benchmark against which to
measure progress. For example, if the chosen diversity measure is native species richness, the standard of
comparison might be the maximum expected native species richness for a defined geographic area and
time period. Historical conditions in the region should be considered when establishing a standard of
comparison. If current conditions in a river are degraded, it may be best to establish the standard for a
period in the past that represented more natural or desired conditions. In some cases historical diversity
might have been less than current diversity due to changes in hydrology and encroachment of native and
exotic riparian vegetation in the floodplain (Knopf, 1986). Thus, it is important to agree on what conditions
are desired prior to establishing the standard of comparison.
For a hypothetical stream restoration initiative, the following biological diversity objective might be
developed. Assume that a primary concern in an area is conserving native amphibian species and that 30
native species of amphibians have been known to occur historically in the watershed. The objective
could be to manage the river ecosystem to provide and maintain suitable habitat for the 30 native
amphibian species. River ecosystem restoration efforts must be directed toward those factors that can be
managed to increase diversity to the desired level. Those factors might be the physical and structural
features of the river ecosystem. Diversity can be measured directly or predicted from other information.
Direct measurement requires an actual inventory of the element of diversity, such as counting the
amphibian species in the study area.
Direct measures of diversity are most helpful when baseline information is available for comparing
different sites. It is not possible, however, to directly measure certain attributes, such as species richness
or the population level of various species, for various future conditions. Predicting diversity with a model
is generally more rapid than directly measuring diversity. In addition, predictive methods provide a
means to analyze alternative future conditions before implementing specific restoration plans. The
reliability and accuracy of diversity models should be established before their use.
10.3.3.3
Classification Systems
The common goal of classification systems is to organize variation. Classification systems include
(
FISRWG, 1997
):
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