Environmental Engineering Reference
In-Depth Information
of tolerance for speciic conditions (such as low-dissolved oxygen, toxicity, habitat, and geographic
area), the spatial and temporal (such as based on reproductive cycles, etc.) availability of reference
conditions, and the degree of taxonomic classiication. For example, depending on the required
level of taxonomic classiication, many hours may be required in the laboratory for each hour in
the ield.
7.5.1 f ISH
Fish have commonly been used as biological indicators, and it is typically not the more well-
known sports ish that are used, but often the less commonly known species. Certain ish species
are sensitive to changes in habitat or water quality, and the presence or absence of ish can impact
other aquatic organisms. For example, the parasitic life phase of freshwater mussels depends on
ish hosts, often of speciic species, and the ish contribute to the distribution of the mussels.
The following lists of the advantages and disadvantages of ish as indicators are provided from
Grabarkiewicz and Davis (2008) based on Karr (1981) and Hocutt (1981):
Advantages
1. Long lived: some families possess long lifespans.
2. Ubiquitous: ishes occur in a wide variety of habitats.
3. Extensively studied: there is a large amount of published information regarding the occur-
rence and habitats of ishes.
4. Diversity: North American ishes exhibit a wide range of feeding habits, reproductive
traits, and tolerances to environmental perturbations.
5. Easily identiied: relative to other groups of aquatic biota, ishes are among the easier
groups to identify to the species level.
6. Well known: many ish species are familiar to the general public and provide recreational
opportunities.
7. Toxicity trends: presence/absence, growth, and recruitment data analysis may detect acute
and sublethal effects.
Disadvantages
1. Manpower: with most sampling equipment, a three-person crew is required to effectively
and safely sample ish communities.
2. Migratory: the movement of ishes may provide misleading data.
3. Sampling bias: each sampling method (electroshocking, seining, etc.) has associated biases.
7.5.2 p erIpHyton and M acropHyteS
Periphyton and macrophytes have also been used as indicators of aquatic health. Both can be
impacted by changes in currents or substrates, and both respond to excess nutrients, resulting in
large increases in biomass and large diel variations in dissolved oxygen concentrations, as a func-
tion of production during the day and respiration during nighttime hours. The advantages of mac-
rophytes as indicators are that they (available at: http://www.epa.gov/bioiweb1/html/indicator.html):
Respond to nutrients, light, toxic contaminants, metals, herbicides, turbidity, water level
change, and salt
Are easily sampled through the use of transects or aerial photography
Do not require laboratory analysis
Are easily used for calculating simple abundance metrics
Are integrators of environmental conditions
Search WWH ::




Custom Search