5 Exercise Strawberry Creek: Biotic Interactions and Rapid Biological Assessments Pre-Exercise Assignment Jong Park (J.P.) 1. Insects, snails, worms, and crayfish are some examples of invertebrates that are important in forest ecosystems. Also emerging insects are important food source for terrestrial consumers. 2. Functional groups describe organisms that are analogous in consumption of types of food, meaning that they all eat the same type of food, though they might not be closely related taxonomically. (An Introduction to Stream Ecology: Organisms and Energy Flow) 3. In the headwaters of a stream most of carbon comes from allochthonous input, which consists of Coarse Particulate Organic Matter, such as leaves. The carbon source changes to sunlight toward the lower stream. Since the stream widens, more sunlight can reach the stream, whereas in the headwaters, the stream is covered by canopy of vegetation. 4. There are more shredders, which feed on leaves, than grazers, which feed on algae, near a streams headwaters, because there is less penetration of sunlight in the headwater. Less penetration of sunlight in headwaters means that there will be fewer algae available for grazers. Thus, the number of grazers is fewer in the headwaters than near the downstream area, where the sunlight helps algaes survival. The shredders can thrive in the headwaters because there is proportionately more Coarse Particulate Organic Matter readily available for them. 5. The basic idea behind RCC is to predict river processes at different positions along a river depending on how far those points are from the headwaters. It reasons based on the tenet that processes within a river are linked along its length. I think the concept of RCC is invalid, because there are many more aspects, than just the distance from the headwaters, about river that can contribute in determining its ecological status. Terrestrial vegetation and amount of rainfall can substantially vary for rivers all around the earth. The 6. purpose of a biological assessment is to classify the status of water resources and to assess the condition of biological communities that are associated with human perturbation. 7. The Clean Water Act in 1972 mandated that maintenance of the biological integrity of all surface waters. In response to this Act, the development of rapid biological assessment has been encouraged. 8. The significance of comparing test sites and reference sites is that impairment can be found without conducting measurements if and only if the reference sites could be distinguished easily from test sites. One example could be when the impaired sites were used for calibration of metrics and were determined using three criteria of amount of dissolved oxygen, chlorine toxicity, and the forest cover. Whereas other criteria were used for selecting reference sites such as presence of drainage within the ecoregion of interest, no upstream impoundments, no known discharges or contaminants in place, no known spills or other pollution incidents, low human population density, low agricultural activity, low road and highway density, minimal non-point source problems, and no known intensive fish stocking. 9. Resh et al. suggests the Number of taxa, number of EPT (that is, Ephemeroptera, Plecoptera, Trichoptera) taxa, the biotic index, and the percentage of individuals in the scraper functional group should be included in all assessment programs.
10. The Resh et al. (1995) article is very reliable, because it is by three university academic researchers intending to provide academic and educational information to students and scholars interested in this field of Environmental Science. The researchers are not trying to argue or persuade anyone but to educate. They have no intention to fool anyone or exaggerate their argument in order to gain advocates. The numerous references suggest that the article is synthesis of much information, which would be more accurate than information drawn from few sources.