Core Concepts

The Ecological vernacular is concerned with the morphological and physiological characteristics of organisms and their relationship to the environment. Although finding this correlation does not necessarily indicate cause and effect, ecologists have often assumed that it does and have proposed ecological generalizations to describe it (Collier, p.21).  These ecological rules seek to explain/represent/measure/characterize life processes/adaptations/abundance/distribution/energy dynamics within a system.

The verbiage can be a bit viscous.  Luckily this inquiry is concerned with a few decisive concepts limited to aquatic ecosystems.

Biodiversity:

The big umbrella topic. Biodiversity is concerned with “the variety of living organisms, the genetic difference among them, the communities and ecosystems in which they occur, and the ecological and evolutionary processes that keep them functioning, yet ever changing and adapting (Collier, p.19).”

Biological Integrity:

When we drop the term, biological integrity, we’re referring to a term coined by the EPA, which refers to the “pristine” conditions of aquatic environments and, for our purposes, freshwater ecosystems.  But what is pristine?  Depends who’s asking.  A management agency’s classification is typically contingent on the particular use of a body of water (Murdoch, 19).  Other theoretical models (like the River Continuum Concept) may postulate a virgin state (a body of water untouched, unaffected by man), as it pertains to the maturation or natural cycling of a body of water.

Water Quality:

Water quality follows from this notion of integrity.  Assessing water quality is concerned with predicting, tracking, and determining the symptoms and proximate causes of ecosystem degradation.  Water quality data includes documentation of physicochemical parameters (such as pH, dissolved oxygen, temperature, suspended materials) and biotic sampling.  Regulation agencies can look to the local flora and fauna as bioindicators, organisms shaped by present in-habitat forces.  River monitoring is particularly concerned with the sampling of macroinvertebrates.  As in-stream inhabitants, whose morphology, reproduction, and life history patterns are tethered to their biogeography, the presence or absence of these organisms can speak volumes to the processes and patterns acting upon the entire stream community.  

Refs--

"Biological Integrity." EPA. Environmental Protection Agency, n.d. Web. 09 Oct. 2012. <http://www.epa.gov/bioiweb1/html/biointeg.html>.

Collier, Boyd D. Dynamic Ecology. Englewood Cliffs, NJ: Prentice-Hall, 1973. Print.

Erickson, Donna L. MetroGreen: Connecting Open Space in North American Cities. Washington: Island, 2006. Print.
Lenz, Bernard N., and Michael A. Miller. Comparison of Aquatic Macroinvertebrate Samples Collected Using Different Field Methods. [Reston, Va]: U.S. Dept. of the Interior, U.S. Geological Survey, 1996. Print.
Murdoch, Tom, Martha Cheo, and Kate O'Laughlin. The Streamkeeper's Field Guide: Watershed Inventory and Stream Monitoring Methods. Everett, WA: Adopt-a-Stream Foundation, 1996. Print.