Biological Condition Gradient
A scientific model that describes the biological responses within an aquatic ecosystem to the increasing effects of stressors.
Qualitative Habitat Evaluation Index
A qualitative habitat evaluation assessment tool, used by professionals after taking training, that is applied to streams and rivers in Ohio and which is used to identify habitat variables that are important to attainment of the Ohio biological criteria.
Threshold
The measurable point at which an effect becomes evident in an ambient biological response, i.e., the concentration or otherwise measured level or quantity of a particular chemical, physical, or land use stressor corresponding to a change in a biological assemblage measure.