![[logo] US EPA](http://www.epa.gov/epafiles/images/logo_epaseal.gif){kind=logo}
Ecological Attributes
The biological indicator or set of indicators that a State or Tribe develops is dependent on their ability to measure ecological attributes of the aquatic flora and fauna. Ecological attributes are those aspects of an aquatic assemblage or community that correspond to the structure and function of that assemblage or community for a given condition. The Biological Condition Gradient (BCG) represents a continuum of condition in response to human disturbance and is determined or measured by an understanding of these attributes (USEPA 2005). Ten primary ecological attributes have been identified as the basis for evaluating the BCG and establishing a viable biological indicator (USEPA 2005; Davies and Jackson 2006). The first six attributes relate to taxonomic identity, composition, and tolerances. They are 1) historically documented, sensitive, long-lived, or regionally endemic taxa, 2) sensitive rare taxa, 3) sensitive ubiquitous taxa, 4) taxa of intermediate tolerance, 5) tolerant taxa, and 6) non-native taxa that tend to displace endemic taxa. The seventh attribute is organism condition, which provides information on individual health. The remaining three attributes are functional integrity, ecosystem connectance, and spatial and temporal extent of stressors. These attributes are not directly measured by bioassessment, but rather are inferred from the condition and well-being of the aquatic biota; hence, they are not discussed herein.
The ecological attributes of a BCG (Table below) and a calibrated biological index are not mutually exclusive. In most instances the components of an index reflect several of the ecological attributes. We have found that having biological information that correspond to the attributes aids in defining biological condition tiers along the gradient and to characterize the highest expectation for the ecosystem. An agency can use the underpinnings of the attributes to improve this biological index.
References
Davies SP, Jackson SK (2006) The Biological Condition Gradient: A Descriptive Model for Interpreting Change in Aquatic Ecosystems. Ecological Applications: Vol. 16, No. 4 pp. 1251–1266
For more information, please visit Biological Attributes in Lessons Learned for Bioassessment