Puget Sound Stream Benthos

Benthic Taxa Attributes

Five of the ten metrics that comprise the Puget Sound Lowland B-IBI are based on several characteristics, or attributes, of the organisms that represent feeding method (predator), habit (clinger), life history characteristics (long-lived), and tolerance to human disturbance (tolerant, intolerant). Two sets of taxa attributes are currently available for calculating B-IBI on the Puget Sound Stream Benthos and they are described below.

It is not always practical or even feasible to uniquely identify benthic macroinvertebrates that have similar phenotypes (appearances) during their aquatic life stages. Therefore, some macroinvertebrates are identified to a taxonomic level that is higher than Genus or Species, such as Family or Order. However, in other cases the organisms can be positively identified as belonging to a select subset of Genera; therefore, these organisms can be identified at a custom taxa level that is in between the standard taxa hierarchy. These custom taxa levels are indicated with a “Group” (e.g., Rhyacophila Angelita Group) or a “Complex” (e.g., Orthocladius Complex) designation, or they can be designated with a slash (e.g., Kogotus/Rickera). Some examples of these custom taxa levels are included in the attribute table below.

Fore, Wisseman, 2012 (recommended for 0-100 B-IBI)

Attributes were updated in 2012 to represent best available science. Bob Wisseman updated the predator, long-lived, and clinger attributes by consulting published literature. Leska Fore used existing data to empirically test each taxon’s response to a gradient of watershed urbanization. The most tolerant and intolerant taxa were selected for the corresponding attribute lists. This version of taxa attributes was used to re-calibrate the Puget Lowland B-IBI and adjust the scoring to a 0-100 scale.

Wisseman, 1998 (recommended for 10-50 B-IBI)

The 1998 attribute list was compiled by taxonomist Bob Wisseman based on his best professional judgment for predator, long-lived, tolerant, and intolerant classifications and based on the habit designation in Merritt and Cummins 1996 for clinger. This version of taxa attributes was used to develop and calibrate the original Puget Lowland B-IBI.