B-IBI, which stands for "Benthic Index of Biotic Integrity," is a measure of stream health based on the type and number of various benthic invertebrates found in a sample. High-scoring streams tend to have a large variety of invertebrates. Extra points are given for species that cannot survive without clean, cool water. Low-scoring streams are generally dominated by a few species able to survive under the worst conditions. B-IBI was chosen by the Puget Sound Partnership as an indicator of stream health in the Puget Sound watershed.

Source: Puget Sound Vital Signs

Benthic invertebrates range in size from those easily seen with the naked eye to those that cannot be spotted without the use of a microscope. Photo: Christopher Dunagan


Healthy stream, healthy bugs

Many groups have been formed around the goal of saving salmon, but few people talk about a concerted effort to save microscopic creatures. Whether or not a pro-bug movement catches on, future strategies to save salmon are likely to incorporate ideas for restoring streambound creatures known as benthic invertebrates.