Number of Benthic Insectivorous Species

 

This metric is a modification of several metrics used in the original IBI (Karr 1981). Darter

species make up a relatively small component of the New Jersey fish fauna. However,

several other benthic species require clean gravel or cobble substrate for reproduction and/or

living space. Degradation of this habitat from siltation is often reflected by a loss of benthic

species richness (Karr et al. 1986) and abundance (Berkman and Rabeni 1987). Several

benthic fish require quiet pool bottoms and may decline when benthic oxygen depletion

occurs (Ohio EPA 1987). Further, reductions of some benthic insectivorous fish may

indirectly indicate a toxics problem. Benthic macroinvertebrates are an important food source

for benthic insectivorous fish and their sessile mode of life make them particularly

susceptible to toxicant effects. Metric recalibration has resulted in the elimination of white

suckers and bullheads, as these species are designated as tolerant by the USEPA (Plafkin et al. 1989).