INVERTEBRATE COMMUNITIES IN COMPENSATION CREEK, A MAN-MADE STREAM IN BOREAL NEWFOUNDLAND: THE INFLUENCE OF LARGE WOODY DEBRIS

摘要

Benthic invertebrate communities were examined in Compensation Creek, a man-made stream in south-central Newfoundland, Canada. Samples taken in September 2006 and September 2007 from large woody debris (LWD) were compared with samples from benthic environments to determine whether LWD supported a more diverse and abundant invertebrate community. Benthic habitats in a nearby natural stream were also sampled. Taxa composition was similar between the man-made and the natural stream, highlighting successful colonization for the majority of taxa. Within Compensation Creek, taxa richness was higher in benthic habitats than on LWD, likely influenced by the successional age of the stream and surrounding habitat. The more complex benthic substrate provided refugia and allowed for the accumulation of fine detritus as a food source. Scrapers were almost completely absent from LWD and collector-gatherer abundance was greater in the benthos. Collector-filterer abundance was more than six times greater near the pond outflow than farther downstream when discharge was high, but abundances were almost equal when discharge was reduced. Riparian vegetation has not fully established around the man-made stream, whereas it is overhanging and extensive at the natural stream, leading to more leaf-litter input for shredders. As the morphology of Compensation Creek changes, the invertebrate community will continue to develop and likely increase utilization of accumulated detritus at LWD.