February 1, 2003 - January 31, 2004

Description

The effects of 3-trifluoromethyl-4-nitrophenol (TFM) lampricide on aquatic macroinvertebrates and periphyton were examined after treatment of a portion of the Boquet River, Essex County, New York, in the fall of 2003.   The null-hypothesis was that there would be no significant impacts of TFM exposure on benthic or drifting macroinvertebrate total abundance, individual taxa abundance or on periphyton biomass following lampricide treatment of the Boquet River.

Upon completion of a before-and-after sampling regime of macroinvertebrates, the null-hypothesis was rejected after results indicated that there were significant (P<0.05) decreases in density in 16 of 83 benthic taxa:  Acentrella, Baetis, Epeorus,Heptagenia, Taeniopteryx, Ochrotrichia, Leucotrichia, Psychomyia, Rhyacophila, Neophylax, Orthocladiinae, Chironomidae pupae, and Antocha.  Significant increases were shown by Prostoma, Capniidae, and Taenionema.  Reductions in Ceratopsyche and Chimarra were also witnessed, however, these results were not found to be significant.  The results of drift samples indicated that Oligochaeta and Trichoptera showed significant (P<0.05) increases in drifting behavior on the dates following TFM treatment, while Chironomidae pupae and Simuliidae showed significant decreases in drift.  Trichoptera showed the highest decline in density of all benthic taxa, as well as the highest increase in drift.  The majority of changes shown by the effected organisms occurred on October 24, the first sampling date following TFM application.  Post-treatment changes in taxa density were considerable enough to affect the community composition of both benthic and drifting populations.  A full recovery of affected organisms was not evident by the final sampling date, 33 days after TFM application.  Periphyton biomass was not found to be significantly affected by TFM treatment.