Effects of lamprey larvicides on invertebrates in streams

This study was conducted on five streams tributary to Lake Superior and four tributary to Lake Michigan. Samples of the bottom fauna before and after chemical treatment revealed that most groups of aquatic organisms were not adversely affected by exposure to larvicides. The total number of invertebrates was smaller 1 week after treatment than before treatment, increased somewhat by 6 weeks after treatment, and had returned to pretreatment levels 1 year after treatment. Aquatic insects were affected less than other organisms, and invertebrates were more severely affected and recovered more slowly in areas of sand and detritus than in riffle areas.