Annual Production of Macroinvertebrates in Three Streams of Different Water Quality

Macroinvertebrate annual production was estimated in three Minnesota streams that differed in watershed geologic origin and in total alkalinity. Annual mean alkalinities (as CaCO 3 ) in the Caribou River, Blackhoof River, and North Branch Creek were 34, 83, and 245 mg/L, respectively. Annual production by herbivore—detritivore invertebrates was lowest in the Caribou River (wet mass: 27.0 g/m 2 ), intermediate in the Blackhoof River (36.9 g/m 2 ), and highest in North Branch Creek (119.6 g/m 2 ). Estimates of annual production by invertebrate carnivores followed the same patter: lowest in the Caribou River (5.5 g/m 2 , intermediate in the Blackhoof River (6.5 g/m 2 ), and highest in North Branch Creek (12.8 g/m 2 ). These estimates of annual production were positively associated with alkalinity, nitrates, and fish standing stocks.