Production estimates of the benthic invertebrate community in a small Danish stream

Abstract

Quantitative samples were used to investigate density, biomass and annual production of the benthic invertebrate fauna in a small Danish stream. Forty-eight taxa were found and the total invertebrate densities varied from 3 810 m⁻² in July to 20 040 m⁻² in December. The total mean annual biomass of the invertebrate fauna was 6.1 g ash-free dry wt m⁻². The annual production of the invertebrates was estimated from their mean annual biomass and their annual P/B ratio. Production of the primary consumers (herbivores and detritivores) was 21.4 g ash-free dry wt m⁻² y⁻¹ and of secondary consumers (carnivores) 1.1 g m⁻² y⁻¹. The amount of invertebrate production available to the trout population and the importance of the species as food for trout are discussed.