Abundance and Biomass of the Meiobenthos in Nearshore Lake Michigan with Comparisons to the Macrobenthos

摘要

The meiobenthos of nearshore southeastern Lake Michigan was quantified by taking cores from three depths (11, 17, and 23 m) at monthly intervals from May to November 1976-79. Total meiobenthic abundance rangedfrom 69,700/m2 to 1,300,000/m2 and total biomass rangedfrom 0.03 to 0.87 g/m2. Nematodes accounted for 80% of all individuals and 66% of the biomass. Most of the major groups peaked in late spring/summer, but some peaked in early spring and fall. With the exception of nematodes, mean annual densities varied from two-fold to twelve-fold at a given station. Harpacticoids, tardigrades, and ostracods tended to be more abundant at the deeper depths, while cyclopoids and cladocerans were less abundant. There was no consistent relationship between sampling depth and the abundance of nematodes and rotifers. Temporal and spatial variation in many of the groups appeared related to changes in the amount of bottom detritus. The overall macrobenthos:meiobenthos biomass ratio was 15:1 and ranged from 5:1 to 45:1 on an annual basis.