Although invasive zebra (Dreissena polymorpha) and quagga (Dreissena rostriformis) mussels are known to increase
water column concentrations of nitrogen and phosphorus, the relative roles of direct nutrient release by the mussels
and mussel-induced alterations to sediment fluxes are little understood. In short-term microcosm experiments comparing
the presence and absence of mussels on sediments from Oneida Lake, New York, USA, both dreissenid species approximately
doubled benthic oxygen consumption and fluxes of ammonium. The impact on soluble reactive phosphate (SRP)
flux varied from 40% to 140% depending on whether mussels were located in the water column or directly on sediments.
The additional flux was attributable directly to release by the mussels, with fluxes from the sediments remaining largely
unchanged. However, mussels located directly on sediment surfaces released twice as much SRP as mussels located higher
in the water column, with a molar N:P ratio as low as 4:1. The high rate of SRP release by mussels on sediment, possibly
caused by mobilization of iron-bound phosphorus from sediment particles in the anoxic guts of the mussels, could contribute
to observed increases in SRP, abundance of nuisance algae such as Cladophora, and abundance and toxicity of the cyanobacteria
Microcystis in dreissenid invaded ecosystems