Influence of profundal quagga mussels on phosphorus cycling at the sediment-water interface

Session: Mud, Macrofauna and Microbes: Benthic Organism-Abiotic Interactions at Varying Scales (1)

Rae-Ann MacLellan-Hurd, University of Wisconsin-Milwaukee, [email protected]
Harvey Bootsma, University of Wisconsin-Milwaukee, [email protected]
Lou Lamartina, University of Wisconsin Milwaukee, [email protected]
Qian Liao, University of Wisconsin-Milwaukee, [email protected]
Tong Jin, University of Wisconsin-Milwaukee, [email protected]
Cary Troy, Purdue University, [email protected]
David Cannon, Purdue University, [email protected]

Abstract

Models exploring the effects of quagga mussels on primary production tend to focus on grazing rates and excretion of dissolved phosphorus (P) excretion, but focusing solely on these two processes may miss a significant part of the phosphorus story: changes at the sediment water interface. Historically in Lake Michigan, apatite-bound P was an important source for the water column during the isothermal period. As dissolved P was utilized by the phytoplankton, concentrations above the sediment decreased, promoting dissolution of apatite-bound P within the sediment. Quagga mussels may have altered this process by elevating dissolved P concentrations in the benthic boundary layer. In addition to excreting dissolved P, quagga mussels produce biodeposits which may promote microbial growth at the sediment-water interface. The work presented here will show that biodeposits promote microbial uptake of dissolved P which, when combined with the effect of grazing, may exacerbate the removal of P from the water column. Along with biodeposits experiments, cores from 55 meter depth in Lake Michigan were analyzed for P binding species in order to explore potential changes to apatite-bound P and organic P.