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4541070 
Journal Article 
Dreissena and the disappearance of the spring phytoplankton bloom in Lake Michigan 
Vanderploeg, HA; Liebig, JR; Nalepa, TF; Fahnenstiel, GL; Pothoven, SA 
2010 
Yes 
Journal of Great Lakes Research
ISSN: 0380-1330 
36 
50-59 
WOS:000281654700006 
We determined the clearance rates of the profunda morph of the quagga mussel (Dreissena bugensis) using seston and Cryptomonas ozolini, a high-quality algal food, for the temperature range 1-7 degrees C, which is the full temperature range this morph is likely to experience during isothermal conditions or in the hypolimnion of deep lakes. Experiments at 3 degrees C with the shallow-water morph of the quagga and the zebra mussel provided very similar results. The clearance rates were combined with dreissenid abundance in 0-30 m, 30-50 m, 50-90 m, and >90 m depth zones of the southern basin of Lake Michigan to calculate a maximum (using Cryptomonas) and minimum (using seston) fraction of the water column cleared (FC) per day in the different depth zones at 3 degrees C to determine dreissenid impact on the spring phytoplankton bloom from 1994 to 2008. Starting in 2003 or 2004 with the replacement of zebra mussels by quagga mussels in shallow water and expansion of quagga mussel biomass in deep water, FC began to exceed likely phytoplankton growth in the 30-50 m zone. In 2007-2008, FC greatly exceeded likely phytoplankton growth by a factor of about 5 in the 30- to 50-m depth zone, where dreissenids were extremely abundant. Low FC in the offshore region led to the hypothesis of a mid-depth carbon (C) and phosphorous (P) sink caused by mussel uptake of seston-associated C and P that affected not only the mid-depth region, but also the offshore region "downstream" of the mid-depth zone. Published by Elsevier B.V. 
Quagga mussel; Zebra mussel; Nearshore phosphorus shunt; Mid-depth phosphorus sink