Unfathomable Resilience: Survival and Nutrient Recycling of Profundal Quagga Mussels under Starvation Conditions

The quagga mussel, Dreissena rostriformis bugensis, invaded large portions of the Laurentian Great Lakes and today is the most abundant benthic organism by biomass in the profundal zones of Lakes Erie, Ontario, Huron and Michigan. To better understand the ability of quagga mussels to invade profundal habitats and their response to food availability, we investigated the effects of starvation on quagga mussels under laboratory conditions.

In a 7-month trial, we compared survival, growth, tissue composition as well as respiration and nutrient transformation rates of starved mussels and of mussels fed a high-quality diet. Our results indicate that profundal quagga mussels are highly starvation tolerant at temperatures characteristic of the hypolimnia of the Great Lakes, with survival times &gt200 days under starvation conditions. Starved mussels lost tissue mass, had reduced glycogen content and had lower excretion rates of P and N compared to well-fed mussels. We compared our laboratory results on effects of starvation to data collected on profundal quagga mussels during the summer of 2019 in Lakes Huron and Michigan, finding large spatial variation of quagga mussel physiological status. We show that profundal quagga mussels are highly resilient to disruptions in food supply, which helps explain their invasion success in the cold and food-limited profundal zone of the Great Lakes.

Our comparison of the physiological status of quagga mussels across Lakes Huron and Michigan offers insights into the optimal habitat for this species and their effects on the Great Lakes ecosystem.