Meeting Abstract

11.3  Monday, Jan. 4  Morphology and the Mechanics of Zebra and Quagga Mussel Movement PEYER, S M*; HERMANSON, J C; LEE, C E; Univ. Wisconsin-Madison; Forest Products Laboratory, Madison, WI; Univ. Wisconsin-Madison smpeyer@wisc.edu

While the invasive zebra mussel initially colonized shallow habitats in the Great Lakes, the invasive quagga mussel is becoming the more dominant species in both shallow and deep water habitats. In contrast to zebra mussels, quagga mussels have greater variation in shell morphology, particularly between shallow rocky and deep soft sedimentary habitats. Such morphological variation might have functional consequences that affect the ability of each species to colonize diverse substrates. We examined the effect of shell morphology on movement of zebra and quagga mussels across hard and soft substrates. We quantified movement of mussels with rotational (K_rot) and translational kinetic energy (K_trans), and shell morphology with the polar moment of inertia (J), a variable in K_rot that describes resistance to rotation. On hard substrate, K_rot:K_trans did not differ between zebra and shallow quagga mussels, but was 4 times higher for deep quagga than zebra and shallow quagga mussels. On soft substrate, K_rot:K_trans of deep quagga mussels was 1/4 of that on hard substrate and did not differ significantly from zebra and shallow quagga mussels. J, contributed significantly to the mechanics of movement and might also affect the ability of mussels to float on or burrow into soft substrate, depending on their shell orientation. The orientation of deep quagga mussels increased J and resulted in higher K_rot on hard substrate, but might improve floatation on soft substrate. By reorienting and minimizing J, deep quagga mussels increased K_trans relative to K_rot and might also achieve greater burrowing efficiency on soft substrate. Thus, quagga mussels, with shallow and deep morphology, might have greater ability to utilize hard and soft sedimentary substrates and colonize a wider range of habitats than zebra mussels.