Are Post-larval Zebra Mussels Attracted To Conspecifics and/or Unionids?
Zebra mussels have recently invaded inland lakes and rivers in lower Michigan, including Loon Lake and the upper Clinton River, Oakland County. Settling larvae and early post-larval stages may be somewhat selective as to surface preference. One surface type that becomes conspicuously settled is the shells of native unionid clams. Some authors have suggested that unionids attract zebra mussels and consequently become more heavily settled than comparable surfaces (stone, wood) nearby. We hypothesized that zebra mussels prefer to settle on unionid shells over other natural or man made surfaces available. Four quadrats of about 1m2 each were placed on the bottom of Loon Lake in June 1994 in about 1m deep water. Test settling surfaces of various kinds were replicated in each quadrat: plastic, wood, ceramic tile, mesh, living and dead unionids. After 99 days in situ, the test settling surfaces were recovered and evaluated. The results suggested that zebra mussels reached higher densities on
