Temporal trends in condition and reproduction of quagga mussels (Dreissena rostriformis bugensis) in southern Lake Michigan

摘要: Abstract Currently little is known about the condition and spawning patterns of quagga mussels ( Dreissena rostriformis bugensis ) in deeper, consistently cold regions Great Lakes. This lack information limits our ability to predict future expansion D. r. offshore Lakes other large, deep lakes. We collected on a monthly basis 2013 (April–September) at three established sites along depth transect (25, 45, 93 m) southern Lake Michigan calculated index (CI), ratio dry soft tissue weight internal shell capacity, assess condition, gametogenic reproductive activity. also measured size–frequency, density, biomass March, July, October. Condition was highest 25 m, population average length were 45 m, density 93 m. At all depths, CI decreased with increasing suggesting that food availability may be limiting for larger individuals. Mussels 45 m spawned earliest over 50% spent by July while 93 m began August. 25 m had not yet September. Long-term trends indicate populations continued expand site but stabilizing 45 m. Consistent trends, lower than 2004 2008.