TURBIDITY AND TEMPERATURE EFFECTS ON OXYGEN-CONSUMPTION IN THE ZEBRA MUSSEL (DREISSENA-POLYMORPHA)

The effects of acute exposure to suspended inorganic sediment (bentonite clay) on oxygen consumption rates of the zebra mussel (Dreissena polymorpha) were examined to estimate their maintenance costs for colonizing the Ohio River. Adult D. polymorpha were acclimated to 10, 18, or 26-degrees-C for 2 wk (10 replicate groups for each acclimation temperature) and respiration was measured in a closed recirculating system using oxygen electrode probes. Each replicate group of mussels was tested at their acclimation temperature under five turbidity levels: 0 (clear water), 5, 20, 80, and 1 60 NTU (nephelometric turbidity units). Respiration rates were significantly affected by acclimation temperature (direct relationship) and turbidity (inverse relationship, which leveled off with increasing turbidity). Warmer-acclimated animals showed a more dramatic drop in oxygen consumption with increasing turbidity, and all size-classes were equally affected by turbidity. Our results suggest that the normal ranges of temperatures and turbidity levels in the Ohio River may depress growth rates of adult D. polymorpha by increasing maintenance costs but probably will not by themselves prevent establishment of viable populations in this river.