THE INFLUENCE OF DIET ON SURVIVAL OF LAMPSILIS CARDIUM JUVENILES IN LABORATORY 
EXPOSURES.

Casey Sleznikow1, Teresa Newton2, and Michelle Bartsch2  
1Central High School, 1801 Losey Blvd, La Crosse, WI  54601; 2USGS, Upper 
Midwest Environmental Sciences Center, 2630 Fanta Reed Road, La Crosse, WI 
54603.

We evaluated the effects of diet and laboratory holding time on the survival of 
juvenile Lampsilis cardium mussels in a 7-week study.  The diets included a 
water only exposure, river sediment, a commercial shellfish diet, and a 
combination of the commercial diet and river sediment.  The experimental design 
consisted of 3 38-L flow-through aquaria per diet, each containing 8 suspended 
PVC chambers (5 cm tall x 2 cm OD with 153 µm mesh on bottom).  Fifteen 3-day 
old juveniles (cultured in vivo) were added to each chamber on day 0.  Chambers 
receiving sediment diets received (200 g of surficial sediment from an 
uncontaminated reach of the Upper Mississippi River at the start of the test and 
aquaria receiving the commercial diet received 250 µL three times per week.  
Temperature, dissolved oxygen, and flow rate were measured in each aquarium 
three times per week.  One chamber from each aquarium was randomly removed 
weekly for 7 weeks to assess survival.  Survival of juveniles varied 
significantly among diets and over time.  Survival exceeded 80% in all diets 
through week 3, exceeded 60% in the sediment diets through week 5 and then 
declined to 0% in all diets by week 7.  These data suggest that diets containing 
sediment enhanced survival of juveniles for a longer duration than non-sediment 
diets, but no diet maintained juveniles in a healthy condition for more than (4 
weeks.

Keywords:  unionid mussels, diet, survival, juveniles, laboratory