toxicity using native mussel species. 



continuous monitoring program should be developed for the mussel beds of the Upper 



ppi River to prevent another massive mussel die-off in the future. AjL^-OT^n^^iJLa^Z^ 



6. Recommendations 



The tests results of this study determined that toxic conditions do occur in the 

 sediments of Reach 15 of the Mississippi River. These findings warrant environmental 

 monitoring of the sediments of Reach 15. To insure populations of native mussels continue to 

 exist in our river systems, extensive monitoring programs are needed (Havlik and Marking 

 1987). Therefore we recommend the following: 



1. Monitor the sediments of Reach 15 and other Illinois mussel refuges with recently 

 approved sediment toxicity methods and species. 



Recently, the U. S. Environmental Protection Agency announced the acceptance of the 

 two assays as standard protocols for the determination of sediment toxicity: the Hyalella 

 azteca 10-day survival test and the Chironomus teutons 10-day survival and growth test. 

 Since chironomid larvae are commonly found in the sediments of large rivers, sediment 

 toxicity tests using C teutons, rather the C. dubio. would be more appropriate for any future 

 sediment toxicity projects for Reach 15 of the Upper Mississippi River. 



2. We also recommend standardizing the mussel filtering assay and then using this procedure 

 as an economical screening tool for the assessment of toxic sediments in Reach 1 5 ot the 

 Upper Mississippi River. 



27 



