Digestive physiology and dietary overlap of aquatic invertebrates in the upper Mississippi river basin

Abstract

Zebra mussels Dreissena polymorpha are invasive species in North America posing significant threats to native ecosystems and organisms. Costs to waste-water treatment and electrical power plants are in the hundreds of millions of dollars. Resource managers lack control tools that selectively target zebra mussels. One potential avenue to control zebra mussels is their digestive physiology, of which little information is known. If specific enzyme(s) can be identified as unique to zebra mussels, a species-specific biocide potentially can be formulated. The api�ZYM kit was modified to screen 19 enzymes in the digestive tract of zebra mussels to identify potential differences between zebra mussels and native invertebrates. Digestive enzymes from zebra mussels, threeridge mussels Amblema plicata, and a caddisfly Hydropsyche orris were screened over four months at three sites along the Mississippi River to observe relative enzyme profiles. Results suggest sample location and time did not affect digestive enzyme profiles; however species were different (p < 0.01). Four enzymes (alkaline phosphatase, acid phosphatase, leucine arylamidase, and N-acteyl-?-glucosaminidase) were quantified using specific enzyme kits. Zebra mussel acid phosphatase did not respond to temperature decrease. Acid phosphatase may be exploitable to develop a selectively targeted control tool.