Performance in Shrimp and Crabs:
Treadmill Studies—Louis E. Burnett

In our investigations of the responses of shrimp, crabs, and oysters to infections with the pathogenic bacterium Vibrio campbellii, we have become interested in how a bacterial challenge can influence the performance of organisms in the field. One way to study this is to induce an organism to engage in some elevated activity similar to what might be encountered in the natural environment. We have demonstrated that shrimp respond to the moving belt of a treadmill submerged in water by walking or swimming. Crabs do the same in walking and they, like shrimp, are capable of movement for hours. This allows us to investigate how things like a bacterial infection can influence the ability of shrimp to perform.

We have designed a treadmill that is contained within a respirometer to measure oxygen uptake to provide us with a measure of an animal's overall aerobic metabolism.The Atlantic blue crab, Callinectes sapidus, will walk on a treadmill elevating its oxygen uptake and producing lactic acid.

We have also studied the mechanics of walking in the Atlantic blue crab, learning how they walk and how they fatigue during walking and how they fatigue during mate-guarding behavior (i.e., when a male crab guards a female after she has molted). These studies have also given us insights into how blue crabs respond to low oxygen and elevated carbon dioxide in the water. Low oxygen (hypoxia) and elevated carbon dioxide (hypercapnia) are becoming more common as stressors in coastal waters associated with development and climate change.

Most recently, we have discovered that black gill disease in the Atlantic white shrimp, Penaeus setiferus, significantly impairs the ability of shrimp to take up oxygen under low oxygen conditions when they are actively walking on treadmills. These results provide a mechanistic basis for potential negative impacts of shrimp populations suffereing with outbreaks of black gill disease in coasal waters.