Temperature effects on burrowing behavior of Potamalis alatus, the Pinkheelsplitter, a freshwater mussel abundant in Kentucky Lake

Background/Question/Methods  

Temperature can greatly affect the biological processes in many organisms, especially in ectotheerms.  Various processes in mussels’ life histories are at least partially affected by temperature, such as reproductive activities, release of larvae, and, potentially, burrowing.  Mussels’ ability to burrow is important in their life histories and may be affected by ambient temperature. Our question was: how is the burrowing behavior of Potamilus alatus, a relatively common and abundant freshwater mussel,  affected by changes in ambient temperature at which burrowing takes place. We studied the effects temperature has on success in, latency to and duration of burrowing.  We collected Potamilus alatus (Pink Heelsplitters) from Kentucky Lake and subjected each of them to three temperature treatments (10, 20, and 30 ± 3°C) using a repeated measures design.  Each treatment took place in a temperature regulated aquarium preceded by at least 24 hrs acclimation.  The time it took for each mussel to begin to burrow (latency) and the duration of burrowing was recorded.  The number of times mussels failed to burrow within a 3 hr time period was also recorded.

Results/Conclusions

The percent of mussels that failed to burrow was significantly higher at low (10¢ªC) temperatures than higher temperatures.  We found no significant difference in the latency to burrowing or in burrowing duration. In most ectothermic animals, decreasing temperatures typically decrease the rates of physiologically processes underlying whole animal performance resulting in a large reduction in movement abilities.  Interestingly, the finding that duration of burrowing was unaffected by temperature is contrary to other studies on different animals and this potential lack of temperature dependence on burrowing rates could be vital to survival during periods of changing ambient temperatures in nature.  It is important to understand how burrowing may be affected by ambient temperature for the management of mussel populations.  Choosing temperatures at which mussels are able to re-burrow will help ameliorate the effects of surveys.  Anthropogenic changes to ambient temperatures through manipulation of rivers, such as by dams, and through climate alteration might affect mussel burrowing, which could in turn affect other aspects of their life history.