Can recently-hatched crayfish cling to moving ducks and be transported during flight?

Abstract

The red swamp crayfish (Procambarus clarkii) is a freshwater invasive species which has become a worldwide problem. Recent work on ectozoochory of freshwater macrocrustacean species indicated that there might be a possibility of transport of recently-hatched crayfish by birds. In this context, we applied a new set of methods to quantify the probability of transport of recently-hatched crayfish, namely with moving animal vectors. First, we tested the desiccation resistance of crayfish and the capacity of crayfish to cling to mallard's feet, depending on the standing time of the feet. We also determined the ability of recently-hatched crayfish to cling to an artificially moving freshly dead mallard (Anas platyrhynchos) and finally, we determined the time required for the death of 50% and 90% of the individuals of recently-hatched crayfish under conditions similar to those of mallard flight.

Recently-hatched crayfish were able to survive up to 225 min out of water, withstanding longer at a lower temperature and therefore transport does not seem to be limited by desiccation survival. The duration of the standing period of duck's feet positively affected the probability of transport of crayfish. Recently-hatched crayfish were able to cling to a moving duck and the probability of clinging was significantly affected by the water depth, being lower at greater depths. Moreover, when transported on a freshly dead duck under flight simulation conditions the time required for the death of 50% and 90% of the individuals were 2 min 14 s and 4 min 53 s, respectively. These flight durations correspond to transport distances of 2.8 km and 6.1 km, respectively, which is enough for transport to another aquatic system. The results demonstrate that passive transport of recently hatched P. clarkii by actively moving waterbirds is possible, and therefore it will likely enhance the local process of invasion.