A method for reconstruction of zebra mussel (Dreissena polymorpha) length from shell fragments

Zebra mussels (Dreissena polymorpha) are subject to size-selective predation by several species of diving ducks and fish in Europe and North America. Ingested mussels are crushed, but the internal septum in the umbonal region of the mussel usually remains intact. Using mussels collected at Point Pelee, Lake Erie, I showed that there is a strong relationship between the length of the septum and of the mussel (r2 = 0.96). I compared this with a similar relationship developed for European zebra mussels and tested both models on mussels collected from Point Pelee and from Stoney Point, Lake St. Clair. Septal length relative to mussel length was greatest at Stoney Point and least at Point Pelee. The European estimates fell between the two. I concluded that to obtain accurate estimates of mussel length when investigating size-selective predation on zebra mussels, the relationship between mussel and septal lengths should be determined at each study location.