Within-basin variation in the shell morphology and growth rate of a freshwater mussel

Abstract

We measured a correlation between the habitat of the freshwater mussel Lampsilis radiata siliquoidea (Barnes, 1823) from several sites in Inner Long Point Bay, Lake Erie, and its shell morphology and growth rate. Morphometric analysis revealed that mussels in more exposed areas of the bay (areas with more turbulence and sandier sediments) had thicker shells than those from less exposed areas (areas with little turbulence and muddier sediments). Two growth rate analyses showed that the mussels from high exposure areas also grew faster. The results demonstrate the importance of (i) a multivariate consideration of shell form (as opposed to the use of ratio variables) when assessing form–habitat correlations, (ii) quantitatively defining habitat variation in examining such relationships, and (iii) measuring form–habitat relationships among more than two sites in a given basin or stream reach.