Burrowing behavior of freshwater mussels in experimentally manipulated communities

We experimentally manipulated mussel community structure and observed mussel burrowing behavior in mesocosms held in a greenhouse. Vertical positions, vertical movements, and horizontal movements of Actinonaias ligamentina, Amblema plicata, Fusconaia flava, and Obliquaria reflexa were recorded during five 11-d trials. Community structure was manipulated by constructing communities with 11 different diversity treatments crossed with 3 different density treatments. Vertical positions, vertical movements, and horizontal movements of mussels differed significantly among diversity treatments, and vertical movements differed among density treatments. Differences among diversity treatments were caused by differences in species composition because the burrowing activity of mussels in multispecies communities could be predicted additively from single-species communities. The species used in our study vary in body size, but differences among species were still significant after accounting for body length. We think that differences in species burrowing behavior might be a result of niche partitioning of vertical space, might be a result of differing effects of temperature between species, or might be related to mechanisms to avoid dislodgement during high flows. The burrowing behavior of freshwater mussels has implications for mussel sampling protocols, the sensitivity of mussels to zebra mussel attachment, and how mussels influence benthic ecosystems.