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DETECTING INTERACTIONS BETWEEN ELLIPTIO WACCAMAWENSIS AND LEPTODEA OCHRACEA: THE INFLUENCE OF EXPERIMENTAL SCALE.
Citation:
DiDonato, G. T. DETECTING INTERACTIONS BETWEEN ELLIPTIO WACCAMAWENSIS AND LEPTODEA OCHRACEA: THE INFLUENCE OF EXPERIMENTAL SCALE. BASIC AND APPLIED ECOLOGY 3(4):371-379, (2002).
Description:
Manipulative field experiments are used in ecology to study biotic interactions in populations and communities. In benthic suspension-feeding organisms, these interactions can occur over multiple spatial scales, but this has rarely received experimental attention. A field experiment in Lake Waccamaw, North Carolina, USA, explored scale-dependent interactions in the freshwater mussels Elliptio waccamawensis and Leptodea ochracea (Bivalvia: Unionidae). Mussel density and patch size were manipulated in situ during summer 1996. Density treatments (Low: 32 monospecific individuals m-2, High: 64 monospecific individuals m-2, Mixed: 64 individuals m-2 at a 1:1 ratio of the two species) were maintained in benthic enclosures (0.25 m2), and a scale treatment altered mussel patch size (Small-scale: 0.25 m2, Large-scale: 3 m2). Large-scale patches were achieved by supplementing the area around each 0.25 m2 enclosure with additional mussels. Bivalve shell growth, tissue weight, and shell weight were analyzed. E. waccamawensis did not respond to any of the treatments, including spatial scale. For L. ochracea, shell growth and weight were not influenced by experimental treatments; however, average tissue weight of mussels in small patches (0.25m2) was significantly higher in the High and Mixed treatments compared to the Low treatment. This positive effect was not observed in larger patches. These data provide evidence for scale-dependent interactions in unionids. In addition, they further an intriguing hypothesis linking spatial aggregation and reproductive success in freshwater mussels.