Meeting Abstract

P2.107  Thursday, Jan. 5  Ontogeny of Body Shape and Diet in Freshwater Drum (Aplodinotus grunniens) ESSNER, JR., R.L.*; PATEL, R.; REILLY, S.M.; Southern Illinois University Edwardsville; Southern Illinois University Edwardsville; Ohio University

Ontogenetic changes in body shape were studied in Freshwater Drum Aplodinotus grunniens, using geometric morphometrics. We examined a single cross-sectional sample of juveniles, sub-adults and adults collected from the Ohio River near Racine, OH. Eleven landmarks on lateral profiles of fish were digitized and body shape was compared using relative warp analysis. Significant allometric growth was identified between four relative warp axes and centroid size. Several of the shape changes characterizing growth in A. grunniens appear to be functionally related to feeding. Gut content analysis was consistent with other research that found a dietary shift from soft-bodied prey (e.g., copepods, chironomids) in smaller individuals to hard-bodied prey (e.g., fish) in larger individuals. Key shape changes that correspond to a shift in diet to larger and harder prey types include a more anteriorly positioned mouth, more expansive gape and increased body depth.