Meeting Abstract

58.5  Thursday, Jan. 6  A Three-Dimensional Approach to Morphological Variation in Bluegill FEILICH, K.L.*; GERRY, S.P.; ELLERBY, D.J.; Wellesley College; Wellesley College; Wellesley College kfeilich@wellesley.edu

Bluegill sunfish, Lepomis macrochirus, show intraspecific morphological and behavioral differences dependent on their environment. Previous metrics quantifying morphological variation in this species have measured two-dimensional external variation in the sagittal plane. This research takes a new mechanistic approach to morphological variation by incorporating fin position relative to the center of mass. This three-dimensional ‘moment arm’ based approach is important in assessing the functional implications of morphological differences between ecomorphs. Morphological analyses were carried out on bluegill from littoral and pelagic habitats in Lake Waban, MA, USA that differed in water depth and macrophyte density. Pelagic bluegill have more fusiform bodies, a higher pectoral fin aspect ratio, a larger spiny dorsal fin area, and pectoral fins located farther from the center of mass than littoral bluegill (P < 0.05). The shape of the body and pectoral fins, in particular, are suggestive of adaptation for sustained high-speed and/or economical labriform swimming. Littoral bluegill have a deeper and wider body, deeper caudal fins and wider mouths than pelagic bluegill (P < 0.05). Additionally, the soft dorsal, pelvic, anal, and caudal fins of littoral bluegill are positioned farther from the center of mass (P < 0.05). The size and placement of these fins suggest that they will be effective in creating turning moments to facilitate maneuvering in the macrophyte-dense littoral habitat.