Meeting Abstract

P2.172  Tuesday, Jan. 5  Intraspecific Morphological Differences in Bluegill Sunfish WANG, J.*; HAYASHI, M.; GERRY, S.P.; ELLERBY, D.J.; Wellesley College; Wellesley College; Wellesley College; Wellesley College jwang2@wellesley.edu

Bluegill sunfish, Lepomis macrochirus, show intraspecific morphological and behavioral differences dependent on environment. We hypothesized that Lake Waban bluegill would show morphological differences between open water (OW) and densely vegetated (DV) regions that correlate to differences in swimming performance: DV bluegill would show a truncated, maneuverable body form, while OW bluegill would have a streamlined body suitable for cruising. Bluegill were caught by hook and line and photographed for morphometric analysis. Using Image-J, fin size, area, and location relative to center of mass were measured and expressed relative to body length. OW bluegill had higher aspect ratio pectoral fins, larger dorsal fin area, and more elongated bodies than DV bluegill (p<0.05). The pectoral fins of OW bluegill were farther from the center of mass than DV bluegill (p<0.05). Elongated pectoral fins farther from the center of mass are likely to be effective in exerting power and torque during labriform swimming. Body elongation indicates a streamlined form that may experience lower drag forces. DV bluegill had longer soft dorsal fins, wider caudal fins, and larger eyes (p<0.05). The soft dorsal, anal, and caudal fins of DV bluegill were farther from the center of mass than in OW bluegill (p<0.05). The size and placement of these fins suggest that they will be effective in creating turning moments to facilitate maneuvering. These morphological features are shared by maneuvering fishes. Therefore, DV bluegill morphology is specialized for maneuverability, while OW bluegill are specialized for cruising. Future energetics, kinematics, and respirometry experiments will provide further insight into the biomechanics of bluegill swimming performance, and potential studies in genetics and diet may address questions in intraspecific diversification.