Meeting Abstract

39.6  Jan. 6  Feeding kinematics and performance of Hawaiian Stream Gobies, Awaous guamensis and Lentipes concolor: implications for habitat distribution MAIE, Takashi*; PRUETTE, M. E.; SCHOENFUSS, H. L.; BLOB, R. W.; Clemson University; Clemson University; Saint Clout State University; Clemson University tmaie@clemson.edu

Distributions of Hawaiian stream fishes are typically interrupted by waterfalls that divide streams into lower and upper segments. Hatched larvae are flushed into the ocean, and must climb the waterfalls to reach adult habitats when returning back to freshwater streams as part of an amphidromous life cycle. Stream surveys and studies of climbing performance show that Lentipes concolor can reach fast-flowing upper stream segments, but that Awaous guamensis reaches only slower, lower stream segments. Gut content analyses indicate that diet differs between these species only by 10% or less dry weight for most major components (green algae and small invertebrates). This might suggest that feeding kinematics and performance of these two species would be similar. Alternatively, feeding kinematics and performance of these species might be expected to differ in relation to the different flow regimes where they live (faster feeding for L. concolor, slower feeding for A. guamensis). To test for such differences, we compared suction feeding kinematics and performance between A. guamensis and L. concolor through analysis of high-speed video footage. L. concolor showed significantly faster jaw opening performance than A. guamensis, which may facilitate suction feeding in the fast stream reaches L. concolor typically inhabits. Morphological differences between the feeding structures of these species appear to contribute to their differences in performance, which might also help to explain the absence of L. concolor from lower stream reaches inhabited by A. guamensis.