MAIE, T.**; SCHOENFUSS, H.L.; BLOB, R.W.; Clemson Univ., SC; St.Cloud State Univ., MN; Clemson Univ., SC: ONTOGENETIC SCALING OF BODY PROPORTIONS IN WATERFALL-CLIMBING FISHES FROM DOMINICA AND HAWAI�I: IMPLICATIONS FOR LOCOMOTOR FUNCTION

Potential effects of body size changes on locomotor performance in gobiid fishes were studied by collecting morphometric data from the sicydiine species Sicydium punctatum from Dominica, West Indies and Sicyopterus stimpsoni from the Hawaiian Islands. These taxa are distinctive in possessing a pelvic sucker that is used to adhere to rock surfaces during bouts of waterfall climbing. If propulsive structures scale isometrically as body size increases in these fishes, locomotor performance might be disrupted or more energetically costly in larger fish because body mass increases much faster than linear dimensions as animals grow. To test for changes in the shape of locomotor organs that could help maintain climbing and swimming performance as body size increases, we measured total body length, pelvic sucker area, and caudal fin height from Sicydium and Sicyopterus specimens across a range of body sizes, and calculated reduced major axis regressions to evaluate patterns of fin and sucker scaling with body length. Pelvic sucker area scaled isometrically with body length for both goby taxa, suggesting that climbing performance could decline as these fishes grow larger. In contrast, caudal fin height exhibited strong positive allometry relative to body length in both species, potentially aiding thrust generation for swimming as these fishes increase in size. The difference in these allometric patterns may reflect an increase in the importance of swimming over climbing in sicydiine gobies as they grow in size. The similarities in the scaling patterns of these traits among gobies from geographically distant islands suggest that species in this lineage may be subject to common ontogenetic constraints.