MEPS 383:239-249 (2009) - doi:10.3354/meps07988
Spatial variation in larval growth and gut fullness in a coral reef fish
Su Sponaugle1,*, Joel K. Llopiz1, Lisa N. Havel1,2, Tauna L. Rankin1
ABSTRACT: Successful feeding and fast growth is thought to be critical for surviving the pelagic larval stage of benthic marine fishes, yet few measures of these processes are available for tropical reef fishes. We tested the hypothesis that larvae experience faster growth in more productive coastal waters due to increased prey availability. We examined spatial patterns in larval growth and gut fullness for a common coral reef fish, the bluehead wrasse Thalassoma bifasciatum. During 2 ichthyoplankton cruises (September 2003 and October 2004), larvae were collected using a coupled MOCNESS at 17 stations along an 80 km east–west transect (25.5°N) across the Straits of Florida between Florida, USA, and the Bahamas. For a subsample of larvae collected at different distances along the transect, we examined sagittal otoliths to estimate growth rates and we inspected gut contents and estimated gut fullness for the same individuals. We also identified and enumerated the available prey of T. bifasciatum from a subsample of zooplankton samples collected simultaneously with the larvae. Larval T. bifasciatum collected at the western stations grew significantly faster, were larger-at-age, and had fuller guts than those collected at the central and eastern stations. Further, gut fullness of larvae was directly related to cross-straits prey abundance. Despite these repeatable patterns of growth and gut fullness, larval T. bifasciatum were consistently more abundant at the central and eastern stations, possibly reflecting particular transport processes or differential predation mortality. These results begin to bridge the gaps in our understanding of pelagic processes and the successful recruitment of nearshore populations.
KEY WORDS: Fish larvae · Larval growth · Early life history · Larval trophic ecology · Otolith microstructure · Zooplankton prey
|Full text in pdf format|