SEMINAR: MBF 602 Martha Hauff Friday 4-1-11, 2pm S/A 103

["Martha Hauff" <mhauff@rsmas.miami.edu>]

Multiple indices shed light on transport-related condition of coral reef fish larvae

 

In coastal marine organisms with protracted pelagic larval durations, there is potential for long distance dispersal and extensive population connectivity.  Yet, recent coral reef fish research indicates that local retention of larval fish may be more important in replenishing populations than influx of larvae from distant sources. Because of carryover effects from one life stage to another, larvae that exhibit different levels of condition in the plankton may experience different levels of post-settlement mortality. Thus, in order to better understand the relative contributions of local retention and long-distance dispersal in maintaining reef fish populations, it is necessary to examine the relationship between larval condition and larval dispersal trajectory. To this end, we analyzed the condition of reef fish larvae collected during three cruises in the summers of 2007 and 2008.  On each cruise, ichthyoplankton and environmental measurements (MOCNESS and CTD) were collected at 90 stations on cross-shelf transects along the Florida Keys (FK) reef tract, and in the Loop Current upstream of the FK. MOCNESS tows at each station yielded larvae from a broad range of coral reef fish taxa and, for a subset of these larvae that were identifiable to species, RNA/DNA ratios were obtained, allowing for the evaluation of condition in individual larvae collected across distinct water masses. While results varied among species, data indicated that, for some taxa (bluehead wrasse, pearly razorfish), larvae collected closer to shore exhibited significantly higher RNA/DNA ratios compared to larvae collected offshore, and this pattern became more pronounced with increasing larval size and age. Otolith-based indices of larval condition (growth rate, size at age) corroborated these findings, which provide support for the theory that locally retained larvae benefit from enhanced condition and subsequent increased survivorship on the reef. In addition to RNA/DNA assays and otolith-based techniques, Illumina sequencing of bluehead wrasse cDNA has led to the discovery of over 56,488 single nucleotide polymorphisms (SNPs) (>2000 SNPs per chromosome), and ongoing work seeks to identify associations between individual SNPs, locations of larval origin, and condition-related larval traits.

 

Martha J. Hauff

B.S. in Biology, B.A. in Literature, Claremont McKenna College (2003)

Entered Ph.D. Program in Fall 2005

 

Advisor: Dr. Robert K. Cowen