SEMINAR: TOMORROW: MBF602 STUDENT SEMINAR: FRIDAY NOV. 11 @ 1PM---DAN HOLSTEIN & RACHEL SILVERSTEIN

[Pam Harris <pharris@rsmas.miami.edu>]

 

MBF Student Seminar Series

Dan Holstein

Advisor: Dr. Claire Paris

“Multi-species source-sink dynamics of the Caribbean”

For many coastal marine species larval dispersal is driven by ocean and coastal currents. The confluence of the physical environment, reproductive behavior and larval characteristics can establish source and sink populations that can be variable or stable over time. Marine resource management seeks to optimize efforts through understanding how protected populations exchange larvae with proximate and distal populations; however, this endeavor is often hindered by difficulties in empirical data collection and mired in complexity. Here we demonstrate the utility of a biophysical individual-based model of larval dispersal in describing the source-sink characteristics of twenty-three regions in the Caribbean for multi-species assemblages of fish and hermatypic coral. Several indices of connection diversity were developed to describe each region’s network role. Regions become important to metapopulation connectivity when they have diverse network connections, or by being responsible for a high proportion of settlement as a source, sink or both. Examples are the Bahamas, due partially to extensive habitat area, Northern Cuba, the Cayman Islands, Jamaica and the Colombian Archipelago. In contrast, Puerto Rico, the Windward and Leeward Islands and the Venezuelan Corridor are relatively isolated, making these regions particularly sensitive to continued habitat and network fragmentation. These indices of connection diversity can serve resource managers by simplifying a fundamental yet complex management question.

Rachel Silverstein
Advisor: Dr. Andrew Baker
“Coral thermotolerance increases as a result of

 post-bleaching changes in Symbiodinium communities,

not prior thermal stress exposure”

 

Corals that have recently recovered from bleaching events have been found to be more resistant to heat stress.  It is not known, however, whether this is due to physiological acclimatization and/or changes in the composition of corals’ Symbiodinium communities. To differentiate these hypotheses, we used quantitative PCR and imaging Pulse Amplitude Modulation fluorometry to assess the composition, abundance, and photosynthetic efficiency of Symbiodinium in Montastraea cavernosa coral in a two-phase experiment. In the first phase, corals containing only clade C Symbiodinium were bleached by a 10-day exposure to either high temperature (32^oC) or to herbicide (600µg/L DCMU) at  24^oC;  unbleached control corals were also included. Corals then recovered at 24^oC or 29^oC for three months. All stressed corals recovered with thermotolerant clade D Symbiodinium.  In the second phase, a subset of the heat-bleached, herbicide-bleached, and control corals were exposed to 32^oC stress for 10 days. Corals that had previously bleached did not bleach during this phase, regardless of the stress used to induce the initial bleaching. In contrast, previously unbleached control corals bleached as before. These results indicate that increased coral thermotolerance is mainly a result of changes in the Symbiodinium communities, rather than physiological acclimatization mechanisms that may have been activated as a result of exposure to high temperature.

Friday, November 11, 2011

1:00pm

RSMAS campus, S/A 103

Pamela Harris
Administrative Assistant
Marine Biology and Fisheries
Rosenstiel School of Marine and Atmospheric Science
University of Miami
4600 Rickenbacker Causeway/SLAB-118
Miami, FL 33149
(305) 421-4176
fax - (305) 421-4600
pharris@rsmas.miami.edu
http://www.rsmas.miami.edu/academics/divisions/marine-biology-fisheries/