SEMINAR: MBF602 - Phillip Gillette - Friday 4-29-11, 1pm S/A 103

["Phillip Gillette" <pgillette@rsmas.miami.edu>]

Intraspecific genetic variability in temperature tolerance in the coral
Pocillopora damicornis: Effects on growth, photosynthesis and survival

Coral reef ecosystems worldwide are in decline, with thermal stress
representing one of the most significant threats. Acute exposure to
extreme high (>32 ºC) and low (<20 ºC) temperatures usually leads to coral
bleaching and/or mortality.  However, effects are characteristically
variable between colonies, and it is not yet known to what extent this
variability is due to differential sensitivity of coral genotypes/clones.
I investigated how exposure to 4 different temperatures (20, 26, 30 and
32ºC) affected 6 (putatively) different genets of Pocillopora damicornis
from Panama that had been maintained under laboratory conditions for
several years at 26ºC prior to experimentation.  Treatment temperatures
were ramped at a rate of 0.5ºC day-1, determined by preliminary
experimentation as an optimal rate to distinguish thermal response.  
There was a significant reduction (p<0.001) in growth between the control
(26ºC) and all other temperature treatments, as well as a significant
difference in growth rate between colonies (p<0.001).  There was 100%
mortality in all genets in the 32ºC treatment by week 6, and partial
mortality of some genets in the 20 and 30ºC treatments by week 8. 
Comparison of combined growth, photosynthesis and mortality data suggest
that fast-growing coral genets may have a narrow thermal window for
optimal growth, while slower-growing corals have a relatively wider
window. Verification of the genetic identity of these reef coral symbioses
(using microsatellites for the coral host and quantitative real-time PCR
for the algal symbiont community) is currently underway. These different
growth strategies emphasize the role of the coral host in determining
thermotolerance, and may help restoration efforts designed to increase the
resilience of coral reefs to climate change, by identifying coral
genotypes best suited to the prevailing thermal environment.


Phillip Gillette
B.S. Marine Science, University of Miami, 2004
Entered part-time Master?s Program Fall 2006
Advisor: Dr. Andrew Baker



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