[Coral-List] New manuscript on coral bleaching available

Cheryl Woodley - NOAA Federal cheryl.woodley at noaa.gov
Sat Dec 14 16:58:49 EST 2013

Dear Coral  List Members
I'd like to draw your attention to our recently published paper in PLOS One..
Downs, CA, McDougal, KE, Woodley CM, Fauth JE, Richmond RH, et al. (2013)
Heat-Stress and Light-Stress Induce Different Cellular Pathologies in the
Symbiotic Dinoflagellate during Coral Bleaching. PLoS ONE *(12): e77173.


Coral bleaching is a significant contributor to the worldwide degradation
of coral reefs and is indicative of the termination of symbiosis between
the coral host and its symbiotic algae (dinoflagellate; *Symbiodinium* sp.
complex), usually by expulsion or xenophagy (symbiophagy) of its
dinoflagellates. Herein, we provide evidence that during the earliest
stages of environmentally induced bleaching, heat stress and light stress
generate distinctly different pathomorphological changes in the
chloroplasts, while a combined heat- and light-stress exposure induces both
pathomorphologies; suggesting that these stressors act on the
dinoflagellate by different mechanisms.  Within the first 48 hours of a
heat stress (32°C) under low-light conditions, heat stress induced
decomposition of thylakoid structures before observation of extensive
oxidative damage; thus it is the disorganization of the thylakoids that
creates the conditions allowing photo-oxidative-stress. Conversely, during
the first 48 hours of a light stress (2007 μmoles m-2 s-1 PAR) at 25°C,
condensation or fusion of multiple thylakoid lamellae occurred coincidently
with levels of oxidative damage products, implying that photo-oxidative
stress causes the structural membrane damage within the chloroplasts.
Exposure to combined heat- and light-stresses induced both
pathomorphologies, confirming that these stressors acted on the
dinoflagellate via different mechanisms. Within 72 hours of exposure to
heat and/or light stresses, homeostatic processes (e.g., heat-shock protein
and anti-oxidant enzyme response) were evident in the remaining intact
dinoflagellates, regardless of the initiating stressor. Understanding the
sequence of events during bleaching when triggered by different
environmental stressors is important for predicting both severity and
consequences of coral bleaching.
Cheryl M. Woodley, Ph.D.
Coral Health and Disease Program

Center for Coastal Environmental Health and Biomolecular Research
Hollings Marine Laboratory
331 Fort Johnson Rd
Charleston, SC 29412
843.762.8862 Phone
843.762.8737 Fax
cheryl.woodley at noaa.gov

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