[Coral-List] Ideal Temperatures for Coral growth
douglasfennertassi at gmail.com
Tue Sep 9 19:14:00 EDT 2014
I believe that NOAA's "Coral Watch" program, which uses satellite SST
data to predict bleaching events, uses a bleaching threshold of 1 deg C
above the local maximum monthly mean summer high sea surface temperature.
Time is also involved, as stress builds over time, and Coral Watch uses a
4 "Degree Heating Weeks" (DHW) threshold for expecting some bleaching in
more sensitive corals, and 8 DHW for more extensive bleaching. See
They constantly try to improve their ability to predict bleaching events.
But the fact that the thresholds differ by location, and can be predicted
from the local summer high temperatures, indicates some sort of adjustment
to local conditions.
Of course, as pointed out, each species at a single location has a
different threshold. This is shown most clearly in a report by Done et al.
to TNC, entitled "Testing bleaching resistance hypotheses for the 2002
Great Barrier Reef bleaching event" in Figure 15. Individual species
within genera and families had a wide range of response level during that
bleaching event, in this very extensive study. The report is listed on
Google Scholar and can be downloaded there open access. Different colonies
within species vary in the intensity of their bleaching response as well,
as do different parts of colonies.
In general, many poikilotherms, which includes invertebrates like
coral, have metabolism that increases with increasing temperature, up to a
maximum. I don't remember the exact equation, but I seem to remember a
variable "Q" that was a measure of how fast it rose with temperature.
Along the rising limb, changes in metabolic rate are generally reversible
(though at very low temperatures they probably aren't). Above the peak,
however, metabolic rate decreases can be abrupt and are likely not to be
reversible, they are due to damage to the organism by the high temperature.
Probably mostly due to denaturing of proteins. Essentially, the animal is
being cooked. Coral bleaching up to a point is reversible (though there
are lingering effects such as reduced reproduction), but beyond that may be
a symptom of such a process. So ideal temperatures for a coral are below
that maximum, and as others have pointed out, there could be problems
approaching that peak temperature as well.
Lough (2008) shows changes in rate of extension, skeletal density, and
calcification with temperature in massive *Porites*, below the point of
maximum metabolism. The Lough paper is also available through Google
Scholar open access.
Lough, J.M. 2008. Coral calcification from skeletal records revisited.
Marine Ecology Progress Series 373: 257-264.
On Tue, Sep 9, 2014 at 9:05 AM, Wiedenmann J. <
joerg.wiedenmann at noc.soton.ac.uk> wrote:
> Dear all,
> I think it is worth to highlight the corals of the Persian/Arabian Gulf in
> this context: The species there are considered to represent mainly a subset
> of the Indian Ocean community including several cosmopolitan species.
> Despite being located close to the northern margin of reef distribution,
> these communities endure regular summer temperatures of 35 deg. C for
> several weeks (and cold temperatures in winter). So, the origin of the
> corals plays certainly a defining role in shaping the temperature optimum..
> Also, evidence is accumulating that the temperature tolerance is shaped by
> the nutrient environment.
> A few references:
> Sheppard, C. R. C., Price, A. R. G. & Roberts, C. J. Marine Ecology of the
> Arabian Area. Patterns and Processes in Extreme Tropical Environments.
> (Academic Press, London., 1992).
> Coles, S. L. Coral species diversity and environmental factors in the
> Arabian Gulf and the Gulf of Oman: A comparison to the Indo-Pacific region
> (2003). Atoll. Res. Bull., J1-J19.
> Riegl, B. M., Purkis, S. J., Al-Cibahy, A. S., Abdel-Moati, M. A. &
> Hoegh-Guldberg, O (2011). Present limits to heat-adaptability in corals and
> population-level responses to climate extremes. PLoS One 6, e24802,
> Hume B, D’Angelo C; Burt J, Baker A, Riegl B, Wiedenmann J (2013).. Porites
> lobata from the Persian/Arabian Gulf as model for heat-stress tolerant
> corals. Mar Pollut Bull (Special Issue: Coral Reefs of the Arabian/Persian
> Gulf). Mar. Poll. Bull. 72, 313-322
> D’Angelo C, Wiedenmann J (2014) Impacts of nutrient enrichment on coral
> reefs: new perspectives and implications for coastal management and reef
> survival. Current Opinion in Environmental Sustainability 7:82-93.
> Best wishes,
> Prof. Dr. Jörg Wiedenmann
> University of Southampton, Waterfront Campus, NOCS
> Southampton, SO14 3ZH, U.K.
> email: joerg.wiedenmann at noc.soton.ac.uk
> Mobile: +44 (0)7912564356
> Projects on thermal stress tolerance of corals:
> Impact and Outreach:
> Coral-List mailing list
> Coral-List at coral.aoml.noaa.gov
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