[Coral-List] starvation?

Andrew Baird andrew.baird at jcu.edu.au
Fri Jun 2 10:04:46 EDT 2006

Dear Corallist

The following reference has some of the only data on species level rates of
mortality on the GBR. Some die fast, some slow, possibly related to
differing levels of heterotrophy and there was considerable variation
between individuals in rates of recovery.

Baird AH, Marshall PA (2002) Mortality, growth and reproduction in
scleractinian corals following bleaching on the Great Barrier Reef. Mar
Ecol Prog Ser 237: 133-141

ABSTRACT: Despite extensive research into the coral bleaching phenomena
there are very few data which examine the population biology of affected
species. These data are required in order to predict the capacity of corals
to respond to environmental change. We monitored individual colonies of
4common coral species for 8 mo following historically high sea-surface
temperatures on the Great Barrier Reef in 1998 to compare their response
to, and recovery from, thermal stress and to examine the effect of
bleaching on growth and reproduction in 2 Acropora species. Platygyra
daedalea and Porites lobata colonies took longer to bleach, longer to
recover and longer to die. In contrast, Acropora hyacinthus and A.
millepora colonies bleached quickly and most had either recovered, or died,
within14 wk of the initial reports of bleaching. Whole colony mortality was
high in A. hyacinthus (88%) and A. millepora (32%) and partial mortality
rare. In contrast, most colonies of P. daedalea and P. lobata lost some
tissue and few whole colonies died. The mean proportion of tissue lost per
colony was 43 ± 6.6 % and 11 ± 1.1 % respectively. Consequently, observed
hierarchies of species susceptibility will depend critically on the time
since the onset of stress and must consider both whole and partial colony
mortality. Colony mortality was highly dependent on visual estimates of the
severity of bleaching but independent of size. Growth rates of Acropora
colonies were highly variable and largely independent of the severity of
bleaching. A. hyacinthus was more susceptible to bleaching than A.
millepora with 45% of surviving colonies gravid compared to 88%. High
whole-colony mortality combined with a reduction in the reproductive output
of surviving Acropora suggests that recovery to former levels of abundance
is likely to be slow.
Dr Andrew H. Baird, Senior Research Fellow ARC Centre of Excellence for
Coral Reef Studies, Department of Marine Biology, James Cook University,
Townsville, Qld, 4811, Australia. Tel + 617 47814857, Fax:  + 617 47251570,
email: andrew.baird at jcu.edu.au 


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