11th ICRS Abstract book - Nova Southeastern University

12-5
The Contribution Of Heterotrophy To Recovery From Bleaching in A Cnidarian-
Algal Symbiosis
Cameron JOHNSON* 1 , Tamar GOULET 1
1 Biology, University of Mississippi, University, MS
When elevated sea-surface temperatures cause the decoupling of cnidarian-algal
symbioses, leading to reductions in the densities of the host’s autotrophic endosymbionts,
some species of hosts will compensate by increasing heterotrophic feeding. In this study,
we experimentally bleached the symbiotic sea anemone Aiptasia pallida, and then either
starved (S) or fed (F) them during a 5 week period in order to see what effect
heterotrophy may have on recovery rates. In each of three repeated factorial experiments
(bleaching x feeding), half of the anemones were bleached (B) by elevating the
temperatures from 25°C to 32°C for one week (week 0), while non-bleached anemones
(NB) remained at 25°C. At the beginning of week 1, the bleached anemones were
returned to their normal temperature (25°C), and both B and NB anemones were evenly
divided among 2 additional treatments; starvation (SB and SNB), and fed (FB and FNB).
Zooxanthella densities were monitored using photographic analysis of reflected spectra,
which was calibrated with traditional bio-assays. Over the five week recovery period,
zooxanthella densities had increased in the SNB, SB and FB treatments, while the
zooxanthella densities in the FNB treatment remained constant. FB anemones had higher
recovery rates than SB anemones (P=0.0044). Additionally, SNB anemones had
significantly increased their zooxanthella densities (P=0.0331). These results suggest
heterotrophy may play an important role in the reestablishment of endosymbiont
populations after a bleaching event. Monitoring availability of plankton on a given reef
may therefore be another important factor in determining reef recovery from a bleaching
event.
12-6
Bleaching Effects On Scleractinian Coral Reproduction And Lipids Stores On The
Great Barrier Reef, Australia
Devin TU* 1 , Selina WARD 1
1 Centre for Marine Studies, University of Queensland, Brisbane, Australia
This study investigated if bleaching reduced coral fecundity and lipids in the Great
Barrier Reef. A secondary objective was to monitor the recovery rate of different coral
species by using fecundity and percentage of lipid tissue in coral as a biological indicator.
In addition, the study compared the severity of conditions in 1998 to the 2006 bleaching
periods on the reef-flat, based on temperature and weather data. Many studies on coral
bleaching focused on the 1998 bleaching event, which was considered the most severe
event on the Great Barrier Reef (GBR) in that century (Hoegh-Guldberg 1999, NOAA
1998, ICRS 1998). Few have studied the effects of the 2006 bleaching event that took
place in the southern Great Barrier Reef, Australia.
Results demonstrate bleaching may not always impact negatively on the physiology of
Acropora corals. Because of high variability of samples, there were no obvious
differences in fecundity between bleached and unbleached Acropora aspera and
Acropora millepore colonies based on percentage of reproductive polyps, and egg size
and egg number per polyps. We hypothesize that there were no significant differences in
lipid content between bleached and healthy corals in several species, however complete
results were not available at the time of this submission. Bleached corals may have
recovered before reproductive development. Basic in situ data suggests that summer
2006 conditions had abnormally high SSTs and light, but were not as elevated as 1998 at
Heron Island, Australia. Potentially, zooxanthellae loss in bleached coral was not
significant enough to reduce reproduction and lipids in Acropora species. This suggests
that 2006 bleaching event, unlike pervious events, did not have a major impact on corals.
Future research anticipates examining changes in chlorophyll a and zooxanthellae
densities to identify the relationship between the severity of bleaching and the
physiological impact on corals.
Oral Mini-Symposium 12: Reef Resilience
12-8
Thailand’s Coral Reefs Show Resilience in The Face Of Repeated Natural Stressors
Niphon PHONGSUWAN 1 , Anchalee CHANKONG 2 , Ronawon BOONPRAKOB 2 ,
Chaimongkol YAMARUNPATTHANA 1 , Sathika PAOKANTA 1 , Niphon PHONGSUWAN* 1
1 Marine and Coastal Resources, Phuket Marine Biological Center, Phuket, Thailand, 2 Marine
and Coastal Resources, Eastern Marine and Coastal Resources Research Center, Rayong,
Thailand
Thailand’s coral reefs in the Andaman Sea and Gulf of Thailand have been repeatedly affected
by both man-made and natural stressors over the last 20 years and yet have demonstrated
considerable resilience, in particular to natural perturbations. Natural stressors have included
Acanthaster infestations on the Andaman Sea coast in the mid 1980s; monsoon storms in 1986;
elevated sea water temperatures which led to extensive coral bleaching in 1991 and 1995 in the
Andaman Sea and in 1998 in the Gulf of Thailand; sea-level depression in 1997-98 and the
tsunami of 2004, both of which only affected reefs in the Andaman Sea. Repeated monitoring
of reefs in the periods 1988-1989; 1995-1998, in 2002 and again during 2006-2007 has revealed
remarkable recovery at sites affected by major bleaching in 1991 and 1995 with virtually no
impacts of minor localised bleaching noted at some sites in 2003, 2005 and 2007. The tsunami
of 2004 had a very limited effect on coral reefs of the Andaman Sea and where damage
occurred recovery is well underway at several locations. Such resilience appears to be restricted
to sites affected only by natural perturbations since many shallow reefs near the mainland,
which are chronically affected by siltation from land development, show little recovery.
12-9
Reefs, Resilience, And Refuges - Theoretical Considerations And Real-Life Examples
Bernhard RIEGL* 1 , Samuel PURKIS 1
1 National Coral Reef Institute, Nova Southeastern University, Dania, FL
If global changes impact reefs relatively uniformly, reefs with viable population dynamics will
be resilient but some, and maybe eventually all, corals may be forced into refuges. Resilience or
refuge character can be rooted in a more clement environment, adaptation to a harsh
environment, or readjustments of population (community) dynamics caused by modified
mortality-, survival- and recruitment-characteristics among species. Since many “traditional
reefal settings” (tropical reef crests and slopes) seem to be degrading, one may search for
sustainable dynamics in different habitats such as upwelling areas, deep reefs, or non-reefs.
While these habitats may harbor less species or individuals, their population dynamics may be
more advantageous. Even if the environments appear less suitable and the communities
depauperate, a positive net population growth identifies potential refuges. Also, pulse-instability
within dominance hierarchies may promote, or be a sign of, resilience. Opportunistic species
may be naturally prone to large swings in abundance and find refuge in meta-populations that
allow easy expansion or restriction of range. These species may adapt to only temporarily
dominate communities of more resilient species. Their adaptation to changed environments may
be less likely, since their reaction to stress would be population restriction and relocation into
other, presumably more favorable, habitats. Temporary local absence would be part of survival
strategy. Thus monitoring and assessment programs that primarily focus on coral cover, and not
the underlying dynamics, may misunderstand resilience or refuge value of a habitat – since the
present abundances are variable and may be misleading. Stochasticity of timing and distribution
of impacts may allow apparently rich, but increasingly maladapted communities to persist, and
lead to false conclusions regarding the nature of resilience or refuge. The presently richest areas
may not be those with highest survivability. We use examples from all oceans to illustrate our
point.
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