11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 25: Predicting Reef Futures in the Context of Climate Change
25-29
Prevalence Of Background Populations Of An Opportunistic Symbiodinium Among
Caribbean Coral Communities.
Robin SMITH* 1 , Todd LAJEUNESSE 1
1 Florida International University, Miami, FL
The ecology of Symbiodinium D1a in Caribbean corals is different than other symbionts.
Distribution surveys indicate that the prevalence of Symbiodinium D1a may increase on
reefs experiencing irradiance and/or thermal disturbance. Some species within this
lineage demonstrate physiological tolerance of irradiance fluctuations while others
display increased thermal tolerance. It is therefore important to delineate the natural
distribution patterns of this species to gain a better understanding of the acclimation
and/or adaptation potential of coral reefs. The fine spatial distribution of Symbiodinium
D1a in a wide diversity of coral taxa from Caribbean reefs was evaluated using real-time
PCR to detect it's presence as a background population. For comparison, host
communities in Hawaii and the eastern Pacific were analyzed. Results show that these
Symbiodinium spp., namely D1a, exist in many corals in the absence of environmental
stress; often in low abundance and below the detection limits of conventional
fingerprinting techniques. These findings suggest that the rise of population shifts to Dtype
Symbiodinium following environmental disturbance are most readily explained as
the disproportionate growth of resident Symbiodinium D populations that otherwise exist
at low concentrations. Symbiodinium D1a appears to be a globally distributed hostgeneralist
capable of associating with most coral genera as a background population
during periods of environmental stability with the potential to become opportunistically
dominant during periods of physiological stress.
25-30
Symbiont Specificity Within And Among Soft Coral Genera During The 1998 Gbr
Mass Coral Bleaching Event
Tamar GOULET* 1 , Todd LAJEUNESSE 2 , Katharina FABRICIUS 3
1 Biology, University of Mississippi, University, MS, 2 Biology, Pennsylvania State
University, University Park, PA, 3 Australian Institute of Marine Science, Townsville,
Australia
Coral bleaching (the loss of symbiotic intracellular dinoflagellates, Symbiodinium spp.) is
not restricted to scleractinian corals but also occurs in soft corals. In the 1998 mass coral
bleaching event, soft coral species were severely affected, with considerable variability in
bleaching within and among soft coral taxa. In the midst of the bleaching event on the
central Great Barrier Reef (GBR), tissue samples were taken from bleached and
unbleached colonies representative of 17 soft coral genera in the order Alcyonacea
(Octocorallia: Cnidaria). The Symbiodinium types in these samples were determined
using PCR-denaturing gradient gel electrophoresis (DGGE) fingerprinting analysis of the
internal transcribed spacer (ITS) regions 1 and 2. Alcyonaceans from the GBR exhibited
a high degree of symbiont specificity. Nine different Symbiodinium clade C types
occurred. Clade B (B1n and B36) symbiont types were only recorded from Nephthea sp.
and a rare clade D type (D3) was found only associated with Clavularia koellikeri.
Symbiodinium clade populations were homogenous in all but one colony. Colonies with
a bleached appearance hosted symbiont types that were genetically indistinguishable
from those in non-bleached conspecifics. These data suggest that parameters other than
the resident endosymbionts play an important role in determining bleaching susceptibility
within and among soft coral species.
25-31
Coral Physiology: The Interaction Between Symbiodinium Genotype And Environment
Jos MIEOG* 1 , Madeleine VAN OPPEN 2 , Ray BERKELMANS 2 , Bette WILLIS 3 , Wytze
STAM 1 , Jeanine OLSEN 1
1 University of Groningen, Haren, Netherlands, 2 Australian Institute of Marine Science,
Townsville, Australia, 3 James Cook University, Townsville, Australia
The influence of different Symbiodinium types on the physiology of corals has been difficult to
study as coral host x environment interactions interfere when comparing different coral species
or populations harboring different algal types. To address this, offspring of the same Acropora
millepora parental colonies were infected with three different types of algal symbionts found at
the Great Barrier Reef (GBR) of Australia: one rare clade A-type found mostly in cooler areas,
one common, generalist clade C-type, and one clade D-type that is common in warm and turbid
habitats. All groups were grown out at a warm, turbid (Magnetic Island) and a cold, clear
(Keppels Islands) inshore location of the GBR. Their growth and survival was monitored and
after seven months their heat-tolerance was determined.
At Magnetic Island, C-corals grew 2-3 times faster and survived 2-4 times better than D-corals.
Corals with A either died here or changed to D within the first two months. At the Keppels
Islands, growth of C-corals was only slightly better compared to D-corals, while A-corals
showed the slowest growth. D-corals survived about 2 times better here than A- or C-corals. Acorals
were highly susceptible to heat-stress, while D-corals were the most heat-tolerant at both
locations.
This study demonstrates that physiological characteristics can differ strongly between
conspecific corals in the same environment harboring different algal types, and that changes in
the dominant symbiont type of a coral may represent a trade-off (e.g. growth vs. heat-tolerance).
The relative fitness of each coral-algal association (as estimated from growth, survival and heattolerance),
however, was found to vary with environmental factors.
25-32
Can Hosting Different symbiodinium spp. Lead To Thermal Adaptation Within
pocillopora Verrucosa Around Guam?
Lisa CHAU* 1 , Robert ROWAN 1
1 Marine Laboratory, University of Guam, Mangilao, Guam
During moderate bleaching events on Guam coral reefs, caused by increased irradiance and sea
temperatures, corals hosting Symbiodinium genotype C typically bleach, while corals hosting
Symbiodinium D do not. Symbiodinium D corals are thought to be adapted to high temperatures,
whereas Symbiodinium C corals, though more common, are thought to be temperature-sensitive.
In this study corals were challenged by reciprocally transplanting them between two reefs that
varied in mean temperature by 0.5oC. This temperature difference was not extreme enough to
cause bleaching but provided enough stress to stimulate a potential change in zooxanthellar
community structure. In this year-long field study, transplanted colonies of Pocillopora
verrucosa with known zooxanthellar genotypes (C, D, or a mixture of C and D) were sampled
periodically and examined for genotypic changes in their zooxanthellar populations. Results
from PCR and restriction fragment length polymorphisms (RFLPs) showed that 40% of
transplants retained the same proportion of genotypes after transplantation to a different
temperature regime. However, 20% of corals from both sites changed genotypes from C to D
or D to C, and 30% remained mixed proportions of C and D throughout the experiment. Ten
percent of our transplants died during the experiment; all contained genotypes that were mixed
or had shifted. We showed that Symbiodinium populations within some corals have the ability
to vary their symbiont community structure with changing sea temperatures. However, this
mechanism of change through adaptation, shuffling, or recombination is unknown and poorly
studied. The coral-algal symbiosis is a dynamic system that requires more investigation to
elucidate the mechanisms of change so that we can comprehend the adaptability of corals to
increasing sea surface temperatures.
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