11th ICRS Abstract book - Nova Southeastern University

14-18
Meso-Scale Hydrodynamic Features And The Structure Of Great Barrier Reef Fish
Communities
Michael EMSLIE* 1 , Alistair CHEAL 1 , Angus THOMPSON 1 , Hugh SWEATMAN 1 ,
Severine CHOUKROUN 1 , Julian CALEY 1
1 Long Term Monitoring, Australian Institute of Marine Science, Townsville, Australia
Coral reef communities are among the most diverse and threatened ecosystems on Earth
leading to strident calls for urgent conservation measures, particularly the establishment
of extensive networks of Marine Protected Areas. As well as protecting a range of species
and habitats the reserves in a network should be linked by larval dispersal. The scale of
connectivity in reef environments is uncertain. Recent findings suggest that selfrecruitment
is much more common than originally thought, but the balance between selfrecruitment
and long distance dispersal is unknown. Here we use long-term monitoring
data from a significant section of Australia’s Great Barrier Reef that integrates the effects
of ecological processes on communities comprising more than 200 species of fishes over
more than a decade. This revealed previously undescribed, strong meso-scale structure of
GBR reef fish communities that were associated with major hydrodynamic features. We
postulate that these oceanographic features provide temporally stable barriers to
ecologically significant fish dispersal among seven major community types within 1200
kilometres of reef matrix. We also propose that self-recruitment can apply not only to
local scales but also has a regional context defined by oceanographic features.
14-19
Distribution, Abundance, And Genetics Of Corals Throughout The N. Gulf Of
Mexico: The World’s Largest Coral Settlement Experiment
Paul W. SAMMARCO* 1 , Amy D. ATCHISON 1 , Daniel A. BRAZEAU 2 , Gregory S.
BOLAND 3 , Steven B. HARTLEY 4 , Angela LIRETTE 1
1 Louisiana Universities Marine Consortium (LUMCON), Chauvin, LA, 2 Pharmaceutical
Genetics Laboratory, University of Buffalo, Buffalo, NY, 3 Minerals Management
Service, US Department of the Interior, New Orleans, LA, 4 National Wetlands Research
Center, US Geological Survey, Lafayette, LA
Thousands of oil/gas platforms in the N. Gulf of Mexico (GOM) provide hard substratum
where none existed prior to the Pleistocene. This has facilitated biogeographic extension
of Caribbean reef fauna in the GOM. We quantified the distribution and abundance of
scleractinian corals, hermatypic and ahermatypic, by surveying a total of 48 platforms
around the Flower Garden Banks (FGB) and along four transects across the continental
shelf: (T-I) Corpus Christi, TX, USA; (T-II) Lake Sabine, TX; (T-III) Terrebonne Bay,
LA; and (T-IV) Mobile, AL. We also assessed genetic affinities between coral
populations on the platforms and on the FGB to < 37 m using AFLPs. The western limit
for hermatypes was near the shelf edge in T-IV. The highest densities of hermatypes
were at the shelf edge, ~175-225 km offshore, in T-II&III. Some hermatypes were found
in T-IV - their eastern limit. Ahermatypes (Tubastraea coccinea, Oculina diffusa,
Phyllangia americana) were absent inshore and in the north-central region. A GIS
analysis of coral data, salinity, temperature, dis-O2, phosphate, and nitrate concentrations
indicated that lower salinities and temperatures are the major factors forcing community
structure. Hermatypic species diversity peaked near the FGB. Genetic analyses
performed on Madracis decactis revealed high self-recognition and site fidelity in M.
decactis in T-III&IV, with little recognition across the mouth of the Mississippi River. In
Tubastraea coccinea (invasive species), cross-recognition was higher between platforms
within a transect, but absent across the river mouth. The Mississippi River is an effective
biogeographic barrier to dispersal. These brooders are highly effective at colonizing
patchy habitats at this scale – moreso than the broadcasters Diploria strigosa and
Montastraea cavernosa - rare or absent over most of the Gulf, indicating less effective
dispersal capabilities.
Oral Mini-Symposium 14: Reef Connectivity
14-20
Genetic Connectivity Of Two Scleractinian Corals In Indonesia On Multiple Spatial
Scales
Craig STARGER* 1,2 , Paul BARBER 3 , Mark ERDMANN 4 , Andrew BAKER 5
1 Boston University Marine Program, Boston, MA, 2 Sackler Institute for Comparative
Genomics, American Museum of Natural History, New York, 3 Department of Biology, Boston
University, Boston University Marine Program, Boston, MA, 4 Indonesia Marine Program,
Conservation International, Denpasar, Bali, Indonesia, 5 Marine Biology and Fisheries,
Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL
The Indonesian seas are home to some of the most biologically diverse marine ecosystems on
Earth. They are also among the most threatened marine regions in the world. Studies focusing
on genetic connectivity can shed light on the natural history of threatened populations while
providing data that are useful to conservation managers. We have chosen the stony corals
Pocillopora damicornis and Seriatopora hystrix to test hypotheses on barriers to larval dispersal.
Microsatellite markers indicated that although coral populations are significantly differentiated
across Indonesia, the level of genetic structure is much lower than that seen in other taxa. Gene
flow and immigration estimates indicate that most populations are primarily self-seeding,
however long distance dispersal is also occurring, maintaining connectivity across the entire
Indonesian archipelago. A closer examination of connectivity on a regional scale was performed
in the Bird’s Head Seascape of West Papua, where conservation managers are currently
incorporating genetic data into the design of marine protected area networks. Similar to the
country-wise assessment, there do not appear to any major barriers to dispersal within the
Bird’s Head region. However, populations of both coral species are still primarily self-seeding,
and the majority of genetic diversity is explained by within-population variation. A Bayesian
assignment test and jackknifing approach were applied to examine the effect of population
decline on overall connectivity in West Papua. Self-recruitment nearly always increased when
populations were removed from the estimation of overall connectivity. This high sensitivity of
the entire system to the decline of any individual population suggests that a network of marine
protected areas covering a large geographic range is the best conservation strategy for
maintaining connectivity in the Bird’s Head Seascape. In general, coral populations exhibit
much lower genetic structure on a regional scale than other taxa.
14-21
Routine And Rare Genetic Connections in Corals Off Northwest Australia
Jim UNDERWOOD* 1 , Luke SMITH 1 , Madeleine VAN OPPEN 2 , James GILMOUR 1
1 Australian Institute of Marine Science, Perth, Australia, 2 Australian Institute of Marine
Science, Townsville, Australia
The extent to which marine populations are connected by larval dispersal has profound
influences on the ecology and evolution of species; from the short-term regulation and survival
of communities to the long-term processes of adaptation to environmental change and
speciation. Here, we use microsatellite DNA markers to quantify the genetic structure and infer
the ecologically and evolutionarily relevant scales of dispersal of broadcast spawning coral
(Acropora tenuis) and a brooding coral (Seriatopora hystrix) from isolated reefs off northwest
Australia. For the brooder, whose larvae are competent to settle immediately after release,
significant genetic subdivision over scales of tens of metres indicated that the majority of larvae
recruit to within 100 m of their natal colony. However, occasional dispersal over tens of
kilometres supplemented this localised recruitment, with putative source and sink dynamics
associated with levels of disturbance and recovery from a recent and catastrophic coral
bleaching. Additionally, prodigious genetic differences were detected among reef systems,
indicating that dispersal over multiple generations of S. hystrix larvae over 100s of kilometres is
rare. In contrast to the brooder, the broadcast spawned larvae of A. tenuis require about three
days before competency is obtained, and as expected, levels of subdivision were an order of
magnitude smaller compared with S. hystrix. However, significant differences were detected
between sites separated by less than ten kilometres, providing evidence that these systems, reefs
and some reef patches are predominantly self-seeding. However, genetic divergence between
the coastal and offshore zones was greater than expected by the geographic separation of
systems, indicating that connectivity between these zones via transport of A. tenuis larvae on
oceanic currents occurs rarely. The primary management implication is that short-term recovery
after severe disturbance requires the input of larvae from viable coral communities within
kilometres to a few tens of kilometres away.
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