11th ICRS Abstract book - Nova Southeastern University

14.432
Gene flow of Symbiodinium on the Great Barrier Reef is limited and primarily
mediated by sea circulation patterns
Emily HOWELLS* 1 , Madeleine VAN OPPEN 2 , Bette WILLIS 1
1 Australian Research Council Centre of Excellence and School of Marine and Tropical
Biology, James Cook University, Townsville, QLD, Australia, 2 Australian Institute of
Marine Science, Townsville, QLD, Australia
The resilience of Symbiodinium types harboured by corals depends on population genetic
diversity and inter-reef connectivity. This study presents genetic analyses of Great Barrier
Reef (GBR) populations of clade C Symbiodinium hosted by the alcyonacean coral,
Sinularia flexibilis. Allelic variation at 4 microsatellite loci demonstrated that 12 reef
populations of Symbiodinium were genetically differentiated at spatial scales from 16 to
1,300 km (mean pairwise ΦST = 0.21). For 11 of 12 populations, genetic differentiation
was strongly related to geographic distance between populations (r = 0.77), indicating
that gene flow is restricted for Symbiodinium hosted by S.flexibilis on the GBR. Patterns
of population structure reflect longshore circulation and limited cross-shelf mixing on the
GBR, suggesting that passive transport by currents is the primary mechanism by which
low levels of dispersal occur in Symbiodinium types acquired horizontally. Genetic
diversity of Symbiodinium populations was on average 1.5 to 2 times higher at mid to
outer shelf reefs than on inner-shelf reefs. Patterns of genetic diversity were consistent
with immigration of Symbiodinium genotypes to the northern GBR which have been
spread to mid and outer shelf reefs via longshore currents. Additional factors that may
have shaped cross-shelf differences in diversity are historical sea-level fluctuations and
recent bleaching events. Symbiodinium populations hosted by S.flexibilis are suggested to
be susceptible to losses of genetic diversity, such as those likely to occur with increased
threats to coral reefs. There is little opportunity for lost genetic diversity to be replenished
by migration or for beneficial alleles potentially involved in adaptive processes to be
spread beyond local reefs.
14.433
Testing Natural Markers in Otoliths From Known-Origin Larvae Of Coral Reef
Fish
Michael BERUMEN* 1 , Harvey WALSH 1 , Serge PLANES 2 , Geoffrey JONES 3 , Simon
THORROLD 1
1 Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, 2 Ecole
Pratique des Hautes Etudes, Université de Perpignan, Perpignan, France, 3 ARC Centre of
Excellence for Coral Reef Studies, James Cook University, Townsville, Australia
Analysing the chemical composition of otoliths from fish is a commonly employed
technique to search for a signal indicative of a particular habitat at some point in a fish’s
environmental history. In connectivity studies, this method frequently runs into a problem
as the origin of most larval fish is unknown, reducing the ability of the technique to
definitively identify a source location among locations with subtle water mass
differences. Following an intensive self-recruitment study on an isolated island in Kimbe
Bay, Papua New Guinea, genetic parentage analysis (genotyping) confirmed the origin of
about 50% of 110 new recruits of the orange clownfish, Amphiprion percula, on Kimbe
Island. Known-origin larvae were those confirmed to have been spawned by parents on
Kimbe Island, while the remainder would have been spawned by parents on other reefs
(with the nearest reef ~10km away). Using standard otolith composition analyses (laser
ablation inductively coupled mass spectrometry, LA-ICPMS), we were able to compare
the known-origin (self-recruiting) larvae against those known to have originated from
reefs at least 10km away, testing for differences in elemental composition of their
otoliths. We will discuss these findings and the implications for future studies attempting
to use natural markers in studies of connectivity in coral reef fish populations.
Poster Mini-Symposium 14: Reef Connectivity
14.434
Temporal Variations of Mangroves, Soft Bottoms and Coral Reefs Shorefishes
Assemblages within a Lagoon Seascape, New Caledonia
Laurent WANTIEZ* 1 , Michel KULBICKI 2
1 University of New Caledonia, Noumea, New Caledonia, 2 IRD, Perpignan, France
The shorefishes of St Vincent Bay (New Caledonia) were studied on a monthly basis during one
year in three adjacent habitats: coral reefs, mangroves and soft bottoms. The objectives were to
analyze the overlap and compare the temporal variations of the fish communities between the
three habitats. Coral reefs were sampled using visual census, mangroves using gill nets and fyke
net, and soft bottoms using a shrimp trawl and a fish trawl. In total, 485 species were censused
in all three habitats. The species richness was significantly higher on coral reefs (300 species)
than on soft bottoms (200 species) and in the mangroves (126 species). The number of families
was not significantly different between habitats. Only 16 species and 19 families were observed
in all three habitats. The species overlap was higher for mangroves, which shared 61.9% of its
species with the other habitats, than soft bottoms (50.0%) and coral reefs (29.3%). The
similarity (Kulczinski Index) was higher between mangroves and soft bottoms (Ik=34.3%) than
between soft bottoms and coral reefs (Ik=23.1%), mangroves and coral reefs being the most
different (Ik=16.7%). The monthly variations of the species richness were significantly different
between habitats and the monthly variations of the standardized density and biomass indices
were not correlated, indicating different temporal patterns between habitats. The monthly
variations of the number of overlapping species between habitats were not significant. Only
four species were successively present as juveniles in the mangroves and as adults on the soft
bottoms. Our results suggest that the links between the coral reefs and the mangroves, and to a
lower extend the coral reefs and the soft bottoms, are limited and lower than in the Caribbean.
14.435
Are Montastraea Faveolata Populations Connected Along The Mesoamerican Barrier
Reef System?
Isabel PORTO* 1 , Camilo SALAZAR 2 , Tonya SHEARER 3
1 Department of Biology, Universidad de los Andes, Bogota, Colombia, 2 Department of
Biology, Genetics Institute, Universidad de los Andes, Bogota, Colombia, 3 School of Biology,
Georgia Institute of Technology, Atlanta, GA
For benthic sessile coral reef dwellers, the larval stage is very important for dispersal. There has
been controversy between larval retention versus long distance dispersal as the main life history
strategy for marine organisms. There is limited information concerning coral reef larvae
dispersal in the Caribbean where coral reefs are widespread and sustain a huge diversity of
marine organisms. Understanding levels of biological connectivity between and among reefs
has important ecological and management implications. It is necessary to determine the
potential resources of reef recruits in order to successfully create Marine Protected Areas
(MPA) and assess the efficacy of already established MPAs. Montastraea faveolata has
widespread distribution on Caribbean reefs and is considered one of the major reef-builders in
the area. Using eight variable microsatellite loci, the population structure of M. faveolata was
discerned to answer the following questions with regard to the Mesoamerican Barrier Reef
System: What is the biological connectivity among M. faveolata over time and space? Have
larvae sources or patterns of connectivity changed over time? Are M. faveolata generally selfseeding
or dependent on non-local larval source populations? Locations included in this
analysis are Mexico (Puerto Morelos and Cozumel), Belize (Glover’s reef, Columbus reef,
Turneffe and Ambergris), Guatemala (Punta Manabique) and Honduras (Cayo Cochinos,
Roatan and Bahia Cortes).
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