11th ICRS Abstract book - Nova Southeastern University

14.466
South East African, High-Latitude Coral Communities, A Canary For Western
Indian Ocean Coral Reefs?
Angus MACDONALD* 1 , Michael SCHLEYER 1 , Jennifer LAMB 2
1 Oceanographic Research Institute, Durban, South Africa, 2 University of KwaZulu-Natal,
Durban, South Africa
Coral reefs are important to coastal communities throughout the western Indian Ocean
(WIO). Coral reef health is deteriorating in this region and resources associated with
reefs are thus dwindling. In order that reef resources are sustained for future generations,
intervention, in the form of management, is necessary. Effective management of human
behaviour associated with coral reef use must incorporate realistic information on coral
population dynamics. In this study, stony coral population diversity and relatedness were
investigated at several scales using molecular methods. Genetic diversity may be used as
a proxy to gauge both the population dynamics and resilience of a community. Genetic
variability was thus measured in two corals with different reproductive modes, larval
dispersal capabilities and life history strategies. The corals Acropora austera and
Platygyra daedalea were chosen as molecular markers were available for these species.
We used intron regions in the nuclear DNA of A. austera and the ITS region of the
ribosomal DNA of P. daedalea to compare population genetic variability and to separate
phylogenetic history from phylogeography. There appears to be regular genetic exchange
between populations of both corals in the region. The local oceanography would indicate
that northern reef systems may be considered source populations and southern systems,
sink populations. This is corroborated by greater genetic diversity in the north.
Considering this information, southern reef coral genetic diversity may be a valuable
gauge of reef deterioration in the true accretive coral reef systems in the north.
14.467
Using A Multi-Locus Technique To Assess Population Genetic Structure And Infer
Dispersal Patterns in Adult Populations Of The Temperate Coral Oculina
Arbuscula.
Daniel BRAZEAU* 1 , Daniel GLEASON 2
1 Pharmaceutical Sciences, University at Buffalo, Buffalo, NY, 2 Department of Biology,
Georgia Southern University, Statesboro, GA
The population structure of adult corals is determined by the genetic diversity of the
settling larvae each season and subsequent recruit survivorship. On hard-bottom reefs of
the southeastern U.S., the broadcast spawning temperate coral, Oculina arbuscula, exist
within a patchwork of rocky outcrops surrounded by large expanses of soft substrate.
These “live bottom” reefs provide topographic complexity and serve as critical habitat for
fish and invertebrate communities. In this paper we employ highly polymorphic genetic
markers to assess the genetic structure of adult populations of O. arbuscula on 5 reefs
within the vicinity of Gray’s Reef National Marine Sanctuary off Georgia, USA.
Juveniles were also collected from recruitment plates at one of the sites and assessed for
likely origin. A total of 143 adults and 28 juveniles were studied using 85 polymorphic
AFLP markers. The overall frequency of markers was 0.23 (SD = 0.17), ranging from
0.05 to 0.81. Two assignment-based analyses (AFLPOP and Structure) were used to
assess the genetic heterogeneity of adults and recruits. Both AFLPOP and Structure
showed significant structure among adult populations though there was no relationship
between allele frequency divergences between sites and geographic distance. Genetic
heterogeneity among adult populations was sufficient to allow either analysis to correctly
assign randomly chosen individuals back to the populations they were collected from
with probabilities from 41% to 72%. Based upon adult frequencies, AFLPOP and
Structure identified the natal reef as the most likely source for 57% and 61% respectively
of the juveniles. The next site with the highest probabilities of recruit origin accounted
for 21% to 25% of the recruits. This site was not the next nearest site to the reef where
the juveniles were collected. These limited data suggest significant structure among adult
populations for this broadcast spawning species perhaps driven in part by self seeding.
Poster Mini-Symposium 14: Reef Connectivity
14.468
Genetic structure of the giant barrel sponge Xestospongia muta in Northern Caribbean
Susanna LOPEZ-LEGENTIL* 1 , Joseph PAWLIK 2
1 Center for Marine Science, University of North Carolina Wilmington, Wilmington, NC,
2 Center for Marine Science, University North Carolina Wilmington, Wilmington, NC
Sponges play key functional roles in coral reef ecosystems. In the Caribbean, the giant barrel
sponge, Xestospongia muta, is a dominant reef constituent. In recent years reports of sponge
bleaching, disease and subsequent mortality have alarmingly increased. Population recovery
may strongly depend on colonization capabilities of the affected species. However, little is
known about population structure and gene flow among sponge populations. The mitochondrial
gene Cytochrome Oxidase subunit I (COI) fragment amplified with Folmer’s universal primers
is frequently used for population genetic and phylogeography studies in marine taxa, but this
fragment presents very low nucleotide variability in sponges. In this study, we tested the
usefulness of the I3-M11 partition of COI to determine the genetic structure of Xestospongia
muta in the Northern Caribbean. 116 sequences of 544 bp were obtained corresponding to four
haplotypes. The nucleotide diversity found for the I3-M11 partition (π = 0.00386) was higher
than the one found for Folmer’s, indicating better resolution at lower taxonomic levels. Pairwise
tests for genetic differentiation among geographic locations based on FST values showed
significant genetic divergence between most populations. However, this genetic differentiation
was not due to isolation by distance. While limited dispersal may have led to differentiation
among some of the populations, the patterns of genetic similarity appear to be most strongly
related to patterns of ocean currents. As determined for other marine invertebrates, our results
suggest that geographic barriers play a major role in sponge colonization in the Caribbean and
need to be considered in existing and future plans for management and conservation of coral
reef ecosystems.
14.469
Pelagic Larval Durations And Settlement Size in The Western Atlantic lutjanus Spp.
Benjamin VICTOR* 1
1 Ocean Science Foundation, Irvine, CA
The pelagic larval duration for all of the eight shallow-water snappers from the Western
Atlantic is three to four weeks with remarkably little variation. Divergent reports of PLDs in the
literature probably reflect different interpretations of the otolith microstructure near the center
and at the settlement mark. I estimated larval durations from the otoliths of settling larvae from
several sites in the Caribbean. Both inter and intra-specific variation in PLD was very low,
especially considering some inevitable counting error. In contrast to the consistency in PLD, the
size at settlement varied greatly between species, with grey snappers settling at particularly
small sizes (10-15 mm SL) and mahogany snappers settling at the largest sizes (17-22 mm SL).
There was less variation in size at settlement within species. Given the consistency of the larval
duration, the variation in size at settlement is due primarily to varying growth rates while
pelagic. This indicates that there are species-specific growth trajectories in the open ocean that
likely reflect species-specific larval ecology amongst the snappers in the region.
380