11th ICRS Abstract book - Nova Southeastern University

12.413
Spatial Patterns Of Stony Coral Population And Community Demographics As An
Indicator Of Resistance And Tolerance To Ambient Environmental-And
Anthropogenic-Induced Stress On South Florida Reefs.
Rowena GARCIA* 1 , Philip KRAMER 1
1 The Nature Conservancy, Sugarloaf Key, FL
The existence of natural refuges to climate stress has been widely speculated and
anecdotally observed, but there are few quantitative ecosystem-wide studies documenting
their distribution. A synoptic study of surviving stony coral population demographics was
conducted to examine possible coral bleaching refuges within the south Florida reef
system. A two-stage, spatially balanced probabilistic survey was designed to sample
representative coral populations from a large domain extending 500 km from Martin
County, Florida to the Lower Florida Keys. Stony corals (≥4 cm in diameter) were
visually assessed within two belt transects (1 x10m) located randomly within a Reef
Primary Unit (RPU), defined spatially as a 200 x 200m cell. Sampled RPU’s were
randomly chosen each year within 21 strata (sub-regions and cross shelf zones) using
digital reef maps (0-30 m) delineating all possible RPU’s (33,949). During the three years
(2005-2007), a total of 21,490 colonies were sampled within 431 primary sites
representing approximately 1% of the total reef area. Coral density and coral size of
common species, such as Siderastrea siderea, were positively correlated across all strata
but disproportionately distributed. Inshore and mid-channel patch reefs representing 7 of
the strata had significantly higher coral densities and size-frequency distributions were
skewed towards larger sizes compared to offshore and fore reef zones and all reef zones
north of Miami. Corals in these inshore zones may have coped better with stress during
the 1998 and 2005 bleaching years because of the highly variable environmental
conditions (temperature, visibility) that persist year round, although several other factors
(intrinsic and extrinsic) are currently also being tested. The spatial framework resulting
from this study gives resource managers an immediate tool to incorporate representative
demographics of resistant stony coral population into zoning schemes that may improve
ecosystem-wide adaptation to future climate stress.
12.414
Bleaching And Resilience Of Florida Keys Coral Reefs
James KIDNEY* 1
1 Fish & Wildlife Research Institute, Florida Fish & Wildlife Conservation Commission,
Marathon, FL
Elevated seawater temperatures during the summer of 2005 caused a coral bleaching
event in the Florida Keys. We surveyed 2 Hawk Channel patch reefs (DPR, WTPR) and
a shallow forereef (LKFR) during August and September 2005, to assess the severity of
bleaching. The patch reefs are located inshore of the forereef, in closer proximity to land,
and are under greater influence by waters flowing out of Florida Bay - a body of water
with greater temperature extremes and dissolved nutrients. Sampling consisted of video
belt-transects. Video frames were analyzed to determine abundance and percent cover of
healthy and bleached coral. There were significantly more bleached coral colonies per
m 2 at patch reefs than at LKFR. Furthermore, all species present at WTPR showed signs
of bleaching, 85% of species at DPR exhibited bleaching, but only half the species at
LKFR were bleached. LKFR had the highest coral cover of the sites with 33.5% cover.
Bleached coral cover was 3.2 %. In comparison, DPR had 20.3% total stony coral cover
and 9.2 % bleached cover. WTPR had 19.1 % total stony coral cover, with 9.5%
bleached cover. Ten percent of coral bleached at LKFR, while 46 % bleached at DPR,
and 50 % of the coral cover bleached at WTPR. Bleaching was more severe at the patch
reefs than at the shallow forereef. Both percent cover and the percentage of species
affected were greater at the patch reefs than the forereef. Surveys in 2006 determined
that percent coral cover remained unchanged at LKFR and DPR, with only a slight
decrease at WTPR. Although closer to land, in areas of reduced water clarity, and greater
water temperatures fluctuations, the patch reefs were equally resilient to bleaching as
LKFR. Further research into mechanisms by which patch reefs respond to physical
stressors is warranted.
Poster Mini-Symposium 12: Reef Resilience
12.415
Effect Of Elevated Temperature On The Settlement Success And Early Ontogeny Of A
Coral-Algal Symbiosis: A Case Study in The Brooding Coral porites Astreoides
Andrew BAKER 1 , Paul JONES 1 , John PARKINSON* 2,3 , Wade COOPER 1
1 Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science,
University of Miami, Miami, FL, 2 Marine and Atmospheric Science, University of Miami,
Coral Gables, FL, 3 Marine Biology and Fisheries, Rosenstiel School of Marine and
Atmospheric Science, University of Miami, Miami
Symbiosis flexibility in coral-algal symbiosis has been a research focus for over a decade, but
the majority of studies have focused on adult corals and the potential response of their symbiont
communities to different environmental conditions or disturbances. Several studies have
suggested that flexibility in coral-algal symbiosis might be less common in brooding corals that
transmit their symbionts maternally, compared with broadcasting corals that acquire symbionts
from the environment. Here we investigated the degree to which brooding corals are capable of
flexibility in early ontogeny by settling larvae and rearing them at three different temperatures
(28, 30 and 32°C) and three irradiance levels (using 0, 1 and 2 layers of neutral density mesh to
reduce ambient light). We collected 900 larvae in April and May 2006 from each of two adult
Porites astreoides colonies, and introduced 100 larvae per colony to each treatment.
Temperature was increased at a rate of 2°C per day to reach target temperatures. Symbiodinium
DNA was extracted periodically from both swimming larvae and settlers, to compare with the
symbionts identified from samples taken from five locations across the parent colony.
Settlement success and mortality rates were tracked, and chlorophyll fluorescence properties
monitored using an Imaging-PAM (Walz, GmbH). Initial settlement was highest under the high
light treatment (although on the undersides of tiles), but there was no clear temperature effect.
Long-term survivorship of settlers was generally poor, with 12 months)
results from the 2006 larvae.
12.416
Flicker condition reduces light-induced inhibition of photosynthesis of symbiotic algae in
the reef-building coral Acropora digitifera
Takashi NAKAMURA* 1,2 , Hideo YAMASAKI 1
1 Faculty of Science, University of the Ryukyus, Okinawa, Japan, 2 Amakusa Mar Biol Lab,
Kyushu University, Kumamoto, Japan
Reef-building corals inhabit a variety of habitats with a range of light conditions. Because the
host coral depends on photosynthesis by endosymbiotic algae, reef-building corals have to cope
with dynamic change in irradiance level from instantaneous to seasonal time scales. In
oligotrophic coral reef environments, moving patterns of interspersed light and shadows on the
substrate are prominently observed on a sunny day. The high-frequency light fluctuation,
known as flicker light is produced by a lens effect of moving water surface that simultaneously
focuses and diffuses sunlight in the upper few meters. Although light is essential for
photosynthesis of coral symbiont, excessively strong light destroys the photosynthetic
apparatus, a phenomenon referred as to photoinhibition. Because flicker light potentially
produces excessively strong light as well as dimmer light, such fluctuations may have profound
effects on photosynthesis of shallow inhabiting corals. We conducted experiments with the reefbuilding
coral Acropora digitifera, a species dominantly found in shallow reef habitats. The
effects of flicker light on endosymbiont photosynthesis were evaluated with pulse amplitude
modulation (PAM) chlorophyll fluorometry. At super-saturating light intensities for
photosynthesis, exposure to a flicker light condition resulted in less photoinhibition of
photosynthesis compared with the ones exposed to a constant super-saturating light. Reduction
in photoinhibition by flicker light was pronounced at high water temperatures. These results
indicate that flicker light condition would enable endosymbiont photosynthesis to withstand a
period of strong irradiance and high water temperature. We suggest that the doldrums-like
condition with flat water surface can lead to severe damage to the photosynthetic apparatus of
endosymbiotic algae.
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