11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 10: Ecological Processes on Today's Reef Ecosystems
10.359
Population Projections And Management Recommendations For The Threatened
acropora Palmata: What Life History Stage Should We Protect?
Tali VARDI* 1 , Dana E. WILLIAMS 2,3
1 Scripps Institution of Oceanography, La Jolla, CA, 2 Cooperative Institute for Marine and
Atmospheric Studies, University of Miami RSMAS, Miami, FL, 3 Southeast Fisheries
Science Center, NOAA Fisheries, Miami
Acropora palmata was once the dominant hermatypic coral throughout the Caribbean,
Florida, and Bahamas. Since the 1980s it has suffered a 97% decline in abundance
throughout its range and was included on the US Endangered Species List in 2006.
Despite the dramatic nature of this decline, and the implications a potential extinction
would have for loss of habitat to other species, neither abundance nor rates of decline
have been documented systematically throughout the Caribbean. In Autumn 2007,
abundance of A. palmata was estimated in Florida, Puerto Rico, Jamaica, Virgin Gorda,
and Curaçao. Abundance in Florida was dramatically lower than in other sites. Causes of
the rarity of A. palmata in Florida have not been clearly identified. To explore
population changes in more detail, a size-based population model was developed to help
identify life history stages most affected. Based on A. palmata’s population trajectory
since 2004, as measured by a standardized, size-based demographic monitoring protocol
in the Florida Keys, the local population will reach a stable distribution in 20 years. At
that time, the current population structure, in which 35% are pre-reproductive and 45%
are reproductive, will have become dominated by pre-reproductive individuals with only
20% of colonies capable of sexual reproduction. This loss of large individuals would also
reduce the number of asexually derived fragments, leading to an overall reduction in
abundance of colonies in Florida. Parallel research on the island of Curacao shows both a
greater abundance of A. palmata overall and no significant change in the relative
abundance of larger individuals. These results suggest that protecting the largest adults
may reverse the current trend toward a left-skewed A. palmata population structure in
Florida.
10.360
Top-Down Factors Explain Benthic Community Structure On A Near-Pristine
Coral Reef Ecosystem
Kimberly PAGE-ALBINS* 1 , Peter VROOM 2 , Celia SMITH 3 , Edward DEMARTINI 4 ,
Scott GODWIN 5
1 Zoology, Oregon State University, Corvallis, OR, 2 Joint Institute for Marine and
Atmospheric Research, Honolulu, HI, 3 Department of Botany, University of Hawaii at
Manoa, Honolulu, HI, 4 Coral Reef Ecosystem Division, NOAA Fisheries, Honolulu, HI,
5 Hawaii Institute of Marine Biology, Kaneohe, HI
The debate continues over the relative contributions of top-down mechanisms such as
removal of herbivores, and bottom-up mechanisms such as eutrophication, to coral reef
decline and phase shifts from coral to algal dominated reefs. While it is likely that both
of these mechanisms influence coral reef community composition, the dominant
mechanism regulating a particular community is likely determined, in part, by the level of
anthropogenic impact present. In order to effectively manage remaining intact reef
systems, it has become increasingly important to pinpoint which factors regulate the
composition of coral reef communities. Here, we examine models of top-down and
bottom-up community regulation in a near-pristine coral reef system, Pearl and Hermes
Atoll (PHA), Northwestern Hawaiian Islands. PHA represents one end of a continuum in
coral reef health. Percent cover of benthic organisms along with herbivorous fish density
and biomass, urchin density, and nutrient availability were measured. Multi-linear
regressions revealed that for each of the benthic functional groups examined (coral,
frondose macroalgae, crustose coralline red algae, and turf algae) herbivorous fish
density was a significant explanatory factor. Herbivorous fish biomass and urchin
density were also significant explanatory factors in models explaining benthic community
composition. When all benthic functional groups were combined in a multivariate
analysis, herbivorous fish density combined with wave exposure was identified as having
the highest significant correlation with benthic community composition at PHA.
Conversely, nutrient availability, based on algal tissue nutrient content, did not correlate
with percent cover of benthic organisms. These results suggest that at PHA, a site which
represents one end of a global continuum ranging from near-pristine to highly degraded,
top-down mechanisms have primacy over bottom-up mechanisms.
10.361
The Effect Of Increased Seawater Temperature On The Skeletal Development Of favia
Fragum And porites Astreoides New Recruits
Lara GATES 1,2 , Samantha DE PUTRON* 2
1 2
The College of William and Mary, Williamsburg, VA, Bermuda Institute of Ocean Sciences,
St Georges, Bermuda
Recent studies show that rising seawater temperatures affect the vitality of both adult corals and
planulae. Data is lacking, however, concerning the intermittent life-history stage - new settled
coral recruits (spat). The proper development of spat is critical to the success of the coral, as
well as the success of the reef in terms of population sustainability. To address this, an analysis
of spat skeletal development with respect to temperature was performed. Adult corals of two
common brooding species, Favia fragum and Porites astreoides were collected from Bermuda’s
inshore platform just prior to their known planulation period during the summer of 2007, and
planulae were collected in aquaria upon release. Planulae were settled and grown in varying
temperatures. Upon termination of growth, skeletons were evaluated quantitatively in terms of
height and volume as well as qualitatively concerning maturity of development. F. fragum spat
grown in the highest temperature (33°C) were significantly smaller than those grown in ambient
temperature (28.5°C) over the course of one and two weeks of growth. Similar results were
found within the first week of growth for P. astreoides spat. Qualitatively, the evaluation of
maturity of F. fragum skeletons indicated reduced developmental stage with higher
temperatures. In addition, visual observations of the live spat revealed that those in higher
temperatures appeared white and transparent while those in lower temperatures maintained a
green translucence, indicating possible bleaching (zooxanthellae loss) in the higher temperature
treatments. These results suggest a biological basis for decreased growth in higher temperatures
via the expulsion of zooxanthellae resulting in a lack of energy or shortage of skeletal ‘building
blocks’. In this age of predicted global warming, our results suggest a possible disruption of
foundational skeletal development, which may lead to decreased survivorship of coral recruits
of some species and subsequent depletion of coral reefs.
10.362
Recruitment Dynamics Of Scleractinian Corals in A Network Of National Parks And
Marine Protected Areas: West Coast Hawai’i Island
Lawrence BASCH* 1,2 , Angela LEEMHUIS 3 , James WHITE 3 , William WALSH 4
1 National Parks Service, Honolulu, HI, 2 University of Hawaii, Cooperative Ecosystems Study
Unit, Honolulu, 3 University of Hawaii, Cooperative Ecosystems Study Unit, Honolulu, HI,
4 Hawaii State Department of Land and Natural Resources, Division of Aquatic Resources,
Kailua-Kona, HI
Maintenance of adequate levels of coral settlement and recruitment is vital to sustain coral reefs.
Because early life stages are often more susceptible than adults to environmental stressors, data
on settlement and recruitment can help predict potential effects of disturbance from, and
resilience to environmental change. This study is a large scale, multi-year effort to assess
recruitment of Scleractinians along the west coast of Hawai’i Island in support of long term
benthic monitoring and marine protected area management. Terra cotta tiles have been used at
nine sites over three years as settlement substrate to help determine spatial and temporal
variation in coral settlement and recruitment. Tiles are replaced biannually before and after
known seasonal peaks in coral reproduction and recruitment.
Several spatial and temporal trends were discovered in this ongoing study. Peak settlement of
coral larvae consistently occurred across years in summer (approximately April-September) in
species with and without planktonic larvae. Most species showed spatial patterns in settlement
patterns at the 1-10 km scale (between sites). The northernmost site, Waikalio, had significantly
higher densities of juvenile corals with settlement among sites decreasing immediately toward
the south. Porites spp. had the highest recruitment overall, followed by Montipora spp., then
Pocillopora spp. for most sites. Most Montipora spp. juveniles observed were single polyps
with little or no extension of skeleton beyond the corallite wall; none had multiple polyps.
The north to south pattern in settlement density suggests large scale oceanography is not driving
settlement-recruitment dynamics. Possible alternative influences include smaller, sub regional
differences in ocean currents, habitat structure, disturbance regimes, and anthropogenic
influences.
Combined with emerging oceanographic data, this work provides an initial basis for long term
benthic monitoring of ecological change in, and conservation of, park’s marine resources.
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