11th ICRS Abstract book - Nova Southeastern University

24-45
Alternate Benthic Assemblages On Artificial Reef Restoration Structures And Their
Effects On Coral Larval Settlement
Margaret MILLER* 1 , Abel VALDIVIA 2,3 , K. Lindsey KRAMER 4 , Benjamin
MASON 5 , Dana WILLIAMS 3,6 , Lyza JOHNSTON 5
1 Southeast Fisheries Science Center, NOAA Fisheries, Miami, FL, 2 CIMAS, University
of Miami, Miami, FL, 3 Southeast Fisheries Science Center, NOAA Fisheries, Miami, 4 US
National Park Service, Hilo, HI, 5 Marine Biology and Fisheries, University of Miami,
Miami, FL, 6 CIMAS, University of Miami, Miam, FL
Acute physical reef injuries are sometimes addressed by construction of on-site artificial
structures to secure fractured framework and enhance architectural complexity of
damaged sites. To characterize benthic assemblages, four restoration structures (RS)
along with adjacent natural reef substrates (Reference) in the Florida Keys, USA (age
range 6-13 yrs) were sampled via line-intercept transects. Multivariate clustering
analysis indicated a high degree of divergence between RS and Reference samples, as
well as among sites. RS had significantly higher cover of thick cyanobacterial turfs (up
to 30% cover) than Reference substrates. Assemblage differences were primarily
attributable to macroalgal and cyanobaterial groups with fast growth and turnover, rather
than to slow-growing corals and crustose coralline algae. Thus, divergence of
assemblages is not simply attributable to incomplete succession, but appears to be a
persistent, possibly stable state.
Since cyanobacteria have known ill effects on adult and larval corals, we tested if
exudates of these distinct algal assemblages (RS and Ref) chemically inhibit coral larval
settlement. Seawater exudates were prepared from 1m 2 of macroalgae, including turf,
collected from RS and Reference substrates at two sites (Wellwood and Maitland).
Competent larvae of three broadcast spawning scleractinian species were exposed to
natural substrate in exudates or seawater controls and allowed three days to settle.
Acropora palmata and Diploria strigosa larvae were subject to exudates from a single
site (Wellwood) while Montastraea faveolata larvae were tested with exudates from both
sites. Reference exudates from the Wellwood site displayed greatest settlement inhibition
for all 3 species while, for M. faveolata, RS exudates from the Maitland site were more
inhibitory than Maitland Reference exudates. A.palmata larvae displayed greater
sensitivity than the other species with 100% mortality in the Wellwood Ref treatment.
Both RS and Reference substrates in these locations appear to have compromised
‘recruitment potential’ for spawning corals.
24-46
Natural And Enhanced Coral Reef Recovery After Injury
Alison MOULDING* 1 , David GILLIAM 1 , Vladimir KOSMYNIN 2 , Richard DODGE 1
1 National Coral Reef Institute, Nova Southeastern University, Dania Beach, FL, 2 Bureau
of Beaches and Coastal Systems, Florida Department of Environmental Protection,
Tallahassee, FL
The coral reefs of Broward County, southeast Florida, USA are located offshore a highly
urbanized area. Because of the close proximity of a major shipping port and its
associated anchorage, Broward reefs have been impacted by more than 10 ship
groundings over the last 15 years. These injuries usually require restoration to speed
recovery and compensate for damage. However, the recovery process on injured sites is
not well understood, and even less is known about how restoration aids in recovery. This
study examines coral recruitment, growth, and mortality in permanent quadrats on injured
sites to asses their potential for natural recovery. It also investigates substrate materials
commonly used in reef restoration, including limestone, concrete, and terracotta, to
determine their efficacy in attracting and retaining coral recruits. Lastly, transplantation
of juvenile corals collected on settlement plates from areas of higher coral recruitment
and of corals raised in the lab from the larval stage is examined as a potential method to
enhance reef restoration. Preliminary results indicate coral recruitment rates to injured
sites were higher compared to reference sites. Mortality rates at the injured sites were
also higher than reference sites. After one year of deployment, more corals settled on
limestone plates than on concrete or terracotta. Hence, recovery on injury sites may be
hampered by high juvenile coral mortality rates, and the choice of substrate materials
used in restoration may influence recovery.
Oral Mini-Symposium 24: Reef Restoration
24-48
Recruitment Of The Temperate Scleractinian Coral, oculina Arbuscula, To Natural And
Artificial Substrata On Reefs Of The South Atlantic Bight, U.s.a.
Daniel GLEASON* 1 , Leslie SUTTON 1
1 Department of Biology, Georgia Southern University, Statesboro, GA
Similar to their tropical counterparts, temperate reefs have high biodiversity, but are in peril
from anthropogenic impacts. Primary threats include commercial trawling, recreational fishing,
ocean acidification, and increased sedimentation. Oculina arbuscula is a temperate, broadcast
spawning coral and is the only structurally complex Scleractinian occurring on hard-bottom
reefs of the South Atlantic Bight, U.S.A. Oculina arbuscula is an important contributor to reef
rugosity in this ecosystem, but can be easily damaged by dredges and trawls. To investigate the
sustainability of these coral populations on reefs off the Georgia coast we monitored
recruitment of O. arbuscula to 30x30 cm plots over 3 years. Treatments consisted of 10
replicates of each of the following: 1) unmanipulated natural substrata, 2) natural substrata
initially cleared of all encrusting organisms, and 3) artificial substrata consisting of concrete
paving tiles. These plots were photographed at least 13 times between July 2004 and June 2007
using a digital camera mounted to a PVC frame to control for distance and exposure level.
These images showed that O. arbuscula recruits throughout the year with peak recruitment
exhibited in September/October. While recruitment rates were higher than death rates in all
treatments and resulted in a net gain of O. arbuscula colonies, recruitment to artificial substrata
far exceeded that found on natural surfaces. Competition with other sessile invertebrates, such
as tunicates and sponges, appeared to contribute little to these differences because recruitment
rates were similar on unmanipulated and cleared natural substrata. Likewise, the high
recruitment rate observed on the artificial substrata rules out the possibility that maintenance of
O. arbuscula populations is limited by larval supply. While the reasons are unclear currently,
these results suggest that deploying artificial substrata, such as concrete paving tiles, may be
useful as a mechanism of enhancing recruitment of O. arbuscula to damaged temperate reef
structure.
24-49
Brazilian Corals Early Growth And Survival
Clovis CASTRO* 1 , Bruna CASTRO 1
1 Departamento de Invertebrados, Museu Nacional, Rio de Janeiro, Brazil
Early growth and survival of coral recruits are crucial for the renewal of coral populations and
restoration initiatives. In order to assess these parameters, we set up experiments with different
recruitment plates (plastic and ceramic) and environmental conditions (open sea and tanks). In
the laboratory, coral spats were recorded using a dissecting microscope. Each individual spat
was measured and its position recorded using a coordinate system. Plastic plates were deployed
in January, 2004, and initially kept in the Itacolomis Reefs (16°54’S, 039°04’W) for circa 15
months. Censuses occurred in June, 2005 (T0) and March, 2006 (T1 – 9 months). This
experiment started with 1762 live spats and ended with 574. Survival rates were higher in tanks
(61%, excluding spats in lost plates, vs. 15% in open sea). Survival was also higher in larger
spats, both in tanks and open sea. Growth rates were slightly higher in tanks. Larger spats grew
faster than smaller ones. Ceramic tiles were deployed in March, 2006, and kept in the “Recife
de Fora” (16°24’S, 038°59’W) for circa seven months. Censuses occurred in October, 2006
(T0), March (T1 – 5 months) and October, 2007 (T2 – 12 months). This experiment started with
1078 live spats. The last census showed 206 live spats, 19% of the original spats. Survival rates
agreed with those from plastic plates. However, differences between tanks (T0-T1 = 48%; T1-
T2 = 34%) and open sea (T0-T1 = 27%; T1-T2 = 5%), as well as in larger spat size classes,
were more evident. Growth rates in tanks were substantially higher than in open sea (up to 7
times higher in the same size class). These preliminary results suggest that rearing coral recruits
in captivity may become an alternative for coral reef restoration in the long term.
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