Over the last two decades, more than 10 major vessel groundings have occurred on coral reefs offshore southeast Florida. Lack of any published information on coral settlement, post-settlement survival, and juvenile coral growth in the southeast Florida region inhibits efforts to determine if coral populations will be able to effectively re-establish themselves. The ]]>
-2. Although the density of coral recruits was generally higher at the grounding sites, mortality rates were high at all sites during the study period. Growth rates of individual colonies were ]]>
Key words: recruitment, reef recovery, vessel ]]>
Resumen
En las dos últimas décadas, más de 10 grandes encallamientos de embarcaciones se han producido en ]]>
-2. Aunque la densidad del reclutamiento fue generalmente más alta en los sitios de encallamiento también hubo mayor mortalidad de corales juveniles en esos sitios durante el período de estudio. Las tasas de crecimiento de las colonias ]]>
]]>
Palabras clave: reclutamiento, recuperación de coral, encallamiento de barcos, tasas de crecimiento, sobrevivencia post-asentamiento The southeast Florida reef tract consists of four shore-parallel ridges with a ]]>
et al. 2003, Banks et al. 2008). Though similar in fauna, community structure of this high latitude (26° N) region differs from that found in other areas of the Caribbean and Florida Keys (Moyer et al. 2003). Montastraea cavernosa Linnaeus, 1767 replaces the
Montastraea annularis (Ellis & Solander, 1786) species complex as the dominant species. Additionally, average coral colony size is typically small, and cover is generally low (Moyer et al. 2003).
Coral reefs in southeast Florida are located near a highly developed and heavily populated coastline. As a result, they are subjected to ]]>
M/V Eastwind) (Marine Resources Inc. 2005). However, efforts have been relatively small scale as compared to the larger scale efforts to stabilize reef framework and restore reef topography further south in ]]>
et al. 2006).
Recovery of damaged sites is generally defined as the return of both community structure and function to a state similar to that which existed pre-impact (Edwards & Gomez 2007). Although there are thousands of organisms which ]]>
et al. 1984, Hughes & Jackson 1985, Smith 1997, Miller et al. 2000). ]]>
-1 for many Caribbean species (Bak & Engel 1979, Rogers et al. 1984, van Moorsel 1988, Edmunds 2000) can influence recovery times. Currently no information on coral recruitment rates or juvenile survival and growth rates has been published for southeast Florida. Therefore, the goal of this study was to examine these ]]>
Methods
Two ship grounding sites were ]]>
M/V Eastwind grounded in March 2004 and resulted in approximately 11 000 m2 of damage on the inner reef just north of Port Everglades (Hudson Marine Management Services 2004a). The M/V ]]>
created approximately 23 400 m2 of damage 0.4 km south of the Eastwind grounding site when it ran aground in October 2004 (Hudson Marine Management Services 2004b). Both groundings destroyed the existing relief, creating large rubble fields from which large rubble was subsequently removed or stabilized during restoration activities (Marine Resources Inc. 2005), but smaller sized debris remained on site.
]]>
Two control sites were chosen for comparison to the grounding sites. Because most of the large vessel groundings and anchor damage events off Ft. Lauderdale have occurred just west of the Port Everglades anchorage, this area was avoided when control sites were selected due to the potential for previous impact. Using GIS, a grid consisting of 15x15 m plots was overlaid on the inner reef just north of the anchorage area, and two plots were randomly picked for the control sites (control sites one: 26°9’37”N, 80°5’18”W and two: 26°10’4”N, 80°5’15”W).
Twenty permanently marked 1 m2 quadrats at each of the four sites were surveyed annually between May 2006 and June 2009. Quadrats were marked at the corners using a stainless steel pin and galvanized nails. A 1
m2 pvc frame subdivided into 100 squares 10x10 cm in size was placed over the pins to accurately locate corals within the quadrat. All juvenile corals (≤5 cm in diameter) in each quadrat were identified, measured, and mapped. Juvenile corals appearing in the quadrats that were not present in the previous years and were not a product of colony fission were considered coral recruits. Any corals that appeared in the quadrats but were absent in subsequent ]]>
Differences in density of recruits among sites and among years were tested using a two-way ANOVA on ranks after data transformations failed to achieve normality due to the presence of multiple zero values. Differences in average annual ]]>
To further examine similarity in species composition of recruits among sites, a Bray-Curtis similarity index was determined. Species abundance data were pooled for all quadrats within a site during a survey year, and the data were square-root transformed (PRIMER v6). The results were also used to ]]>
Results
Mean juvenile coral density ranged from a low of 0.5±0.1 (SE) juveniles m-2 at control site 1 to a high of 11.6±1.4 juveniles m-2 at the Eastwind grounding site (Fig. 1). The density of recruits ranged from 0.2±0.1 recruits m-2 at control site 2 to 7.1±1.0 recruits m-2
at the Eastwind grounding site (Fig. 2). The results of a two-way ANOVA on ranks indicated that there was a significant difference in density of new recruits both among sites (p<0.001) and years (p<0.001). A Tukey pair-wise comparison test indicated that the two grounding sites each had a significantly higher density of recruits than either control site (p<0.001) and that density of recruits was significantly higher at the Eastwind grounding site than at the Federal Pescadores grounding site (p<0.001). There was no significant difference in recruit density between the two control sites. Recruit density was significantly higher in 2008 than in 2007 (Tukey, p<0.001) or 2009 (p<0.01).
Annual mortality rates of juvenile corals ranged from 11% to 58%. Mean annual mortality rates were higher at the grounding sites than the control sites during the study period, but the difference was not significant (Fig. 3). Survival of juvenile corals for longer than one year ranged from 0 to 30% of the total corals observed at each site in 2008 and 2009 (Fig. 4). ]]>
A total of 18 species recruited to the study sites, but the maximum number of species that recruited to any one site was 15 (Table 1). Twice as many species recruited to the grounding sites compared to the control sites (Table 1). Four common species, Siderastrea ]]>
(Ellis & Solander 1786), Siderastrea radians (Pallas 1766), Porites astreoides Lamarck, 1816, and Montastraea cavernosa, recruited to all the sites. Over half of the recruits at the grounding sites were S. siderea. Porites astreoides and S. siderea comprised a majority of the total recruits (64% to 67% combined) at the control sites though M. cavernosa ]]>
A non-metric multi-dimensional scaling (MDS) plot was used to visualize the Bray-Curtis similarity of sites based on species abundance of recruits (Fig. 5). Two main clusters with 60% similarity were formed, one consisting of all the ]]>
Growth rates were highly variable both within and between species and often between sites (
Table 2). Most species grew less than 1 cm yr-1 except for Agaricia agaricites (Linnaeus 1758) which was only observed at the grounding sites. Many colonies (23%) suffered partial mortality, resulting in smaller colony size in subsequent years, and 6% of the colonies did not grow between survey periods. For some species, the number of corals measure has been observed at higher latitudes (Hughes et al. 2000, St. Gelais 2010), which may contribute ]]>
et al. 2001, ]]>
et al. 2006, Vermeij 2006, Arnold et al. 2010).
As is the case in other studies (Rylaarsdam 1983, Babcock 1985, van Moorsel 1988, Vermeij 2006), growth rates of individual colonies in this study were highly variable. Nevertheless, mean growth rates were within the range reported in the literature though on the lower end for most ]]>
-1 . However, many of the colonies (23%) experienced negative growth and shrank in size due to partial mortality. Average colony size in the region tends to be small (< 50 cm, Moyer et al. 2003) in comparison to other areas, and partial mortality and slow growth rates observed in the current study likely contribute to these patterns.
Although mean annual mortality rates were not significantly different among sites, total mortality of juvenile corals was about 50% at the grounding sites and 40% at the control sites during the study period, indicating a slightly higher mortality of juvenile corals at the grounding sites over the three year study period. Additionally, the percentage of corals that survived more than one year was generally ]]>
Low survival of corals was likely mediated by different processes at the grounding and control sites due to the differences in habitat. Although no physical measurements were taken, qualitatively it appeared that sand and rubble movement occurred at the grounding sites at an increased rate in ]]>
]]>
Low survival at the control sites may have been affected by competitive interactions with more established benthic organisms and algae (Birkeland 1977, Bak & Engel 1979, Maida et al. 2001, Kuffner et al. 2006, Vermeij 2006). Though no quantitative data of percent cover were taken within the quadrats, visually the grounding sites appeared more barren in comparison to the control sites (
Fig. 6). In contrast, Thanner et al. (2006) found that community structure on artificial reefs in southeast Florida reached between 45% to 58% similarity to natural reefs in benthic species composition 4 to 5 years after deployment and that scleractinian corals on the artificial reefs had similar cover, though higher abundance of juvenile corals, compared to the natural reef after the same period. The impoverished benthic community at the grounding sites 5 years post-grounding provides a sharp contrast to the moderately high ]]>
et al. (2006) reported and indicates that topographic complexity may be important for the recovery of the grounding sites.
Community structure of newly settled recruits was distinct at the grounding sites. More species ]]>
siderea. Siderastrea spp. are able to live in conditions generally considered inimical to coral survival such as fluctuating salinity, low temperatures, and high sedimentation (Macintyre & Pilkey 1969, Muthiga & Szmant 1987, Lirman & Manzello 2007). Their dominance at the grounding sites might be a result of their tolerance to the high sedimentation observed ]]>
Montastraea cavernosa, the dominant species in the region (Moyer et al. 2003), comprised a much smaller proportion of the recruits at the grounding sites (<8%) compared to the reference sites (14-20%).
The concern is that even though ]]>
et al. 1990, Rogers 1984, Cook et al. 1994, Rogers & Garrison 2001). Corals that have low recruitment and growth rates, as many of the broadcast spawning, reef building corals do, may take even longer to recover as models have determined that convergence to ]]>
Recovery is generally defined as ]]>
In conclusion, ship groundings on ]]>
Acknowledgments ]]>
We thank Nova Southeastern University graduate students for their assistance with field work and Brian Walker for GIS assistance. The Hillsboro Inlet District and Florida Department of Environmental Protection provided funding for this project. ]]>
References
Arnold, S.N., R.S. Steneck & P.J. Mumby. 2010. Running the gauntlet: inhibitory effects of algal turfs on the processes of coral recruitment. Mar. Ecol. Prog. Ser. 414: 91-105. [ Links ]
Aronson, R.B. & D.W. Swanson. 1997. Video surveys of coral reefs: uniand multivariate applications. Proc. 8th Int. Coral Reef Symp., Panama 2: 1441-1446. [ Links ]
Babcock, R.C. 1985. Growth and mortality in juvenile corals (Goniastrea, Platygyra, and Acropora): the first year. Proc. 5th Int. Coral Reef Congr., Tahiti 4: 355-360. [ Links ]
Bak, R.P.M. & M.S. Engel. 1979. Distribution, abundance and survival of juvenile hermatypic corals (Scleractinia) and the importance of early life history strategies in the parent coral community. Mar. Biol. 54: 341-352. [ Links ]
Banks, K.W., B.M. Riegl, V.P. Richards, B.K. Walker, K.P. Helmle, L.K.B. Jordan, J. Phipps, M.S. Shivji, R.E. Spieler & R.E. Dodge. 2008. The reef tract of continental southeast Florida (Miami-Dade, Broward and Palm Beach Counties, USA), p. 175-220. In B.M. Riegl and R.E. Dodge (eds). Coral Reefs of the USA. Springer, London, England. [ Links ]
Birkeland, C. 1977. The importance of rate of biomass accumulation in early successional stages of benthic communities to the survival of coral recruits. Proc. 3rd Int. Coral Reef Symp., Miami 1: 15-21. [ Links ]
Cook, C.B., R.E. Dodge, & S.R. Smith. 1994. Fifty years of impacts on coral reefs in Bermuda. p. 160-166. In R.N. Ginsburg (compiler). Proc. Colloquium on Global Aspects of Coral Reefs: Health, Hazards, and History. University of Miami, Miami, Florida, USA. [ Links ]
Edmunds, P.J. 2000. Patterns in the distribution of juvenile corals and coral reef community structure in St. John, US Virgin Islands. Mar. Ecol. Prog. Ser. 202: 113-124. [ Links ]
Edwards, A.J. & E.D. Gomez. 2007. Reef restoration concepts and guidelines: making sensible management choices in the face of uncertainty. Coral Reef Targeted Research & Capacity Building for Management Programme, St. Lucia, Australia. [ Links ]
Gittings, S.R., T.J. Bright & B.S. Holland. 1990. Five years of coral recovery following a freighter grounding in the Florida Keys. p. 89-105. In W.A. Jaap (ed). Diving for Science: Proceedings of the American Academy of Underwater Sciences 10th Annual Scientific Diving Symposium. American Academy of Underwater Sciences, Costa Mesa, California, USA. [ Links ]
Harriott, V.J. 1999. Coral recruitment at a high latitude Pacific site: a comparison with Atlantic reefs. Bull. Mar. Sci. 65: 881-891. [ Links ]
Harriott, V.J. & S.A. Banks. 1995. Recruitment of scleractinian corals in the Solitary Islands Marine Reserve, a high latitude coral-dominated community in eastern Australia. Mar. Ecol. Prog. Ser. 123: 155-161. [ Links ]
Hatcher, B.G. 1984. A maritime accident provides evidence for alternate stable states in benthic communities on coral reefs. Coral Reefs 3: 199-204. [ Links ]
Hudson Marine Management Services. 2004a. M/V Eastwind Grounding Site Ft. Lauderdale, Florida Injury Assessment. Thomas Miller Inc., Miami, Florida, USA. [ Links ]
Hudson Marine Management Services. 2004b. M/V Federal Pescadores Site Ft. Lauderdale, Florida Injury Assessment Report. Vandeventer Black LLP, Norfolk, Virginia, USA. [ Links ]
Hughes, T.P. & J.B.C. Jackson. 1985. Population dynamics and life histories of foliaceous corals. Ecol. Monogr. 55: 141-166. [ Links ]
Hughes, T. P. & J. Tanner. 2000. Recruitment failure, life histories, and long-term decline of Caribbean corals. Ecology 81: 2250-2263. [ Links ]
Hughes, T.P, A.H. Baird, E.A. Dinsdale, N.A. Moltschaniwsky, M.S. Pratchet, J.E. Tanner & B.L. Willis. 2000. Supply-side ecology works both ways: the link between benthic adults, fecundity, and larval recruits. Ecology 81: 2241-2249. [ Links ]
Jaap, W.C., J.H. Hudson R.E. Dodge, D. Gilliam & R. Shaul. 2006. Coral reef restoration with case studies from Florida. p. 478-514. In I.M. Cote & J.D. Reynolds (eds). Coral Reef Conservation. Cambridge University, Cambridge, England. [ Links ]
Kuffner, I.B., L.J. Walters, M.A. Becerro, V.J. Paul, R. Ritson-Williams & K.S. Beach. 2006. Inhibition of coral recruitment by macroalgae and cyanobacteria. Mar. Ecol. Prog. Ser. 323: 107-117. [ Links ]
Lirman, D. & M.W. Miller. 2003. Modeling and monitoring tools to assess recovery status and convergence rates between restored and undisturbed coral reef habitats. Restor. Ecol. 11: 448-456. [ Links ]
Lirman, D. & D. Manzello. 2007. Patterns of resistance and resilience of the stress-tolerant coral Siderastrea radians (Pallas) to sub-optimal salinity and sediment burial. J. Exp. Mar. Biol. Ecol. 369: 72-77. [ Links ]
Macintyre, I.G. & O.H. Pilkey. 1969. Tropical reef corals: tolerance of low temperatures on the North Carolina continental shelf. Science 166: 374-375. [ Links ]
Maida, M., P.W. Sammarco & J.C. Coll. 2001. Effects of soft corals on scleractinian coral recruitment. 2: Allelopathy, spat survivorship and reef community structure. Mar. Ecol. 22: 397-414. [ Links ]
Marine Resources Inc. 2005. Proposed Restoration Plan for Post-Grounding Activities: M/V Eastwind Grounding Site Offshore Broward County, Florida. Houck, Hamilton, & Anderson, P.A., Miami, Florida, USA. [ Links ]
Miller, M.W., E. Weil & A.M. Szmant. 2000. Coral recruitment and juvenile mortality as structuring factors for reef benthic communities in Biscayne National Park, USA. Coral Reefs 19: 115-123. [ Links ]
Moyer, R.P., B. Riegl, K. Banks & R.E. Dodge. 2003. Spatial patterns and ecology of benthic communities on a high-latitude South Florida (Broward County, USA) reef system. Coral Reefs 22: 447-464. [ Links ]
Muthiga, N.A. & A.M. Szmant. 1987. The effects of salinity stress on the rates of aerobic respiration and photosynthesis in the hermatypic coral Siderastrea siderea. Biol. Bull. 173: 539-551. [ Links ]
Rogers, C.S, H.C. Fitz III, M. Gilnack, J. Beets & J. Hardin. 1984. Scleractinian coral recruitment patterns at Salt River Submarine Canyon, St. Croix, U.S. Virgin Islands. Coral Reefs 3: 69-76. [ Links ]
Rogers, C.S. & V. Garrison. 2001. Ten years after the crime: lasting effects of damage from a cruise ship anchor on a coral reef in St. John, U.S. Virgin Islands. Bull. Mar. Sci. 69: 793-803. [ Links ]
Rylaarsdam, K.W. 1983. Life histories and abundance patterns of colonial corals on Jamaican reefs. Mar. Ecol. Prog. Ser. 13: 249-260. [ Links ]
Smith, S.R. 1997. Patterns of coral settlement, recruitment and juvenile mortality with depth at Conch Reef, Florida. Proc. 8th Int. Coral Reef Symp., Panama 2: 1197-1202. [ Links ]
St. Gelais, A.T. 2010. Reproductive ecology of Siderastrea siderea: histological analysis of gametogenesis, spawning, and latitudinal fecundity variation. Master’s Thesis, Nova Southeastern University, Dania Beach, Florida, USA. [ Links ]
Thanner, S.E., T.L. McIntosh & S.M. Blair. 2006. Development of benthic and fish assemblages on artificial reef materials compared to adjacent natural reef assemblages in Miami-Dade County, Florida. Bull. Mar. Sci. 78: 57-70. [ Links ]
Van Moorsel, G.W.N.M. 1988. Early maximum growth of stony corals (Scleractinia) after settlement on artificial substrata on a Caribbean reef. Mar. Ecol. Prog. Ser. 50: 127-135. [ Links ]
Vermeij, M.J.A. 2006. Early life-history dynamics of Caribbean coral species on artificial substratum: the importance of competition, growth and variation in life-history strategy. Coral Reefs 25: 59-71. [ Links ]
*Correspondencia: Alison L. Moulding: National Coral Reef Institute, Nova Southeastern University, Oceanographic Center, 8000 North Ocean Dr., Dania Beach, FL 33161 USA; moulding@nova.edu Vladimir N. Kosmynin: Florida Department of Environmental Protection, Bureau of Beaches and Coastal Systems, 3900 Commonwealth Boulevard, Mail Station 300, Tallahassee, Florida 32399 USA; Vladimir.Kosmynin@dep.state.fl.us David S. Gilliam: National Coral Reef Institute, Nova Southeastern University, Oceanographic Center, 8000 North Ocean Dr., Dania Beach, FL 33161 USA; gilliam@nova.edu
1. National Coral Reef Institute, Nova Southeastern University, Oceanographic Center, 8000 North Ocean Dr., Dania Beach, FL 33161 USA; moulding@nova.edu, gilliam@nova.edu 2. Florida Department of Environmental Protection, Bureau of Beaches and Coastal Systems, 3900 Commonwealth Boulevard, Mail Station 300, Tallahassee, Florida 32399 USA; Vladimir.Kosmynin@dep.state.fl.us
Received 12-VII-2011. Corrected 22-XI-2011. Accepted 20-XII-2011.
