In response to dramatic losses of ]]>
Acropora palmata and A. cervicornis (Acroporidae)] and another fast-growing species [Porites porites (Poritidae)] were collected from environments hostile to coral fragment survival and transplanted to degraded reefs. Inert nylon cable ties were used to attach transplanted coral fragments to dead coral substrate. Survival of 75 reference colonies and 60 transplants was assessed over 12 years. Only 9% of colonies were alive after 12 years: no A. cervicornis; 3% ]]>
A. palmata transplants and 18% of reference colonies; and 13% of P. porites transplants and 7% of reference colonies. Mortality rates for all species were high and were similar for transplant and reference colonies. Physical dislodgement resulted in the loss of 56% of colonies, whereas 35% died in place. Only A. palmata showed a difference between transplant and reference colony survival and that was in the first year ]]>
A. palmata reference colonies and after year 10. Even though the tested methods and concepts were proven effective in the field over the 12-year study, they do not present a solution. No coral conservation strategy will be effective until underlying intrinsic and/or extrinsic factors driving high mortality rates are understood and mitigated or eliminated. Rev. Biol. Trop. 60 (Suppl. 1): 59-70. Epub 2012 March 01.
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En respuesta a la dramática pérdida de corales constructores de arrecifes y la continua falta de recuperación, un proyecto de pequeña escala de transplante de corales, al cual se le dio seguimiento por 12 años, se inició en el Caribe (Islas Vírgenes de EUA) en 1999. Los principales objetivos fueron (1) identificar fuentes de colonias de coral para el trasplante, que no produjeran daños a los arrecifes, (2) evaluar la viabilidad del trasplante de fragmentos de coral generados por tormentas, y (3) desarrollar un ]]>
Acropora palmata y A. cervicornis (Acroporidae)] y otras especies de crecimiento rápido [Porites ]]>
(Poritidae)] fueron recolectadas en ambientes no adecuados para la supervivencia de fragmentos de coral y se trasplantaron a los arrecifes degradados. Fajitas de nylon inerte fueron utilizadas para unir los fragmentos de corales transplantados al sustrato de coral muerto. La sobrevivencia de 75 colonias de referencia y de 60 transplantadas fueron monitoreadas por más de 12 años. Sólo el 9% de las colonias estaban vivas tras 12 años, sin presencia de A. cervicornis, el 3% de ]]>
A. palmata y el 18% de las colonias de referencia de Acropora. El 13% de los transplantes de P. porites y el 7% de las colonias de referencia sobrevivieron. El desprendimiento físico resultó en la pérdida del 56% de las colonias, mientras que el 35% murió en el lugar. Solamente A. palmata mostró una diferencia en sobrevivencia entre los trasplantes y las colonias de referencia, eso fue solo en el primer ]]>
A. palmata y después de 10 años. A pesar de que los métodos y los conceptos fueron probados efectivamente en el campo por más de 12 años de estudio, no mostraron ser la solución. Ninguna estrategia de conservación va a ser efectiva hasta que se delimiten y sean entendidos, mitigados o eliminados los factores intrínsecos y/o extrínsecos que conducen a las ]]>
Palabras clave: Acropora cervicornis, A. palmata, mortalidada de coral, Porites porites, restauración de arrecifes, transplantes de corales ]]>
Continuing declines and the lack of recovery on coral reefs worldwide have sparked renewed calls for action by the scientific, conservation, and reef management communities (e.g., Bruno & Selig 2007, Mumby & Steneck 2008, Rinkevich 2008, Teplitski & Ritchie 2009). Consensus exists around the need to maintain as much genetic diversity, structural and biological integrity, and ecological ]]>
et al. 2006, Shearer et al. 2009). Less agreement surrounds how best to achieve those goals and how to proceed in response to declining abundance of corals and other reef organisms. In cases of acute physical damage to reefs, such as in ship groundings, sophisticated engineering methods have been developed to mitigate damage and to maximize recovery and are used in combination with substrate stabilization and colony transplantation (e.g., Jaap
et al. 2006). But increasingly, loss of live coral has been related to disease and abnormally high water temperatures and not to direct impacts from human activities (e.g., Miller et al. 2009). As researchers work to deepen understanding of reef ecology, coral reproduction, disease processes, and predation and to identify environmental drivers and effects from a changing climate, what is the appropriate response to the continuing loss of coral? What response at the local level will most effectively reduce further losses, minimize species ]]>
Recently, restoration strategies have focused on the broader conservation effort, emphasizing the need to combine local management actions, such as establishment of no-harvest marine reserves and effective ]]>
et al. 2005, Edwards & Gomez 2007, Mumby & Steneck 2008, Young 2000). Transplantation of coral colonies or fragments, whether from aqua-, mariculture or harvesting from a healthy colony, has been the most frequently recommended action for increasing coral abundance on damaged or degraded reefs and for conserving listed or “at-risk” species (e.g., Epstein et al. ]]>
et al. 2009), which is considered essential. Debate continues over the effectiveness of transplantation in conserving threatened coral species, increasing coral abundance, and accelerating reef restoration or enhancement at ecologically relevant temporal and spatial scales. This controversy is due in part to the small scale of transplant studies compared to the ]]>
et al. 2009), although reports from proprietary restorations (e.g., ship groundings) exist but are difficult to access. Recently, a few large-scale transplantation studies have been initiated (Normile 2009). Their findings after 5 years, 10 years and ]]>
In 1999, a small-scale coral fragment transplantation project was initiated in a Caribbean marine protected area (Virgin Islands National Park, U.S. Virgin Islands). The primary objectives were to (1) identify a source of coral colonies for transplantation that would not result in damage to reefs, (2) test the feasibility of collecting and transplanting stormgenerated ]]>
Materials and ]]>
Study: This study was conducted from May 1999 to April 2011 on four reefs within Virgin Islands National Park (VINP, St. John, U.S. Virgin Islands; Fig. 1). The study sites, experimental design, field methods (coral fragment collection, handling, transport, placement and orientation), criteria for attachment-substrate, data collection and analysis, and statistical ]]>
Acropora palmata (Lamarck, 1816) (elkhorn coral), A. cervicornis (Lamarck, 1816)(staghorn coral), and Porites porites (Pallas, 1766)(finger coral)] were collected from shallow (1-3m) sandy or bare substrate unfavorable for ]]>
A. palmata skeletons for ]]>
A. palmata skeletons or other reef framework (see Garrison & Ward 2008).
To follow the natural mortality rates of each of the three species over the timespan of the experiment ]]>
Table 1). There was no reference colony monitoring at Scott Beach due to hazardous boat traffic, and coral abundance was too low at Trunk Cay and Scott Beach for monitoring. One hundred thirty-five corals (60 transplanted fragments and 75 reference colonies) were tagged, photographed, measured, and qualitatively assessed at 6-month intervals from May 1999 to July 2001, ]]>
Data analysis: In survivorship analyses, coral colonies were considered dead and were removed from further inclusion in the dataset if: (1) the entire colony or fragment ]]>
et al. 2002).
After 12 years, the complexity of the experimental design and size of the data set resulted in categorical independent variables that were often defined by low sample sizes and/or risk sets. In conjunction with coarsening of sampling periods over a relatively long-duration study, a more parsimonious ]]>
2-distribution, relative to a constant time-effects model ]]>
Results
Coral survival: After 12 years, only 9% (12) of the initial 135 colonies were alive: 3% of
A. palmata transplants (1 of 30) and 18% (8 of 45) of reference colonies; no A. cervicornis colonies; and 13% (2 of 15) of P. porites transplants and one reference colony (7%; Fig. 2). The mean mortality rates of A. palmata and P. porites colonies remained constant over the study (31 and 33% yr-1 likelihood of colony loss, respectively), ]]>
A. cervicornis the mortality rate increased on average by a factor of 1.5 annually (Fig. 2; Garrison & Ward 2008). Acropora palmata transplants were 2.3 times more likely to die in the first year than reference colonies, but not thereafter (Fig. 2). There was no significant difference between transplant and reference colony survival for
A. cervicornis (χ2(0.05, 2 =0.359, p=0.836), P. porites (χ2(0.05, 3)=1.848, p=0.605), or between A. palmata colonies transplanted from Hawksnest Bay to Trunk Cay and reference colonies in Hawksnest ]]>
χ2(0.05, 2) =2.51, p=0.285; Fig. 1). However, the mean probability of A. palmata transplant mortality in Whistling Cay was 4.8 times greater than the Leinster Bay reference colonies in the first year of the study (χ2(0.05, 1) =11.74, p<0.001) ]]>
Over the 12-year study, 56% of the initial 135 corals were lost due to physical dislodgement and 35% died in place. The relative roles of physical dislodgement and mortality in place varied among years (Fig. 2). ]]>
A. palmata (56%) than in A. cervicornis (47%) or P. porites losses (27%; Fig. 2) and was most likely the result of disease, predation, high-temperature stress, or some combination. Physical damage was ]]>
Survival of A. palmata transplants (χ2(0.05, 3)=2.804, ]]>
A. cervicornis and P. porites transplants and reference colonies did not show a site effect, whereas survival of A. palmata reference colonies differed significantly among sites (Table 2 and Fig. 1; Leinster 47%, Hawksnest 7%, and Whistling Cay 0%). In the first year,
A. palmata reference colonies exhibited a 12% yr-1 mean probability of mortality at all sites. Reference colonies in Leinster Bay continued on this trajectory for 12 years, whereas the mean mortality rate at Whistling Cay and Hawksnest Bay increased annually by 1.25- and 1.32-fold, respectively (χ2(0.05, 2)=8.688, ]]>
The initial log-mean live-tissue size of transplanted coral fragments differed from reference colonies across all species, with reference colonies generally larger than transplants (see Table 2, Garrison & Ward 2008). Size was a factor in survival only for A. ]]>
colonies in the first 5 years; the probability of mortality or dislocation of an A. palmata colony or transplant in the following year decreased by 15% per year with every 0.1 unit increase in log-maximum colony length over the first 5 years (β=-1.60, 95% C.I.=-2.59, -0.61; Garrison & Ward 2008).
Colony growth: Two of the three ]]>
A. palmata transplant increased more than 6-fold over the 12-year study [from 20 cm in 1999 to 130 cm prior to being physically dislodged in spring 2011 (Fig. 3)].
Cost: Transplantation costs were ]]>
]]>
Discussion
The transplantation methods and concepts tested in the field over the 12-year study were shown to work. (1) Storm-produced coral fragments of A. palmata, A. cervicornis, and ]]>
P. porites that were collected, transplanted, and attached to the reef using nylon cable ties had survival rates similar to reference colonies over 12 years. (2) No damage was inflicted on reefs or coral colonies in obtaining coral transplants. (3) Although physical displacement was the primary cause of mortality overall, the loss of a greater proportion of reference colonies than transplants to physical displacement supports the effectiveness of inexpensive and easyto-use cable ties for transplant attachment and confirms ]]>
et al. 2011). However, concepts and processes shown to work in the field do not necessarily translate into viable solutions for coral reef rehabilitation.
Coral mortality was striking with ]]>
A. cervicornis by year-5 and most A. palmata and P. porites transplant and reference colonies by year-12 (Fig. 2). Although the high rates of mortality observed could be an artifact of small sample size and the dramatic diminishing of sample size through time, the findings are consistent with most Caribbean region research (e.g., Hughes 1994, Aronson & Precht, 1997, 2001, Rogers 1999, Bruckner etal. 2009). Patches of ]]>
A. palmata and A. cervicornis exist (e.g., Vargas-Ángel & Thomas 2002, Vargas-Ángel et al., 2003) but the regional picture is one of decline (e.g., Gardner et al. 2003, Rogers et al. 2009, and references ]]>
A. cervicornis and P. porites. Both A. palmata and A. cervicornis have been key reef-building species in the Caribbean for thousands of years (e.g., ]]>
et al. 2005) and even though the life spans of individual colonies may be relatively short, populations may persist over time (Jaap et al. 2006). Nonetheless, the accelerating decline of A. cervicornis documented in the first 5 years and the high mortality rates of transplants and reference colonies of all three species documented here invoke concern. ]]>
Most coral transplantation research spans months, with few studies continuing for more than 2 years. Acropora palmata transplant survival documented in this study was similar to but lower than that reported in the only other long-term study of reattached A. palmata fragments (Bruckner et al. 2009), despite the ]]>
et al. 2009), indicating a realistic range of A. palmata fragment survival over time that could be expected in restoration efforts in the NE Caribbean. Storm-generated coral fragments were selected as ]]>
et al. 2011), and (3) damage to intact colonies from unattached fragment projectiles was reduced. A valid concern is that at all sites, colonies with disease-resistant genotypes or more robust immune function would be more likely to resist and survive infection (e.g., Ritchie 2006, Rosenberg et al. 2007, Vollmer & ]]>
et al. 2007, Teplitski & Ritchie 2009); impaired calcification; and/or genetic sensitivity to environmental stressors. The factors driving differences in survival among sites remain unknown but multiple factors are likely (e.g., Birkeland 2004, Bruno et al. 2007, Muller et al. 2008, Nyström et al. 2008).
Many restoration scientists have stressed the need for coral transplantation to be sustained over time and at an appropriate scale if it is to be effective (e.g., Rinkevich 1995, 2008, Epstein et al. 2005, Edwards & Gomez 2007). Results from this small-scale study bring into question whether such a major effort could be successful if underlying ]]>
et al. 2005, Rinkevich 2005, 2008). If chronic global or regional stressors such as abnormal water temperatures, contaminants, or disease are the primary ]]>
To retain A. palmata genetic diversity when restoring damaged coral reefs, Shearer et al. (2009) suggest that fragments from 7-10 donor colonies would retain 50% of allelic diversity and fragments from 30-35 colonies would retain 90% diversity. What fraction of that ]]>
A. cervicornis, a threatened species that has been decimated by epizootics, has limited sexual recruitment, and has been shown to have low gene flow (Vollmer & Palumbi, 2007): (1) protect remnant populations that have survived epizootics or other extrinsic insults; and (2) transplant laboratory or maricultured diseaseresistant genotypes. This could be extended to A. ]]>
, which in this study at this location in this time period appeared to be more robust than A. cervicornis.
Conclusions
This project was initiated to test ]]>
• ]]>
• transplant survival varied among species; • survival rates ]]>
• inexpensive, inert nylon cable ties effectively attach coral fragments to dead coral skeleton. • the low ]]>
A. palmata, A. cervicornis, and P. porites transplant and reference colonies at 12 years brings into question the efficacy of transplantation for conservation of coral species or reversal of reef degradation; • coral transplantation will not be effective in conserving coral species or in assisting reef recovery over time until the underlying ]]>
• community involvement is important in building what Brightsmith et al. (2008) call “conservation constituencies,” an informed and engaged public that in turn educates the wider community, thereby reducing damage to reefs.
Acknowledgments
Thanks go to the National Park Foundation, Canon U.S.A., Inc., and the U.S. Geological Survey for funding the project and to Friends of Virgin Islands National Park, the Trust for Public Land, and Virgin ]]>
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*Correspondencia: Virginia H. Garrison: U.S. Geological Survey, 600 Fourth Street South, St. Petersburg, Florida 33701, U.S.A.; ginger_garrison@usgs.gov Greg Ward: U.S. Geological Survey, 600 Fourth Street South, St. Petersburg, Florida 33701, U.S.A. Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, South Florida Regional Lab, 2796 Overseas Highway, 119, Marathon, Florida 33050; greg.ward@MyFWC.com ]]>
1.U.S. Geological Survey, 600 Fourth Street South, St. Petersburg, Florida 33701, U.S.A.; ginger_garrison@usgs.gov 2.Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, South Florida Regional Lab, 2796 Overseas Highway, 119, Marathon, Florida 33050; greg.ward@MyFWC.com
Received 8-VII-2011. Corrected 16-XII-2011. Accepted 20-XII 2011.