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Harnessing natural recovery processes to improve restoration outcomes: an experimental assessment of sponge-mediated coral reef restoration.

Biggs BC - PLoS ONE (2013)

Bottom Line: Restoration is increasingly implemented to reestablish habitat structure and function following physical anthropogenic disturbance, but scientific knowledge of effectiveness of methods lags behind demand for guidelines.Differences in overall sponge species performance suggest species selection is important to consider.Employing organisms that jump start successional pathways and facilitate recovery can significantly improve restoration outcomes; however, best practices require techniques be tailored to each system.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Science, Florida State University, Tallahassee, Florida, USA. Biggs@bio.fsu.edu

ABSTRACT

Background: Restoration is increasingly implemented to reestablish habitat structure and function following physical anthropogenic disturbance, but scientific knowledge of effectiveness of methods lags behind demand for guidelines. On coral reefs, recovery is largely dependent on coral reestablishment, and substratum stability is critical to the survival of coral fragments and recruits. Concrete is often used to immobilize rubble, but its ecological performance has not been rigorously evaluated, and restoration has generally fallen short of returning degraded habitat to pre-disturbance conditions. Fragments of erect branching sponges mediate reef recovery by facilitating rubble consolidation, yet such natural processes have been largely overlooked in restoring reefs.

Methods: On two reefs in Curacao, four treatments - coral rubble alone, rubble seeded with sponge fragments, rubble bound by concrete, and concrete "rubble" bound by concrete - were monitored over four years to investigate rubble consolidation with and without sponges and the ecological performance of treatments in terms of the number and diversity of coral recruits. Species specific rates of sponge fragment attachment to rubble, donor sponge growth and tissue replacement, and fragment survival inside rubble piles were also investigated to evaluate sponge species performance and determine rates for sustainably harvesting tissue. FINDINGS/SIGNIFICANCE: Rubble piles seeded with sponges retained height and shape to a significantly greater degree, lost fewer replicates to water motion, and were significantly more likely to be consolidated over time than rubble alone. Significantly more corals recruited to sponge-seeded rubble than to all other treatments. Coral diversity was also greatest for rubble with sponges and it was the only treatment to which framework building corals recruited. Differences in overall sponge species performance suggest species selection is important to consider. Employing organisms that jump start successional pathways and facilitate recovery can significantly improve restoration outcomes; however, best practices require techniques be tailored to each system.

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Related in: MedlinePlus

Influence of treatment and water depth on rubble pile height over time.Conditional boxplots of rubble pile height for Sea Aquarium and Barracuda point. A and C. Rubble pile height conditional on water depth at Sea Aquarium and Barracuda Point, respectively. B and D. Rubble pile height conditional on treatment at Sea Aquarium and Barracuda Point, respectively. Thick solid and broken bars inside boxes indicate median and mean height, respectively. Letters above boxes indicate significant differences (P<0.05) between factor levels based on pairwise comparison of means with Bonferroni correction.
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pone-0064945-g003: Influence of treatment and water depth on rubble pile height over time.Conditional boxplots of rubble pile height for Sea Aquarium and Barracuda point. A and C. Rubble pile height conditional on water depth at Sea Aquarium and Barracuda Point, respectively. B and D. Rubble pile height conditional on treatment at Sea Aquarium and Barracuda Point, respectively. Thick solid and broken bars inside boxes indicate median and mean height, respectively. Letters above boxes indicate significant differences (P<0.05) between factor levels based on pairwise comparison of means with Bonferroni correction.

Mentions: At both sites treatment significantly influenced rubble pile height over time (LME, F 1, 38 = 4.77, P = 0.035, and LME, F 1, 36 = 14.37, P = 0.0006 for SA and BP, respectively), and temporary stabilization of coral rubble by sponges resulted in significantly greater retention of initial pile height (Figure 3B and 3D). Water depth also influenced rubble pile height at each site over time (LME, F 2, 39 = 13.39, P<0.0001, and LME, F 2, 36 = 6.88, P = 0.003 for SA and BP, respectively). As expected if water motion decreases with increasing water depth, pile height at SA was positively related to depth, and mean height differed significantly between each depth stratum (Figure 3A). A similar trend was noted at BP, with mean pile height significantly greater in intermediate and deep water compared to shallow (Figure 3C). Across treatments pile heights at all depths reflected differences in water motion between sites (greater intensity at SA as determined by the relative proportion of mobile substrata at each site [Figure S1]): mean heights of all piles in shallow, intermediate and deep depths at BP were 94.1%, 135.9%, and 32.4% taller than those at SA, respectively. Across all depths mean heights of rubble-alone and sponge-rubble piles at BP were also taller than at SA by 21.1% and 49.5%, respectively.


Harnessing natural recovery processes to improve restoration outcomes: an experimental assessment of sponge-mediated coral reef restoration.

Biggs BC - PLoS ONE (2013)

Influence of treatment and water depth on rubble pile height over time.Conditional boxplots of rubble pile height for Sea Aquarium and Barracuda point. A and C. Rubble pile height conditional on water depth at Sea Aquarium and Barracuda Point, respectively. B and D. Rubble pile height conditional on treatment at Sea Aquarium and Barracuda Point, respectively. Thick solid and broken bars inside boxes indicate median and mean height, respectively. Letters above boxes indicate significant differences (P<0.05) between factor levels based on pairwise comparison of means with Bonferroni correction.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3672152&req=5

pone-0064945-g003: Influence of treatment and water depth on rubble pile height over time.Conditional boxplots of rubble pile height for Sea Aquarium and Barracuda point. A and C. Rubble pile height conditional on water depth at Sea Aquarium and Barracuda Point, respectively. B and D. Rubble pile height conditional on treatment at Sea Aquarium and Barracuda Point, respectively. Thick solid and broken bars inside boxes indicate median and mean height, respectively. Letters above boxes indicate significant differences (P<0.05) between factor levels based on pairwise comparison of means with Bonferroni correction.
Mentions: At both sites treatment significantly influenced rubble pile height over time (LME, F 1, 38 = 4.77, P = 0.035, and LME, F 1, 36 = 14.37, P = 0.0006 for SA and BP, respectively), and temporary stabilization of coral rubble by sponges resulted in significantly greater retention of initial pile height (Figure 3B and 3D). Water depth also influenced rubble pile height at each site over time (LME, F 2, 39 = 13.39, P<0.0001, and LME, F 2, 36 = 6.88, P = 0.003 for SA and BP, respectively). As expected if water motion decreases with increasing water depth, pile height at SA was positively related to depth, and mean height differed significantly between each depth stratum (Figure 3A). A similar trend was noted at BP, with mean pile height significantly greater in intermediate and deep water compared to shallow (Figure 3C). Across treatments pile heights at all depths reflected differences in water motion between sites (greater intensity at SA as determined by the relative proportion of mobile substrata at each site [Figure S1]): mean heights of all piles in shallow, intermediate and deep depths at BP were 94.1%, 135.9%, and 32.4% taller than those at SA, respectively. Across all depths mean heights of rubble-alone and sponge-rubble piles at BP were also taller than at SA by 21.1% and 49.5%, respectively.

Bottom Line: Restoration is increasingly implemented to reestablish habitat structure and function following physical anthropogenic disturbance, but scientific knowledge of effectiveness of methods lags behind demand for guidelines.Differences in overall sponge species performance suggest species selection is important to consider.Employing organisms that jump start successional pathways and facilitate recovery can significantly improve restoration outcomes; however, best practices require techniques be tailored to each system.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Science, Florida State University, Tallahassee, Florida, USA. Biggs@bio.fsu.edu

ABSTRACT

Background: Restoration is increasingly implemented to reestablish habitat structure and function following physical anthropogenic disturbance, but scientific knowledge of effectiveness of methods lags behind demand for guidelines. On coral reefs, recovery is largely dependent on coral reestablishment, and substratum stability is critical to the survival of coral fragments and recruits. Concrete is often used to immobilize rubble, but its ecological performance has not been rigorously evaluated, and restoration has generally fallen short of returning degraded habitat to pre-disturbance conditions. Fragments of erect branching sponges mediate reef recovery by facilitating rubble consolidation, yet such natural processes have been largely overlooked in restoring reefs.

Methods: On two reefs in Curacao, four treatments - coral rubble alone, rubble seeded with sponge fragments, rubble bound by concrete, and concrete "rubble" bound by concrete - were monitored over four years to investigate rubble consolidation with and without sponges and the ecological performance of treatments in terms of the number and diversity of coral recruits. Species specific rates of sponge fragment attachment to rubble, donor sponge growth and tissue replacement, and fragment survival inside rubble piles were also investigated to evaluate sponge species performance and determine rates for sustainably harvesting tissue. FINDINGS/SIGNIFICANCE: Rubble piles seeded with sponges retained height and shape to a significantly greater degree, lost fewer replicates to water motion, and were significantly more likely to be consolidated over time than rubble alone. Significantly more corals recruited to sponge-seeded rubble than to all other treatments. Coral diversity was also greatest for rubble with sponges and it was the only treatment to which framework building corals recruited. Differences in overall sponge species performance suggest species selection is important to consider. Employing organisms that jump start successional pathways and facilitate recovery can significantly improve restoration outcomes; however, best practices require techniques be tailored to each system.

Show MeSH
Related in: MedlinePlus