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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

Location of study sites.A. Map of the Caribbean with the location of Curaçao indicated. B. Map of Curaçao, Netherlands Antilles. Filled triangle and circle indicate location of study sites Sea Aquarium reef and Barracuda Point reef, respectively.
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pone-0064945-g001: Location of study sites.A. Map of the Caribbean with the location of Curaçao indicated. B. Map of Curaçao, Netherlands Antilles. Filled triangle and circle indicate location of study sites Sea Aquarium reef and Barracuda Point reef, respectively.

Mentions: The rubble consolidation and coral recruitment experiments reported here were conducted on two fringing reefs along the south-east coast of Curaçao, in front of the Curaçao Sea Aquarium (SA) (12° 5′ 0.68″ N, 68° 53′ 40.81′ W) and eastward along the coast at Barracuda Point (BP) (12° 3′ 44.91″N, 68° 51′ 22.35″ W) (Figure 1). Growth and tissue replacement rates of donor sponges were investigated at BP, as were rates of attachment of individual sponge fragments to single pieces of coral rubble (Figure 1B). Using these sites to address our questions is meaningful from a management perspective in that fringing reefs form in relatively shallow coastal waters where boat traffic and recreational activities increase their risk of physical disturbance [49]–[51]. Furthermore, these sites allow examination of sponge stabilizing performance and rubble pile consolidation under different degrees of water motion. Atlantic and Gulf Rapid Reef Assessment surveys (AGRRA 2005, v. 4.0) conducted prior to the study revealed similarity in coral composition (Tables S1 and S2) between the sites but difference in substratum composition (Figure S1): mobile substrata (e.g., coral rubble and sand) accounted for 35% of substrata at BP but only 15% at SA. Reduced accumulation of mobile substrata on the benthos at SA suggests greater intensity of water motion at this site, which can disrupt consolidation of loose rubble. Additional sources of disturbance include tropical cyclones, which pass within 180 nmi of Curaçao at a frequency of roughly 0.39 storms per year [52]. While wave heights from 0.3 to 1.5 m are typical year round along the south-east coast, average heights may be exceeded during the hurricane season [53].


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

Biggs BC - PLoS ONE (2013)

Location of study sites.A. Map of the Caribbean with the location of Curaçao indicated. B. Map of Curaçao, Netherlands Antilles. Filled triangle and circle indicate location of study sites Sea Aquarium reef and Barracuda Point reef, respectively.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0064945-g001: Location of study sites.A. Map of the Caribbean with the location of Curaçao indicated. B. Map of Curaçao, Netherlands Antilles. Filled triangle and circle indicate location of study sites Sea Aquarium reef and Barracuda Point reef, respectively.
Mentions: The rubble consolidation and coral recruitment experiments reported here were conducted on two fringing reefs along the south-east coast of Curaçao, in front of the Curaçao Sea Aquarium (SA) (12° 5′ 0.68″ N, 68° 53′ 40.81′ W) and eastward along the coast at Barracuda Point (BP) (12° 3′ 44.91″N, 68° 51′ 22.35″ W) (Figure 1). Growth and tissue replacement rates of donor sponges were investigated at BP, as were rates of attachment of individual sponge fragments to single pieces of coral rubble (Figure 1B). Using these sites to address our questions is meaningful from a management perspective in that fringing reefs form in relatively shallow coastal waters where boat traffic and recreational activities increase their risk of physical disturbance [49]–[51]. Furthermore, these sites allow examination of sponge stabilizing performance and rubble pile consolidation under different degrees of water motion. Atlantic and Gulf Rapid Reef Assessment surveys (AGRRA 2005, v. 4.0) conducted prior to the study revealed similarity in coral composition (Tables S1 and S2) between the sites but difference in substratum composition (Figure S1): mobile substrata (e.g., coral rubble and sand) accounted for 35% of substrata at BP but only 15% at SA. Reduced accumulation of mobile substrata on the benthos at SA suggests greater intensity of water motion at this site, which can disrupt consolidation of loose rubble. Additional sources of disturbance include tropical cyclones, which pass within 180 nmi of Curaçao at a frequency of roughly 0.39 storms per year [52]. While wave heights from 0.3 to 1.5 m are typical year round along the south-east coast, average heights may be exceeded during the hurricane season [53].

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