An evaluation of artificial reef structures as tools for marine habitat rehabilitation in the Maldives
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Published source details
Clark S. & Edwards A.J. (1999) An evaluation of artificial reef structures as tools for marine habitat rehabilitation in the Maldives. Aquatic Conservation: Marine and Freshwater Ecosystems, 9, 5-21.
Published source details Clark S. & Edwards A.J. (1999) An evaluation of artificial reef structures as tools for marine habitat rehabilitation in the Maldives. Aquatic Conservation: Marine and Freshwater Ecosystems, 9, 5-21.
Actions
This study is summarised as evidence for the following.
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Transplant wild-grown coral onto artificial substrate Action Link |
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Stabilize damaged or broken coral reef substrate or remove unconsolidated rubble Action Link |
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Transplant wild-grown coral onto artificial substrate
A study in 1990–1993 at an area of degraded coral reef in Galu Falhu, Maldives (Clark & Edwards 1999) reported that transplanting coral fragments onto flexible concrete mats (Armorflex) did not lead to an increase in coral cover compared to mats naturally colonized by coral recruits, but approximately half the transplanted fragments survived. After 10 months, coral recruits were observed on the edges of the paving slabs anchoring the Armorflex mats and, after 16 months, recruits were observed on the mats both with and without transplants (data not reported). There was no difference in density of coral recruits after 2.5 years with an average of 4/m2 recorded on mats and 18/m2 on the vertical edges of the paving slabs with and without transplants. After 2.5 years, 41–59% of coral transplants were still alive on the mats. In 1990–1991, Armorflex mats, weighted down using paving slabs, were installed on two 10 × 5 m areas of previously mined coral rubble substrate 0.5–1.8 m deep at four sites. Fragments of coral (number and species not reported) were taken from colonies near the study site and attached to one of the Armorflex mats at each site using marine cement; the other mat was left bare. Monitoring took place every 8–12 months for 2.5 years. Armorflex mats with transplants cost £97/m2 and bare Armorflex mats cost £66/m2 (1999 value).
(Summarised by: Ann Thornton)
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Stabilize damaged or broken coral reef substrate or remove unconsolidated rubble
A study in 1990–1993 at an area of degraded coral reef in Galu Falhu, Maldives (Clark & Edwards 1999) reported that using artificial structures to provide greater stability to coral rubble substrate led to an increase in the number of coral colonies. After 3.5 years, approximately 500 coral colonies (average density 13/m2) were recorded on structurally complex concrete/PVC blocks that provided high substrate stability. After 3.5 years, average density on concrete mats that provided medium stability was 3 recruits/m2 but 18/m2 on the edges. After 3.5 years, some corals were observed attached to chain link fencing designed to provide low stability (numbers not reported). After 2.5 years, coral coverage on the unstabilized rubble had declined from 0.8% to 0.19%. In 1990–1991, four 10 × 5 m areas of previously mined coral rubble substrate at four sites each received one of three artificial substrate-stabilizing structures or were left unstabilized. Structures comprised complex concrete/PVC blocks (providing high stability), concrete mats (medium stability), or chain-link fencing (low stability) (see paper for design). Structures were deployed 0.5–1.8 m deep and were either sufficiently heavy to prevent movement by wave action or, for the concrete mats and chain-link fencing, weighted down using paving slabs. Monitoring took place at 8–12-month intervals for 2.5–3.5 years. Costs (presented in 1999): concrete/PVC blocks £210/m2; concrete mats £66/m2; chain-link fencing £26/m2.
(Summarised by: Ann Thornton)
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