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Strategies for Gardening Denuded Coral Reef Areas: The Applicability of Using Different Types of Coral Material for Reef Restoration

Authors

  • N. Epstein,

    1. Minerva Center for Marine Invertebrate Immunology and Developmental Biology, Israel Oceanographic and Limnological Research, National Institute of Oceanography, Tel Shikmona, P.O.B. 8030, Haifa 31080, Israel
    2. Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O.B 94766, 1090 GT, Amsterdam, The Netherlands
    3. Address correspondence to N. Epstein, email nimrod@ocean.org.il
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  • R. P. M. Bak,

    1. Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O.B 94766, 1090 GT, Amsterdam, The Netherlands
    2. Netherlands Institute for Sea Research (NIOZ), P.O.B 59, 1790 AB, Den Burg, Texel, The Netherlands
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  • B. Rinkevich

    1. Minerva Center for Marine Invertebrate Immunology and Developmental Biology, Israel Oceanographic and Limnological Research, National Institute of Oceanography, Tel Shikmona, P.O.B. 8030, Haifa 31080, Israel
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Abstract

Recreational and other human activities degrade coral reefs worldwide to a point where efficient restoration techniques are needed. Here we tested several strategies for gardening denuded reefs. The gardening concept consists of in situ or ex situ mariculture of coral recruits, followed by their transplantation into degraded reef sites. In situ nurseries were established in Eilat's (Northern Red Sea) shallow waters, sheltering three types of coral materials taken from the branching species Stylophora pistillata (small colonies, branch fragments, and spat) that were monitored for up to two years. Pruning more than 10% of donor colonies' branches increased mortality, and surviving colonies displayed reduced reproductive activity. Maricultured isolated branches, however, exceeded donor colony life span and reproductive activity and added 0.5–45% skeletal mass per year. Forty-four percent of the small colonies survived after 1.5-year mariculture, revealing average yearly growth of 75 ± 32%. Three months ex situ maintenance of coral spat (sexual recruits) prior to the in situ nursery phase increased survivorship. Within the next 1.5 years, they developed into colonies of 3–4 cm diameter. Nursery periods of 2 years, 4–5 years, and more than> 5 years have been estimated for small colonies, spat, and isolated branches, respectively. These and other results, including the possible use of nubbins (minute fragments the size of a single or few polyps), are discussed, revealing benefits and drawbacks for each material. In situ coral mariculture is an improved practice to the common but potentially harmful protocol of direct coral transplantation. It is suggested that reef gardening may be used as a key management tool in conservation and restoration of denuded reef areas. The gardening concept may be applicable for coral reefs worldwide through site-specific considerations and the use of different local coral species.

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