Fixed and suspended coral nurseries in the Philippines: Establishing the first step in the “gardening concept” of reef restoration

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Abstract

The worldwide degradation of reef ecosystems has promoted the advocators of restoration acts to the foreground. Here, we describe the results of the first step of large-scale restoration based on the “gardening with corals” concept. During June–September 2005, two coral nurseries were established in Bolinao, the Philippines, in front of Silaqui Island, in a shallow (2 m depth) sandy lagoon. Two types of nurseries were employed: (1) suspended nursery; (2) leg-fixed nursery. The nursery held a total number of 6824 ramets, from seven coral species representing different growth forms (branching, leaf-like and sub-massive forms) and different growth rates (fast and slow growing species). Each species was represented by several genotypes. During one year, we analyzed and compared survivorship, bleaching and growth rates of fragments between the different nurseries, species and genotypes. Survivorship, which was high in both nurseries, > 85%, fluctuated between the different species indicating that different species require different rearing methodologies. Mortality and detachment was subjected to environmental conditions, especially affected by the typhoons prevailing in this part of the world. The one-year nursery phase produced sizeable colonies, especially of branching forms, suitable for transplantation.

Introduction

Coral reefs are of the most rich, diverse, and productive marine ecosystems (Hoegh-Guldberg et al., 2007). For countless local communities along the coasts of developing countries, this ecosystem provides livelihood and protection against strong waves and coastal erosion (Gomez, 1997, Latypov, 2006, Ahmed et al., 2007). Over the last decade, coral reefs around the world have been increasingly declining, stressed by global changes and anthropogenic impacts; that they seem unable to regenerate adequately and overcome those factors (Rinkevich, 1995, Rinkevich, 2005a, Chadwick-Furman, 1996, Hodgson, 1999, Epstein et al., 2001, Wilkinson, 2002, Manning et al., 2006, Shafir et al., 2006a).

Unfortunately, passive rehabilitation measures and traditional management acts have proven to be insufficient or ineffective in ameliorating long-term damage and have failed to yield quantifiable returns or suitable responses to key anthropogenic threats (Edwards and Clark, 1998, Yap et al., 1998, Lindahl, 2003, Rinkevich, 2005a, Rinkevich, 2005b, Rinkevich, 2006, Forsman et al., 2006, Tsuchiya, 2006). To avoid the pitfalls associated with the traditional management measures, Rinkevich, 1995, Rinkevich, 2000, Rinkevich, 2005a, Rinkevich, 2005b, Rinkevich, 2006 suggested shifting management efforts from passive conservation to active rehabilitation strategies. The proposed remediation strategy is based on the ‘gardening concept’ (Rinkevich, 1995, Rinkevich, 2000, Epstein et al., 2001), a two-step restoration measure, featuring mass farming of coral nubbins, fragments and spats in specially designed underwater nurseries, which are transplanted onto degraded reefs upon reaching adequate size. Recently, an improved method involving the use of a floating mid-water coral nursery has been successfully tested in the northern shore of Eilat, Gulf of Eilat, Red Sea (Rinkevich, 2006, Shafir et al., 2006a, Shafir et al., 2006b). This nursery prototype met expectations, such as successful, cheap and fast farming of thousands of coral colonies from several coral species, with impressive rates of survivorship, fast growth and improved reproductive efforts (Bongiorni et al., 2003, Rinkevich, 2006, Shafir et al., 2006a, Shafir et al., 2006b, Amar and Rinkevich, 2007). Furthermore, farmed coral colonies from the Eilat mid-water nursery, which have recently been transplanted onto denuded reef sites, have yielded encouraging results in improving biological condition, such as high coral survivorship, increased conscription of reef dwelling invertebrates and fish and enhanced recruitment of coral spats (B.R., unpublished). However, in order to decide on the best applicable method for conserving reef biodiversity, prior to adopting the ‘gardening concept’ as an ubiquitous methodology for coral reef restoration, the newly developed methodologies should be tested and substantiated in other reef sites and on different coral species worldwide.

In Eilat, the floating mid-water nursery prototype (placed at depth of 6 m, 14 m above seafloor, in the nutrient-enriched environment of a fish farm) yielded colonies ready for transplantation within 144–200 nursery days (Shafir et al., 2006a, Shafir et al., 2006b). Results also revealed that a successful nursery could constitute a simple and cheap structure, built from locally available material, with little technical manipulations and extremely low maintenance costs (Shafir et al., 2006a). For example, gluing thousands of coral fragments within a few days to substrates by cyanoacrylate adhesives (super-glue) was found to be the easiest and cheapest technique for preparing new colonies by untrained workers (Shafir et al., 2006a). Since there is much more to learn about proper restoration of coral reef ecosystems, it would be inevitable to initiate similar restoration assays in other reefs worldwide for testing and comparing various aspects of both gardening concept steps; the nursery phase and the transplantation act.

This work tests the issue raised above in the Philippines where an estimated 10–15% of the total fish yield comes from coral reefs (Gomez, 1997). A 2004 Global Coral Reef Monitoring Network studies (Tun et al., 2004) found that the Philippine reefs were undergoing an annual steady decline in coral cover of 3–5%. Here we present the results of employing the first step of the ‘‘gardening of the coral reefs’’ concept (Rinkevich, 1995, Rinkevich, 2000, Rinkevich, 2005a), in a large in situ coral nursery at the eastern edge of the South China Sea, Luzon, the Philippines. Growth and survival of 6824 coral ramets prepared from seven different coral species, were observed for one year in two types of in situ nurseries (suspended, leg-fixed). The leg-fixed nursery model was tested for the first time because of the shallow waters at the experimental site, allowing the comparison of the two types for future reference. Cost effectiveness and invested person–months were taken into consideration.

Section snippets

Area description

The study was conducted in Bolinao, Pangasinan, a coastal town in northwestern Philippines (16°22′ and 16°27′ N latitude and 119°52′ and 120°00′ E longitude, Fig. 1) along the eastern side of the South China Sea. The fringing reefs of Bolinao with slopes dropping to 120 m in certain areas, experience the northeast monsoon from November to March and the southwest monsoon from June to October. Reef flats are mostly fine sediments, covered with sea grasses and seaweed, whereas some fore-reefs

Coral collection and transplantation in the nurseries

We studied seven coral species, representing different colony morphologies and growth rates (Table 1). Five of the species were abundant in the study area and two (Acropora formosa, Montipora aequituberculata) were collected from Caniogan Island, 20–22 km from Silaqui lagoon (45 min by boat). Coral fragments were taken from 1–3 genotypes per coral species, grown at maximum depth of 4 m (Table 1).

The colonies were detached from their natural substrates by chisel and hammer, carried in a basket

Results

We used 13 genotypes from seven coral species. Constructing the two nurseries and stocking them with 6824 coral ramets was completed within four months by a team of up to five people (total of ca. 16 person–months; Table 2). Building the nurseries construction on land was done by two people within one month (June 2005), whereas setting up the constructions, sinkers and ropes and assembling all parts was achieved by five people in two working days. Collecting coral source material, fragmenting

Discussion

In this study, a simply constructed nursery, composed of common and cheap material was successfully established in Bolinao, the Philippines. A team of four (two scientists and two technicians) assembled two prototype nurseries (leg-fixed and suspended) within a short period of three months, holding about 7000 coral fragments. While constructing these nurseries, we had considered Shafir et al., 2006a, Shafir et al., 2006b and others' (Yap et al., 1990, Edwards and Clark, 1998, South et al., 2001

Conclusion

This study evaluates the first step of the ‘gardening of the coral reefs’ concept (Rinkevich, 1995, Rinkevich, 2000, Rinkevich, 2005a) by establishing two types of large in situ coral nurseries in Bolinao, the Philippines, and testing the applicability of several nursery properties, such as simultaneous cultivation of multi-species under the same nursery conditions. Both nursery types that held several coral species of different morphological architectures were equally adapted to the Bolinao

Acknowledgments

This study is part of the PhD dissertation of L. Shaish and supported by grants from the GEF/World Bank Coral Reef Targeted Research and the INCO-DEV (REEFRES-510657) projects. We thank Bolinao Marine Laboratory staff for their help and hospitality. This is UPMSI Contribution No. 364. [SS]

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