Coral reef restoration in the Eastern Tropical Pacific: feasibility of the coral nursery approach

Abstract

Due to the worldwide degradation of coral reefs, the active restoration of these ecosystems has received considerable attention in recent decades. This study investigated (1) the feasibility of using coral nurseries for restoration projects, (2) the minimum size required for a Pocillopora damicornis (Pocilloporidae) coral fragment to survive and grow in a nursery, and (3) the optimal transplant size of a fragment when transplanted to a degraded reef at Gorgona Island (Colombian Pacific). For this investigation, 230 fragments were transplanted directly to El Remanso reef, and another 150 fragments were maintained in in situ nurseries. Every 2 months, the length, weight, and survival of the fragments were recorded. After growing for 134 days in the nurseries, the 52 surviving fragments were transplanted to El Remanso reef, and after 5 months, the same variables were measured. Among the nursery-reared fragments, the largest (4 to <8 cm) had the highest survival and growth rates, whereas among the directly transplanted fragments, the smallest fragments (<2 cm) had the highest survival and growth rates. However, the nursery-reared fragments acquired greater structural complexity (arborescent morphology), and they were all alive 156 days after transplantation and presented a maximum linear growth rate of over 2 cm, which was higher than that of the directly transplanted fragments. Apparently, the arborescent morphology acquired during the nursery period provides advantages to the colonies that favor greater success when transplanted. Therefore, nursery-reared fragments of P. damicornis between 2 and 4 cm are the most appropriate for use in restoration projects.

Micro-Fragmentation as an Effective and Applied Tool to Restore Remote Reefs in the Eastern Tropical Pacific

“…In the same way, annual extension (2.74 cm year −1 ) and calcification rates (6.03 g cm −2 year −1 ) obtained for Pocillopora spp. are similar to other documented outcomes in the ETP region [14,56,87,[93][94][95]. The same applies to Pavona, one of the fastest growing massive coral species in the ETP region [49,87,88,[94][95][96][97].…”

“…The overall first 13 months survivorship (60%) is similar to results obtained in previous, more time-consuming restoration approaches [17,25,30,[51][52][53]56,[83][84][85], even though the actual survival is much higher (about 90%), as most coral mortality was associated with fragment dislodgements (30%) due to the Willa hurricane forces, reflecting the impacts of natural catastrophes on other restoration projects [29,86]. The 10% of natural coral mortality is most probably due to competition with macroalgae (Padina sp.)…”

“…The number of active restoration projects in the ETP has increased dramatically in the last decade [ 51 , 52 , 53 , 54 , 55 , 56 , 57 ]. Yet, more studies are required in order to integrate and enhance restoration efforts in the region and other remote and marginal reefs, where accessibility to absent or scarce infrastructures and facilities is limited, and active restoration measures are not commonly implemented [ 58 , 59 ].…”

The Meta-Organism Response of the Environmental Generalist Pocillopora damicornis Exposed to Differential Accumulation of Heat Stress

“…Although P. damicornis is well characterized as a thermally sensitive coral species, the aforementioned studies and the cosmopolitan distribution of P. damicornis suggest that changes in P. damicornis physiology in response to bleaching temperatures could be related to local environmental conditions. The well-studied reproductive biology, feeding ability, and widespread availability of P. damicornis (Harriott, 1983;Harii et al, 2002) have also made it a low-cost and successful target for coral restoration efforts on degraded reefs in the Tropical Eastern Pacific (Yeemin et al, 2006;Toh et al, 2013;Lizcano-Sandoval et al, 2018;Ishida-Castañeda et al, 2020). Nonetheless, evidence related to how coral microorganisms function and contribute to the success of P. damicornis corals under future ocean conditions, especially in response to the rising frequency and severity of coral bleaching, is still equivocal.…”

Comparing different farming habitats for mid-water rope nurseries to advance coral restoration efforts in the Maldives

“…We used an average stocking size of about five cm, with fragments ranging from 2.7 to 10 cm in maximum linear extension. In comparison, P. damicornis reared in rope nurseries in the Eastern Tropical Pacific exhibited a higher survival for fragments bigger than two cm but no significant difference in growth rate was found between size classes ( Ishida-Castañeda et al, 2020 ).…”