Size determination of Ecklonia cava for successful transplantation onto artificial seaweed reef

Abstract

The objective of this study was to determine the optimal blade size and timing to transplant seed-stock of Ecklonia cava Kjellman onto the reef structure. We used the modified artificial stepped reef structure. A total of 14 units (3.0 m length × 3.5 m width × 1.1 m height) were deployed 7-8 m deep under the water to examine the optimal blade size and timing to transplant seed-stock of E. cava onto the structures. Sporophytes of E. cava <1 cm in length were all died within 1 month of transplantation. The blades of 5-10 cm in length which were transplanted in March 2007 survived and grew well on the artificial reefs. Growth rates of 5-10 cm size class were higher than those of longer blade sporophytes (20-30 cm size class, transplanted in April) while the survival rates showed no difference between the classes of blade size. Both classes of 5-10 and 20-30 cm in length grew until July, and a reduction in size had occurred in September. These results indicate the importance of the blade size of E. cava and timing for successful transplantation of the seaweed on artificial reef structures.Key Words: artificial reef; barren grounds; Ecklonia cava; seed-stock; transplantation INTRODUCTIONBarren grounds are currently being expanded by destruction of seaweed habitats due to over harvesting, increases in herbivory (e.g., sea urchin and abalone) and sea temperature, and industrial pollution (Serisawa and Ohno 1995, Serisawa et al. 2002, 2003. The situations could lead to a decline in the fisheries of the country (Kim et al. 2006(Kim et al. , 2007(Kim et al. , 2010. It has been observed that both the diversity and biomass of seaweed species are declining in the coastal waters of Korea due to increasing occurrences in whitening event, changes in the oceanic conditions and increased number of grazers. Impacts of the expanded barren fields are particularly serious in waters off Jeju Island and the south and east coasts of the Korean peninsula (Choi et al. 2009, Kang 2010, Kim et al. 2012 -61-280-4750, Fax: +82-61-285-1949 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. . These transplants successfully grew on the artificial reefs and even produced sporelings on the reef and adjacent rocky substrata. However, these artificial reefs (3.0 m length × 3.5 m width × 1.1 m height and a weight of 4.6 tons) (Kim et al. 2012) were affected by grazing invertebrates, such as sea urchins (Strongylocentrotus nudus, S. intermedius, Hemicentrotus pulcherrimus), and mollusks (Chlorostoma turbinate, Haliotis gigantea). In the present study, modified artificial reefs were developed to overcome this grazing issue. The objective of this study was to determine the optimal plant size and timing for transplantation of E. cava seed-stock using the modified artificial stepped reef structure. MA...

Seaweed resources of Korea

“…E. cava, a perennial kelp found from Jeju Island to Samcheok, Gangwon Province, has mainly been utilized to construct the artificial seaweed forests, and it makes up about 56% of the artificial forests, followed by Sargassum fulvellum (31%), E. bicyclis (7%) and E. stolonifera (6%). To date, marine seaweed forests have been created using various techniques such as anchoring bags containing mature seaweeds (called spore bags) to supply spores, transplanting ropes with juvenile plants attached on artificial seaweed reefs, and removing seaweed-feeding grazers (Kim et al 2013b). To restore deforested areas, the Korean government has invested over US$280 million from 2009 to 2019 (Table 3).…”

Kelps in Korea: from population structure to aquaculture to potential carbon sequestration

“…The two major cultivated in Korea are kelp species U. pinnatifida and S. japonica. Some other kelp species have also been cultivated to provide biomass for the kelp forest restoration efforts (Kim et al 2013). These species include the perennial Ecklonia bicyclis (formerly known as Eisenia bicyclis), E. cava, and E. stolonifera.…”

Artificial Seaweed Reefs That Support the Establishment of Submerged Aquatic Vegetation Beds and Facilitate Ocean Macroalgal Afforestation: A Review

“…There is a need to review the cost-effectiveness of current restoration tools for macroalgal beds, mangrove wetlands, salt marshes, shellfish reefs, tidal freshwater wetlands, and coral reefs [33,34]. Artificial seaweed reefs (ASRs) (also known as artificial seaweed beds or marine forest artificial reefs) have been placed in generally shallow seawaters to provide light and firm (stable) substrates for seaweeds [7,[35][36][37][38][39]; man-made reefs have often been used for restoration and/or the enhancement of ocean afforestation in recent years. For example, ASRs have been employed to restore kelp under the Korean Fish Stock Enhancement Program; this increased the annual income of fishermen by 95% and thus secured livelihoods that were at risk [31].…”