Growth, reproduction and recruitment of Silvetia siliquosa (Fucales, Phaeophyceae) transplants using polyethylene rope and natural rock methods

Abstract

Anthropogenic disturbances such as shoreline development and sediment loading can reduce or eliminate Nereocystis luetkeana populations and commercially important species associated with N. luetkeana. Hence, kelp restoration will become increasingly important in urbanized nearshore areas. Techniques to establish N. luetkeana populations in the northwestern waters of Washington State, USA, were examined and compared: (1) out-planting recently settled zoospores and microscopic sporophytes (0.5 to 1.0 mm blade length) grown in laboratory culture, in the field onto natural substrate, and at elevated positions, and (2) transplanting juvenile sporophytes (<15 cm stipe length) from natural populations, bypassing the culturing phase. Juvenile transplants were found to be more successful than cultured out-plants. The restoration cost for juvenile transplants was 12 US dollars (USD) per installed plant with a maximum cost estimate of 200 USD m -2 . These had a 10 to 30% higher survival rate than previously reported kelp transplant efforts using larger individuals. The collection of smaller individuals for transplanting imposes smaller ecological costs to natural populations than does the collection of larger, established plants. Stipe breakage caused by the grazing gastropod Lacuna vincta posed the largest limiting factor on transplant survival. Lack of survival among the out-planted zoospores and microscopic sporophytes indicates that other methods will be more successful. Restoration efforts in the nearshore marine environment will benefit from an adaptive management approach in which techniques can be tailored to the specific physical and biological conditions at the restoration site.

Ecological restoration using intertidal foundation species: Considerations and potential for rockweed restoration

“…Transplantation of whole individuals, or thalli, in particular, has been relatively successful (Figure 3). For example, Gao et al (2017) attributed the recruitment of ~1000 rockweed individuals to a transplant method they applied involving the attachment of fertile rockweed thalli to polyethylene rope, which, in turn, was affixed to the substratum.…”

“…Certainly, the marked global decline of fucoid algae (Piñeiro‐Corbeira et al, 2016; Vogt & Schramm, 1991; Wahl et al, 2015) and their influence on community structure have spurred an increased urgency in developing strategies to halt and reverse their loss. Thus far, fucoid restoration has predominantly focused on nonrockweed, subtidal taxa, such as Sargassum and Cystoseira (Campbell et al, 2014; La Fuente et al, 2019; Lardi et al, 2022; Perkol‐Finkel et al, 2012; Yoon et al, 2014); only a handful of studies have focused on the restoration of intertidal rockweeds in the family Fucaceae (e.g., Gao et al, 2017; Jonsson et al, 2006; Kautsky et al, 2019; Stekoll & Deysher, 1996; Tronske, 2020; Whitaker et al, 2010).…”

“…Transplantation of whole individuals, or thalli, in particular, has been relatively successful (Figure 3). For example, Gao et al (2017) attributed the recruitment of ~1000 rockweed individuals to a transplant method they applied involving the attachment of fertile rockweed thalli to polyethylene rope, which, in turn, was affixed to the substratum. Experimental transplantation of S. compressa by chipping off rock pieces with rockweeds attached from donor sites and affixing the rock to the substrate at restoration sites using marine epoxy resulted in survival rates as high as ~60% (Tronske, 2020; Whitaker et al, 2010).…”

Seaweed resources of Korea

“…However, the population of this species has declined from the mid-1990s onward (Lee et al 1997;Song et al 1996). Now this alga can be found only along the rocky shores of the offshore islands of southern Korea (Gao et al 2017). Although the causes of population decline for these two species, M. papulosa and S. siliquosa are not fully understood, overharvesting and environmental changes have been suggested as the main reasons.…”

“…Although the causes of population decline for these two species, M. papulosa and S. siliquosa are not fully understood, overharvesting and environmental changes have been suggested as the main reasons. To overcome this issue, there have been recent efforts by Korean scientists to restore these species (Gao et al 2017;Kim et al 2019).…”