Early development and substrate twine selection for the cultivation of Sargassum muticum (Yendo) Fensholt under laboratory conditions

Abstract

The phaeophyte macroalgae Sargassum muticum is under investigation as a cultivation crop within its native range in SE Asia, alongside other members of the Sargassum genus. During the critical hatchery phase, germlings are grown to ≥ several millimeters ready for outplanting. By optimising the growth medium and twine substrate used for the germling attachment, hatcheries can become more efficient and cost-effective. An 8-week replicated laboratory experiment investigated these factors. It found that adding 0.125 mL L−1 of saturated germanium dioxide during the first week increased mean germling size by 23% (p < 0.005), whereas additional nutrients in the form of F/2 medium made no difference (p > 0.05). Six twine substrates were also tested: jute, cotton, polyamide/cotton, polyester, polyvinyl alcohol and polypropylene. Sargassum muticum grew similarly well on all, although attachment success during the first week was highest on the rougher natural fibres, particularly jute. A negative density-dependent effect of germling density on growth was seen across all materials, with the highest growth seen on the materials with the lowest germling density. Jute is recommended as a highly suitable substrate for hatchery cultivation in this species, although the initial density should be carefully controlled to prevent intraspecific competition.

Twine selection is essential for successful hatchery cultivation of Saccharina latissima, seeded with either meiospores or juvenile sporophytes

“…Leaching compounds are thought to be responsible, as aqueous extract from dried sisal and jute reduce seed germination and growth in some higher plants (Chowdhury et al 2009). Nevertheless, it should be noted that other macroalgae are unaffected by this leachate (Geng et al 2015;Le et al 2018) and so sisal or jute may only be toxic to specific species or groups.…”

“…Small sporophytes of kelp (< 1 cm) grow in a viscous-dominated, low Reynold's number condition (Vogel 1996), and so remain attached despite weak bioadhesion (Kerrison et al 2017). Yet, with a weak attachment, they can be easily detached due to abrasion or drag as they grow larger and experience the more turbulent environment of higher Reynold's numbers (Kerrison et al 2018(Kerrison et al , 2019. This is a very important in the context of hatchery cultivation, as a dense coverage of juveniles is not a guarantee that once outplanted a high yield will be achieved.…”

“…In E1, we found differences in the sporophyte coverage between PES twine produced by two manufacturers. Also, in previous studies, solid PA was determined to be a highly suitable material for S. latissima cultivation due to a low θ w and strong bioadhesion (Kerrison et al 2017(Kerrison et al , 2018(Kerrison et al , 2019). Yet, in the present study, PA twine was equally successful to PP twine, which has a weak bioadhesion with S. latissima.…”

Culture of Gracilaria gracilis and Chondracanthus teedei from Vegetative Fragments in the Field and Carpospores in Laboratory

“…When unialgal cultures are carried out, it is necessary to eliminate the presence of epiphytes since these can grow faster than the algae to be cultivated [61]. For this reason, sterilised seawater is usually used, to which GeO 2 is added to reduce the presence of diatoms in different concentrations (0.1-0.2 mg L −1 ) depending on the species [25,43,62]. It is recommended that the maximum concentration be 1 mg L −1 in brown algae culture [61] and antibiotics for the presence of organisms such as fungi and bacteria [21,63].…”

Naturally Occurring Rock Type Influences the Settlement of Fucus spiralis L. zygotes

“…Fucoids are common members of intertidal and subtidal hard substrate communities worldwide, ranging from the Arctic to the tropics [48]. Studies have addressed the importance of surface roughness [49,50], water flow and wave action [16,49,51], and substrate type and surface properties [43,44,52] on the settlement and early development of fucalean algae. No studies that we are aware of, however, have addressed differences in settlement among different bedrock types where these algae regularly occur.…”