Non-sporogenous individuals of S. latissima, first- or second- year sporophytes,
were sampled at Vanvikan in Trondheimsfjorden (63° 52′ N, 9°
37′ E) in the sublittoral zone in April, July, and October 2010 and in
February 2011. The lowermost portion of the sporophyte with stipe and
haptera was cut off, and the blade was transferred to tanks for sorus induction
according to Forbord et al. (2012). Induced sorus portions were
used for release of zoospores and seeding of 6-mm ropes for cultivation
of juvenile sporophytes. The ropes were incubated on horizontal plates
in 30 L tanks at 10 °C with continuous water exchange of nutrient-rich
deep water (0.5 L min−1) from day 2 after seeding under a 12:12 light/
dark cycle. The surface PAR was 30 μmol photons m−2 s−1, and the
ropes were situated 10 cm below the surface.