Helgolandic S. latissima and L. hyperborea predominantly grow in winter and early
spring similarly as in Norway (Bartsch et al. 2008). While growth of L. hyperborea
totally stops in July, growth of S. latissima decreases substantially but does not
cease. In contrast, the growth period of L. digitata from Helgoland extends from
spring to summer and in September, it exhibits a growth rate of still 50% of the
optimum (Lüning 1979). The seasonal variations in abiotic conditions affect growth
performance, particularly in algae from high latitudes with a more pronounced
seasonality of temperature, irradiance and photoperiod (Bartsch et al. 2008).
Exploring the feasibility of offshore kelp cultures, potential forces experienced
by the attached algae were studied extensively. Sporophytes were seeded on ropes,
which were designed for the use in offshore environments (Fig. 11.3a, c).
Land-based cultivation took place in tank devices, where the day length could be
adapted according to the development of sorus (Fig. 11.3b, e). When Laminarian
thalli reached market size (1.5–2.0 m in length) plants were harvested and transferred to the lab to test its dry weight ratio (Fig. 11.3d).
The degree of exposure influenced morphology and shape of the algae and their
resistance to environmental forcing considerably. Laminaria originating from
sheltered conditions had wider blades with thick and undulate margins, while offshore sporophytes grown at exposed sites were thin and streamlined (Bartsch et al.
2008; Buck and Buchholz 2005). S. latissima sporophytes pre-cultivated onshore but
transferred to the sea at very early stages developed a streamlined blade and resisted
current velocities up to 2.5 m s
−1 . If grown singly in currents of >1 mm s
−1 ,
S. latissima can withstand the high energy environment experienced in offshore
cultivation (Buck and Buchholz 2005). These experiments on Laminaria species
show that adapted to strong currents as young individuals, they will grow well and
produce large amounts of biomass at exposed sites of the German Bight (Buck and
Buchholz 2005; Fig. 11.4a, b).
When combining Laminaria aquaculture with offshore wind farms, the foundations would provide a stable fixing structure for the seaweed cultivation systems
(e.g. Buck 2002; Krause et al. 2003; Buck et al. 2004). These ideas led to several
multi-use projects in the German Bight, such as No. 1–4, 9, 13, 15 (see Fig. 11.1)
(Buck 2002; Michler-Cieluch et al. 2009a, b, Buck and Buchholz 2004a, 2005;
Buck et al. 2012), where for the first time Laminaria species were tested in an
IMTA approach with partners from the offshore wind industry.
Mass culture of Laminaria sp. and Saccharina latissima under the high energy
offshore environment in the North Sea requires a rigid cultivation system for
withstanding rough conditions, which can be handled while retaining the
macroalgae. Buck and Buchholz (2004a) tested various carrier constructions and
different mooring systems and their results led to a new patented ring carrier for
macroalgae offshore cultivation (see subchapter on techniques and system design
below) (Figs. 11.32 and 11.33).
For IMTA approaches in the German Bight, the three native Laminaria species
are ideal extractive candidates: Laminaria cultivation brings clear advantages for
the environment. Apart from their CO 2 -consumption, kelps are also able to absorb
large amounts of nitrogen and phosphate, thus helping to abate coastal
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B.H. Buck et al.
spring similarly as in Norway (Bartsch et al. 2008). While growth of L. hyperborea
totally stops in July, growth of S. latissima decreases substantially but does not
cease. In contrast, the growth period of L. digitata from Helgoland extends from
spring to summer and in September, it exhibits a growth rate of still 50% of the
optimum (Lüning 1979). The seasonal variations in abiotic conditions affect growth
performance, particularly in algae from high latitudes with a more pronounced
seasonality of temperature, irradiance and photoperiod (Bartsch et al. 2008).
Exploring the feasibility of offshore kelp cultures, potential forces experienced
by the attached algae were studied extensively. Sporophytes were seeded on ropes,
which were designed for the use in offshore environments (Fig. 11.3a, c).
Land-based cultivation took place in tank devices, where the day length could be
adapted according to the development of sorus (Fig. 11.3b, e). When Laminarian
thalli reached market size (1.5–2.0 m in length) plants were harvested and transferred to the lab to test its dry weight ratio (Fig. 11.3d).
The degree of exposure influenced morphology and shape of the algae and their
resistance to environmental forcing considerably. Laminaria originating from
sheltered conditions had wider blades with thick and undulate margins, while offshore sporophytes grown at exposed sites were thin and streamlined (Bartsch et al.
2008; Buck and Buchholz 2005). S. latissima sporophytes pre-cultivated onshore but
transferred to the sea at very early stages developed a streamlined blade and resisted
current velocities up to 2.5 m s
−1 . If grown singly in currents of >1 mm s
−1 ,
S. latissima can withstand the high energy environment experienced in offshore
cultivation (Buck and Buchholz 2005). These experiments on Laminaria species
show that adapted to strong currents as young individuals, they will grow well and
produce large amounts of biomass at exposed sites of the German Bight (Buck and
Buchholz 2005; Fig. 11.4a, b).
When combining Laminaria aquaculture with offshore wind farms, the foundations would provide a stable fixing structure for the seaweed cultivation systems
(e.g. Buck 2002; Krause et al. 2003; Buck et al. 2004). These ideas led to several
multi-use projects in the German Bight, such as No. 1–4, 9, 13, 15 (see Fig. 11.1)
(Buck 2002; Michler-Cieluch et al. 2009a, b, Buck and Buchholz 2004a, 2005;
Buck et al. 2012), where for the first time Laminaria species were tested in an
IMTA approach with partners from the offshore wind industry.
Mass culture of Laminaria sp. and Saccharina latissima under the high energy
offshore environment in the North Sea requires a rigid cultivation system for
withstanding rough conditions, which can be handled while retaining the
macroalgae. Buck and Buchholz (2004a) tested various carrier constructions and
different mooring systems and their results led to a new patented ring carrier for
macroalgae offshore cultivation (see subchapter on techniques and system design
below) (Figs. 11.32 and 11.33).
For IMTA approaches in the German Bight, the three native Laminaria species
are ideal extractive candidates: Laminaria cultivation brings clear advantages for
the environment. Apart from their CO 2 -consumption, kelps are also able to absorb
large amounts of nitrogen and phosphate, thus helping to abate coastal
262
B.H. Buck et al.