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RELEVANCE

Global fossil fuels supplies dwindling


SUSTAINABILITY

Fast-growing, easily utilised marine algae which fix carbon dioxide


BIOTECHNOLOGY

Oil production from cultivated micro-organisms


BIOFUEL

Energy readily convertible from marine plants

Cultivating seaweeds

Lars Brunner reports on BioMara’s macroalgal cultivation research which ‘feeds’ material into the anaerobic digestion trials and polyphenol characterisation.

SAMS has been active in macroalgal cultivation for several years, and has contributed actively to this growing field with its knowledge base.  Macroalgal cultivation for BioMara is the latest stage in an evolving process that allows us to improve our method, and increase the yields of the kelp species that we grow.  The Macroalgal cultivation component in the BioMara project requires the provision of cultivated stock to the project over three years, at months 9, 18 and 27.  The material provided ‘feeds’ into work that Ian Rae and Peter Schiener are undertaking on AD trials and polyphenol characteristic analysis.

We utilise three kelp species, Alaria esculenta, Sacchoriza polyschides and Saccharina latissima in our trials at present.  These species offer the advantage of ready local availability, fast growth and ease of handling.  The natural seeding cycle of the plant is used to dictate the annual outplanting cycle and we aim to collect wild plants from the Argyll area in early-mid November, just as they are becoming ripe.  They are brought back to the hatchery at SAMS where the blade (the large frond area of the plant) is dried and cooled overnight.  The following day, the blade is re-immersed in room temperature seawater, upon which it releases spores en masse – in the space of just 15 minutes several million spores can be released from an area of ten square centimetres.

The spores are then decanted into a larger tank containing the substrate that we wish them to settle on – in our instance 1.5mm kuralon twine tightly wrapped around a spool.  Each spool can contain up to 400 metres of line, and will be unwound at the outplanting site after just over a month’s on-growing in the hatchery (usually late December or early January).  The kuralon twine itself is not strong enough to support the plants as they grow, so it is attached to a thicker polypropylene rope with cable ties to provide it with support as it grows.

In the first year of BioMara outplantings we utilised a site in Moidart (around two hours drive north from SAMS) that had been used successfully in previous work. The beginning of the year 2 outplantings saw us using a site located closer to home.  This confers advantages in shorter transport time for the young plants, and an ability to visit the site more regularly to check on progress.

Writing this in mid-June, we are aiming for a harvest of our crop at the beginning of July.  After this time the plants start to degenerate slightly, and are more prone to being grazed by small snails.  Having visited our site in the last week, we look to have a healthy crop of S. lat and S. pol, although our harvest of A. esc will be smaller than usual as it has not come away this year as successfully as the other two species.  Once harvested, the plants will be brought back to SAMS for characterisation work, as feedstock for Dr Rae’s anaerobic digestion trials, and for general length-weight studies.  And after a couple of months’ break, planning will commence in September for the year 3 outplanting – with a keen eye on beating this year’s harvest totals!

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