WHAT ARE THE EFFECTS ON THE MARINE ENVIRONMENT OF LARGE-SCALE KELP CULTIVATION?

Do seaweeds take up nutrients from the marine environment? Do their production of oxygen give a much-appreciated contribution of oxygen? And what happens to the biodiversity in areas with seaweed cultivation?

These were some of the headlines, when 12 scientists at the end of May 2018 set out for a week-long cruise on board Aurora, the research vessel of Aarhus University. The cruise took them to two of the areas in Danish waters where seaweeds are cultivated: north of Grenaa, at the research site of AlgaeCenter Denmark (20 hectares), and to the mouth of Horsens Fjord, where Hjarnø Havbrug runs Denmarks largest cultivation site of 100 hectares.

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The weather was sunny and relatively calm, so plenty of data were produced on effects on biodiversity, nutrient and carbon cycle, oxygen, current, benthic and light conditions. Data and samples will be analysed during the coming months. The expectation is that by the end of this year we have a much deeper knowledge on the positive and potential negative effects of kelp cultivation in large scale. This knowledge will benefit authorities, industry and research.

The EcoMacro cruise was supported by the Danish Centre for Marine Research and gathered scientists from Denmark and Norway under the projects: Tang.nu, MAB4, Macrofuels, MacroSea and Marine Forests (Havets skove). Annette Bruhn from Aarhus University was cruise leader.