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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

Ecosystem effects of harvesting seaweed for biofuel

PhD student Kyla Orr is modelling ecosystem effects of seaweed harvesting

Three sources of seaweed have been suggested for the extraction of biomass for biofuel: harvesting of wild seaweed that is attached to rocks; collection of storm-cast seaweed from beaches; and aquaculture of seaweed on long-lines. This PhD project focuses on the ecological importance of beach-cast seaweed and the potential impacts of its removal for biofuel. The study area is North and South Uist in the Outer Hebrides, where large amounts of seaweed are cast ashore each year. I currently travel out to the Uists approximately every six weeks and quantify the seaweed on selected beaches, as well as conduct bird counts and collect invertebrates. These trips have yielded some interesting results, with the last bout of October gales creating mounds of seaweed more than two metres high on some beaches. Kyla and seaweed on beach

When you look at a beach you may think of it as a desert, with little in situ primary production. This is because the mobile sand prevents plants and algae communities from establishing. All the fauna living on beaches have to rely on the import of food, such as storm-cast seaweed, to survive. When the seaweed is cast ashore it starts to decompose and becomes a veritable feast for invertebrates. I recorded more than 50,000 invertebrates per square metre in seaweed mounds in September 2010. Large numbers of shorebirds then arrive to feed on the invertebrates and you get a complex and dynamic food web. The data collected in my project will be used to build a food web model and help us predict what the impacts would be to sandy beach food webs if seaweed were removed.

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