Seaweed as food, fodder and fertiliser in the North Atlantic Islands
Résumé
Seaweed has long been neglected in coastal archaeological interpretations as a potential food-source and resource more generally, likely because archaeological evidence of seaweed presence on archaeological sites tends to be sparse due to its fast decay in most contexts. However, analysis of archaeological skeletal material may provide direct evidence of seaweed consumption. Recent research on the Orkney Islands (Scotland) has shown that around a quarter to possibly up to half of all Neolithic Orkney sheep bone collagen and tooth enamel δ13C values were significantly elevated, consistent with the consumption of seaweed (ntotal = 117). Similar seaweed foraging practices by domesticated animals particularly in winter are known historically from France, Ireland and Iceland, among others, but further research is required to assess the occurrence of prehistoric seaweed-foraging outside of Orkney. Fertilisation of terrestrial crops with seaweed has also been suggested to affect markers, including δ13C, that allow for the identification of seaweed consumption. To investigate these effects, a field trial was conducted involving the fertilisation of bere barley with seaweed, which showed that δ15N, but not δ13C was significantly affected by fertilisation with seaweed. This research into prehistoric seaweed consumption and use has great potential to improve present understanding animal foraging ranges, human adaptation to local environments, and human land use.