Knotted Wrack, Ascophyllum nodosumThe brown marine alga Ascophyllum nodosum (Knotted Wrack) has long been recognised as agriculturally important due to its efficacy as a fertiliser. It has been shown to have a wide range of beneficial effects such as increased yield, increased nutrient uptake, increased frost and stress resistance and reduced incidence of fungal and insect attack (Patier et al., 1993 Journal of Applied Phycology 5 pp. 343-349). A. nodosum is found throughout the North Atlantic in the upper and mid-shore of the intertidal zone. It favours sheltered areas as it has only a small disc like hold fast to anchor itself to its substrate. It has egg shaped bladders along its frond length that act as flotation devices to increase contact with sunlight, which lend it its name Knotted (or Egg) Wrack (Sterry 2004, Collins Complete Guide to Irish Wildlife p. 286).
However the agricultural applications of A. nodosum have recently been increased. Dierick et al. (2010, Livestock Science) replicated pig jejunum and caecum conditions in vitro on a diet of the A. nodosum. It was found that the algal diet had a supressive effect on total numbers of E. coli, Streptococci and Lactobacilli in the simulated small gut conditions. The supression of E. coli was especially pronounced, meaning A. nodosum based pig feed could potentially reduce incidence of scour in herds.
Knotted Wrack, Ascophyllum nodosum
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