Here are a few naked (i.e., without leaf sheaths) stems from the wrackline on Nannygoat Beach on Sapelo Island. The major decay agent in these stems is Passeriniella obiones. P. obiones releases purple-red quinonic molecules, one of which is obionin-A, into the decaying tissue, and thereby gives the stem wrack this colorful tint. This reddishness is quite common in decaying stems, not surprisingly considering the predominance of P. obiones over other stem-rotting ascomycetes. Does this red pigment provide defense against other ascomycetes? Against shredding invertebrates? No one knows, but obionin-A has shown toxicity for brine shrimp. See Poch & Gloer, 1989, Obionin-A: a new polyketide metabolite from the marine fungus Leptosphaeria obiones, Tetrahedron Letters 30:3483-3486; Newell, 1996, Established and potential impacts of eukaryotic mycelial decomposers in marine/terrestrial ecotones, J Exp Mar Biol Ecol 200:187-206; Newell & Porter, 2000, Microbial secondary production from saltmarsh-grass shoots, and its known and potential fates, pp. 159-185 in Weinstein & Kreeger, Concepts and Controversies in Tidal Marsh Ecology, Kluwer.