River Parrett is a 'pre-English river-name of obscure origin'. The River Parrett, the Bristol Channel and the Severn Estuary are believed to have been used for riverine bulk transportation of people and supplies in Somerset under Roman and later Anglo-Saxon and Norman occupation. Roman Somerset, which lasted for over 250 years until around the beginning of the 5th century, had various settlements, including Bath ("Aquae Sulis"), Ilchester ("Lindinis") and lead mines at Charterhouse; and four roads surrounding the Somerset Levels. There is evidence of two Roman ports on the Parrett. The port at Combwich, on the west bank, was ill-recorded before its
Aphanizomenon flos-aquae (dietary supplement) from the air, and water to synthesize proteins, carbohydrates, and lipids. AFA is also able to directly use molecular nitrogen from the air to produce proteins and other nitrogen-containing biomolecules. This ability is widespread in prokaryotes, but unknown in eukaryotes. "Aphanizomenon flos-aquae" as a species has both toxic and non-toxic forms. While benefits have been indicated, toxicity has been shown in some strains of the species "Aphanizomenon flos-aquae", with cylindrospermopsin and saxitoxins present, and microcystins found contaminating AFA dietary supplements. The World Health Organization's "Guidelines For Drinking Water Quality" note Anatoxin-a, saxitoxins, and cylindrospermopsins are present in the Aphanizomenon genus.