Studies on marine algae of Newfoundland. I. Occurrence and distribution of free-living Ascophyllum nodosum in Newfoundland

Abstract

The free-living "beach form" of Ascophyllum nodosum (L.) Le Jol. ecad mackaii (Turn.) Cotton is described for the first time from 10 of a total of 60 Newfoundland localities investigated. Development and form of the free-living plants are similar to descriptions of British populations of the same entity, and the same ecological conditions appear to cause their development in both areas. Plants arise from fragments of attached plants and have flattened or terete branches which are markedly dichotomous in the advanced stages. In extreme forms a terete, highly dichotomous, and disoriented branching habit is adopted, resulting in globular thalli. Plants generally lack air-bladders and are seldom fertile in intermediate and advanced forms of the ecad. Populations occur in the mid intertidal zone in areas of extreme shelter near a freshwater source, and on muddy or sandy/mud substrates. Parasitic Polysiphonia lanosa (L.) Tandy is absent from ecad mackaii in Newfoundland.