Ulva intestinalis Linnaeus (BC/Ar/A)

This species forms grass green hollow and unbranched tubes, which are highly variable in size from 1-3 mm wide and <10 cm in height (Image A) to 2-3 cm wide and ~70 cm in height (Image B). This species is hollow in section with a monostromatic cell layer, 15-30 µm wide, with parietal chloroplasts that contains 1-2 pyrenoids (Image C).

There are a number of other tube-forming (exclusively or only in certain environments being blades in other habitats) species of Ulva spp. in our waters and confident identification requires molecular data.

We have genetically verified records from throughout BC, the Canadian Arctic, throughout Atlantic Canada extending south of Cape Cod to CN. Individuals range from the uppermost intertidal pools to lower pools are rarely subtidal (4.5 m) growing on rock, as well as on wood and, inverts and occasionally other algae.

GWS043185Image A. Smaller specimen from a northerly location (mid intertidal on cobble, Churchill, MB; GWS043185).

GWS011659Image B. Larger specimen from a sheltered location (mid intertidal on cobble, Pownal, PE; GWS011659).

EGWS000693-0002a.jpgImage C. Outer cell layer of the hollow tube displaying parietal chloroplasts with 1-2 pyrenoids per cell (upper intertidal pool on rock, Letete exposed biodiversity site, NB; EGWS000693).