Laminaria ephemera Setchell (BC)

This species is distinctive for its small discoid holdfast and typically narrow ribbon-like blade, which is an olive to dark brown colour (Image A). Blades are typically 30 cm to 2 m long and 5-10 cm wide with a tapered or wedge-shaped transition from the stipe to the blade even for our deepest collection from a less exposed site (Image B).

Typically locally abundant in the shallow subtidal (to 6 m) to low intertidal in surge channels at exposed locations. In our experience this is a spring to early summer annual, although we have a subtidal collection in July from Haida Gwaii, BC (Image B). Interesting, Laminaria ephemera consists of two closely related genetic groups in the BC flora based on COI-5P data and further study is needed. The second variant has a different morphology lacking the typically wedge-shaped base (Image C). Laminaria ephemera overlaps in range with Laminaria yezoensis Miyabe, but typically is less robust, has a much smaller discoidal holdfast, is a short-lived annual (sporophyte stage) and has a simple (undivided) blade.

Image A. Specimen from the subtidal (4 m) on rock at Tahsis, Rosa Harbour, Esperanza Channel, BC. Note the small discoid holdfast and wedged transition from the stipe to blade (GWS010197).

Image B. Specimen from the subtidal (6 m) on rock at a less exposed location (Murchison Is., East End, Gwaii Haanas, BC; GWS028130).

Image C. Specimen from a subtidal (3 m) sheltered location, which has a slightly divergent COI-5P sequence from our other collections (Bamfield, opening of Grappler Inlet, BC; GWS019628).