Incredible plants: Pleurophycus gardneri

Pleurophycus gardneri sporophyte with Laminaria
setchellii and other seaweeds on low intertidal rocks
at Glass Beach, Fort Bragg, CA, April 2016.

I came across a rare treat tidepooling earlier this month at Glass Beach in Mendocino County – Pleurophycus gardneri!

Pleurophycus is a moderately-sized kelp, consisting of a single photosynthetic blade at the end of a stipe than can be up to a half meter long (Abbott and Hollenberg 1976). Like other kelps, it is attached to the rocks with a holdfast, a structure that resembles roots. Pleurophycus lacks branches or the pneumatocysts (floats) that are present in some other kelp species. Its distinguishing feature for identification in the field is the presence of a wide midrib on the blade with a ruffled blade surface immediately next to each edge of the midrib. The species is perennial and deciduous with blades dying back each year (Germann 1986, Lindeberg & Lindstrom 2010).

The species is distributed from central California into Alaska (Silva 2009) but in my experience it is uncommon in California, particularly in the intertidal zone where I stumbled across a single individual in a narrow channel.

Western phycologists first collected the species from San Juan and Whidbey Islands in Washington state and from Alaska in the late 1890s (Silva 2009). Setchell and Gardner (1925) described its distribution from Alaska to Coos Bay, Oregon. Decades later a large population was found in the low intertidal at Ft. Bragg (Kjeldsen 1972) and the species was later discovered to occur subtidally off of San Luis Obispo County and Big Sur (Silva 2009).

For me, finds like this make an early morning rise to catch the spring low tides well worth it. In fact, though I am not naturally a morning person, I can’t say I ever regret a 4 or 5 AM wake up for a low tide adventure along the coast. During intertidal exploration I often find something new, but even when I do not, my curiosity and love of natural history is re-invigorated by the cool salty air and the beauty and complexity of the rocky shores of the Pacific.

References

Abbott IA, Hollenberg GJ. 1976. Marine Algae of California. Stanford University Press, Stanford, CA.

Germann I. 1986. Growth phenology of Pleurophycus gardneri (Phaeophyceae, Laminariales), a deciduous kelp of the northeast Pacific. Canadian J Botany 64:2538-2547.

Kjeldsen CK. 1972. Pleurophycis gardneri Setchell & Saunders, a new alga for northern California. Madroño 21:416.

Lindeberg MR, Lindstrom SC. 2010. Field Guide to Seaweeds ofAlaska. Alaska Sea Grant College Program, Univ. Alaska, Fairbanks.

Setchell WA, Gardner NL. 1925. The Marine Algae of the Pacific Coast of North America. Part III Melanophyceae. UC Publications in Botany 8:383-898.

Silva PC. 2009. Historical, nomenclatural, and distributional notes on two Pacific coast kelps: Lessoniopsis littoralis and Pleurophycus gardneri (Phaeophyceae, Laminariales, Alariaceae). Madroño 56:112-117.