Below you’ll see examples of common intertidal brown algae from exposed surf-swept shores of the northern Oregon coast. These are ones you are likely to encounter on the rocks or in and around tide pools, or as drift on the beaches. Most of these are common and easy to identify with the readily available field guides (see References, below). I’m just trying to give some alternative looks and a few natural history notes for anyone interested in digging a little deeper after encountering an interesting specimen. I’m not an algae expert so I think of my IDs as tentative, and mistakes are always possible. I hope you will let me know if you see a mistake or an out-of-date usage. The organization more or less follows Lamb and Hanby (2005), showing species in the order they might be encountered in the field, from highest to lowest in the intertidal. Common names are usually some combination of those in Lamb and Hanby (2005) and Mondragon and Mondragon (2010). All photos are from northern Oregon unless otherwise noted in the caption.

Rockweed, Fucus  In the rocky intertidal, Fucus grows most luxuriantly in sheltered sites. On surf-swept rocks it’s smaller and frequently interspersed with Cladophora, Endocladia, and Pelvetiopsis. Fucus appears in Rockweed, Fucus, in the drift line and Common Marine Algae in the Northern Oregon Drift Line: A Gallery of Images.


Little Rockweed, Pelvetiopsis limitata – P. limitata is at home only on the exposed outer coast, where it is usually abundant on the tops of high intertidal rocks. Even though much more abundant here than Fucus, it is much less common in the drift line.


Sea Cauliflower, Leathesia marina – There are some similar saclike epiphytic browns, but I think this one is Leathesia marina. I found it on a piece of drift Sargassum.

Leathesia marina, an epiphyte on drift Sargassum


Sea Palm, Postelsia palmaeformis – You can see stubby sea palms bobbing and poking through wicked surf, but on my home waters they tend to live out on exposed headlands where reaching them is tricky, even at the lowest tides. Detached clumps are fairly common in the drift line, so that’s what you see below.


Sea Cabbage, Saccharina sessilis – Sea cabbage is usually abundant on larger reefs. Depending on age of the blades and wave exposure, S. sessillis can give you a lot of looks. It’s one of the few kelps with no stipe, so that should help with identification. I rarely see sea cabbage in the drift line.


Feather Boa Kelp, Egregia menziesii – Feather boa is common on mid to low intertidal rocks, and not unusual in the drift line. It’s a photo-friendly brown, giving lots of good looks.


Winged kelp, Alaria, probably Alaria marginata – Alaria marginata appeared in Seaweeds in the Sand. In exposed places with low rocks and active sand, it experiences seasonal burial. In some of the photos below you can see the “wings” near the base of the stipe.


Split kelp, Laminaria setchellii – Laminaria setchellii appeared in Seaweeds in the Sand because in some places, it experiences seasonal burial. It’s also featured in Kelp Curves because it’s just so dang photogenic.


Dense-clumped kelp, Laminaria sinclairii – I featured Laminaria sinclairii in Finding Yourself in the Infralittoral Fringe. In northern Oregon, it’s a good marker for mean lower low water.


Strap kelp, Lessoniopsis littoralis – You know you’re on the exposed outer coast when you run into Lessoniopsis littoralis.

Strap kelp, Lessoniopsis littoralis, is known for it's large extensively branached holdfast
Strap kelp, Lessoniopsis littoralis, is known for its large, extensively branched holdfast


Bladder chain, Stephanocystis osmundacea – My home beaches are a bit north of bladder chain strongholds. I’ve never seen S. osmundacea on it’s home rocks; my examples are from the drift line, southern Oregon.


Wireweed, Sargassum muticum – Not really at home on the exposed outer coast, small drift clumps is pretty much all I see of Sargassum muticum. Wireweed appeared in Common Marine Algae in the Northern Oregon Drift Line: A Gallery of Images.

Sargassum, Sargassum muticum
Sargassum muticum, note lots of tiny floats


Acid weed, Desmarestia – You can find this Desmarestia in low tide pools. It seems to tolerate active sand and sesonal sand burial.


Giant kelp, Macrocystis pyrifera – On my home beaches Macrocystis is subtidal, so I only know it from drift masses on the beach. Macrocystis drift is common enough that it appeared in my post, Common Marine Algae in the Northern Oregon Drift Line: A Gallery of ImagesMacrocystis is featured on the Monterey Bay Aquarium Logo.


Bull kelp, Nereocystis luetkeana – Bull kelp is subtidal, but in the wrack, it’s an important component of intertidal ecosystems. I wrote a little bit about this in Bull Kelp Drift: A Subtidal-to-Surf Zone Connection.


Pterygophora californica – Old growth kelp is mostly subtidal in Oregon, though you may run across it on the lowest tides. I don’t see it often, even on the drift line. The ones shown below were featured in Browns Put On a Shine in the Drift Line.



How about this one? If you know what this one is, please let me know. Check out the bullae on the blades. The blades are so shiny they inspired Browns Put On a Shine in the Drift Line.

A mystery brown with shiny blistered blades


This one appeared in the drift line back in November, 2013. The proportions and wavy blade don’t seem a good match for the browns I’m familiar with. Any ideas?.

Unidentified kelp
Unidentified kelp



Harbo, R. M. 2011. Whelks to Whales: Coastal Marine Life of the Pacific Northwest. 2nd ed. Harbour Publishing Co.

Kozloff, E. N. 1993. Seashore Life of the Northern Pacific Coast. 3rd ed. University of Washington Press.

Lamb, A. and B. P. Hanby. 2005. Marine Life of the Pacific Northwest. Harbour Publishing.

Mondragon, J., and J. Mondragon. 2010. Seaweeds of the Pacific Coast. Shoreline Press.

Sept. J. D. 2009. The Beachcomber’s Guide to Seashore Life in the Pacific Northwest. Revised ed. Harbour Publishing.

Web Resources

The brown algae page on the Netarts Bay Today website is one of the best references you’ll find for the Pacific Northwest.

Biodiversity of the Central Coast has a great page on browns.

Seaweeds of Alaska is a standard reference for the Pacific northwest. It has a great brown algae page.

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