Below you’ll see examples of common intertidal brown seaweeds, mostly from exposed surf-swept shores of the northern Oregon coast. These are seaweeds you are likely to encounter on the rocks or drift on the beaches. Some are common and easy to identify with readily available guides (you’ll see a few in References below). Others are tricky. I try to get the IDs right, but I’m far from an expert. I apologize for any misidentifications. If you see something amiss, please let me know. There’s nothing new here, just my photos of common browns and a natural history note if I can think of something that hasn’t been said or seems over or underemphasized. I’ll show some browns I can’t identify too. Please drop me a line if you can resolve a mystery.
My organization more or less follows Kozloff (1993) and Lamb and Hanby (2005), showing species in the order they might be encountered in the wild, from highest to lowest in the rocky intertidal. Common names are my choice. I go to Algaebase for scientific names and other juicy information, and I learn a ton from the pages of Druehl and Clarkston (2016) and Kozloff (1993). All photos are from northern Oregon unless noted in the caption.
Let’s explore some browns!
Fucus seems to grow most luxuriantly in sheltered or semi-sheltered places. It’s smaller on surf-swept rocks than at protected sites and frequently interspersed with Cladophora, Endocladia, and Pelvetiopsis. Drifted Fucus shows up commonly on the beaches. I’m guessing all the images below show Fucus distichus.
Pelvetiopsis limitata, little rockweed
Pelvetiopsis limitata is at home only on the exposed outer coast, where it can be abundant on the tops of high intertidal rocks. I don’t often find drift Pelvetiopsis on the beaches.
These high intertidal dark tubes, some of which are twisted, might be Melanosiphon intestinalis, but there are alternatives. The images immediately below are from early March 2020, at a high wall that gets spray, splash, and a rare winter dunking.
The close-ups below are of individuals inhabiting the brown zone just below the zone of Ulva intestinalis. It’s a high site wetted only by spray, splash and a rare winter dunking. The guides say this is Petalonia fascia.
Leathesia marina, sea cauliflower
There are some similar saclike epiphytic browns. This is Leathesia marina. Sea cauliflower can attach to rocks or live as an epiphyte.
Soranthera ulvoidea, studded sea balloon
Soranthera is an epiphyte on Neorhodomela and Odonthalia. It’s not uncommon to find Soranthera on the beach, attached to its drifted host.
Fir Branch, Analipus japonicus
I’ve also seen A. japonicus referred to as bottle brush. My sketch looks more like a bottle brush, so I’ve got to mention it. The images shown here are from the central Oregon coast. I haven’t noticed it on my home beaches in northern Oregon. Look for it in the mid to intertidal.
Postelsia palmaeformis, sea palm
It’s a treat to see stubby sea palms bobbing and poking through wicked surf. They live out on exposed headlands where reaching them is tricky, even at the lowest tides. Detached clumps are fairly common as sea wrack.
Hedophyllum sessile, Sea Cabbage
The accepted scientific name has bounced around a bit. You may see it as Saccharina sessilis. Depending on the age of the blades and wave exposure, it’ll give you different looks. It’s one of the few kelps with no stipe, so that should help with identification. I don’t see much 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.
Phaeostrophion irregulare, sand-scoured false kelp
Winged kelp, Alaria marginata
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 stipe base. Alaria marginata appears in Seaweeds in the Sand.
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.
Laminaria sinclairii, dense-clumped kelp
In northern Oregon, Laminaria sinclairii‘s a good marker for mean lower low water.
You know you’re on the exposed outer coast when you run into Lessoniopsis littoralis. It also goes by northern tree kelp, for its tree-like look, and strap kelp, for its strap-like blades.
Stephanocystis osmundacea, bladder chain
My home beaches are a bit north of bladder chain strongholds. I only know it from the drift line.
Sargassum muticum, wireweed
Not really at home in exposed surf-swept settings, it can be dense in protected waters and semi-protected pools. Drifted Sargassum is common on beaches.
Desmarestia, acid weed
The Desmarestia shown here, I’ve always assumed it’s D. ligulata, can be found on low rocks and in low tide pools where it seems tolerant of active sand and seasonal burial.
Walking or woody-stemmed kelp is mostly subtidal in Oregon. I don’t see it often, even on the drift line. Those shown here were featured in Browns Put On a Shine in the Drift Line.
Macrocystis pyrifera, giant kelp
My home beaches in northern Oregon are a lot of miles from the nearest Macrocystis beds. I only know it from drift masses washed up on the beaches. Despite the distance, Macrocystis drift is common enough to appear in Common Marine Algae in the Northern Oregon Drift Line: A Gallery of Images. Macrocystis is featured on the Monterey Bay Aquarium Logo.
Nereocystis luetkeana, bull kelp
Bull kelp is subtidal, pretty much so, but it’s important to intertidal ecosystems as sea wrack. I wrote a little bit about this in Bull Kelp Drift: A Subtidal-to-Surf Zone Connection.
I know Dictyota only as sea wrack.
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.
Druehl, L. D. and B. E. Clarkston. 2016. Pacific Seaweeds: A Guide To Common Seaweeds of the Pacific Coast. 2nd ed. Harbour Publishing Co.
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.
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.
The Seaweed Sorter app is fun and very useful!
This page was updated July 24, 2021