Friends of Netarts Bay-Brown Seaweeds

Soranthera ulvoidea
Studded Sea Balloons
Alaska to Mexico
Family Punctariaceae

Soranthera is an epiphyte typically growing on bushy red algae, usually Neorhodomela and Odonthalia. It has slightly elongated globose sporangia, up to five centimeters (two inches) in diameter, studded with dark sori that resemble warts on a grape. These sori release flagellated swimming spores. Studded sea balloons attach to the stems of the host algae with small discoid holdfasts.

So far, here between the Capes, I have found it growing mostly on Odonthalia.

Desmarestia ligulata
Acid Kelp
Alaska to South America
Family Desmarestiaceae

The sporophyte of this alga, which you see in the picture, appears in the summer and dies back in the winter, leaving only a microscopic gametophyte to survive during the cold season. The thallus of the sporophyte is flat with two orders of opposite branches that are generally less than one centimeter wide. You can find it growing on rocks or in the san at mid tide, especially along Tunnel Beach. It was named after a French phycologist, A. G. Desmarest.

Desmarestia is called the “acid kelp” because it produces and stores high concentrations of sulfuric acid. This strong acid, with a pH as low as 0.5, is harbored in small vacuoles within the cells of the thallus. If you collect Desmarestia, keep it isolated from other algae because, when damaged, it can release the sulfuric acid which will discolor and begin to decompose any algae next to it.

Desmarestia aculeata
Witches Hair
Alaska to Oregon
Family Desmarestiaceae

Witches hair is not common beween the Capes, but can be found at low tide on the south side of Cape Lookout. The thallus is mostly cylindrical or slightly compressed and branching is primarily alternate. The alga you find, which can be a couple of feet long, is the sporophyte; the gametophyte is microscopic. It is epilithic or saxicolus, both meaning it grows on rocks. Oregon is probably the most southern part of its range, possibly as far south as Coos Bay..

Sponsored by the Friends of Netarts Bay Watershed, Estuary, Beach and Sea (WEBS)

Alaria marginata
Ribbon Kelp
Alaska to central California
Family Alariaceae

Alaria marginata is a saxicolous (grows on rocks) brown seaweed from the lower intertidal zone to subtidal regions, where its highly branched but not particularly large holdfast secures the thallus in surf-prone areas. It has a single, quarter inch diameter stipe up to 3 inches long that supports two kinds of blades, a single vegetative blade and sporophylls. Running the length of the vegetative blade, which may reach 10 or more feet, is a thick, flattened midrib, usually colored lighter, more golden, than the wider but thinner “ribbons”. Projecting from opposite sides of the stipe are much smaller spore-producing wing-like blades, the sporophylls, which can be seen in the second picture. Each sporophyll has its own secondary stipe that supports its relatively thick, rather elliptical blade. You can see the sporophylls in the picture to the far right at the base of the alga.

Alaria nana
Small Ribbon Kelp
Alaska to Claifornia
Family Alariaceae

The small ribbon kelp is, as its common and specific name imply (Alaria is from Latin for “wing” and nana is from Greek for “small”), is smaller than Alaria marginata. It is also distinguished by narrower sporophylls, usually more than five times longer than their width. The petioles on the sporophylls are also narrow, down to one millimeter in diameter. Its stipe, however, is relatively thick. It has been found that if the sporophylls are experimentally removed, the vegetative portion will develop functional reproducing structures, indicating that this alga has a compensating mechanism for injury to loss of reproductive tissue.

This kelp is mainly mid-intertidal.

Pterygophora californica
Woody-stemmed Kelp, Old Growth Kelp
Alaska to Mexico
Family Alariaceae

This kelp is primarily subtidal, but you can see it during the lowest tides directly off Maxwell Point in Oceanside. This kelp is built to withstand the roughest of surf. It attaches to boulders or rocky outcrops with a robust holdfast, has a tough woody stipe that can flex with waves and fast currents, and is topped with two opposing rows of sporophyll blades and a single larger vegetative blade at the apex. These blades can be ripped off during winter storms but new blades grow the following spring. It is a perennial that can live up to 25 years and grow to more than three feet high. A cross section of the stipe will show annual growth rings. In some areas it will form dense underwater forests.

Laminaria sinclairii
Dense-clumped Kelp
Vancouver Island, British Columbia to southern California
Family Laminariaceae

We have two species of Laminaria that you can easily see and identify at low tide. One is the colonial, stoloniferous L. sinclairii found on the sand-impacted rocks along Tunnel beach. It grows in dense patches, often on the tops of rocks in the middle intertidal zone. These patches are formed from a single, prostrate, branching, rhizome-like holdfast that gives rise to numerous thin, flexible, but strong, stipes, each terminating in a single, undivided, strap-like blade. Like some other intertidal algae in the area, L. sinclairii is frequently covered by sand, often for weeks or months at a time, yet it still survives. The blades break off during winter storms but soon begin to regenerate, so you will see them again in the spring

Laminaria setchellii
Stiff-stiped Kelp
Alaska to Baja California
Family Laminariaceae

Laminaria setchellii usually grows slightly lower in the intertidal zone than L. sinclairii, often on the sides of large rocks. Each branched holdfast supports a single stipe, and each stipe a single, divided blade. Its stipe is thicker, and stiffer that that of L. sinclairii, so it is called the stiff-stiped kelp. When the stipe is cut, you can see annual growth rings looking similar to those found in trees. These rings may be the result of circannual growth rhythms where growth starts in the winter but stops in the summer. The blade is divided into several straps almost to the base of the blade. Growth of the blade occurs in a patch of cells in a transition zone between the stipe and the blade called intercalary meristem. It is here where cells divide to produce the rest of the blade. L. setchellii can be used in soups and is related to the Japanese kombu. Recent genetic studies have brought the taxonomy of the Laminariales under review, so names may change in the future.

Saccharina latissima (Formerly Laminaria saccharina)
Sugar Wrack Kelp, Sugar Kelp, Kombu, Devil's apron, sea belt
Aleutian Islands, Alaska to southern California
Family Laminariaceae

Sugar wrack kelp is common along the shallow bottom of the northeast section of Netarts Bay just off Netarts and Happy Camp. The waters here are protected from heavy surf, and the bottom is cobbled, offering solid substrates on which numerous rock-loving seaweeds can attach.

The blades of Saccharina latissima can be up to three meters long. Each has undulating margins and often two rows of corrugations that extend its length between the middle of the blade and its ruffled edges. There is no midrib. Its stipe is cylindrical and narrow and its holdfast is highly branched. One key characteristic of Saccharina latissima is the absence of mucilage ducts in its stipe.

Saccharina latissima is called sugar kelp (sacchar refers to sugar) because it contains high levels of laminarin, a polysaccharide carbohydrate that is an energy storage product resulting from photosynthesis, and it is harvested for use as a thickener in ice cream, tooth paste, and jelly. Extracts of Saccharina latissima are also used in skin care products.

Saccharina sessillis (Formerly Hedophyllum sessile)
Sea Cabbage
Aleutian Islands, Alaska to central California
Family Laminariaceae

This olive drab seaweed is common in the middle and lower tide zones and can be seen attached to rocks along Tunnel Beach. The Laminariaceae have been undergoing a taxonomic review in the last decade, so we are seeing a lot of name changes, hence what was Hedophyllum is now in the genus Saccharina. The specific name 'sessillis' refers to ‘sitting’ or having a’broad foot’, that is, mature Saccharina sessillis has no stipe. There is a short stipe on young individuals. Its highly branched holdfast anchors the thallus directly to the rocks. The thallus splits almost from its base into individual blades that may be a couple of feet long in calm waters but shorter on rough open coast. There is only one species. Saccharina sessillis is eaten by a number of herbivores, including the black chiton Katherina tunicata, which can weaken young algae by grazing on their holdfasts and make them susceptible to storms.

Lessoniopsis littoralis
Strap Kelp
Kodiak Island, Alaska to central California
Family Lessoniaceae

The Strap Kelp, Lessoniopsis littoralis, (The genus is named after French phycologist René Primevère Lesson) is found at about the same intertidal zone as Laminaria setchellii and is attached to the sides of rocks where individuals are exposed to heavy surf. Its stipe is stiff, rather woody, and repeatedly branched, each branchlet leading into a single, strap-like, vegetative (having no reproductive structures) blade with a midrib. There can be as many as 500 blades in large individuals. The holdfast is highly branched and massive, build to withstand high energy waves. The alga you see is sporophyll. Sporophyll blades, blades that are smaller and produce spores, grow at the base of the thallus and lack midribs. The gametophyte generation is microscopic. Lessoniopsis is a perennial, but it may lose it blades in winter storms.

You may wonder why an alga would evolve to live in such a high energy and violent habitat as the wave-beaten sides of rocks exposed to heavy surf. Algae such as Lessoniopsis and another brown alga, Postelsia palmaeformis, which live only on rocks exposed to high energy waves and are built to withstand severe poundings, gain an advantage because they have a better ability to acquire nutrients and use sunlight, find fewer organisms to compete with, and have few predators that can withstand the turbulent waves

Nereocystis leutkeana
Bull Kelp
Aleutian Islands, Alaska to central California
Family Laminariaceae

Nereocystis leutkeana is the most impressive brown seaweed in the Pacific Northwest. The genus name comes from Nereidos, the name of a sea nymph from Greek mythology, and from “kytos”, Greek for a hollow vessel. There is only one species. This seaweed often grows in “beds”, that is dense assemblages, often in rather protected waters, but sometimes along the highly energetic outer coast. We don’t find it growing much between the Capes, but we do see it washed up on our beaches in massive tangled windrows after it has been torn from rocks during winter storms. Nereocyctis consist of a holdfast, a long, tapering, hollow stipe that can reach more than 100 feet, a terminal gas-filled floating bulb, the pneumatocysts, and the attached blades. The anchoring holdfast can reach a diameter of more that a foot. It can harbor its own collection of organisms by offering them protection among the haptera. The pneumatocyst and the expanded hollow part of the stipe serve as a float to keep the alga vertical. The blades branch off the pneumatocyst in two cliusters of up to 30 blades each. These blades, which hang down from the floating pneumatocyst like curtains, contain spore-forming cells arranged in patches called sori. Interestingly, the sori are released from the blades during the autum at specific times of the day and tidal cycle, and they sink to the bottom where the spores are released to develop into gametophytes.

There are numerous other interesting aspects to this kelp. The gasses in the pneumatocyst includes up to 12 percent carbon monoxide (the same poisonous gas released by automobile exhaust), in addition to nitrogen, oxygen and carbon dioxide found in air. Nereocyctis is an extremely fast growing kelp. It is an annual with some individuals persisting over the winter. But it reaches its full size within its first year, growing over 5 inches per day. The shape of the blade can be determined by the amount of current in which the kelp lives. Narrow, flat blades with less drag develop where there is fast current; ruffled blades that spread out develop in slower currents.

A tangled mass of Nereocystis

Pelvetiopsis limitata
Dwarf Rockweed
British Columbia to central California
Family Fucaceae

Located high in the intertidal zone, anchored among the barnacles and limpets, is the dwarf rockweed, Pelvetiopsis limitata. This olive green perennial looks like a miniature Fucus but without the midrib in the thallus branches. Its dichotomously branched thallus ends in swollen tips called receptacles, which hold the bumpy reproductive structures, the conceptacles. Pelvetiopsis is one of those intertidal algae that can withstand a certain amount of desiccation, but water loss can reduce photosynthesis. Like other seaweeds that desiccate, one of its adaptations to drying is that when rehydrated, it can take up nitrogen and ammonia faster than algae lower in the intertidal zone. This is important in nutrient recycling and possibly the production of chlorophyll a, the major photosynthetic pigment. Though this alga is a perennial it may be ripped from rocks by winter waves.

Fucus distichus
Rockweed
Bering Sea and Aleutian Islands, Alaska to central California
Family Fucaceae

The most recognizable seaweed during the summer low tides is rockweed Fucus gardneri, also called bladderwrack, bubble kelp, and popweed. (from Greek meaning "seaweed" and pronounced "FEWcus") is ubiquitous in the higher intertidal zones along the Pacific Coast from Alaska to Point Conception, California. It grows on rocks, large and small, in sheltered areas or on open coast with moderate wave action and can withstand heating and desiccation from direct sunlight. Each thallus, attached by a single holdfast, branches more or less dichotomously until it is five to twenty inches long, individuals in sheltered bays and estuaries growing larger than those battered by waves on the open coast. Dense assemblages will form a canopy that shades and protects other algae and invertebrates.

Reproduction in the Fucales is unique among seaweeds in that they do not reproduce by spores, only gametes, and there no alternation of sporophyte and gametophyte generations. The bumps on the gas-filled bladders on the tips of the thallus (called receptacles) are minute cavities (cryptostomata) in the cortex that, when they mature, become swollen structures (conceptacles) that produce gametangia, cells that in turn produce gametes. The eggs and sperm are released through a small hole in the conceptacle, the ostiole. Fertilized eggs (zygotes) settle and attach to the substratum. There is also evidence of vegetative reproduction. Individuals, especially those in protected areas, may live up to five years.

Stephanocystis osmundacea
Chain Bladder Kelp
Northern Oregon to Baja California
Family Sargassaceae

This seaweed has a discoid holdfast and a woody stipe that is triangular in cross-section. Its other distinctive feature is its multiple chains of five or more, small pneumatocysts (floats) that look like strings of beads, thus its common name, the chain-bladder kelp. It grows in the mid-tidal zone, attached to rocks that are well exposed to sunlight. Young Stephanocystis can be heavily grazed, but those that survive can develop into robust individuals. Here, between the Capes, we are near the northern extent of its range, Seaside, Oregon. You will usually find it washed up on the beach where it has drifted in from another location. I have not yet found it growing in our area.

Sargassum muticum
Japanese Sargassum or Wireweed
Alaska to Baja California
Family Sargassaceae

This seaweed grows every summer along the eastern side of Netarts Bay between the boat launch and Happy Camp where it forms a dense floating canopy over the shallow cobble bottom. It has a discoid holdfast that attaches to the cobbles and extends into a narrow stipe and a highly branched, bushy thallus with roundish pneumatocysts, often in clusters, tucked into the axils of small leafy blades. You may often find detached pieces of this alga washed onto the beaches.

An invasive species, it was introduced into the U.S. in the 1930s, probably into Puget Sound but maybe other places along the coast, on oysters imported from Japan. Bisexual and capable of self fertilization, it spread rapidly along the entire west coast of North America as fertile pieces drifted with the currents, especially with the California Current, to be distributed southward as far as Baja California. It has also been introduced into European waters.

Dense summer growth of Sargassum in Netarts Bay

Egregia menziesii
Feather Boa Kelp
British Columbia to Mexico
Family Alariaceae

I have not yet found the feather boa kelp growing between the capes, but it is commonly washed ashore and can be found on beaches. It is saxicolus, meaning it is attached to and grows on rocks, to which it clings with a massive, branched holdfast. It is a large kelp, its perennial sporophyte up to fifty feet long, and it is often colored an olive green. Above the holdfast is a single stipe, covered with papillae, that becomes flattened as it progresses outward. This stipe branches into several long sub-stipes, each around a half to one-and-a-half inches wide. All of these stipes are fringed on their opposite edges by many small blades up to three inches long. The stipes are also decorated with teardrop-shaped pneumatocysts, gas-filled floats. Some blades are sporophylls and are covered with sproangia.

On a personal note, when I was a kid along the Northern California coast, I would collect the pneumatocysts that had dried on the beaches and throw them into a campfire where they would explode like small fire crackers. It was great fun.

Postelsia palmiformis
Sea Palm
British Columbia to California
Family Lessoniaceae

Although I have not found the sea palm growing between the Capes, it probably occurs on the surf side of the outer rocks, perhaps on the Three-Arch sea stacks. You can commonly find it in the summer and fall washed up on the beaches. They do indeed resemble assemblies of miniature palm trees, growing in patches on the outer shore. Sea palms live where there is heavy surf, and they are magnificently adapted to this harsh existence. Each has a multi-branched holdfast that supports a cylindrical but tapered and hollow stype. The upper end of the stype is crowned with an array of drooping, strap-like blades, each with parallel groves running its entire length. This palm-like stage of its life cycle is the sporophyte. Sporangia line the grooves on both sides of the blade. Non-motile spores develop in late spring and are released during low tide. They slide down the blades and fall close to the parent thallus, where they adhere to rocks or the shells of mussels and develop into small, filamentous gametophytes. During the following sprung, the gametophytes produces oogonia and motile sperm, the sperm fertilize the eggs, and the resulting embryos develops into sporophytes.

The generic name is after Alexander Philipov Postels, an Estonian-born naturalist and artist, who at the request of Czar Nicolas I, participated in a three-year Russian expedition that began in 1826 to explore and survey Pacific islands, Asian coastlines, and Russian North America, collecting more than 4000 biologic specimens, including more than 100 seaweeds.

Phaeostrophion irregulare
Sand-Scoured False Kelp
Alaska to California
Family Phaeostrophiaceae

This perennial brown alga, usually colored light brown or tan, is common on the sand-scoured rocks along Tunnel Beach. When not buried with sand, it is easily seen at low tide attached to the sides and upper surfaces of rocks by means of a crustose holdfast. Several to many stiped, spatulate blades arrise from the holdfast, some reaching a length of ten inches. The ends of the blades may be lobed and are often ragged and perforated from being beaten by sand and heavy surf. It appeares in early spring and dies back in summer, perhaps because germlings are heat sensitive.

Phaeostrophion irregulare has been placed in a number of other families: the Punctariaceae, the Coilodesmaceae, even the Laminariaceae. The generic name is from Greek and means “dark and twisted.”

Scytosiphon dotyi
Whiptube
Oregon to Mexico
Family Scytosiphonaceae

Scytosiphon dotyi (the genus is from Greek meaning leather siphon, and the species named after biologist Maxwell Doty (was found in small rocky tide pools in the upper intertidal zone at Tunnel Beach. It is tubular, each tube about a millimeter in diameter and seven to eight centimters long, unbranched, with one to several tubes extending from a single discoid holdfast. It has been reported only from southern Oregon and south, so this may be an extension of its northern range. The common name is actually applied to the related but larger S. lomentaria which is distributed from Alaska to Mexico.