Practical ecological knowledge for the temperate reader.

Desmarestia Sp.- Acid Kelp

Family: Desmarestiaceae [E-flora]

Local Species;


"...species of Desmarestia, a brown alga (Phaeophyta), contain esters of sulfuric acid and can cause severe gastrointestinal upset if consumed excessively, an unlikely occurrence since they taste very sour." [Turner, Kuhnlein]

Non-local Species

Desmarestia dudresnayi subsp. tabacoides (Okamura) A.F. Peters


"Phenolic compounds such as chromenols have been identified as the cytotoxic molecules in Desmarestia menziesii (Davyt et al., 1997)." [HMA]

"The brown alga Desmarestia menziesii elaborates the meroterpenoid menzoquinone which deters sea star herbivores [ 131 ]." [NPMA, Strengel] "In the congener Desmarestia menziesii, no differences were detected between thallus parts, which the authors explained by the lower level of thallus differentiation in this species when compared to D. anceps (Fairhead et al., 2005). The optimal defence theory is further supported by studies showing that seaweeds preferentially defend younger or more vulnerable portions of the thallus, reproductive structures, or the more exposed parts (reviewed by Paul and Puglisi, 2004)." [Wink APR39]

9'-Hydroxysargaquinone in Desmarestia menziesii [Thomson NOQ]

Desmarestia [species unspecified] 20% algin (dry wt.) [SATU, Chapman]

Nutritional Information

Desmarestia menziesii 3.45-4.57 % protein (dry matter basis) [Dominguez FIAFN]

Desmarestia aculeata - Witch's hair

"The conspicuous generation is the sporophyte, which is a dark brown, coarsely cylindrical (or wiry) alga growing only on rocks. In Europe, it is reported to be bright green when young and brown when older. The branching pattern is alternate or irregular, but some side branches are pinnate (feather-like) while others are simple. The meristems of the side branches are located near where they branch off the main axis. The main axis is up to 5 mm (0.2 in) in diameter and the whole individual can be 120-185 cm (about 4-6 feet) in length.

"Individuals from southern British Columbia/northern Washington can withstand immersion for a week in water at a temperature of 23°C (74°F), but succumb if placed in warmer water.

"You will need a good minus tide to see Witch's Hair where it grows, but often masses of this species wash up on the beach during storms.

"Other species of Desmarestia form vast kelp forests on the shallow sea floor around Antarctica. This genus is named after A. G. Desmarest, a French naturalist.

"Thalli of Desmarestia aculeata (Linnaeus) J.V. Lamouroux (1813), a worldwide cold water species, are 30–120-cm long. The cartilaginous main axis is covered with short side branches that end in a tuft of hairs (trichothallic growth). The species, as do some other members of the family, contains sulfuric acid in the cell vacuole that may have a pH as low as 0.1." [Fleurence SHDP]

"Habitat / Range Bathymetry: extreme low intertidal and upper subtidal World Distribution: Aleutian Islands, Alaska, to Oregon; Arctic Ocean; western North Pacific; North Atlantic; North Sea" [E-flora]




Desmarestia ligulata - flattened acid kelp 

"At first glance this does not seem to be a Desmarestia, thanks to the flattened (although highly branched) blades, but like other species in this genus, in nature Flattened Acid Kelp secretes sulfuric acid that damages other species (and even its own tissues, resulting in wide color changes and eventual disintegration of some branches)." [E-flora]

"The central axis is up to 2 cm (about 0.8 in) wide with a conspicuous midrib, but the side branches are narrower. The whole organism can reach 80 cm (2.5 feet) in length, although most of the specimens we have seen have been only half that. Many different varieties of this species are described in the scientific literature, and some workers think at least two species of ligulate Desmarestia occur in the waters of British Columbia—true D. ligulata and a much larger strictly subtidal species called D. munda." [E-flora]

"Individuals from southern British Columbia/northern Washington can withstand immersion in water at a temperature of 20°C (68°F) for a week, but die if immersed in warmer water." [E-flora]

"Flattened Acid Kelp is somewhat weedy; in Southern California, it can become established after Giant Perennial Kelp forests are swept away during severe winter storms." [E-flora]

"Habitat / Range Bathymetry: extreme low intertidal and subtidal World Distribution: Unalaska Island, Alaska, to Baja California, Mexico; western North Pacific; Iceland; eastern North Atlantic; southern Australia" [E-flora]


Anticancer Activity

Total phenolic content = 1.22% (dw) +/- 0.10 [M. Zubia et al.(2009)]

"Among the crude extracts under study, those from D. ligulata and D. dichotoma exhibited the strongest cytotoxic activities with all of the tested tumoural cell lines. This is in accordance with literature data about evidences of cytotoxic activities in D. dichotoma (Duran, Zubia, Ortega, & Salva, 1997; Kolesnikova, Kalinovsky, Fedorov, Shubina, & Stonik, 2006), where diterpenes were identi- fied as the cytotoxic compounds. In fact, the Dictyotaceae family has been extensively studied for its wide variety of bioactive diter- penes with marked biological activities (Kornprobst, 2005). Phenolic compounds such as chromenols have been identified as the cytotoxic molecules in Desmarestia menziesii (Davyt, Enz, Manta, Navarro, & Norte, 1997). It is thus worth wondering about the relationship between the cytotoxic activities of D. ligulata and D. dichotoma crude extracts and their pro-oxidant activities measured in the b-carotene assay. Indeed, oxidative stress is known to be implicated in the process of carcinogenesis (Halliwell, 2007). Any increase in the formation of reactive oxygen species (ROS) in the cells can contribute to the process of carcinogenesis through either direct genotoxic effects, or indirect ones via modification of signaling pathways leading to an altered expression of numerous genes. Further to their production by various biochemical reactions or as a by-product of oxygen metabolism in mitochondria, ROS can damage different types of cellular molecules such as proteins, lipids and nucleic acids (Kohen & Nyska, 2002). DNA mutation is considered as a crucial step in carcinogenesis, and the recording of more numerous oxidatively-derived DNA lesions in many tumours is in favour of the strong implication of such damage in the etiology of cancer (Cooke, Olinski, & Evans, 2006). Additional studies are needed to gain more insight into the mechanism of action of D. ligulata and D. dichotoma crude extracts through studies, for example, of its cell cycle impact, its ability to activate caspases, or mitochon- drial and DNA damages." [M. Zubia et al.(2009)]



Desmarestia munda - coarse acid kelp 

"Coarse Acid Kelp is an annual species that can attain a length of 8 m (26 feet). The holdfast can be quite variable, but is not branched; it grows to a diameter of about 4 cm (1.6 in). A single, flattened stipe arises from this holdfast. The blade supported by this stipe is 4 to 10 cm (1.6 to 4 in) wide and has flattened branches at least as wide as the blade bearing them. In mature individuals, these branches have distinct midribs, and slender veins from these midribs lead into side branches." [E-flora]

"In Desmarestia the characters of different species can overlap somewhat." [E-flora]

"Habitat / Range Bathymetry: strictly subtidal World Distribution: northern British Columbia to Baja California, Mexico" [E-flora]



Desmarestia viridis - stringy acid kelp 

"Stringy Acid Kelp is the most acidic of all the acid kelps, and should be avoided. It is light brown in color, often with greenish areas, more finely branched than Witch's Hair, and usually up to 120 cm (about 4 feet) in length. Most of the side branches come off the central axis in opposite pairs. This is a fragile species that grows only on rocks and is rarely as abundant as Witch's Hair. Look for it especially in areas recently grazed by sea urchins." [E-flora]

"When Stringy Acid Kelp is exposed to air (as during a good minus tide) the vacuoles containing the acid break down, releasing large quantities of this acid, turning the individual dull green and damaging nearby organisms. If you must collect it (and there seems little reason for doing so) place it into a container by itself and keep it entirely submerged in sea water" [E-flora] "... sulphuric acid released by the brown alga stringy acid kelp (Desmarestia viridis), which seems to help repel sea urchins." [Mouritsen Seaweeds]

"Individuals collected from southern British Columbia/northern Washington survived a week of immersion in water at 23°C (74°F) but died when placed in warmer water." [E-flora]

"Habitat / Range Bathymetry: extreme low intertidal and subtidal to 45 meters (148 feet) World Distribution: Aleutian Islands to Baja California, Mexico; Arctic Ocean; western North Pacific; North Atlantic; North Sea; New Zealand, Chile; Argentina; Antarctic and subantarctic islands" [E-flora]




Journals of interest

Page last modified on Friday, June 30, 2023 8:34 AM