Broad winged-kelp (Alaria marginata)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Chromista · Phylum: Ochrophyta · Class: Phaeophyceae · Order: Laminariales · Family: Alariaceae · Genus: Alaria.

Accepted name: Alaria marginata · Authority: Postels & Ruprecht, 1840 · Taxonomic status: accepted · AphiaID: 371791.

Synonyms and superseded combinations recorded for this taxon: Alaria curtipes Saunders, 1901; Alaria fragilis f. bullata Saunders, 1901; Alaria lanceolata Kjellman, 1883; Alaria marginata f. musiformis Postels & Ruprecht, 1840; Alaria marginata f. nana (H.F.Schrader) F.S.Collins, 1913; Alaria nana H.F.Schrader, 1903; Alaria praelonga f. nana (Schrader) Collins; Alaria taeniata Kjellman, 1889; Alaria tenuifolia Setchell, 1903; Alaria tenuifolia f. amplior Setchell & N.L.Gardner, 1903; Alaria tenuifolia f. typica Setchell, 1903; Alaria valida Kjellman & Setchell, 1903; Alaria valida f. longipes Setchell & Gardner; Orgyia marginata (Postels & Ruprecht) Trevisan, 1845; Phasganon marginatum (Postels & Ruprecht) Ruprecht, 1850.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=371791 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (SeaLifeBase)

Measured values published by SeaLifeBase for Alaria marginata. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.

Habitat zone: sessile.

Source: SeaLifeBase species summary (SpecCode 119818) — https://www.sealifebase.se/summary/Alaria-marginata.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Distribution and occurrence records (GBIF)

222,117 georeferenced occurrence records for Alaria marginata are published through GBIF from 5 countries or marine areas. The map above plots 70 distinct locations from a sample of 3,000 records, omitting 55 inland records that carry an institution's coordinates rather than a collection site; it shows where the species has been observed and reported, not a modelled range.

Most records by country or area: United States of America (220,306); Canada (1,781); Mexico (16); Japan (11); Russian Federation (3).

The full country table, WoRMS marine regions and the sampling notes are on this species' Distribution page.

Source: GBIF Occurrence Search (taxonKey 5422588) — https://www.gbif.org/occurrence/search?taxon_key=5422588&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=371791 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-23.

Description and natural history (Wikipedia)

According to a study done by Widdowson(1971), the kelp Alaria marginata has been known to occupy certain wave-exosed intertidal habitats. These habitats can be found in the northeast Pacific from Alaska to near Point Conception, California. Alaria marginata has been the dominant macroalga on this exposed mid-to-low rocky shores along the Big Sur coast of California. The kelp commonly grows in large patches, which offers habitat and sustenance for tide pool organisms.

In the kelp species Alaria marginata, phenolics act as chemical defence against herbivores. Higher concentrations of the phenolics were found in the reproductive fronds when compared to the vegetative blades, which were consumed at a higher rate by herbivorous snails.

According to a study done by McConnico and Foster in the Science Direct, thinning of the kelp patches was inversely related to density. During the growing season from February to July, the kelp would grow in length up to 1.4 meters a month to form thick canopies. The sorus development was found to be positively related to size and begins as early as March (peaking in late August-October). Releasing of the spores would take place most frequently between October and January, being associated with high water movement.

Alaria marginata are an edible kelp, commonly harvested in the spring and early summer to avoid frond harm from the summer storms. The upper frond and midrib can be harvested, leaving the lower portion of the frond to continue to grow.

Once harvested, the alaria marginata can be used fresh or dried. To dry, fronds are hung off clotheslines for an even preservation of both sides of the kelp. The midrib of the alaria marginata can be cut out, separating the two opposing sheets and the stiffer midrib. Dried fronds can be stored in strips or pieces in a cool, dry place.

Source: Wikipedia: Alaria marginata — https://en.wikipedia.org/wiki/Alaria_marginata (CC BY-SA 4.0). Accessed 2026-09-23.