Home — Seaweeds of Alaska

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Three lineages of seaweed

Every seaweed species in this catalogue belongs to one of three phyla based on their primary photosynthetic pigments (green, brown, or red) and color coded accordingly.

Chlorophyta Green seaweeds

Chlorophyta

Green Seaweeds

These seaweeds are mainly seasonal, fast growing, and early colonizers of newly created spaces in the intertidal zone, especially after winter storms. They can form turfs, extensive mats, and grow on many other species of seaweeds. Their morphology (shape) ranges from crusts filaments, blades, and unusual species where cells are visible with the naked eye.

Examples with unusual morphology Coarse spongy cushion Smooth spongy cushion Jade necklace

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Ochrophyta Brown seaweeds

Ochrophyta

Brown Seaweeds

Brown seaweeds can be found year-round or seasonally. Perennials, like Rockweed, often dominate the mid intertidal zone. Brown seaweeds produce an impressive amount of biomass and are considered a valuable natural resource. Kelp forests in the subtidal zone provide critical habitat for marine life with several species that are unique to Alaskan waters.

Examples unique to Alaska and Northern Pacific Golden V kelp Dragon kelp Arctic suction-cup kelp Spiral sieve kelp

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Rhodophyta Red seaweeds

Rhodophyta

Red Seaweeds

This is the most diverse seaweed phyla demonstrated by a wide variety of morphological groups, cellular structures, and complex life histories. There are approximately 350 Species of red seaweeds found in Alaska. Some red seaweeds are known for their nutritional, medicinal, and economic value. Red seaweeds in Alaska are commonly collected for subsistence and mariculture activities are on the rise.

Examples of commonly harvested species in Alaska Red ribbon Stiff red ribbon Black seaweed Rockweed laver

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Beyond the seaweeds

Additional Catalog Sections

Seagrasses

Seagrasses are photosynthetic flowering plants occurring worldwide along the coastline. Seagrasses are true seed-producing plants but are not true grasses. They form dense beds in suitable Alaska coastal areas and provide habitat for diverse groups of invertebrates, seaweeds, forage fish, waterfowl, and shorebirds. There are two main types of seagrasses found in Alaska: eelgrass and surfgrass.

Eelgrass - Zostera marina Serrulated surfgrass - Phyllospadix serrulatus Scouleri's surfgrass - Phyllospadix scouleri

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Marine Lichens

Marine lichens are abundant in the high intertidal and supratidal where only the most salt-tolerant species can live. Lichens dominate this extreme zone and are one of the most striking and visible bio-bands in the intertidal. Three common groups of marine lichens, found along Alaska's shoreline, are briefly described here.

Orange seaside lichens - Caloplaca & Xanthoria spp. White seaside lichen - Coccotrema maritimum Black seaside lichen - Hydropunctaria maura spp.

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Plants

Casually presented here are true vascular plants often found above the high tide line along Alaska's coastal areas. Some are salt tolerant or commonly found along fringing habitats. Most are at their peak during the summer months including glassworts, sedges, grasses, and flowering plants.

Succulents Grasses, sedges, or rushes Flowering plants Shrubs

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