Ascophyllum nodosum is a large, common cold water seaweed or brown alga (Phaeophyceae) in the family Fucaceae.

The air bladders create a way for fronds broken by wave exposure or other causes to be dispersed and regrow in other areas.

Ascophyllum nodosum is found mostly on sheltered sites on shores in the midlittoral, where it can become the dominant species in the littoral zone.

[4] The species is found in a range of coastal habitats from sheltered estuaries to moderately exposed coasts, and often it dominates the intertidal zone (although subtidal populations are known to exist in very clear waters).

This seaweed grows quite slowly, 0.5% per day, carrying capacity is about 40 kg wet weight per square meter, and it may live for 10–15 years.

[6] Excess sperm can be released during the reproduction of Ascophyllum nodosum, which can then act as a food source for plankton consumers.

Christensen is a small red alga, commonly found growing in dense tufts on Ascophyllum whose rhizoids penetrate the host.

[1][2] The southern boundary of A. nodosum ends around Long Island, NY, on account of higher water temperatures when traveling farther south.

[32] Ascophyllum nodosum is harvested for use in alginates, fertilisers, and the manufacture of seaweed meal for animal and human consumption.

[6][33] It has long been used as an organic and mainstream fertilizer for many varieties of crops due to its combination of both macronutrients, (N, P, and K) and micronutrients (Ca, Mg, S, Mn, Cu, Fe, Zn, etc.).

[35][36] Ascophyllum nodosum is frequently used as packaging material for baitworm and lobster shipments from New England to various domestic and international locations.

[38][39] It has been used in this way for over fifty years, and studies have shown that A. nodosum absorbs cobalt, cadmium, lead, and indium metal ions out of the water.

[40] Ascophyllum nodosum is commercially harvested in several countries, including Norway, Ireland, Scotland, France, Iceland, Canada and in USA.