Ascophyllum Nodosum - Ecology

Ecology

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

The species is found in a range of coastal habitats from sheltered estuaries to moderately exposed coasts, often it dominates the inter-tidal zone (although sub-tidal populations are known to exist in very clear waters). However it is rarely found on exposed shores, and if it is found the fronds are usually small and badly scratched. 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. It may typically overlap in distribution with Fucus vesiculosus and Fucus serratus. Its distribution is also limited by salinity, wave exposure, temperature, desiccation and general stress. These, and other attributes of the algae are summarized in Schonbeck & Norton (1980). It may take approximately five years before becoming fertile.

Phlorotannins in Ascophyllum nodosum act as chemical defenses against the marine herbivorous snail, Littorina littorea.

Vertebrata lanosa (L.) T.A. Christensen is a small red alga, commonly found growing in dense tufts on Ascophyllum whose rhizoids penetrate the host. It is considered by some as parasitic, however as it only receives structural support from Knotted Wrack (i.e. non-parasitically), it acts as an epiphyte.