Wire Weed - Invasive Species Information

Reproduction: Both sexual and asexual. Reaches sexual maturity in the summer.

The species is monoecious, i.e. an individual is capable of producing male and female gametes. Its cycle of development is monogenic (only one generation is present during its life cycle).

At the level of fertilization: male gametes are dispersed in seawater while female gametes remain in the receptacle where fertilization takes place.

Development is also done at the receptacle and then once at the stage of seedling, the latter is detached for fixation on a new support and form a new individual. This species can also reproduce asexually. But this has never been observed in temperate environments.

Wireweed is composed of two distinct parts:

a perennial part, which contains the holdfast and one or more short main axes;
an annual part: the secondary axes, which develop on the main axis, whose growth is unlimited and the size is variable.

There are three types of ramifications: laterals with foliaceous expansions called fronds, laterals with fronds and aerocysts and laterals with fronds, aerocysts and reproductive organs called receptacles.

In winter, only the perennial part persists (5 cm). In summer, the lateral part is in maximum development of 2–3 meters to 10 meters.

How To Identify Wire Weed?

Frond: Green/Brown

felty, fibrous discoid holdfast up to 1.5 cm in diameter

Blades: linear-lanceolate on the basal portion of stipe, to 10 cm long, toothed with the upper stipe narrow, often only 4 mm long

Why Is Wire Weed A Problem?

Wire Weed's proliferation is significant, especially during the summer, which causes economical and ecological problems.

Ecological: Because of its large size and dense ramifications, S.muticum forms a screen within the water column preventing the penetration of light.

It also captures the nutrients depriving availability to other species such as phytoplankton. However, can also serves as shelter and protection for fish larva or crustaceans as well as laying support for cuttlefish.

Economical: Fixes itself to the shells of oysters creating problems in shellfish farming through increased manual work to eliminate the algae.

In addition, it can wrap around the farming structures, requiring additional maintenance. It also gets entangled with the propellers of the boats.

What Is Wire Weed - (Sargassum muticum)?

Habitat: Aquatic. Seawater
Distribution in Ireland: Abundant coastal areas

Status: Established
Family name: Sargassaceae