Asparagopsis Armata

Mediterranean invasive species factsheet www.iucn-medmis.org

Species report Asparagopsis armata

AFFILIATION ALGAE

SCIENTIFIC NAME AND COMMON NAME REPORTS Asparagopsis armata 22

Key Identifying Features

A red seaweed with two morphologically different stages during its development, a gametophyte stage and a tetrasporophyte stage. Its cylindrical, bare main stolons (1mm wide, 200 mm long) are irregularly branched, with bushy fronds. Its lower branchlets are long and have hooks that resemble harpoons.

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Another alien species of red algae, Bonnemaisonia hamifera, occurs in similar Identification and Habitat habitats. It can be distinguished in its gametophyte stage by the crozier-shaped, The gametophyte stage is pale purplish-red, hook-like, modified branches that it forms. quickly degenerating when removed from the Other species that look similar water and becoming distinctly orange. It can be found growing as an epiphytic alga on other algal species, especially Corallina sp. The tetrasporophyte stage is a brownish-red, filamentous, branched alga, forming dense cotton-wool-like tufts 15 mm in diameter.

Usually this alga develops on infralittoral rocky bottoms from the surface to a depth of 40 m.

Reproduction

It is able to reproduce sexually and has a two-phase (heteromorphic diplohaplontic) life cycle with two main morphologically different stages during its development. The gametophyte phase, which was the form named Asparagopsis armata, has either male or female organs; this is followed by a microscopic carposporophyte middle stage, and then by the tetrasporophyte phase, which was originally named Falkenbergia rufolanosa. The gametophyte and sporophyte stages are also capable of reproducing vegetatively. Drifting gametophytes readily attach to other algae by barbed branchlets and produce new shoots. ‘Falkenbergia’ also disperses by flotation.

Similar Species

Gametophytes of Asparagopsis armata can be easily misidentified as another successful invader, Asparagopsis taxiformis, but the presence of harpoon-like hooks in A. armata distinguishes it. A. armata is able to survive and thrive in colder environments than A. taxiformis, which has an affinity for much warmer waters. The genus as a whole appears to have a high invasive potential. These seaweeds disperse with water currents, attached to floating objects.

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Economic Impacts

Pharmaceutical trials have shown the potential pharmaceutical compounds of A. armata that exhibites strong activity against fish pathogenic bacteria.

Management Options

Once it has become invasive, eradication and even containment are not possible. The species might be controlled most efficiently and effectively, and at the lowest cost, early in the invasive process.