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Mediterranean invasive species factsheet

Similar species filtration rates, it may affect nutrient cycling, reducing
Limnoperna securis resembles the common the food available to other filter-feeders; it is
Mediterranean species, Mytilaster minimus. The therefore a major competitor of native species. It can
major differences are that L. securis: 1) has a also produce changes in the physico-chemical
generally darker shell; 2) is narrower and more characteristics of the habitat and affect turbidity and
elongated, whereas M. minimus is squatter in shape; sedimentation.
3) lacks internal shell teeth where the two valves are
hinged; 4) is adapted to living at low salinities, unlike Economic impacts
M. minimus which is found in marine waters. The species’ economic impact has not yet been
quantified, but it is highly possible that bivalve culture
and harvesting may suffer due to strong competition.
By overgrowing commercially harvested molluscs,
especially the mussel Mytilus galloprovincialis, it can
reduce their growth and yield. L. securis can act as a
key host for pathogens of commercially cultured
species. Its rapid growth can contribute to the fouling
of submerged structures, pipelines, ropes and boat
hulls.

Management options

Suggested prevention measures include conducting
local public awareness campaigns combined with the
Mytilaster minimus
monitoring of populations, which makes early
detection possible. Black pygmy mussels should be
removed from seed bivalves intended for mariculture
purposes. Control: eradication of this species from
Brief history of its introduction and
pathways the environment is unfeasible at the moment due to
its small size and the large numbers of individuals
Originally from the south-eastern Pacific (New
forming new populations.
Zealand and southern Australia), L. securis was first
reported in the Mediterranean in Italy (in the Po river
delta) in 1992. Since then, it has been found in Further reading
coastal lagoons and estuaries of France and Italy http://www.ciesm.org/atlas/Xenostrobussecuris.html
(the Tyrrhenian, Ligurian and Adriatic Seas) and Barbierie et al., 2011. New records of the pygmy mussel
Spain (northern Catalonia). It was accidentally Xenostrobus securis (Bivalvia: Mytilidae) in brackish-water
biotopes of the western Mediterranean provide evidence of
introduced with seed bivalves for aquaculture
its invasive potential. Marine Biodiversity Records, Vol 4, 1-4
purposes, but it can also be spread in ships’ ballast
waters (water pumped into and out of ships to adjust
their buoyancy) or by fouling (in the communities
encrusting a ship’s hull).

Ecological impacts
Considered to be one of the worst invasive alien
species in Europe (European Environment Agency,
2007), its gregarious behaviour and high-density Drawings: Juan Varela
populations living on muddy bottoms can smother
the native infaunal communities. Due to its high

72 Monitoring Marine Invasive Species in Mediterranean MPAs: A strategy and practical guide for managers