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Mediterranean invasive species factsheet

ALGAE

Reproduction Common name: Green sea fingers

identification

Scientific Name:
Codium fragile subsp. fragile
Picture

Key identifying features
Brief history
A large, dark green alga consisting of one to several
erect fronds, 15–20 cm high, with abundant
cylindrical branches in a dichotomous or fastigiated
Spongy to the touch Y-shaped cylindrical branches
pattern, and attached to the substrate by a broad
spongy basal disc. The cylindrical branches are
0.3–1 cm in diameter. Shape and structure may vary
depending on the environmental conditions.

The species can only be distinguished from several
other similar varieties or subspecies under a
binocular microscope by the shape of the
microscopic flask-shaped outer structures (utricles).
Codium fragile subsp. fragile has a hairy surface and
the utricles at the tips of the branches form regular
cylinders with a sharp terminal point.

Field identification signs and habitat
Like other Codium species, C. fragile subsp. fragile is
soft and spongy to the touch. It tolerates large
variations in salinity and temperature, enabling it to
colonize a wide range of environments. It appears to
thrive on intertidal and shallow subtidal rocky
bottoms, and in sheltered habitats such as harbours
and bays.

Codium fragile. Photo: E. Ballesteros

Reproduction

Its success as a rapid colonizer may be attributed to
its range of propagation techniques. It can reproduce
either sexually or by releasing small propagules in
the water column, which are dispersed locally. It also
reproduces vegetatively by fragmentation of the
thallus, forming new plants that are dispersed by
currents and re-attach elsewhere, or from basal
holdfasts that remain after fragmentation. The plant
is perennial, proliferating each spring from a
persistent basal portion.
Codium fragile subsp. fragile Photo: Poloniato - WWF; Miramare MPA

Monitoring Marine Invasive Species in Mediterranean MPAs: A strategy and practical guide for managers 43