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Mediterranean invasive species factsheet

Similar species
The seagrass species native to the Mediterranean
Sea (Posidonia oceanica, Cymodocea nodosa,
Zostera noltii and Z. marina) are characterized by
longer leaves arranged in groups (not pairs), with
older leaves on the outside.

Caulerpa prolifera, a native green alga, has dark
green, oval-shaped leaf blades that are about 1.5–
2.5 cm wide and 6–15 cm long. The leaves of this
species grow from a few tough stolons, emerging
perpendicularly at 1–2 cm intervals; they are usually
oval or linearly elongated with a smooth edge. C.
prolifera is distinguished from H. stipulacea by the
lack of a prominent mid-rib along the length of the
leaves.
Lack mid-rib Posidonia oceanica. Photo: M. Otero

populations may have originated from fragments
carried by Greek fishing boats, and spread thereafter
probably by ship transport.

Ecological impacts
Studies suggest that H. stipulacea is capable of
displacing native seagrasses such as Posidonia
oceanica and Cymodocea nodosa and their
associated communities. Further research is needed
to confirm this and provide further details of the
Caulerpa prolifera
extent of these interactions. H. stipulacea beds
expand rapidly and tolerate a wide range of
environmental conditions, potentially threatening
local and regional biodiversity. This species is
included among the 100 Worst Invasive Alien
Species in the Mediterranean.
Economic impacts

Unknown.

Management options
Prevention: Unknown. Eradication: Unknown.

Cymodocea nodosa. Photo: J.M. Ruiz
Further reading

Brief history of its introduction and http://www.europe-aliens.org/pdf/Halophila_stipulacea.pdf
pathways Malm T., 2006. Reproduction and recruitment of the
seagrass Halophila stipulacea. Aquatic Botany. 85 (4), 347-
351.
Native to the Indian Ocean, H. stipulacea entered Drawings: Juan Varela
Sghaier, Y. R., et al., 2011. Occurrence of the seagrass
the Mediterranean from the Red Sea after the Halophila stipulacea (Hydrocharitaceae) in the southern
opening of the Suez Canal in 1869. The Aegean Mediterranean Sea. Botanica Marina 54: 575–582.

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