13/12/2003

Ivan GUALA, Antonio ESPOSITO. and Maria Cristina BUIA

Abstract

Subtidal assemblages are affected by biotic and abiotic factors which work at different
spatial scales; moreover human activities can be an important source of variation in
community composition.
In order to detect the macroalgal assemblages variability in relation to anthropogenic
disturbance, a visual assessment of the cover of algal species was performed on sub-
horizontal rocky substrates, at both 5 and 10 m depths, in 12 localities of the Gulf of
Naples (Italy), for a total of 216 observations.
Important taxa in differentiating localities were identified. Among these, Caulerpa
racemosa, recently introduced in the studied area, was one of the most important
species in differentiating impacted and relatively undisturbed localities. Deep non
impacted communities seem to be more vulnerable to the introduction of this alien
seaweed. Its invasiveness, strictly linked to its reproductive modality, may be associated
with summer anchorages of many leisure boats rather than with the environmental
conditions of recipient localities.

PROCEEDINGS OF THE SECOND MEDITERRANEAN SYMPOSIUM ON MARINE VEGETATION