Fig. 2: Average number of native and non-indigenous species recorded after three (A) and
five months (B) in the investigated sites. Letters in brackets refer to the different
treatments of the experimental design: C (control, in Palmaria); T (transplanted panels
from Palmaria to the marinas); M (no-transplanted panels in marinas).
Discussion and Conclusions
In this study, a transplant experiment was carried out to test the biotic resistant
hypothesis in the context of Mediterranean port habitats: results show that native
fouling communities do not exert significant effects in terms of establishment of new
NIS. In general, fouling communities from Palmaria, the “natural” site, were highly
covered by native species, with only a very limited abundance of NIS. After the
transplant, the fouling assemblages from Palmaria demonstrated to maintain their own
identity in the two following months of immersion inside the marinas. However, when
considering the new recruitment after the transplant, the panels moved from Palmaria
and the unmoved panels from the marinas were similarly colonized by new species.
Therefore, with this experiment, the biotic resistance hypothesis has not been observed
as in other studies (e.g., Gestoso et al., 2017); this result could be partially due to the
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
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