field to assess all the species colonizing each panel. Then, 10 panels from Palmaria were
moved to the two marinas (5 in each marina; transplant treatment), while 5 remained in
Palmaria (control treatment); the panels initially deployed in the two marinas were reimmersed there (marina treatment; Fig. 1) for two additional months of immersion. At
the end of the experiment, all panels were retrieved, photographed, and preserved in
70% ethanol for the final species identification in the laboratory. All the panel images
were then analysed to assess the percent cover of the fouling assemblage through an
image analysis software (photoQuad), considering 50 random points.
The experimental units used for the sampling were constructed following the method
proposed by the Smithsonian institute, with the PVC panels (14x14 cm) attached to a
brick and facing downwards at 1 m of depth (Tamburini et al., 2021).
The statistical analyses were carried out with the software PRIMER 6 (with
PERMANOVA+ add-on package) on the sessile component of the fouling assemblages
and considering two different dataset: i) the percentage cover of each species at the end
of the experiment; ii) only the new recruited species after the transplant.
The experimental design had to be slightly modified: six instead of ten panels were
transplanted in the marinas, and four instead of five panels remained in Palmaria (Fig. 1).
Results
After three months of immersion and before the transplantation, the number of NIS was
comparable between Palmaria and the two marinas (Fig. 2), but NIS had a lower
abundance in Palmaria: 71±12% native species (including cryptogenic species) and
2±2% NIS were recorded in the samples from Palmaria; while 34±20% and 33±25%
native species, 23±20% and 31±25% NIS were observed in the panels from Fezzano
and Le Grazie, respectively (average percentage cover ± S.D.).
A two-way PERMANOVA test was performed considering the two sampling times
(three and five months) and the three treatments (control in Palmaria; transplanted and
no-transplanted panels in the marinas), and a significant difference was observed among
treatments (Pseudo-F = 7.9747, P(perm) = 0.0001), sampling times (Pseudo-F = 4.1738,
P[perm] = 0.0001) and their interaction (Pseudo-F = 1.8737, P [perm] = 0.0158). On the
other hand, when considering only the newly recruited species after the transplant, a
non-significant difference was observed between transplanted and no-transplanted
panels (Pseudo-F = 3.5651, P(Monte Carlo) = 0.0641).
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
31
moved to the two marinas (5 in each marina; transplant treatment), while 5 remained in
Palmaria (control treatment); the panels initially deployed in the two marinas were reimmersed there (marina treatment; Fig. 1) for two additional months of immersion. At
the end of the experiment, all panels were retrieved, photographed, and preserved in
70% ethanol for the final species identification in the laboratory. All the panel images
were then analysed to assess the percent cover of the fouling assemblage through an
image analysis software (photoQuad), considering 50 random points.
The experimental units used for the sampling were constructed following the method
proposed by the Smithsonian institute, with the PVC panels (14x14 cm) attached to a
brick and facing downwards at 1 m of depth (Tamburini et al., 2021).
The statistical analyses were carried out with the software PRIMER 6 (with
PERMANOVA+ add-on package) on the sessile component of the fouling assemblages
and considering two different dataset: i) the percentage cover of each species at the end
of the experiment; ii) only the new recruited species after the transplant.
The experimental design had to be slightly modified: six instead of ten panels were
transplanted in the marinas, and four instead of five panels remained in Palmaria (Fig. 1).
Results
After three months of immersion and before the transplantation, the number of NIS was
comparable between Palmaria and the two marinas (Fig. 2), but NIS had a lower
abundance in Palmaria: 71±12% native species (including cryptogenic species) and
2±2% NIS were recorded in the samples from Palmaria; while 34±20% and 33±25%
native species, 23±20% and 31±25% NIS were observed in the panels from Fezzano
and Le Grazie, respectively (average percentage cover ± S.D.).
A two-way PERMANOVA test was performed considering the two sampling times
(three and five months) and the three treatments (control in Palmaria; transplanted and
no-transplanted panels in the marinas), and a significant difference was observed among
treatments (Pseudo-F = 7.9747, P(perm) = 0.0001), sampling times (Pseudo-F = 4.1738,
P[perm] = 0.0001) and their interaction (Pseudo-F = 1.8737, P [perm] = 0.0158). On the
other hand, when considering only the newly recruited species after the transplant, a
non-significant difference was observed between transplanted and no-transplanted
panels (Pseudo-F = 3.5651, P(Monte Carlo) = 0.0641).
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
31