Results and discussion
The invasive C. mutica does not bear an inherent advantage over its native congener in
terms of resistance to hydrodynamic forces; instead, its chances of overcoming vessel
transport highly depend on secondary substrate complexity, confirming that the basibiont
component acts as a refugium for mobile invasive epifauna during vessel voyage.
Fig. 2 a, b (left): Response to waterflow as a function of time. a) predicted probability of
both species remaining attached to the mesh. b) observed individuals remaining attached.
Fig. 3 (right): Predicted probability of C. mutica remaining attached to the mesh when
offered different levels of basibiont complexity.
Fig. 4 a, b, c. Behaviour observations in no distress conditions. a) Time spent resting. b)
Maximum distance covered when crawling. c) Predicted probability of actively departing
the plate into the water column (ie swimming).
Besides, the invasive species also exhibited higher boldness than the native one despite
being more vulnerable to hydrodynamic drag. This may confer an advantage at the postarrival phases of the invasion process (colonization, establishment and spread). In the
case of non-indigenous species with several invasiveness traits that may rely on fouling
refugia to overcome translocation, the most effective management strategy is removal
of biofouling prior to departure to a new destination. A rank 3 Level of Fouling (sensu Floerl
et al., 2005) already incurs a biosecurity risk, as it most probably harbors non-indigenous
mobile epifauna in transit, preventing natural loss of propagules during the transport phase.
Acknowledgements
Financial support: Ministerio de Educación, Cultura y Deporte (predoctoral grant to GML,
FPU15/02223), Ministerio de Economía y Competitividad and European Union (project
CGL2017-82739-P); Ministerio de Ciencia, Innovación y Universidades (internship
EST18/00253); Natural Sciences and Engineering Research Council (Canada) (Discovery Grant
to CDGH). We thank marina staff from Royal Vancouver Yacht Club and Reed Point Marina;
Sandra Emry and Em Lim. We acknowledge the Squamish, Tsleil-Waututh, and Musqueam nations.
Bibliography
FLOERL O., INGLIS G. J., & HAYDEN B. J. (2005) - A Risk-Based Predictive Tool to Prevent
Accidental Introductions of Non-indigenous Marine Species. Environ. Manage., 35(6) : 765-78.
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
108
The invasive C. mutica does not bear an inherent advantage over its native congener in
terms of resistance to hydrodynamic forces; instead, its chances of overcoming vessel
transport highly depend on secondary substrate complexity, confirming that the basibiont
component acts as a refugium for mobile invasive epifauna during vessel voyage.
Fig. 2 a, b (left): Response to waterflow as a function of time. a) predicted probability of
both species remaining attached to the mesh. b) observed individuals remaining attached.
Fig. 3 (right): Predicted probability of C. mutica remaining attached to the mesh when
offered different levels of basibiont complexity.
Fig. 4 a, b, c. Behaviour observations in no distress conditions. a) Time spent resting. b)
Maximum distance covered when crawling. c) Predicted probability of actively departing
the plate into the water column (ie swimming).
Besides, the invasive species also exhibited higher boldness than the native one despite
being more vulnerable to hydrodynamic drag. This may confer an advantage at the postarrival phases of the invasion process (colonization, establishment and spread). In the
case of non-indigenous species with several invasiveness traits that may rely on fouling
refugia to overcome translocation, the most effective management strategy is removal
of biofouling prior to departure to a new destination. A rank 3 Level of Fouling (sensu Floerl
et al., 2005) already incurs a biosecurity risk, as it most probably harbors non-indigenous
mobile epifauna in transit, preventing natural loss of propagules during the transport phase.
Acknowledgements
Financial support: Ministerio de Educación, Cultura y Deporte (predoctoral grant to GML,
FPU15/02223), Ministerio de Economía y Competitividad and European Union (project
CGL2017-82739-P); Ministerio de Ciencia, Innovación y Universidades (internship
EST18/00253); Natural Sciences and Engineering Research Council (Canada) (Discovery Grant
to CDGH). We thank marina staff from Royal Vancouver Yacht Club and Reed Point Marina;
Sandra Emry and Em Lim. We acknowledge the Squamish, Tsleil-Waututh, and Musqueam nations.
Bibliography
FLOERL O., INGLIS G. J., & HAYDEN B. J. (2005) - A Risk-Based Predictive Tool to Prevent
Accidental Introductions of Non-indigenous Marine Species. Environ. Manage., 35(6) : 765-78.
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
108