Dr. Brante-Ramirez, Antonio

Biological invasions and changes in land and sea use are among the five major causes of global biodiversity decline. Shipping and ocean sprawl (multiplication of artificial structures at the expense of natural habitats) are considered as the major forces responsible for marine invasions and biotic homogenization. And yet, there is little evidence of their interplay at multiple spatial scales. Here, we aimed to examine this interaction and the extent to which the type of artificial habitat alters the distribution of native and non‐indigenous biodiversity. Location: Southeast Pacific—Central Chilean coastline.

Aim: Trait‐based approaches are powerful to examine the processes associated with biological invasions. Functional comparison among native and non‐indigenous species (NIS) can notably infer whether novel assemblages result from neutral or niche‐based assembly rules. Applying such a framework to biofouling communities, our study aimed to elucidate their distributions within two marine urban habitats (namely floating vs. nonfloating habitats). Location: Southeast Pacific—Central Chilean coastline. Methods: Here, we examined the distribution of 12 functional traits in fouling communities established on settlement plates, after 3 and 13 months of deployment in the two habitats and across ports in Central Chile. Based upon previously described differences of assemblages and NIS contribution across habitats, we hypothesized that nonindigenous, cryptogenic and native taxon pools would be functionally distinct (and trait biased), and that functional diversity and structure would vary across habitats and successional stages. Results: Our results show, as anticipated, that nonindigenous (13 taxa), cryptogenic (12) and native (18) taxon pools are functionally distinct, though overlapping in the trait space. Non‐indigenous species are rather related to colonizing traits, while native species are more related to competitive traits. Only one widespread NIS was functionally similar to the late successional and most competitive native species, including taxa elsewhere invasives. Despite differences in taxonomic composition between habitats, we did not observe functional differences between them. In contrast, temporal variations across colonization stages were detected along with an increased contribution in large and long‐lived taxa, together with site‐specific trajectories. Main Conclusions: We conclude that the functional distinctness among nonindigenous, cryptogenic and native taxa occupying artificial habitats in ports reflects niche‐based processes. Site‐specific trajectories indicate that scale‐dependent assembly processes, such as dispersal and species interactions, are at play.

Examining the effects of disturbances within marine urban communities can shed light on their assembly rules and invasion processes. The effects of physical disturbance, through the removal of dominant native habitat- builders, were investigated in the recolonization of disturbed patches and colonization of plates on pier pilings, in a Chilean port. On pilings, disturbance substantially affected community structure after 3 months, although it slowly converged across treatments after 10 months. On plates, cryptogenic and non-indigenous species richness increased with removal severity, which was not observed in natives. Opportunistic taxa took advantage of colonizing at an early successional stage, illustrating a competition-colonization trade-off, although indirect effects might be at play (e.g. trophic competition or selective predation). Recovery of the habitat-builders then occurred at the expense of cryptogenic and non-indigenous taxa. Whether natives could continue winning against increasing propagule and colonization pressures in marine urban habitats deserves further attention. The interactions between disturbance and biological invasions herein experimentally shown in situ contribute to our understanding of multiple changes imposed by marine urbanization in a growing propagule transport network.