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Made available in DSpace on 2019-10-06T16:40:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-09-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) Human occupation of coastal areas promotes the establishment of non-native species but information on bioinvasions is usually biased toward the Northern Hemisphere. We assessed non-native species' importance in sessile communities at six marinas along the most urbanized area of the Southwestern Atlantic coastline. We found 67 species, of which 19 are exotic. The most frequent species was the exotic polychaete Branchiomma luctuosum, while the most abundant was the exotic bryozoan Schizoporella errata that monopolized the substrata in three marinas. Along with S. errata, the exotic polychaete Hydroides elegans and ascidian Styela plicata dominated space in the three remaining marinas, while native species were in general rare. We show that communities associated with artificial substrata along this Brazilian urbanized area are dominated by exotic species and that using abundance data along with species identity can improve our understanding of the importance of exotic species for the dynamics of biological communities. Centro de Ciências Naturais e Humanas Universidade Federal do ABC (UFABC), Rua Arcturus, 03 - Jardim Antares Departamento de Zoologia Instituto de Biociências Universidade de São Paulo, R. Matão, Trav. 14 Museu Nacional Universidade Federal do Rio de Janeiro (UFRJ), Quinta da Boa Vista, s/n – São Cristóvão Departamento de Biologia Marinha Universidade Federal Fluminense Universidade Federal do Rio de Janeiro Instituto de Biologia Departamento de Zoologia, Av. Carlos Chagas Filho, 373 Departamento de Biologia Animal Instituto de Biologia Universidade Estadual de Campinas (UNICAMP), Caixa Postal 6109 Laboratório de Estudos de Bryozoa – LAEBry Departamento de Zoologia Centro de Biociências Universidade Federal de Pernambuco (UFPE), Av. Prof. Moraes Rego 1235 - Cidade Universitária Laboratório de Evolução e Diversidade Aquática – LEDA Departamento de Ciências Biológicas Universidade Estadual Paulista (UNESP), FCL/Assis, Av. Dom Antônio, 2100 Departamento de Zoologia Universidade Federal do Paraná Laboratório de Evolução e Diversidade Aquática – LEDA Departamento de Ciências Biológicas Universidade Estadual Paulista (UNESP), FCL/Assis, Av. Dom Antônio, 2100 CAPES: 001 FAPESP: 2015/24408-4 FAPESP: 2016/17647-5 FAPESP: 2016/50389-0 CNPq: 308768/2018-3 CNPq: 309995/2017-5

Predation plays a fundamental role in shaping marine fouling communities. However, its consequences for species diversity and community organization depend on several intrinsic properties of predators and prey. To evaluate how predators of different sizes affect the organization of sessile communities during their development, we deployed an experiment in which PVC plates were assigned to one of four predation exclusion treatments: partial exclusion cage (2.4 cm mesh), total exclusion cage (0.5 cm mesh), and two respective controls. We evaluated community richness and structure after 30, 90, and 150 days. Regardless of size, predation did not affect total species richness. After 30 days, communities on plates protected against all predators had less free space than any other treatments, but their structure was similar to those protected to large predators only. Therefore, the addition of predators smaller than 2.4 cm to the pool of consumers may intensify predation effects rather than change species dominance and composition. After 90 days, intensified consumption by smaller predators had no longer measurable effects. Our data suggest that the removal of dominant species by predation does not increase species richness but modulates the interaction among species. The removal of ascidians seems to facilitate the dominance of predator-resistant bryozoans.

Man-made facilities along coastlines modify water circulation and sedimentation dynamics which can affect the structure of marine benthic and pelagic communities. To test how environmental heterogeneity associated with a recreational marina affects the structure of the fouling community and the benthic-pelagic link, we conducted an experiment in which predation effects on recruitment and community structure were assessed in two artificial habitats: inside the marina, an area of calm waters and often disturbed by boating activity, and the breakwater, a more hydrodynamic area. Using visual censuses and video footages we also described the predation pressure and the identity of predators on the two areas. Inside the marina, the recruitment of ascidians and serpulids, but not of bryozoans, was restricted in some occasions, possibly due to reduced water circulation. Predation, mainly by the silver porgy fish Diplodus argenteus, reduced the survivor of didemnid ascidians on both areas, but predation intensity was 40 times higher in the breakwater than inside the marina. While the two artificial habitats did not necessarily support distinct communities, low recruitment coupled to weak predation inside the marina, a less dynamic environment, likely imply lower resilience and more susceptibility to disturbance.