Stationary substrates facilitate bioinvasion in Paranaguá Bay in southern Brazil

Abstract

Artificial substrates in and near ports and marinas commonly have many non-indigenous species and are the first stepping stone for the establishment of bioinvasors. Substrate movement influences fouling communities and so understanding of how species assemblages are related to specific substrate conditions is crucial as a management tool. Here we describe the species assemblage of the community after six months of development on granite plates in Paranaguá Bay. Species richness was similar in the two treatments, with 12 species on floating (constant depth) plates and 15 on stationary (variable depth) plates. However, species composition differed, with the community on floating plates being dominated by the native bivalve Mytella charruana (66.1 ± 5.5% cover) and that on stationary plates dominated by the barnacles Fistulobalanus citerosum (49.8 ± 3.5% cover) and the introduced Amphibalanus reticulatus (33.9 ± 3.7% cover). Other introduced species were Garveia franciscana, on one stationary plate, and Megabalanus coccopoma also on one stationary plate and not very abundant on half of the floating plates (< 2%). Thus, stationary plates were more susceptible to introduced species that may become very abundant, suggesting that this type of substrate should be a priority in management for bioinvasion control. We also hypothesize that the native bivalve M. charruana is the dominant competitor for space on floating substrates, thereby reducing the invasiveness of that type of substrate.