Bioinvasion of Benthic Invertebrates in a Eutrophicated Tropical Estuarine System in South America (Santos, Brazil)

Abstract

The economic losses due to bioinvasion in Brazil were estimated to be over USD 100 billion since 1984; however, these values are mostly related to terrestrial invasive species, whereas the financial losses in the marine realm continue to be ignored. The bioinvasion of benthic fauna was evaluated in the estuarine channel of Santos Harbor, Brazil. Three recruitment plates were spread along the estuarine channel to assess their colonization progress during two periods: April until July and August until September in 2019. Inner stations presented haline stratification, and low values of dissolved oxygen were registered as signs of eutrophication. Among the identified taxa, six species were considered exotic to the Brazilian coastline: Branchiomma luctuosum, Hydroides elegans, Bugula neritina, Styela plicata, Clavelina oblonga, and Botrylloides giganteus. The diversity was low due to the monospecific dominance of B. luctuosum, which occupied 73.4% and 42.4% of the recruitment plates in the first and second campaigns, respectively. It was possible to observe a gradient pattern in the biovolume averages between the monitoring points, which tended to be higher at the station closer to the sea, despite the lack of significant differences among them. The recruitment plate technique offered reliable results for the identification of invasive species regarding fouling communities along the Santos Harbor channel.