Present knowledge on ascidian biodiversity at the SW Atlantic (Argentine Sea) with emphasis in invasive species

TATIÁN, M.; ALURRALDE G; LAGGER C.; MAGGIONI, T.; SCHWINDT, E; TAVERNA, A; VARELA M.M

Nápoles

Congreso; 7th Tunicate Meeting.; 2013

Stazione Zoologica Anton Dohrn

The Southwestern Atlantic (Argentine Sea) is one of the poorly known regions in terms of its biodiversity, particularly in the case of ascidians. The scanty ascidian records from that extended area are from specimens collected by dredging many decades ago. Besides, recent documentations on the emergence of marine invasive species have resulted in scientific interest considering the impacts of biological invasions on native marine biodiversity. During the last decade, we have been performing samplings along the SW Atlantic which includes coastal (natural and harbour localities) and oceanic areas with the aim to collect ascidians, to determine species richness and especially, to report these considered as exotic species. Although the status of native or exotic is difficult to establish (in part due to the scarcity of taxonomic studies), determinations on old museum collections help us to elucidate at least some of the species standings. The general survey of species revealed, at the moment a total of 79 ascidian species, eight of these whose exotic status is well documented and two species likely candidates to have been introduced to the region. From exotics, five recruited in succesional plates deployed along the Patagonian harbours: this represents a high percentage of the total ascidians and of the total exotic species found in these plates (33.3 and 29.4% respectively). The use of experimental plates is an ongoing work that would enable us to assess the ascidian invasion processes and its impact on native biodiversity.