Benthic non-indigenous species on the southern coast of Chubut (Argentina) at the onset of the 21st century

RICO, A.; RIERA, M.; LÓPEZ GAPPA, J.

Buenos Aires

Congreso; Marine & Freshwater Invasive Species: Ecology, Impact and Management; 2016

Aquatic Ecosystem Health & Management Society

Benthic non-indigenous species on the southern coast of Chubut (Argentina) at the onset of the 21st centuryDuring the last decades, several studies have dealt with benthic marine organisms occurring on the abrasion platforms of Comodoro Rivadavia (45º52´ S, 67º28´ W) and Rada Tilly (45°57′ S, 67°32′ W). Benthic species were sampled using different methodologies. Stone fragments were glued to intertidal and subtidal substrates with epoxy putty and plastic panels were screwed to supporting structures at the subtidal level of Comodoro Rivadavia harbor. Intertidal research at Rada Tilly was based on monthly non-destructive observations. Species richness and diversity (Shannon-Wiener index) were estimated and differences among samples were then tested by two-way ANOVAs followed by post-hoc comparisons. Multivariate data were analyzed with the PRIMER package. The presence of Balanus glandula, a barnacle native to the Pacific coast of North America, was discovered in 2001 on intertidal hard substrates of the harbor. The species then continued its dispersion along Atlantic rocky shores down to Tierra del Fuego. The alien bryozoans Cryptosula pallasiana and Bugula flabellata were previously known from fouling assemblages in harbors of Buenos Aires province. Their geographic distribution was extended towards the southern coast of Chubut. Exotic ascidians were particularly abundant. They were mainly represented by solitary species such as Ascidiella aspersa and Molgula manhattensis, or by the colonial forms Botryllus schlosseri, Diplosoma listerianum and Lissoclinum fragile. The invading kelp Undaria pinnatifida was reported for the first time for Argentina in 1994 at Nuevo Gulf (northern coast of Chubut). In 2005, this species was found in Comodoro Rivadavia harbor. Its life-cycle and the macro- and microstructure of tagged individuals are currently being studied and compared with morphological features of populations from other geographic areas.