NORTHERN EXPANSION OF Undaria pinnatifida RANGE IN ARGENTINA: CAN IT GO FURTHER?

DELLATORRE, F. G.; AMOROSO, R.; SERDÁ, A.; MUZIO, H.; SARAVIA, J.; MIRENDA, R.; JONES, J.; BARON, P. J.

Mar del Plata

Conferencia; 2nd World Conference on Biological Invasions and Ecosystem Functioning; 2011

Grupo de Investigación y Educación en Temas Ambientales

In 1992 sporophytes of Undaria pinnatifida were detected in Puerto Madryn. Since then, it has spread by more than 700 km to the south.  In 2008 the species was first reported northern from its introduction point in the San José Gulf (SJG), trespassing a natural barrier for dispersion (Valdes Peninsula) and raising public concern.  In this work we describe its rapid colonization of the SJG, its recent detection in San Matias Gulf (SMG) and briefly discuss, based on seawater temperature data, the potential for further dispersal northward.  We combined diving sampling along fixed and random transects (1-25 m depth) distributed around the entire gulf (February 2008 - April 2011), as well as active search of beached sporophytes in the coast.  Sea surface temperature (SST) of argentine coast at 40ºS and 36ºS were compiled from global databases and compared with the thermal ranges of tolerance reported for the species.  U. pinnatifida was detected in SJG from February 2008 and three years later it was dispersed around the entire gulf.  During January 2011 mature sporophytes were found growing near the west coast of SMG, and many beach casted sporophytes were found along more than 10 km of its coast.  The gametophytic phase of U. pinnatifida (which occurs during summer) can grow and maturate between 5º and 25º-28ºC.  Average SST in the warmer month at 40ºS and 36ºS are 20.35ºC and 21.38ºC respectively, suggesting that it should not have thermal limitations to invade the northern coast of Argentine.