Breaching biogeographic barriers: The invasion of Haynesina germanica (Foraminifera, Protista) in the Bahía Blanca estuary, Argentina

CALVO MARCILESE, LYDIA; LANGER, MARTIN R.

Universidad de Bonn- Bonn, Alemania.

Simposio; FORAMS 2010- International Symposium on Foraminifera; 2010

Universidad de Bonn

Large populations of the living benthic foraminifera Haynesina germanica (Ehrenberg 1840) are reported for the first time from marsh and intertidal mud flat sediments of the Bahía Blanca estuary (Argentina). Recent and fossil sediment samples were collected between 1990 and 2008, from cross-transects and outcrops. Maximum abundance of living specimens was recorded in shallow intertidal environments. The species was previously recorded from many European and North American shallow-water coastal settings, but has not been documented from Argentina. Our studies of modern foraminiferal assemblages demonstrate that Haynesina germanica is widely distributed and abundant throughout the modern habitats of the estuary. Comparative faunal assemblage analysis from dated core sample material from within the Bahía Blanca Estuary shows that the species has not been present for at least the last 8200 years. This supports the hypothesis that the species has been accidentally introduced outside its natural range as a probable result of ballast water and/or shipping activities. This study is the first report of a successful invasion of non-indigenous benthic foraminifera to the South Atlantic coast of Argentina. The introduction of nonnative foraminiferal species provides new evidence that human-mediated breaching of biogeographic barriers, will ultimately result in the biotic homogenization of foraminiferal intertidal faunal assemblages.