An unexpected reef-building worm in Mar del Plata, Argentina (SW Atlantic)

CHIARADIA, N.M.; MARCHESI, C.; AZZONE, D.P.; SAN MARTIN, A.; GIBERTO, D.A.; BREMEC, C.S.; ELIAS, R.

Portland, Maine, EUA

Congreso; 9th International Polychaete Conference; 2007

This contribution reports the presence of coastal reefs built by the sabellariid Sabellaria wilsoni Lana & Gruet, 1989 in Mar del Plata (38º S). Benthic studies developed in the rocky littoral of the study area do not report the presence of polychaete reefs. The species is known from different localities in the SW Atlantic: Paraná State in Brazil (25° 30’ S), Mar Chiquita (37º S) and Monte Hermoso (39° S) in Argentina, and probably the French Guiana, between 6 and 16,5 m depth. All records correspond to shallow depths in coastal environments; it was never recorded in shelf areas intensively sampled in the Argentine Biogeographical Province. S. wilsoni reefs are conformed by sandy straight tubes and varied between 20-30 cm and nearly 100 cm in diameter; they are located in different pools at the upper rocky intertidal zone, largely extended in the study area. We present information about size distribution patterns of the population and the composition of the associated fauna from samples obtained in June and October 2006 during low tides. The presence and reef-building capacity of the species, not registered previously, in an intertidal exposed zone, strongly influenced by tides, indicates its adaptation to highly variable environments.