Community disruption by introduction of Crassostrea gigas with epizootic Polysiphonia morrowi in north Patagonian coasts

CROCE, M. E; PARODI, E. R.

Mar del Plata

Conferencia; CERF Inaugural International Conference of the Americas; 2012

CERF

Oyster transfer for commercial purposes is considered one of the most important vectors of marine introductions, including macroalgae. Several introductions of exotic macroalgae have been recorded in habitats close to oyster beds. In addition, oysters are considered important ecosystem engineers of the marine environment: Oyster introductions, and especially the Pacific C. gigas, is particularly important when they occur in soft-sediments, because they form dense reefs (also known as 'beds') creating new habitats. On the North Patagonian Atlantic coast of Argentina, the establishment of C. gigas in the tidal flats of Bahía Anegada has led to the formation of dense beds in which the irregular settling of oyster individuals originated intertidal pools. The establishment of these beds has changed the native habitat in such a way that the tidal flats, which were previously inhospitable, became suitable habitats for macroalgae populations. This study demonstrates that conspicuous macroalgal assemblages inhabit these intertidal pools. The biomass calculated showed that the population of the exotic red alga Polysiphonia morrowi (Rhodophyceae) dominated in the intertidal pools on the oyster beds of Bahía Anegada. Significant differences were found in seasonal biomass (p