Reproductive activity of the invasive barnacle Balanus glandula at Cabo Dos Bahias, Chubut, Argentina

PACCOTTI, VANESA; BAZTERRICA, M CIELO; POPOUL RAPOSO; PALACIO, ROMINA; FERNANDO HIDALGO; CAITLIN CRAIN; BERTNESS, M

San José, California.

Congreso; ESA/SER Joint Annual Meeting ?Ecological Restoration in a Changing World?; 2007

The Ecological Society of America

Balanus glandula - a barnacle native of the Pacific Coast of North America – arrived to the South Atlantic Ocean in the mid-1970´s andhas since spread from San Clemente del Tuyu (36º22’ S; 56º44’ W) to Puerto San Julian (49º 30´ S; 67º 69´ W). Patagonian rockyshores are unique in that they have no native intertidal barnacle. Beds of the mussel Perumytilus purpuratus cover wave-exposedheadlands from mid to high intertidal, meaning B. glandula has limited bare substrate available within their preferred elevational range tocolonize. Reproduction is a key process in driving the success of invasive species, so we quantified barnacle reproductive activity on thetwo substrate types (mussel vs. rock) throughout 2006 in Cabo Dos Bahias Park, Chubut, Argentina. To examine reproductive activity,50 B. glandula individuals on each substrate type were randomly chosen each month and the number of individuals with mature eggswas recorded. We found significant differences in the number of individuals with mature eggs between seasons and settlementsubstrate. In Cabo Dos Bahías Park, B. glandula was reproductively active all year; more individuals with mature eggs were found inwinter and spring than in summer and autumn. We also found that barnacles living on top of mussel beds had higher reproductiveactivity (in number and in time-length), than barnacles on bare rock. Other authors have hypothesized that reproduction is aphenotypically plastic trait in barnacles that can be influenced by several variables (water temperature, density, etc). In this study,barnacle densities were lower on mussel beds where reproductive activity was highest, suggesting that plasticity in reproductive activityof Balanus glandula may improve their success as invaders and contribute to their rapid expansion along new shores.