Habitat shifts: invader ecosystem engineer barnacle selectively recruits and survives on salt marsh plants

MENDEZ M.M.; SCHWINDT E.; BORTOLUS A

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

Balanus glandula is a common acorn barnacle of the rocky shores in the west coast of North America. Nowadays, forty years after its introduction in Argentina, this species dominates the high intertidal zone of rocky shores across 17 latitudinal degrees and, also, it was recorded settling on a variety of substrata including salt marsh plants. In this work we experimentally study if its success in colonizing salt marshes is based on the active selection of halophytes as recruitment substrata. To address this problem, a selection experiment was deployed in the field by offering Spartina, Sarcocornia perennis and Limonium brasiliense as potential substrata. Gravels, mussel valves and cleaned quadrats were also included as controls (n = 10-12 for each, 100 cm2) and an inert flexible PVC substratum was added to evaluate the potential selection of artificial substrata (n = 12). The experiment was performed in Punta Ameghino (42°S, 64°W), lasted one year and at the end the variables measured were density of barnacle (dead and alive) and barnacle size frequency distribution, which were statistically analyzed independently with a one way ANOVA. Barnacles showed the highest recruitment in L. brasiliense, the highest survival and the largest barnacles. Density and size of the barnacles were similar to the observed in rocky shores, suggesting that this exotic species successfully colonize the salt marshes mainly based on the active selection of halophytes as recruitment substrata.