Does the native predator Trophon geversianus exert top-down control on the invasive barnacle Balanus glandula on Patagonian rocky shores?

PIO, MARÍA JOSÉ; MENDEZ, MARÍA M.; GALVÁN, DAVID E.; BIGATTI, GREGORIO; WEST, KAYDEE; HERBERT, GREGORY S.

MARINE AND FRESHWATER RESEARCH

CSIRO PUBLISHING

Año: 2019 vol. 70

1323-1650

Trophic interactions between the native gastropod predator Trophon geversianus and the invasive barnacleBalanus glandula may have facilitated the successful expansion of the barnacle along rocky intertidal coastlines inArgentina. In this study, through field observations and a stable isotope reconstruction of the diet of T. geversianus, weassessed whether and how frequently this drilling muricid gastropod consumes the invasive B. glandula on a Patagonianrocky shore. Field observations indicated that B. glandula and T. geversianus co-occur in the middle intertidal. Feedingobservations and stable carbon and nitrogen isotope dietary reconstructions showed that T. geversianus readily andsuccessfully consumes B. glandula, but at low rates (4% of diet) relative to native mussel prey, which compete withB. glandula for space. This study shows that T. geversianus exerts little top-down control on this invasive barnacle onPatagonian rocky shores. The success of B. glandula on these shores is plausibly enhanced directly by this weak interactionand indirectly by the preference of T. geversianus for native prey rather than the absence of predators or invader immunityfrom predation. The results of this study complement previous studies that have shown that tolerance to extremedesiccation stress in harsh intertidal environments is crucial for the establishment of B. glandula