CONICET | Buscador de Institutos y Recursos Humanos

Ascidians are one of the most important taxa in fouling communities of artificialstructures. These organisms can establish new populations and successfully invadenew areas, spreading outside the region where they were initially introduced, due totheir high reproductive and growth rates and their broad tolerance to environmentalconditions. Predation pressure has also an influence on the colonization success ofascidians, with variations depending on their life stage, the fluctuations of theabundance of predators and their identity. Among these factors, the consequences ofinvasive and native predators on different life stages of invasive ascidians have beenpoorly evaluated. Thus, the goal of this work is to assess the survival of different lifestages (juveniles and adults) of the two most successful invasive ascidians in thepresence of different benthic predators in a cold temperate port. To evaluate this, weperformed experiments offering juvenile and adult ascidians to different native andexotic benthic predators, under controlled aquarium conditions. We observed thatjuvenile ascidians were more vulnerable to predation than adults. Moreover, adultvulnerability differed between ascidian species probably because of different physicaland chemical defences. Our results evidence the importance of evaluating the effectsof predation through different stages of the life cycle of the preys, and the role of bothnative and exotic predators. Therefore, we hypothesize that juvenile ascidians dependon the use of different refuges, such as mussel beds and adult ascidians, to escapefrom predation until they reach a less vulnerable adult size. Understanding thedifferential effects of predation through different stages of life-history of the preys, andthe interaction between native and exotic species helps to comprehend the causes ofsuccess in the establishment of invasive species.

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