Data from: Impacts of mussel invasions on the prey preference of two native predators

Biotic invasions can result in the displacement of native species. This
can alter the availability of native prey and the choices made by native
predators. We investigated prey selection by two native South African
predators, the west coast rock lobster Jasus lalandii and the starfish
Marthasterias africana in response to the invasive mussels, Mytilus
galloprovincialis and Semimytilus algosus, and native mussels Aulacomya
atra and Choromytilus meridionalis. As the diets of lobsters and starfish
are broad and have been suggested to reflect prey availability, we
hypothesized that they would consume the most abundant prey, regardless of
its native or alien status. Laboratory studies presented predators with
varying proportions of native and invasive mussels that represented pre-
and post-invasion scenarios. Mussel parameters (shell strength, adductor
muscle size and energy content) that may be of importance in selection by
predators were compared among species. Both predators exhibited preference
towards the native mussel C. meridionalis, even when it was the least
abundant prey. The selection of native species occurred despite mussel
parameters suggesting invasive species would be easier to consume. These
findings highlight the potential for facilitation of prey invasions,
especially when predators avoid alien prey and select for native
comparators that may offer resistance to the invasion through
inter-specific competition. It is presently unclear how often such lack of
predator-driven biotic resistance acts in combination with indirect
facilitation, but interrogating the behaviors that drive such outcomes
will advance our understanding of successful invasions.