Unravelling facilitation among introduced species, a mechanistic approach

PEREYRA, PATRICIO JAVIER; DE LA BARRA, PAULA; SAAD, JUAN FRANCISCO; GASTALDI, MARIANELA; ARCÁNGEL, ANDREA EVANGELINA; RODRÍGUEZ, EMILIANO ALEXIS; GONZÁLEZ, RAÚL; NARVARTE, MAITE

BIOLOGICAL INVASIONS

SPRINGER

Lugar: Berlin; Año: 2021 p. 1 - 14

1387-3547

Interspecific facilitation is a widely recognizedprocess structuring natural communities. Benthicinvertebrates are known to facilitate other invertebratesbut how the former affect macroalgae has been rarelyinvestigated. In the present study we explore some ofthe mechanisms underpinning the facilitation of thekelp Undaria pinnatifida by the solitary ascidian Styelaclava, two species introduced worldwide. First, weevaluated the relationship between habitat complexityand the recruitment of U. pinnatifida in naturalassemblages using the height and density of S. clavaas proxies of habitat complexity. Second, weexperimentally assessed the effect of habitat complexityusing two sizes of mimics of S. clava arranged at twodensity levels in a crossed-factor design. Finally, wetested whether the biologic effect of S. clava was moreimportant than its physical effect, by comparing U.pinnatifida?s recruitment on live S. clava and on themimics. We observed a positive effect of height on U.pinnatifida?s recruitment in natural assemblages as wellas through the experimental approach using themimics.In addition, an effect of density and the interactionbetween density and height was observed in naturalassemblages exclusively. We also found a strongpositive effect due to biological features, as U. pinnatifidarecruitedmore than ten times more on live S. clavathan on the mimics. Our results indicate that a biologicnon-trophic effect plays a more important role in thisfacilitation process than the structure alone.