Interactions between ecosystem engineers: A native species indirectly facilitates a non-native one

SUEIRO, M.C.; SCHWINDT, E.; MENDEZ, M.M.; BORTOLUS, A.

ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY

GAUTHIER-VILLARS/EDITIONS ELSEVIER

Lugar: Paris; Año: 2013 vol. 51 p. 11 - 16

1146-609X

The positive impact that native species have on the survival, persistence and/or range-expansion ofinvasive species, is receiving increasing attention from ecologists and land managers trying to betterunderstand and predict future invasions worldwide. Ecosystem engineers are among the best-knownmodel organisms for such studies. The austral cordgrass Spartina densiflora is an ecosystem engineernative to South America coast, where it colonizes rocky shores that were recently successfully invaded bythe acorn barnacle Balanus glandula. We conducted a field experiment combining living Spartinatransplants and artificial model plants in order to address the following questions: Does the nativeecosystem engineer S. densiflora facilitate the invasion of rocky shores by B. glandula? If so, how much ofthis facilitation is caused by its physical structure alone? We found that S. densiflora had a positive effecton the invasive barnacle by trapping among its stems, the mussels, shells and gravels where B. glandulasettles. Dislodged mussels, cobbles, and small shells covered and agglutinated by living barnacles wereretained within the aboveground structures of S. densiflora while the control plots (without living orartificial plant structures) remained mostly bare throughout the experiment, showing how plantstructures speed the colonization process. Moreover, transplanting living Spartina and artificial Spartinamodels led to a maximum increase in the area covered by barnacles of more than 1700% relative to theunvegetated control plots. Our study clearly shows how a native ecosystem engineers can enhance thesuccess of invasive species and facilitate their local spread