Facilitation of native and non-native species by intermediate foundation species


Facilitation cascades stem from co-occurring habitat-forming species that add biogenic structure to otherwise barren ecosystems. Specifically, they are formed when the primary (basal) foundation species enables the establishment of intermediate (secondary) foundation species. Recent studies have found them to positively influence biodiversity and abundance of species and these effects can be species-specific. While studies have been carried-out on the ecological significance of foundation species, explicit investigation into the effects of intermediate foundation species on the distribution of associated native and non-native species is rare. Here, we used field and laboratory studies to investigate the effects of intermediate algal foundation species (Ascophyllum nodosum and Fucus vesiculosis) on the abundance and distribution of dominant intertidal herbivores, Littorina saxatilis (native) and L. littorea (non-native) in US East Coast cordgrass systems. Our results suggest that the presence of intermediate foundation species facilitates survival of the native species, L. saxatilis. Furthermore, the two intermediate algal foundation species acted in diverse ways to enhance the abundance of the native and the non-native herbivore. F. vesiculosis was important for the early life-history stage (i.e., recruitment) of L. saxatilis while both algal intermediate foundation species were central to the gastropods persistence. In contrast, both algal species were critical for the early life-history stage (i.e., recruitment) of L. littorea while A. nodosum was important for its persistence. These findings reveal that intermediate foundation species can act as regulators of native and non-native species abundance and distribution.


Center for Coastal and Ocean Mapping

Publication Date


Journal or Conference Title

Coastal and Estuarine Research Federation

Conference Date

Nov. 3-7, 2013

Publisher Place

San Diego, California, USA


Coastal & Esuarine Research Federation

Document Type

Conference Proceeding