Paul Gribben1, Iva Nikolaeva2, Louise Firth3, Ziggy Marzinelli2
1University of New South Wales, Australia - 2The University of Sydney, Australia - 3University College Cork, Ireland
Facilitation cascades are emerging as important drivers of patterns of biodiversity. Their utility as a spatial management tool for biodiversity is predicated on understanding the processes that explain spatial variation in facilitation cascades at larger scales. Here we tested whether variation in communities in facilitation cascades was caused by direct environmental effects on the communities associated with cascades, or via indirect environmental effects on the biomass/body size of the habitat-formers within the cascade. On intertidal rocky shores in NSW, we used a large field survey and an experiment to investigate variation in epibiont communities in a cascade consisting of the primary habitat-former, the limpet Cellana tramoserica, and the secondary habitat-former, the alga Ulva australis, which colonises its shell. Because the shell morphology/body size of limpet species and thalli size of Ulva species can vary strongly in response to changes in biotic and abiotic conditions, we hypothesised that 1) epibiont communities on limpets and U. australis would vary among sites, 2) within sites, epibiont communities would be positively correlated to the body size of limpets and biomass of Ulva, 3) variation in limpet size and thalli biomass among sites would explain differences in facilitation cascades among sites. In general, we found support for our predictions. Epibiont communities were positively correlated to limpet shell length but not Ulva thalli biomass. The abundance and richness of epibionts in the facilitation cascade and the size of the habitat-formers varied among sites. Experimental manipulation of limpets between sites characterised by different population structures showed that the shell length of limpets explained among site variation in the communities in the facilitation cascade. Our data suggest that variation in habitat-former body size at larger spatial scales may have predictable effects on communities supported by facilitation cascades.
Biography
Paul’s is a community ecologist whose recent research has focused on understanding habitat-diversity relationships and the processes that influence the performance of habitat-forming species. A key component of his research investigates how environmental gradients or change alters habitat-diversity/habitat-performance outcomes. He combines a variety of research approaches including experimental ecology, environmental science and a microbial ecology to address his research interests.