Foundational biodiversity effects propagate through coastal food webs
via multiple pathways
AbstractRelatively few studies have attempted to resolve the pathways through
which biodiversity effects on ecosystem functioning cascade from one
trophic level to another. Here, we manipulated the richness of
habitat-forming seaweeds in a western Atlantic estuary to explore how
changes in foundation species diversity affect the structure and
functioning of the benthic consumer communities that they support.
Structural equation modeling revealed that macroalgal richness enhanced
invertebrate abundance, biomass, and diversity, both directly by
changing the quality and palatability of the foundational substrate, and
indirectly by increasing the total biomass of available habitat.
Consumer responses were largely driven by a single foundational seaweed,
although stronger complementarity among macroalgae was observed for
invertebrate richness. These findings reconcile earlier inferences from
terrestrial grasslands by demonstrating that foundational biodiversity
effects can simultaneously propagate through multiple pathways to
maintain animal foodwebs. Our work also highlights the potential
ramifications of human-induced changes in marine ecosystems.