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Dryad

Tropicalization shifts herbivore pressure from seagrass to rocky reef communities

Cite this dataset

Santana-Garcon, Julia et al. (2023). Tropicalization shifts herbivore pressure from seagrass to rocky reef communities [Dataset]. Dryad. https://doi.org/10.5061/dryad.nzs7h44vr

Abstract

Climate-driven species redistributions are reshuffling the composition of marine ecosystems. How these changes alter ecosystem functions, however, remains poorly understood. Here we examine how the impacts of herbivory change across a gradient of tropicalization in the Mediterranean Sea, which includes a steep climatic gradient and marked changes in plant nutritional quality and fish herbivore composition. We quantified individual feeding rates and behaviour of 755 fishes of the native Sarpa salpa, and non-native Siganus rivulatus and Siganus luridus. We measured herbivore and benthic assemblage composition across 20 sites along the gradient, spanning 30º of longitude and 8º of latitude. We coupled patterns in behaviour and composition with temperature measurements and nutrient concentrations to assess changes in herbivory under tropicalization. We found a transition in ecological impacts by fish herbivory across the Mediterranean from a predominance of seagrass herbivory in the west to a dominance of macroalgal herbivory in the east. Underlying this shift were changes in both individual feeding behaviour (i.e., food choice) and fish assemblage composition. The shift in feeding selectivity was consistent among temperate and warm-affiliated herbivores. Our findings suggest herbivory can contribute to the increased vulnerability of seaweed communities and reduced vulnerability of seagrass meadows in tropicalized ecosystems. 

Funding

Fundación BBVA, Award: Interbioclima

Ministry of Economy, Industry and Competitiveness, Award: CGL2015-71809-P