Impacts of warming on novel and native plant-herbivore interactions across the Mediterranean Sea

Dr Julia Santana-Garcon1, Dr Scott Bennett1, Dr Núria Marbà1, Dr Adriana Vergés2, Dr Teresa Alcoverro3

1IMEDEA – Spanish Research Council (CSIC), Esporles, Spain, 2The University of New South Wales, Sydney, Australia, 3CEAB – Spanish Research Council (CSIC), Blanes, Spain

Warming can modify species interactions by (1) generating novel interactions through the introduction of new warmer affiliated species into existing communities and, (2) modifying existing interactions through relative differences in the responses of species to warming. Here we examine the sensitivity of existing plant-herbivore interactions to warming and investigate the role of novel herbivores in the Mediterranean Sea and their potential to over-graze native habitat. We quantify herbivory rates on seagrass meadows and rocky reefs across the Mediterranean, to compare how temperature affects the relative performance of dominant habitat formers and fish-herbivores. Our surveys span the full breadth of the thermal distribution of dominant habitat former Posidonia oceanica and the upper thermal limits of the distribution of the native fish herbivore Sarpa Salpa. We also conduct a Mediterranean-wide translocation experiment with P. oceanica and examine feeding preferences and impact of tropical rabbitfish (Siganus rivulatus and Siganus luridus) on P.oceanica.


Herbivores displayed a strong shift in feeding preference across the Mediterranean basin, moving from a strong preference for seagrass in the western Mediterranean to a preference for turf and seaweeds in the warmer eastern Mediterranean basin. Translocation of P. oceanica from western to eastern Mediterranean revealed similar results whereby herbivores in the eastern basin displayed a strong preference for western Mediterranean populations of seagrass. Thermal performance of herbivores across the Mediterranean revealed a mismatch between per-capita feeding rates and population abundance. We discuss the implications of these results on the function and resilience of coastal marine ecosystems in the Mediterranean Sea.


Dr Julia Santana-Garcon is a postdoctoral fellow at the Global Change Research Group at the Mediterranean Institute for Advanced Studies (IMEDEA, UIB-CSIC) in Mallorca, Spain. Her main research fields are marine ecology and fisheries science, and she is interested in understanding how human activities and climate change affect marine ecosystems to help improve the management and use of marine resources.

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