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Interactions between species on the move, habitat-formers and their microbiomes

Dr Ziggy Marzinelli1,2,3, Louise Castro4, Madelaine Langley4, Sandra Straub5, A/Prof. Thomas Wernberg5, Dr Alexandra Campbell6, A/Prof. Symon Dworjanyn7, Dr Melinda Coleman8, Prof. Peter Steinberg2,3,4, A/Prof. Adriana Vergés3,4

1The University Of Sydney, Sydney, Australia, 2Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore, 3Sydney Institute of Marine Science, Mosman, Australia, 4Centre for Marine Bio-Innovation, UNSW Sydney, Sydney, Australia, 5University of Western Australia, Perth, Australia, 6University of Sunshine Coast, , Australia, 7Southern Cross University, Coffs Harbour, Australia, 8NSW DPI, Fisheries, , Australia

Ocean warming is having strong impacts on marine habitat-forming species such as kelps and corals via changes to ecological interactions. In temperate systems, some of these changes involve range-expanding tropical herbivores that graze habitat-forming kelps. Kelp microbiomes are also changing in response to warming, directly influencing host performance. Emerging evidence suggests that such changes in microbiomes may also relate to changes in interactions between habitat-formers and range-expanding herbivores. We combined latitudinal surveys along the SE coast of Australia – a global warming hotspot – with experimental manipulations simulating ocean warming and marine heatwaves to examine interactions between range-expanding herbivores, different kelp species and their microbiomes. We found strong relationships between the structure of kelp microbiomes and grazing intensity, both in field surveys and in manipulative experiments. In the latter, microbial shifts were strongest for kelps under heatwave treatments, which then led to greater grazing by range-expanding herbivores in feeding trials. We found contrasting responses to herbivory between macroalgal species, with higher grazing of the common kelp, Ecklonia radiata, in heatwave treatments and of the fucoid, Sargassum linearifolium, under ambient temperature. This implies Sargassum may be more resilient to grazing under future conditions, but kelp may be more vulnerable. This research highlights that the direct and indirect responses of kelps to climate change may involve complex tri-partite interactions and can be species specific.


Biography:

I am a Lecturer at The University of Sydney and hold an additional visiting appointment at Nanyang Technological University in Singapore. My research focuses on understanding the processes that generate, maintain and impact marine ecosystems. My goal is to provide sensible, practical solutions to environmental problems. I integrate ecological theory and experiments with cutting-edge molecular analyses to understand the mechanisms that cause species’ declines and to restore degraded habitats.

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