Isis Guibert1, Emmett Duffy2, David M. Baker1
1The University of Hong Kong, Hong Kong - 2Smithsonian Institution, USA
Coastal marine environments provide ecosystem services essential to human well-being, acting as important carbon sinks, absorbing carbon dioxide from the atmosphere and mitigating the effect of global warming. These services are underpinned by microorganisms that comprise the greatest biomass in the oceans and regulate biogeochemical cycling and primary productivity. However, these coastal ecosystem services are changing worldwide in the face of anthropogenic nutrient pollution. Here, we conducted a coordinated experiment across 31 sites to assess how experimental fertilisation and climate regime affect decomposition of standardized organic matter (tea bags) and associated changes in the sediment microbiome. We show that water temperature consistently increased the rate of organic matter decomposition, whereas short-term fertilization surprisingly had no effect. Including microbial community structure in our model nearly doubled the explained variance in decomposition rate (k) and revealed indirect effects of salinity and sediment grain size on decomposition mediated by their effects on the microbiome. Analysis of the microbiome species demonstrated variations in the relative abundance of the microbial community with temperature. Despite a site-based clustering, a strong correlation was observed between species diversity and both temperature and salinity. Interestingly, warmer temperatures resulted in higher microbial community diversity (Shannon) indicating a global enhancement in microbial diversity in response to climate warming. We conclude that climate warming, by impacting coastal sediment microbiome, will increase the rate of organic matter decomposition, transforming coastal ecosystems from carbon sink to carbon sources and worsening the effect of global warming.
Biography
Isis’s research is broadly centered on investigating how anthropogenic stressors influence marine ecosystems and understanding how changes in the abiotic environment impact organisms’ physiology. I have taken an integrative approach combining cytology, chemistry (LC/MS, GC/MS, SIA), and genetics (metabarcoding, metagenomics) to investigate these questions