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Program Summary

The importance of seaweed and seagrass habitats is well established, however, the tiny organisms that live among these algal hosts and their ecosystem function are undefined and underappreciated.

The Microbes-to-Macrophytes (M2M) study is a combined ecological, microbiological and biochemical examination of host-associated microbial communities inhabiting marine macrophytes (ie seaweed and seagrass). Marine microbes are tiny, single-celled organisms, too small to see with the unaided eye, that live in the ocean and account for more than 98 percent of ocean biomass. Coastal areas support a large portion of this biomass, especially among seaweed and seagrass habitats or beds.

Marine microbes, mainly bacteria and protists, recycle nutrients and consume dissolved organic matter (DOM) a process that recaptures carbon that would otherwise be lost to higher trophic levels. Entire microbial communities can live on and in plants and animals including seaweeds and seagrass. Microbes are suspected to influence normal development, morphology and growth of seaweeds among other complex ecological functions and symbioses. Quantifying patterns of microbial community structure is an essential step towards a comprehensive understanding of coastal marine community dynamics and its response to a changing environment.

Coastal seaweed communities are dense and highly diverse, providing essential food and habitat for many marine and terrestrial creatures such as this mink. Photo by Katy Hind.
Principal Researchers
Rhea Smith, Hakai Science
Laura Wegener-Parfrey, University of British Columbia
Mary O'Connor, University of British Columbia
Patrick Keeling, University of British Columbia
Patrick Martone, University of British Columbia
Chris Harley, University of British Columbia
Matt Lemay, Hakai Science
Primary Research Questions
  • How host specific are microbial communities among seaweeds and seagrass? 
  • How do these assemblages vary seasonally, spatially and throughout the seaweed and seagrass life cycle?
  • What is the role of seaweed and seagrass associated microbes and how will they respond to changes in the marine environment?

Seaweeds and seagrass are ubiquitous in coastal waters along the west coast of North America and represent a key element of marine primary production and associated nutrient cycling.  They also provide essential structural habitat for communities of marine fish, invertebrates, and other algae. Host-associated microbes that grow on macroalgae facilitate the transfer of energy from seaweed to higher trophic levels by feeding on algal exudates (i.e. seaweed mucus) and in turn make up the base of the heterotrophic food chain of protists, small invertebrates and fish.

Our understanding of coastal marine ecosystems is incomplete without investigating patterns of host-associated microbial diversity and abundance. Based on the myriad roles that host-associated microbes play in other ecosystems, we predict that the impact of macrophyte-associated microbes extends far beyond simple trophic linkages.

Despite having similar ecological functions, coastal seaweed communities are phylogentically and evolutionarily highly diverse. Yet, it is unknown how patterns of seaweed diversity affect microbial community structure or vice versa. The primary goal of this research program is to determine whether patterns of bacterial and eukaryotic microbial diversity show predictable patterns based in their host species.

Collaborating Researchers
Katy Hind, Hakai Postdoctoral Fellow
Margot Hessing-Lewis, Hakai Science
Anne Salomon, Simon Fraser University
Jenn Burt, Simon Fraser University
Kira Krumhansl, Hakai Postdoctoral Fellow