Award: OCE-1060300

Microscopic marine algae (phytoplankton) are responsible for much of Earth’s photosynthesis, serving as the base of a massive food web supporting fisheries. Phytoplankton compete for limiting resources, with some species producing noxious compounds that kill competitors or inhibit their growth – a process known as allelopathy. The red tide dinoflagellate Karenia brevis is one such allelopathic species, whose competitive strategy may play a role in the maintenance of its large blooms which produce potent neurotoxins that negatively impact coastal marine ecosystems. K. brevis is variably allelopathic to multiple competitors, typically causing sublethal suppression of growth. We employed new systems biology tools – metabolomics and proteomics – to investigate the role of chemically mediated ecological interactions between K. brevis and two competitors, the diatoms Asterionellopsis glacialis and Thalassiosira pseudonana. The impact of K. brevis allelopathy on competitor physiology was reflected in the concentrations of metabolites and expressed proteomes of both diatoms, although the diatom that co-occurs with K. brevis blooms (A. glacialis) exhibited more robust metabolism in response to K. brevis. In the more sensitive competitor T. pseudonana, cells suffered compromised energy metabolism and disrupted cellular protection mechanisms such as altered cell membrane components, inhibited osmoregulation, and increased oxidative stress (see Image 1). The observed partial resistance of A. glacialis to allelopathy may be a result of its frequent exposure to K. brevis blooms in the Gulf of Mexico. Identification of the unique metabolites will give insights into metabolic pathways affected by K. brevis based allelopathy and also into the dynamics of bloom formation, propagation, and termination.

In terms of method development for the field of ocean sciences, we have shown that metabolomics and proteomics can together be used to explore ecological interactions among planktonic organisms.  While these systems biology approaches have been well applied in medical research, and each method in isolation is beginning to be more common in ecology and marine science research, a lack of communication among specialists of these techniques has previous prevented a more comprehensive application in biological oceanography. Marine ecologists and biological oceanographers are curious about the role of allelopathy in competition among phytoplankton. Our project contributes to an overall appreciation for the importance of this type of interaction in the marine plankton.

Data from this project are shared in multiple ways: project goals, field data from cruises, metabolomics and proteomics data are publicly available via http://www.bco-dmo.org/project/528925 and via publicly accessible links within that BCO-DMO site.  Data were analyzed, interpreted, and the results summarized in eight manuscripts published in the peer-reviewed scientific literature.  The research was shared publicly with the scientific community as part of eleven conference presentations.

Several activities associated with this project contributed to the broader impacts of this project. Co-PI Brook Nunn held a PAWS on SCIENCE workshop for 3 days at the Pacific Science Center in Seattle.  Dr. Nunn led the workshop with the help of graduate and undergraduate students from University of Washington teaching the basics of chemistry, chromatography and mass spectrometry to hundreds of children.  PAWS on SCIENCE received over 10,000 people.  This outreach and teaching tool was then taken to a similar event in Yakima.  The outreach program in Yakima was specifically designed to reach underpr...