Award: OCE-1435194

The major goals of the project (OCE-1435194) were to evaluate how the Aleutian Ecosystem was impacted by widespread losses of kelp forests. This included 1) measuring patterns of benthic diversity in remnant kelp forests, extant urchin barrens, and areas that are in transition between the two states, and 2) measuring how these changes impacted patterns of net ecosystem production, benthic respiration, and gross primary production. We did this aboard the RV Oceanus during two cruises using a combination of subtidal sampling techniques, deep water trawls, benthic respiration chambers deployments, and shipboard incubations of the dominant organisms. Between our cruise dates, the SDSU and UAF labs coordinated via skype meetings to prepare for the two cruises, which occurred during the summers 2016 and 2017. We discussed the techniques on how to analyze data, and outlined papers that would come from the project. We successfully completed both of our two scheduled research cruises (summer 2016 & 2017). During these cruises, we deployed benthic production/respiration chambers, conducted biological benthic surveys, and completed shipboard organism respiration measurements at ten islands that span the Aleutian Archipelago in order to study the relationship between macroalgal biomass (and loss thereof) and both benthic primary production and diversity. Our work so far has resulted in a manuscript that was published in Continental Shelf Research and is titled "A swath across the great divide: kelp forests across the Samalga Pass biogeographic break". Co-authors on the manuscript include Konar, Edwards, and the four graduate students and one undergraduate student who participated in the sampling needed and in the writing of the manuscript. We have two other manuscripts under review and are currently preparing eight other manuscripts (five of which are being first-authored by graduate students, and one of which will be submitted to Science). Our research demonstrated that the loss of some algal guilds (but surprisingly not the canopy forming kelp) reduced biodiversity and changed community structure, and that this varied on opposing sides of some large oceanic passes but not others. Overall, gross ecosystem production and community respiration were both reduced in areas where kelp forsst were lost throughout the archipelago, though this was spatially and temporally variable. In contrast, net ecosystem production was not affected by kelp loss. Shipboardf incubations revealed mass-specific patterns of respiration for the invertebrates, with larger invertebrates respiring more, although they were more efficient. The dominant algae that contributed tyo production were the kelps, though these exhibited irradiance-specific patterns of production. Together, this suggests substantial changes to broad scale patterns of ecosystem functioning as a result of kelp loss that are geographically variable, and appear to correspond to broad scale differences in oceanographic conditions and kelp condition throughout the archipelago. We deployed an ROV at our sites for outreach purposes and this has resulted in a collaboration between Edwards lab and OPEN ROV, and we are working with a new ROV to explore coastal ecology in a public forum. Further, we worked with research from Washington State and Kansas to build a traveling museum exhibit that is now in its second year of operation and traveling though small museums in Alaska. SDSU hired a total of four graduate students directly on this project (Ph.D. student - Scott Gabara, and M.S. students - Genoa Sullaway, Tristin McHugh and Mike Spector). These students have all led the efforts to build the benthic respiration chambers and deployed these chambers at ten islands in the Aleutian Archipelago. SDSU has also involved an additional M.S. graduate student on this project (Sadie Small), who was trained to measure algal physiology and primary production, and has since used these skills to conduct her Masters thesis. T. McHugh, G. Sullaway and S. Small have all successfully defended their theses; T. McHugh is currently working as the ReefCheck coordinator for northern California, G. Sullaway is working for NOAA in Washington state, and S. Small is working for UC Davis Bodega Marine Labs. PI Edwards is working closely with all the SDSU students to ensure that all manuscripts are submitted to peer-reviewed journals in a timely manner. Edwards is also working with T. Bell (Ph.D student from the UCSB-LTER) to analyze satellite images dating back to the 1980s. Mr. Bell spent a week visiting SDSU and training the graduate students and is now taking the lead on the image analyses. These analyses were more difficult than expected due to variation in fog cover, land masking, and pixilation issues, and thus required assistance from an expert in this field; such a collaboration was initially suggested by NSF at the time of the award. Lastly, we involved a Korean colleague (Dr. Ju-Hyoung Kim) who specializes in measuring seaweed photosynthesis and who accompanied us on each of our cruises. Last Modified: 11/30/2018 Submitted by: Matthew S Edwards