Our newest Quarterly Newsletter (March, 2021) has arrived and is full of exciting updates, including four upcoming webinars, snapshots from our blog, and new resources (our map of Canada's OA resources, and a webinar on OA sensors)! Download the full PDF version (high resolution with interactive links): Page images:

Here are some of the latest happenings in the world of ocean acidification in Canada and beyond! New on our Blog Join us for this video interview with Dr. Brent Else, Associate Professor (University of Calgary) and OA CoP Co-Lead, to learn about his research studying air-sea-ice carbon dioxide exchange in the Arctic and motivations for leading Canada's OA community! Watch the interview and read the audio transcript here: Dr. Brent Else, OA CoP Co-Lead Upcoming MEOPAR OA CoP Webinar MEOPAR Webinar Series Canada’s Ocean Acidification Community of Practice Presenter: Kristina Barclay, OA CoP Coordinator March 10, 2021, 2 pm AST/10 am PST Read the abstract and register here: https://meopar.ca/upcoming-webinar-canadas-ocean-acidification-community-of-practice/ Upcoming Webinar on CRMs The U.S. Interagency Working Group on Ocean Acidification presents: CO2-in-seawater reference materials: yesterday, today, and tomorrow Presenter: Professor Andrew Dickson (Scripps Institution of Oceanography, UC San Diego) March 16, 2021, 9am Pacific Register here: https://register.gotowebinar.com/register/2842491957779599883 New Resource New resource from Oregon Sea Grant for high school students: “Changing Ocean Chemistry: A High School Curriculum on Ocean Acidification’s Cause, Impacts, and Solutions” https://seagrant.oregonstate.edu/sites/seagrant.oregonstate.edu/files/e-19-002_new.pdf New Paper of Interest Miller, C. A., C. Bonsell, N. D. McTigue, and A. L. Kelley. 2021. The seasonal phases of an Arctic lagoon reveal the discontinuities of pH variability and CO2 flux at the air–sea interface. Biogeosciences, 18:1203–1221. https://doi.org/10.5194/bg-18-1203-2021 Have a news item you'd like us to feature? Email coordinator@oceanacidification.ca!

In this video interview, Ocean Acidification Community of Practice Coordinator, Kristina Barclay, sat down with one of our two OA CoP Co-Leads, Dr. Brent Else (University of Calgary), to learn more about his OA research and interests, and motivations behind leading Canada's OA community. This video is captioned. For the full audio transcript, please see text below. Audio Transcript: Kristina: So welcome to our Ocean Acidification Community of Practice "Meet the CoP" blog series where we get to know a little bit more about the research and leadership team guiding our OA Community of Practice. Today I'm speaking with Dr. Brent Else, Associate Professor at the University of Calgary. Welcome! Brent: Great, thanks. Kristina: Could you tell us a little bit about your background and your interest in ocean acidification? Brent: Yes, I'm a geographer, really. I did all my degrees in geography departments. I started out at the University of Calgary and then moved to the University of Manitoba. But of course, the nice thing about geography is that you can study many different things within that field. So I typically consider myself to be, well depending on who I'm talking to, I might consider myself to be an oceanographer, but I've also spent a lot of time working on atmospheric processes so I know a little bit about meteorology, particularly boundary layer meteorology. And then within the field of oceanography, most of my work focuses on marine chemistry and in particular carbonate chemistry. And to answer the question about what my interest is in ocean acidification or how I got into ocean acidification, my main field of research is understanding how greenhouse gases move between the ocean and the atmosphere, specifically carbon dioxide. So that's where I come at this from, you know, understanding how much CO2 moves between the ocean and the atmosphere is pretty important for understanding the global carbon balance. And I work specifically in the arctic to understand how that process occurs in Arctic oceans, well in Arctic seas I guess I should say. And so I'm really coming at it from that angle. I study how the CO2 gets into the ocean. Then when I was, actually I think when I was a master's student, I was working on this and to be honest I don't think I'd even heard of ocean acidification at that point, I think I learned about it somewhere in my PhD and then I realized, oh you know, I'm working on the part where the CO2 gets into the ocean and then starts to drive that ocean acidification so I should probably learn more about ocean acidification itself. And so I started to align my research a little bit more with that and seeing how I could support ocean acidification studies through a little bit more of the chemistry side of things. Kristina: That's awesome. So can you tell us any bit about (you sort of already answered this) but maybe any highlights in terms of your contributions to ocean acidification research from recent papers or studies that you've done? Brent: Yeah, I think probably our biggest recent contribution, well there's a few I'll talk about, and a few students that have been working under my supervision for the last little while. One PhD student who's now a postdoc, Mohamed Ahmed, has published a few papers recently trying to put some numbers on how much CO2 is being absorbed in the Canadian Arctic Archipelago. So if you're not familiar with the geography, if you go north in Canada, eventually you hit the edge of the continent and then if you keep going further north, there's thousands of little islands that make up the Canadian Arctic Archipelago. Mohamed's work has looked at a bunch of data that we collected over several years measuring dissolved CO2 concentrations in the sea water from the research ice breaker, Amundsen, and from that we were able to put some numbers on how much CO2 is is getting into the ocean in those areas. And it turns out that that area is a pretty strong sink for CO2 - there's quite a lot of CO2 that moves into the ocean there and we actually suspect that that absorption of CO2 is increasing, or has been increasing, over the last three or four decades as the sea ice concentration in that area has has declined. So less sea ice means more open water; more open water means more opportunity for CO2 to get into the ocean, and that's one of the big things that he has found. And you know, that's pretty typical of the type of work that my research group does, really trying to put some numbers on CO2 absorption into the ocean. But I'll mention too, in doing that, we've got a little bit more involved in in the chemistry. So CO2 gets into the ocean, whether or not that might be a problem for marine organisms, it doesn't necessarily depend on how much CO2 is in there, but more on this what we call the carbonate saturation state, which is sort of a complicated end of a long chemical equation. But I had a student working out at Cambridge Bay who was able to calculate that for the ocean right around Cambridge Bay and he was able to do that by collecting some really detailed measurements of pH and CO2 concentration. And one of the exciting things we found there was that there's a fairly long period of time over the winter in that particular region where the sea water is undersaturated with respect to the aragonite saturation state. We couldn't really find any other papers that have shown that for the Arctic Ocean for that depth, so this is measured in pretty shallow water. So I think that's an interesting finding and it's one of the first findings where my research group has really taken one step closer to understanding the potential connections to marine organisms. So that's a cool study too. Kristina: That's great! Those studies both sound really interesting. And for people listening, if you are interested in learning a little bit more about Mohamed Ahmed's research, please check out our "Research Recap" blog series for that post. Moving on to the next question for you, why did you decide to lead the Ocean Acidification Community of Practice? You're one of the two co-leads of the program, so what was the motivation there? Brent: Right, good question. I come at this because I was, or I am, a MEOPAR researcher. So of course the Ocean Acidification Community of Practice is funded by MEOPAR and I was lucky enough to join MEOPAR as an early career researcher. Actually, the first research grant I ever got came from MEOPAR. So they brought me into their team that way. And I would say at that time, I was still really focused on the CO2 side of things, but you know the whole point of MEOPAR is to be a network, and so I met many other researchers, many other Canadian researchers, working on these topics and through that got to know one of the scientific leads of MEOPAR, Doug Wallace. And when the MEOPAR leadership was trying to figure out what they were going to do next with respect to ocean acidification within the network, he approached me to to co-lead the CoP and I thought that it was just a great opportunity to broaden my research in different directions. And you know really what we're trying to do in the Community of Practice is to try to bring in many different researchers and stakeholders who have an interest in ocean acidification so I really thought, you know, this is the way for me to get much more involved. And if you think about what I said when I was a master student, just really focused on CO2 flux, knew nothing about ocean acidification, to me this was just the next step in that in that journey to learn more and to align my research more with a topic that I think could be pretty important for Canada and for the world, really. Kristina: All right, next question is: what is one take-home about ocean acidification that you wish all Canadians knew? Brent: Yeah, what I think what I would say to that is that the problem of ocean acidification is strongly linked to CO2 emissions to fossil fuel burning. So you can think of it as kind of like an added motivation to reduce CO2 emissions. You know, I think for the average person, you've got lots of stuff to worry about, maybe don't let ocean acidification keep you up at night. But if we're actively working to reduce our CO2 emissions, we'll be actively addressing this problem too. So I think that that's the thing that I would like all Canadians to know is that if we can make progress on reducing CO2 emissions, we'll be helping out the climate change problem, but we'll also be helping out this problem too. Kristina: All right, next question. My last question for you is: what excites you most about the future of ocean acidification research? Brent: Yeah, I think I'll answer this question kind of personally because I'm excited about certain things that our lab group is working on. I'm excited about the potential to make more measurements using inexpensive sensors. One of the biggest barriers to collecting good, well to collecting large amounts of ocean acidification data has been that it's difficult to measure this with using sensors. To measure ocean acidification properly, it's typically required collecting samples, shipping them back to a lab, and then analyzing them on really specialized instruments. There are some new sensors that are out there now that can probably fill that gap, but they're expensive and they haven't really been deployed at a wide scale yet. And I think what I'd like to see happen over the next five or ten years is the adoption of either those expensive sensors, or maybe the development of less expensive sensors, and getting those sensors out to lots of different locations and then hopefully being able to use that to provide information that might actually be useful, again, to those operators who are worried about the health of the organism that they're working with, either in the short term or in the long term as well. So I'm really excited that we can start to use those new technologies and if we can start to deploy them and use them hand-in-hand with stakeholders, then I think we could really have a big increase in ocean acidification knowledge in this country. Kristina: Awesome, that's really exciting. Yeah, that's everything for me, so thank you very much for your time! Brent: No problem, that was great. To learn more about Brent and his research, please visit his lab website and Google Scholar profiles.

Here are some of the latest happenings in the world of ocean acidification in Canada and beyond! New Resource: A Webinar on OA Sensors In this webinar, Ph.D. student, Patrick Duke, provides us with an overview of the currently available equipment and sensors for monitoring ocean acidification, as well as considerations to make when selecting sensor packages for your needs, including instrument accuracy, drift, and cost. Watch the webinar here! Upcoming MEOPAR Trivia Challenge The Canadian Coastal Resilience Forum and CORC CoP are hosting the inaugural MEOPAR Coast 2 Coast 2 Coast Trivia Challenge on Wednesday, Feb. 24th at 1 pm EST/10 am PST. Register here: https://us02web.zoom.us/meeting/register/tZYtcOmgrjwqHNbaMxdr3B4rf_WXIrF5EBYg Upcoming GOA-ON Webinar GOA-ON is hosting a webinar by Dr. Kirsten Isensee and Dr. Katherina School, entitled: “Measuring ocean acidification to support the 2030 Agenda for Sustainable Development - SDG Target 14.3 and the related Indicator 14.3.1” Time: Wednesday, Feb. 24th, 10 am EST Register here: https://register.gotowebinar.com/register/2329723715326734348 New Video Resource “Community Sampling for Ocean Acidification in South Central Alaska” Video by: Chugach Regional Resources Commission Watch the video here: https://www.youtube.com/watch?app=desktop&v=qt_Ndl7OnMo New Paper of Interest Takeshita, Yuichiro, Brent D. Jones, Kenneth S. Johnson, Francisco P. Chavez, Daniel L. Rudnick, Marguerite Blum, Kyle Conner, Scott Jensen, Jacqueline S. Long, Thom Maughan, Keaton L. Mertz, Jeffrey T. Sherman, and Joseph K. Warren. 2021. Accurate pH and O2 Measurements from Spray Underwater Gliders. Journal of Atmospheric and Oceanic Technology. 38: 181–195. https://doi.org/10.1175/JTECH-D-20-0095.1 Have a news item you'd like us to feature? Email coordinator@oceanacidification.ca!

Here are some of the latest happenings in the world of ocean acidification in Canada and beyond! New Post on our Blog In this Scientist Spotlight post, we interview Dr. Clara Mackenzie (Research Scientist, DFO) to learn more about her research background and experience working on the effects of multiple stressors and OA on marine invertebrate animal physiology and resiliency! Read the post here: Scientist Spotlight: Dr. Clara Mackenzie, Research Scientist (Fisheries and Oceans Canada) Upcoming MEOPAR Trivia Challenge The Canadian Coastal Resilience Forum and CORC CoP are hosting the inaugural MEOPAR Coast 2 Coast 2 Coast Trivia Challenge on Wednesday, Feb. 24th at 1 pm EST/10 am PST. Register here: https://us02web.zoom.us/meeting/register/tZYtcOmgrjwqHNbaMxdr3B4rf_WXIrF5EBYg New EPA Webinar Recordings The EPA hosted webinars on December 1st and 3rd, 2020, entitled “Coastal Acidification: Adaptation and Mitigation Strategies” The recording for these webinars has been posted here: https://www.epa.gov/ocean-acidification/what-epa-doing-address-ocean-and-coastal-acidification In the News “Researcher looks to add fishery voices to climate change research” Source: CBC News Read the article here: https://www.cbc.ca/news/canada/prince-edward-island/pei-climate-change-lobster-research-1.5843363 New Paper of Interest Harvey, Ben P., Koetsu Kon, Sylvain Agostini, Shigeki Wada, Jason M. Hall‐Spencer. In Press. Ocean acidification locks algal communities in a species-poor early successional stage. Global Change Biology. https://doi.org/10.1111/gcb.15455 Have a news item you'd like us to feature? Email coordinator@oceanacidification.ca!

Dr. Clara Mackenzie is a Research Scientist at Fisheries and Oceans Canada, and an affiliate employee of Vancouver Island University. Dr. Mackenzie gives us some insight and background on her experiences with ocean acidification research. What is your background? My research interests: the biology and physiology of marine invertebrate species in response to environmental stressors, and the capacity of species to adapt My discipline/specializations: laboratory-based multi-stressor experiments for investigating climate change impacts on shellfish; selective breeding of shellfish for improved resilience to climate stressors Education/Training: MSc Marine Biology (Bangor University, Wales) – My Master's thesis examined the impacts of OA on growth in adult and larval Psammechinus miliarus (green sea urchin). PhD Marine Biology (Heriot-Watt University, Scotland) – My PhD thesis examined the impacts of hypoxia and warming on Modiolus modiolus (horse mussel) reefs including examination of oxidative stress and energetics (O2 consumption, cellular energy allocation) under warming and hypoxia conditions. I also examined the genetic connectivity and diversity of horse mussel populations as part of a preliminary investigation into population-based effects/resiliencies. What is your interest or background in OA? I hadn’t heard much about OA until I returned to university to complete a MSc in Marine Biology in 2009, after a number of years of drifting and trying out other careers (e.g. high school science teacher). When it came to deciding on a thesis topic, I told my academic supervisor that I was interested in Arctic science or topics relevant to that area of the globe. He connected me with a supervisor at British Antarctic Survey who was investigating the impacts of OA to urchin species. I knew OA was an issue for both polar regions so was keen to be on board. That was really the start of my research into OA and other climate stressors. As well as finding the science of OA interesting and worthwhile, I also found myself really enjoying the technical aspects of working with an aquarium set-up, and discovered a deep curiosity and affection for marine invertebrates. It’s been about 10 years since that first MSc OA research project. Since then, I have worked on a number of projects examining the impacts of climate stressors (OA, hypoxia, warming) on a range of invertebrate species (oysters, urchins, mussels). I worked for Bangor University as a research officer for several years on a project called SUSFISH that examined climate change impacts to various shellfish species of the Irish Sea. My specific research examined impacts of coinciding OA and warming on blue mussels, including investigation of effects to immune response, protein synthesis, shell strength, and energetics. My work on SUSFISH was an invaluable part of my research development and lead to my PhD work which examined the impacts of hypoxia and warming on horse mussel reefs, a habitat of high conservation priority in the UK and EU. I examined oxidative stress and energetic responses and began to consider the population-basis for adaptive capacity, an area of research that continues to hold a lot of interest for me. Currently, I enjoy working as a research scientist for Fisheries and Oceans Canada (in partnership with Vancouver Island University). Our work includes development of an oyster selective breeding program (in partnership with Vancouver Island University) for improved resistance to climate change stressors, and considering how hatchery practices might influence OA responses in later life stages. I’m interested in climate stressor research because the work is varied and stimulating, and key to preserving our precious marine environments. It also has real-life relevance outside of the research sphere, with impacts extending across many areas of life and society. Can you tell us about your past or current contributions to OA research? My past work highlighted that impacts under multi-stressor conditions can be substantially different than additive single-stressor effects. Additionally, I found that detection and magnitude of impact can vary according to type of investigated response (e.g. genome vs cellular vs whole-body). I’m most interested in the idea that genetics and life-history can really set the stage for susceptibility to climate stressors like OA. Some of my more recent work (with T. Green at Vancouver Island University) suggests that what happens to oyster larvae in early life can alter survival in later life stages. For example, changes to the microbiome in early development may potentially play a big role in later life with regards fitness and survival under stressor conditions. What is the one take-home about OA that you wish all Canadians knew? OA is already happening! You hear a lot of talk about climate change impacts in the future but environmental change has/is already occurring, with huge repercussions. For instance, upwelling events on the west coast (where I’m based) regularly deliver low pH seawater to coastal environments, and these events are increasing in magnitude and duration. Oyster hatcheries on the coast have had huge mortality issues as larvae are particularly susceptible to OA. Additionally, oyster farmers in BC are having to contend with mass die-offs in the summer which we suspect are due to a lethal assembly of coinciding stressors (including OA). What excites you most about the current or future of OA research in Canada? I moved back to Canada after 10 years of training and research in the UK to take a post-doctoral research position with Fisheries and Oceans Canada in Nanaimo, British Columbia. It has been particularly intriguing for me to enter into research in a location where OA is already occurring. I couldn’t believe some of the carbonate chemistry values I was measuring in “ambient” water samples. When an idea moves from “in the future” to “now”, it’s a big motivation to start finding solutions. I’m currently working with some excellent shellfish researchers including Chris Pearce (Research Scientist, DFO) and Tim Green (Canada Research Chair in Shellfish Health and Genomics, Vancouver Island University) as well as a great team of biologists, technicians and students at Pacific Biological Station and VIU’s Deep Bay Marine Field Station. There is a wide range of expertise across the research team which leads to interesting and innovative project ideas. I’m greatly enjoying the enthusiasm, open-mindedness and intelligence brought to projects, and of course the thrill of discovering something new. Anything else you’d like to say? I came to this area of research a little later in life and after considerable soul-searching. It took a lot of hard work, determination and definitely some luck to find a good fit for me but I would encourage anyone who isn’t quite sure what they want to do, to keep searching until that fit is made. It’s definitely been worth it for me - working on an global (and local) issue like OA is interesting and exciting and without sounding trite, brings meaning to my life. I would be happy to hear from anyone who is interested, regardless of your background or training, if only to have a chat about ways to get involved. To learn more about Clara’s research, please visit her ORCID Profile.

Here are some of the latest happenings in the world of ocean acidification in Canada and beyond! ICYMI – January updates In case you missed it, here’s a post summarizing all of the OA CoP’s updates and new posts for the month of January. New GOA-ON Webinar Last week, GOA-ON hosted a webinar with Drs. Sam Dupont and Steve Widdicombe entitled “Unifying biological field observations to detect and compare ocean acidification impacts across marine species and ecosystems” Watch the full presentation here and join in the conversation that arose from the talk on the OAIE! In the News “B.C. scientists look at climate change impacts on aquaculture production” Source: Nanaimo News Bulletin Read the article here: https://www.nanaimobulletin.com/news/b-c-scientists-look-at-climate-change-impacts-on-aquaculture-production/ New Paper of Interest Mekkes, Lisette, Willem Renema, Nina Bednaršek, Simone R. Alin, Richard A. Feely, Jef Huisman, Peter Roessingh, Katja T. C. A. Peijnenburg. 2021. Pteropods make thinner shells in the upwelling region of the California Current Ecosystem. Scientific Reports 11:173. https://doi.org/10.1038/s41598-021-81131-9 Have a news item you'd like us to feature? Email coordinator@oceanacidification.ca!

Here’s what’s new from the MEOPAR OA Community of Practice this month: New Resources Our Map of Canada’s OA Resources We launched a new interactive map of Canada’s OA resources to celebrate International OA Day of Action (Jan. 8th, or 8.1 – the current pH of the ocean)! Find resources, projects, and experts in your area, or search the map for your topic of interest! We will be continuously updating this map, so if you have a project, resource, or would like to be added to the map, please let us know (email coordinator@oceanacidification.ca) Check out the map and our video tutorial. Our New Membership List We’ve made it easier than ever to join our OA Community of Practice! If you haven’t done so already, please sign up here, and share our membership list with your colleagues! New Blog Posts In December, we launched a series of new blogs to share resources and highlight the excellent OA research from Canada and beyond. Here are links to our latest posts: Research Recaps: We interview researchers to hear about their latest projects, papers, and OA work. New Paper: Ahmed et al., 2020 – Underestimation of air-sea CO2 fluxes due to freshwater stratification in Hudson Bay The Hakai Institute, British Columbia Meet the CoP: Get to know the people leading Canada’s OA Community of Practice and hear about their interests in ocean acidification. New Coordinator: Kristina Barclay OA News (You Could Use): Find out the latest happenings in the world of OA in Canada and beyond, including new resources, papers, and news articles. Jan. 28, 2021 Jan. 21, 2021 Jan. 14, 2021 Jan. 7, 2021 Dec. 17, 2020 Dec. 11, 2020 Upcoming Events Thurs., March 4, 2021 (1 pm MST) GOA-ON Webinar Series presentation by OA CoP Coordinator, Kristina Barclay Learn all about the CoP, our past activities, MEOPAR OA research, and our current and future research and activities! Wed., March 10, 2021 (Time TBD) MEOPAR Webinar Series presentation by OA CoP Coordinator, Kristina Barclay Learn all about the CoP, our past activities, MEOPAR OA research, and our current and future research and activities! Check out oceanacidification.ca/events and follow us on social media for event updates! Have an idea for content? Want to contribute? We’re always looking for feedback! Email us at coordinator@oceanacidification.ca! Follow us on Twitter, Facebook, and Instagram!

Here are some of the latest happenings in the world of ocean acidification in Canada and beyond! New Post on the Blog In this Research Recap post, we chat with lead-author, Dr. Mohamed Ahmed (University of Calgary) to get the inside scoop on a new paper examining air-sea carbon dioxide fluxes in the Arctic. Read the post here: New Paper: Underestimation of air-sea CO2 fluxes due to freshwater stratification in Hudson Bay New OA Resources The Northeast Coast Acidification Network (NECAN) has launched a new webinar series, focusing on student and early career scientists and their OA research. Follow their YouTube channel to see all of these webinars! Here’s a link to one of their most recent webinars: Ocean Acidification and Warming Act Synergistically to Reduce Cardiac Performance and Increase Disease Susceptibility in Juvenile American Lobster – Amalia Harrington In the News NOAA Research's top 5 stories from 2020 These include stories on how Dungeness crab larvae are affected by OA, a new 10-year roadmap for research on ocean, coastal, and Great Lakes acidification, and updates on carbon dioxide emissions. Read all 5 stories here: https://research.noaa.gov/article/ArtMID/587/ArticleID/2696/NOAA-Researchs-top-5-stories-from-2020 New Paper of Interest Bednaršek, Nina, Richard A. Feely, Marcus W. Beck, Simone R. Alin, Samantha A. Siedlecki, Piero Calosi, Emily L. Norton, Casey Saenger, Jasna Štrus, Dana Greeley, Nikolay P. Nezlin, Miranda Roethler, John I. Spicer. 2020. Exoskeleton dissolution with mechanoreceptor damage in larval Dungeness crab related to severity of present-day ocean acidification vertical gradients. Science of the Total Environment 716:136610. https://doi.org/10.1016/j.scitotenv.2020.136610 Have a news item you'd like us to feature? Email coordinator@oceanacidification.ca!

The exchange of carbon dioxide between the atmosphere and the surface of the ocean plays an important role in the global carbon budget, (i.e., what happens to carbon dioxide emissions). Differences in air-sea carbon dioxide concentrations mean that as carbon dioxide emissions increase in the atmosphere, they are taken up by the ocean, which acts as a major carbon sink. In Arctic regions, these air-sea carbon dioxide fluxes are also influenced by freshwater input from river runoff and melting sea ice. Measurements of marine carbon dioxide that are used to determine the global carbon budget each year are typically collected via automated underway systems onboard research vessels around the world. These underway systems are usually measuring carbon dioxide in the waters that are located below 5 meters from the water’s surface. Typically, these underway measurements are based on the assumption that surface waters (the top ~10 metres) are well mixed enough to get accurate carbon dioxide measurements that are used to air-sea carbon dioxide fluxes at regional and global scale. However, a recent study has suggested that this top surface layer in Arctic waters might not be as well mixed as previously thought. Instead, there might be a gradient of carbon dioxide within the top few metres of the ocean caused by the stratification of freshwater at the ocean’s surface. We spoke with Dr. Mohamed Ahmed, a Postdoctoral Associate at the University of Calgary, who recently published another study where he and his co-authors set out to determine exactly how much freshwater stratification occurs in the Arctic, and how this might influence air-sea carbon dioxide flux estimates used to determine global carbon budgets. Dr. Ahmed is a marine biogeochemist specializing in the marine carbon cycle, air-sea carbon dioxide fluxes in the Canadian Arctic, and geospatial technologies like remote sensing. He obtained his Bachelor’s degree in Geology from Beni-Suef University in Egypt where he explored his interest in fieldwork, and then attained a M.Sc. degree in Geomatics from Lund University in Sweden that allowed him to develop strong technical skills in geospatial technologies. His Ph.D. (University of Calgary, Alberta, Canada) allowed him to combine his love of field work with his technical and programming skills, where he studied marine carbon cycles in the Arctic using both observational and remote sensing data. It was while conducting fieldwork in the Arctic for his Ph.D. research that Dr. Ahmed made an observation that inspired his most recent paper. As he observed sea ice melting and collecting on the surface of the water from a Zodiac while on a research cruise in the Canadian Arctic Archipelago (also known as the Northwest Passage), he started thinking about what was actually being measured when determining air-sea carbon dioxide fluxes. Underway systems on ships are below 5 metres depth, but this freshwater from sea-ice melt appeared to form a shallow stratified layer in near the surface of the water. Other researchers (including his co-author, Dr. Lisa Miller) had also recently suggested that these surface layers might not be as well mixed as we had assumed. So, Dr. Ahmed and his co-authors set out to answer two questions: 1) Is there actually a shallow stratified freshwater layer in the top few metres of the ocean? As in, is this layer widespread across large basins like Hudson Bay in Canada? and 2) How might this shallow layer of freshwater on the surface of Arctic waters be influencing estimates of air-sea carbon dioxide fluxes? To answer these questions, Dr. Ahmed took two sets of seawater chemistry measurements, as well as measurements from the ship’s underway system, on a research cruise of Hudson Bay onboard the CCGS Amundsen in 2018. The first set of water samples were of the top 30-50 cm of seawater collected in specialized horizontal Niskin bottles with the second set taken at 7 m depth to correspond with the ship’s underway system. Water samples were taken either from the foredeck of the ship or a small boat within 2 km of the ship. The research cruise allowed them to collect data representative of Hudson Bay, with over 45 stations across the bay. The timing of the cruise was also important, as they were able to capture the peak window of sea-ice melt in Hudson Bay from late May – mid July when there is the greatest potential for possible stratification of surface freshwater. They found that there was stratification of freshwater near the surface, with surface waters containing having lower carbon dioxide values than those at 7 m depth (differences can reach to ~30 μatm in some stations). This means that underway measurements are likely underestimating air-sea carbon dioxide fluxes by as much as 50% in Hudson Bay. “These are interesting results as the impact of freshwater stratification may not be limited to polar waters, as many coastal areas around the world host many freshwater sources,” says Dr. Ahmed. However, this gradient of carbon dioxide in the surface waters only persisted for about 5 weeks, suggesting that sea-ice melt and river runoff are likely to influence the accuracy of underway system measurements only within the first 5 or so weeks of peak freshwater input during the summer months. Not only that, but after the first week, they were able to apply a correction to the underway system measurements to correct for this shallow freshwater layer. Conducting fieldwork onboard a research vessel in the Arctic is not without its challenges. Dr. Ahmed had originally planned to conduct this research in 2017, but the research cruise was cancelled when the CCGS Amundsen (operated by the Canadian Coast Guard) was called for search and rescue missions. But, Dr. Ahmed took the opportunity to discuss his ideas with other researchers, including co-author Dr. Miller, who also had similar observations and was working on a separate study based on similar observations. When the research cruise happened the following year, another challenge Dr. Ahmed faced was having the ship maneuvered carefully towards the sample stations so as not to disturb the surrounding waters, which was not always possible if the captain had other responsibilities and the ship’s schedule did not allow for the possible delay. A final obstacle was the sea-ice itself, which would sometimes impede collection of bottle samples from the small inflatable Zodiac boat, which unlike the CCGS Amundsen, is not capable of breaking through ice. The take-home of the new study by Dr. Ahmed and co-authors is that we are likely underestimating carbon dioxide sinks in the Arctic, meaning that seawater in at least some areas of the Arctic, such as Hudson Bay, is taking up more carbon dioxide than we are currently estimating. Dr. Ahmed emphasized that these results are important for creating accurate carbon budgets and ensuring that underway system measurements are representative of the surface seawater conditions where air-sea carbon dioxide exchange actually occurs. “It will be interesting to see if our findings are matching other observations in different locations in the Arctic waters as the air-sea gas exchange of other gases might be impacted by the presence of freshwater stratification,” he says. Dr. Ahmed hopes that researchers can use these data to determine freshwater stratification in other areas of the Arctic, and ultimately allow us to estimate global carbon budgets more accurately, especially in the vulnerable Arctic region. Read Ahmed et al., 2020 here: Underestimation of surface pCO2 and air-sea CO2 fluxes due to freshwater stratification in an Arctic shelf sea, Hudson Bay. Elementa: Science of the Anthropocene 8:084 To learn more about Dr. Ahmed and his research, please follow his updates via Twitter (@MohamedMMAhmed). Acknowledgements: Thanks to Dr. Mohamed Ahmed for his interview with OA CoP Coordinator, Kristina Barclay, and for providing edits on this article. All photo/figure captions were provided by Dr. Ahmed. References: Ahmed, Mohamed M. M., Brent G. T. Else, David Capelle, Lisa A. Miller, and Tim Papakyriakou. 2020. Underestimation of surface pCO2 and air-sea CO2 fluxes due to freshwater stratification in an Arctic shelf sea, Hudson Bay. Elementa: Science of the Anthropocene 8:084. https://doi.org/10.1525/elementa.084 Miller, Lisa A., Tonya M. Burgers, William J. Burt, Mats A. Granskog, and Tim N. Papakyriakou. 2019. Air‐Sea CO2 Flux Estimates in Stratified Arctic Coastal Waters: How Wrong Can We Be? Geophysical Research Letters 46:235 – 243. https://doi.org/10.1029/2018GL080099

Here are some of the latest happenings in the world of ocean acidification in Canada and beyond! New OA Resources The 2020 global carbon budget had been released. Read the report here: https://www.globalcarbonproject.org/carbonbudget/ In the News Reaching Consensus on Assessments of Ocean Acidification Trends (EOS - Science News by AGU) https://eos.org/science-updates/reaching-consensus-on-assessments-of-ocean-acidification-trends New Paper of Interest Bullard, Elizabeth M., Ivan Torres, Tianqi Ren, Olivia A. Graeve, and Kaustuv Roy. 2020. Shell mineralogy of a foundational marine species, Mytilus californianus, over half a century in a changing ocean. PNAS 118:e2004769118. https://doi.org/10.1073/pnas.2004769118 Have a news item you'd like us to feature? Email coordinator@oceanacidification.ca!

Here are some of the latest happenings in the world of ocean acidification in Canada and beyond! OA Day of Action was held on Friday, Jan 8th! To celebrate OA Day of Action, we launched a new resource on our website featuring a map of Canada's OA resources! Please visit the link to see the map and our video tutorial. There were several other events held by partner groups to celebrate OA Day, including a Facebook Live event (link includes the video recording) hosted by The Ocean Foundation! New Post on our Blog The Hakai Institute. We interviewed Hakai scientists, Iria Giménez and Wiley Evans, on their collaborative research to combine oceanographic datasets with biological experiments to study how Pacific oysters will respond to future ocean conditions in B.C.! New OA Resources Resources for educators: C-MORE Science Kits - Ocean Acidification https://stempreacademy.hawaii.edu/c-more/ocean-acidification/ In the News Acidifying Oceans Could Get Help from Kelp (EOS - Science News by AGU) https://eos.org/research-spotlights/acidifying-oceans-could-get-help-from-kelp New Paper of Interest Barclay, Kristina M., Murray K. Gingras, Stephen T. Packer, and Lindsey R. Leighton. 2020. The role of gastropod shell composition and microstructure in resisting dissolution caused by ocean acidification. Marine Environmental Research 162:105105. https://doi.org/10.1016/j.marenvres.2020.105105 Call for SDG 14.3.1 Indicator Data Submissions (Repeat post) The Intergovernmental Oceanographic Commission (IOC) of UNESCO would like to invite all researchers and data managers to contribute to the second global ocean acidification data collection in relation to the Sustainable Development Goal (SDG) 14.3.1 Indicator: Average marine acidity (pH) measured at agreed suite of representative sampling stations. The Indicator is a milestone in the global recognition of ocean acidification as a stressor on marine ecosystems and of the importance of observing ocean acidification for the sustainable management of ocean resources. To facilitate data submission, storage and sharing, IOC has developed an online tool: the SDG 14.3.1 Data Portal. The full text of the SDG 14.3.1 Indicator Methodology, the associated data template, the metadata template and the metadata instruction file, as well as guidance on how to upload data can be found on the SDG 14.3.1 Data Portal website: https://oa.iode.org/ Data submitted by 15. January 2021 will be included in the 2021 UN SDG Report.* *Cross posted from the OA Info Exchange Have a news item you'd like us to feature? Email coordinator@oceanacidification.ca!