Due to ongoing anthropogenic CO2 emissions and the parallel active ocean physical CO2 pumping causing acidification of waters, studying past changes in seawater carbonate chemistry has become a major focus in paleoclimate research. Insight into past marine carbon cycling and perturbations therein critically depends on robust reconstructions of the seawater carbonate system (C-system) through well-controlled experimental setups and accurate C-system manipulations. In the ocean, small calcifying micro-organisms (i.e. foraminifera) incorporate various elements into biogenic calcium carbonate in equilibrium with specific environmental parameters. Here we explore the use of deep-sea foraminiferal Sr/Ca ratio as a new C-system proxy for paleoclimate research studies. We use decoupled carbonate chemistry controls, i.e. changing pH at constant Dissolved Inorganic Carbon (DIC) and changing DIC at constant pH. This experiment was performed for the first time with a new generation of environmental simulator designed for experimentation in ecology (Ecolab system – CEREEP-ECOTRON). Four controlled and regulated climatic chambers were used with four different concentrations of atmospheric pCO2 (180 ppm, 410 ppm, 1000 ppm, 1500 ppm) simulating the last glacial maximum, the current and future projection pCO2 values. Preliminary results describe a positive correlation between Sr/Ca and the carbonate system, namely bicarbonate ion concentration.

Estuaries are diverse and important aquatic ecosystems; and yet until now we have lacked information on the response of estuaries to climate change. In this seminar I will present data from a twelve-year monitoring program, involving 6200 observations of 166 estuaries along 1100 kilometers of the Australian coastline. Estuary temperatures increased by 2.16 °C on average over 12 years, at a rate of 0.2 °C/year, with waters acidifying at a rate of 0.09 pH units and freshening at 0.086 PSU/year. Lagoons and rivers are warming and acidifying at the fastest rate because of shallow average depths and limited oceanic exchange. The changes measured are an order of magnitude faster than predicted by global ocean and atmospheric models, indicating that existing global models may not be useful to predict change in estuaries. Estuaries are also home to diverse ecosystems and valuable economies supported by oysters. Oysters rely on bacterial communities forming a microbiome for their health and survival. Oysters are also vulnerable to disease and this is may be exacerbated by climate change in estuaries. We found that warming and acidification can shift the microbiome of Sydney rock oysters (Saccostrea glomerata), however, these effects can be ameliorated by selective breeding. We show that oyster genetic background may influence the microbiome under climate change and that future assisted evolution breeding programs could be used to enhance resilience in the oyster microbiome.

The Southern Ocean accounts for nearly half of the global ocean’s sink of anthropogenic carbon. Despite this important contribution, many climate models do not represent the mesoscale features that characterize the region due to limited spatial resolution. Here we apply a high-resolution ocean model that incorporates biogeochemistry with high-emission (RCP8.5) forcing in order to identify regions of pronounced change due to carbon uptake into the near future. We find that the annual uptake of carbon in the Southern Ocean south of 40° S is projected to double over the first half of the 21st century. The changes due to the increase in carbon will lead to acidification and lowering of aragonite saturation. We will present regions where changes to carbon system variables are respectively more and less pronounced to inform the siting of near-future observations.

The Canary Current and the Benguela Current upwelling systems support significant local and international fish resources along the west coast of Africa. These fisheries contribute to the region's economy and provide important food and employment opportunities to coastal communities. In 2017, the 30-year long Ecosystem Assessment for Fisheries (EAF) Nansen Program, which is supported by the FAO and the Norwegian Ministry of Foreign Affairs, initiated studies on ocean acidification in these upwelling systems. The Canary Current Large Marine Ecosystem survey was performed between May 2017 and December 2019 aboard the R/V Dr. Fridtjof Nansen. It consisted of 110 stations situated at twenty seven sections perpendicular from the coast. Total alkalinity (TA) and pH data were collected using potentiometric titration and spectrophotometric pH measurements, respectively. The other parameters describing the carbonate chemistry and ocean acidification state were derived from TA and pH using the CO2SYS calculation program. Large variability along the coast was observed, connected to salinity changes, primary production, temperature, and biological processes. Results from a similar study focused on the Benguela Current upwelling system will also be shared during this webinar.

The MEOPAR OA Community of Practice (CoP) was formed in 2018, with the overarching goal of sharing knowledge and improving linkages between OA knowledge creators and end-users across Canada. The OA CoP is led by two Co-Leads, Dr. Helen Gurney-Smith (DFO) and Dr. Brent Else (University of Calgary), and a Coordinator, Dr. Kristina Barclay (University of Calgary, MEOPAR), with guidance from an interdisciplinary Steering Committee from across the country. OA CoP objectives include the development of: knowledge transfer and community engagement via accessible content, resources, and databases, and best-practices for data collection and sharing involving research groups, stake-holders, and community-based research. We will present some of our key activities to date, our new online resources and blog series, as well as updates on the development of future projects. Current and future activities are focused on increasing online content and resources to increase OA CoP awareness and engagement, the development of a low-cost OA sensor package to aid aquaculture operations and larger monitoring efforts, conducting regional vulnerability assessments, and participation in partner OA organizations, including the GOA-ON North American Hub, the OA Information Exchange, DFO-NOAA OA Working Groups, the OA Alliance, and MEOPAR.