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Designed by Klara Maisch following our scientific interpretation of the system (Hauri et al., 2018).
The Chukchi Sea Ecosystem Observatory (CEO, shown as the yellow star in the map) is led by Seth Danielson and was started in 2015. It is located in a biological hotspot, in 45 m of water in the northeastern Chukchi Sea. Measurements include ice cover, ocean physics, nutrient and carbonate chemistry, particulate matter, phytoplankton, zooplankton, fisheries, and marine mammal datasets, thereby providing an unprecedented opportunity to study the Chukchi shelf ecosystem. Our group is responsible for the carbon dioxide, pH, and oxygen sensors, which are turned around and calibrated once per year. An overview is given in Hauri et al. (2018) and results are shown in our recent paper Hauri et al., 2024.
The Chukchi Ecosystem Observatory (CEO) location near Hanna Shoal is marked with a yellow star. Figure is from Hauri et al. (2024).
In Hauri et al. (2024) we describe the first 5 years of observed carbonate conditions in the near-bottom waters (33 m depth, 13 m above the seafloor) at the CEO site. High carbon dioxide and low pH and aragonite saturation state (Ωarag) persist in summer and fall, when organic material from the highly productive summer remineralizes. During this time, Ωarag can be as low as 0.4. In winter, when the site was covered by sea ice, pH was <8 and Ωarag remained undersaturated under the sea ice. There were only two short seasonal periods with relatively higher pH and Ωarag, which we term ocean acidification relaxation events. In spring, high primary production from sea ice algae and phytoplankton blooms led to spikes in pH (pH > 8) and aragonite oversaturation. In late fall, strong wind-driven mixing events that delivered low-CO2 surface water to the shelf also led to events with elevated pH and Ωarag.
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