Modeling of Water Quality Indicators in the Western Baltic Sea: Seasonal Oxygen Deficiency

Abstract Hypoxia in coastal seas is a severe threat to marine ecosystems, with the Baltic Sea exhibiting largest hypoxic areas worldwide. While perennial oxygen deficiency deep basins component of environmental assessments, seasonal shallow not routinely assessed. Current measurements alone cannot provide spatio-temporal resolution needed for highly dynamic deficiency, making estimations on its duration and extent uncertain. Utilizing long-term 3D model simulations horizontal 3 nautical miles, we analyzed development western Sea. Different metrics (near-bottom area, water volume, duration, frequency) critical concentrations were exemplary sub-basins as defined by Helsinki Commission. Our results indicate that has continually increased second half twentieth century until end 1980s slightly decreased last two decades. In 1950s, spatial was still at low plateau before increasing, indicating this period could be suitable reference representing good status, including naturally occurring deficiency. Overall, indicator describing ecological status For an application eutrophication areas, sufficient which can gained combination measurements. Further analysis integrate situ obtain most reliable approach.