Image: Maria Samuelsson/Polarforskningssekretariatet
Effects of climate change in the Arctic Ocean and the Baltic Sea
The world's oldest organisms, bacteria, account for 1/3 of all oxygen consumption and production of carbon dioxide in the oceans. To understand the causes and future development of oxygen-free bottoms and greenhouse gases knowledge is needed about the regulation of bacterial oxygen consumption. New results show that most of the oxygen consumption is driven by maintenance activities. What are the maintenance activities of bacteria? How are they regulated, especially in cold arctic environments?
The project aims to improve knowledge of the effects of climate change on the Arctic Ocean and the Baltic Sea. The results will support management for a healthy ocean and ensuring viable stocks of seafood and biodiversity. A dataset from the Synoptic Arctic Survey expedition 2021 will provide a better understanding of Arctic Ocean biodiversity and how it contributes to the metabolism of carbon compounds and oxygen. The regulation of growth and respiration of bacteria will be determined and increase the understanding of how consumption of oxygen and emissions of carbon dioxide is controlled.
What is the state of the environment and how is the carbon cycle in the Arctic controlled?
The expedition Synoptic Arctic Survey to the Arctic Ocean with the icebreaker Oden in 2021, collected one million values by 16 research groups. Bacterioplankton accounts for 50% of the conversion of carbon compounds in the ocean and the project will determine their growth rate and oxygen consumption down to 500 m depth. Variation between Arctic basins will be clarified and contribute to a more reliable assessment of the state of the environment. Through collaboration with other research groups, a carbon budget for the Arctic Ocean will be compiled and improve biogeochemical models.
Which maintenance activities of bacterial plankton cause the most cellular respiration?
Maintenance activity accounts for 2/3 of the oxygen consumption of bacterioplankton in the ocean. Maintaining optimal salinity in the cell, repairing genetic material and enzymes are some important maintenance activities. Low temperatures also lead to increased oxygen consumption, possibly linked to higher production of the energy carrier ATP. In experiments on liter and cubic meter scales, salinity and cold effects on maintenance breathing will be investigated. With sensor technology, even low rates of oxygen consumption will be measured, together with salt regulating substances ATP and their genes expression.
Is breathing temperature sensitivity higher in cold water?
The temperature sensitivity of breathing (Q10-value) is decisive for understanding the regulation of oxygen consumption and carbon dioxide production in changing climate with higher temperatures. To improve the knowledge of temperature sensitivity, field measurements will be performed also below 5 °C with a short temperature range (situ temp. to + 3°C) in increments of 1 °C. A background correction will be developed to handle oversaturation. Similar data are already collected at -1.7 °C temperature during the 2021 Arctic expedition.