Antarctic krill and their role in ocean carbon cycling

Antarctic Krill under a microscope. Photo courtesy of Uwe Kils, CC-BY-SA 3.0

Paper: Manno et al. (2020)

The transfer of carbon from the surface ocean to the deep ocean, or carbon export, can strongly influence climate. The main pathway of carbon export in the ocean is through sinking particles, also known as the biological carbon pump. These sinking particles can include plankton biomass, aggregates of cells, and zooplankton feces and molts. Understanding what contributes to carbon export is important in understanding how this may change as temperatures warm due to climate change.

A recent study by Manno et al. found that Antarctic krill in the Southern Ocean may play a significant role in transporting carbon to the deep ocean through their carcasses, fecal material, and most notably their molts, or shedding of their shells. Exoskeletons are not only an important vehicle for carbon export but also provide food to animals living on the seafloor. This is the first study to investigate the contribution of krill molts to carbon export in the Southern Ocean.

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The role of carbon in a changing Arctic

Paper: Freshening of the western Arctic negates anthropogenic carbon uptake potential

Authors: R.J. Woosley and F.J. Millero

Journal: Limnology and Oceanography

As human generated emissions of carbon dioxide continue to increase, scientists seek to understand the potential for ‘sinks’, or places that the excess CO2 can move in the global carbon cycle, to take up and store some of the increased emissions. Understanding how these carbon sinks may react to increasing global emissions helps to better predict both the rate of atmospheric increase in the future and the potential response of global ecosystems, including major sinks in forests and oceans.

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Isotopes Begin to Unlock the Mystery of Methane Source in the Scheldt Estuary

Scheldt Estuary with tidal flats and water shown

Featured Image: Eastern Scheldt Estuary near Zeeland, Netherlands. Photo courtesy Wikimedia Commons/ Luka Peternel, CC BY-SA 4.0 license.

Paper: Carbon and Hydrogen Isotope Signatures of Dissolved Methane in the Scheldt Estuary

Authors: Caroline Jacques, Thanos Gkritzalis, Jean-Louis Tison, Thomas Hartley, Carina van der Veen, Thomas Röckmann, Jack J. Middelburg, André Cattrijsse, Matthias Egger, Frank Dehairs & Célia J. Sapart

Estuaries are dynamic coastal environments where freshwater and saltwater collide and mix. Across the world, estuaries regularly have higher methane concentrations in the water than would be expected from equilibrium with the atmosphere. If the water was in equilibrium, or at a happy balance, with the atmosphere, then there would be no net transfer of methane to the atmosphere. Because there is more methane than expected in the water, estuaries are a source of this potent greenhouse gas, methane (CH4), to the atmosphere. The problem is that the processes leading to the excess methane in the estuary’s surface water are not well known in many European estuaries.

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Could corals help study the variability of past Indian monsoons?

Featured image: A coral colony from Maldives, Indian Ocean. Picture credit: Андрей Корман from Pixabay (Public domain)

Paper: Potential of reef building corals to study the past Indian monsoon rainfall variability

Author: Supriyo Chakraborty

Paleooceanographers have often used reef-building corals to study oceanic processes like the El Niño and Southern Oscillation, ocean circulation patterns, air–sea gas exchange, and the Indian Ocean dipole (a.k.a Indian Niño), among others. Yet how exactly do corals provide clues about the physical and chemical conditions of their environments? The answer lies in their skeletons. 

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What do deep-sea sediment cores tell us about past fish populations?

Black background with fish teeth of different heights and widths

Featured Image: Ichthyoliths (microfossil fish teeth) from deep-sea sediment cores displaying the variety of tooth morphology. Photo courtesy of Elizabeth Sibert, lead author of the paper.

Paper: No state change in pelagic fish production and biodiversity during the Eocene–Oligocene transition

Authors: Elizabeth C. Sibert, Michelle E. Zill, Ella T Frigyik, Richard D. Norris

The seafloor at the bottom of the ocean records what is happening in the water above. Sediments capture silica from diatoms and phytoplankton, carbon from zooplankton poop and detrital marine snow, and teeth after dead fish sink. This last piece of evidence is particularly important: fossilized fish teeth or icthyoliths can help estimate past fish abundance and can show shifts in fish species or biodiversity in the ocean over time.

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North Atlantic Ice Melt May Increase the Storminess of the Northern Hemisphere

Featured image of sea ice from Free-Photos on Pixabay

Paper: Rapid Cooling and Increased Storminess Triggered by Freshwater in the North Atlantic
Authors: M. Oltmanns, J. Karstensen, G. W. K. Moore, and S. A. Josey

Way up north in the Arctic Circle, sea ice and glaciers are rapidly melting and sending a massive amount of cold, fresh water into the North Atlantic Ocean. At first this influx of cold water may seem beneficial to offset the warming from climate change, but new research suggests that this meltwater from Greenland and the Arctic increases the number of winter storms that occur in the Northern Hemisphere.

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