Feature Image: Outcrop of volcanic rock associated with the Central Atlantic Magmatic Province. This Large Igneous Province has a strong correlation to the onset of a mass extinction ~200 million years ago, however, an exact mechanism for the extinction has been difficult to determine. CC BY-SA 4.0, via Wikimedia Commons
Paper: Two-pronged kill mechanism at the end-Triassic mass extinction
Authors: Calum P. Fox; Jessica H. Whiteside; Paul E. Olsen; Xingquian Cui; Roger E. Summons; Kliti Grice
A recent study by Column Fox and colleagues sheds light on what caused one of the “big five” mass extinctions on Earth since complex life emerged ~540 million years ago. They found that repeated pulses of volcanic activity were responsible for the extinction in two main ways: ocean poisoning caused by gaseous hydrogen sulfide (H2S) rising through the water column (known as euxinia) and ocean acidification.
Continue reading “What caused the end-Triassic Mass Extinction in the Oceans?”
Featured image: Microplastic thread courtesy of M.Danny25 on Wikipedia under CC BY-SA 4.0.
Paper: Ross, P.S., Chastain, S., Vassilenko, E. et al. Pervasive distribution of polyester fibres in the Arctic Ocean is driven by Atlantic inputs. Nat Commun 12, 106 (2021). https://doi.org/10.1038/s41467-020-20347-1
The Arctic is full of plastic–polyester fibers to be exact. Peter S. Ross and his team found upwards of forty polyester fibers for every cubic meter of the Arctic Ocean’s surface. Their new study in Nature Communications also revealed that these fibers were more common in the East Arctic, which is fed by the Atlantic Ocean, than the West Arctic. The scientists suggest that the presence of these fibers coupled with their uneven distribution throughout the ocean could be due to an unlikely source: home laundry.
Continue reading “There’s microplastics in the Arctic, and we can probably blame home laundry”
Paper: Microbial dynamics of elevated carbon flux in the open ocean’s abyss
Authors: Kirsten Poff, Andy Leu, John Eppley, David Karl and Edward DeLong
Cells from blooms of phytoplankton, or tiny plants, can enhance carbon flux all the way down to the deepest parts of the ocean. The authors of this recent study measured the amount of carbon in sinking particles deep in the ocean at a station near Hawaii. Over the course of three years, scientists identified three time periods of unusually high carbon flux, or transport, at this depth, and found that the organisms that made up the sinking particles were significantly different between high flux events and the rest of the time period. The data showed higher abundances of surface-dwelling microorganisms, including phytoplankton, contributing to these particles during high-flux events.
Continue reading “Tiny organisms’ race to the bottom of the ocean”
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.
Continue reading “Antarctic krill and their role in ocean carbon cycling”
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.
Continue reading “The role of carbon in a changing Arctic”
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.
Continue reading “Isotopes Begin to Unlock the Mystery of Methane Source in the Scheldt Estuary”
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.
Continue reading “Could corals help study the variability of past Indian monsoons?”
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.
Continue reading “What do deep-sea sediment cores tell us about past fish populations?”
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.
Continue reading “North Atlantic Ice Melt May Increase the Storminess of the Northern Hemisphere”