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1. Effects of Diel Oxygen Cycling and Benthic Macrofauna on Sediment Oxygen Demand

   https://doi.org/10.1007/s12237-024-01404-0  

   Gadeken, Kara J; Dorgan, Kelly M (July 2024, Estuaries and Coasts)

   Abstract This field study examined how sediment macroinfauna change patterns of sediment oxygen demand (SOD) throughout a diel oxygen cycle. Sediments with a greater faunal presence would be expected to have greater overall SOD, and at night may alter their behavior and influence SOD depending on their response to low-oxygen stress. Dynamic faunal bioturbation or bioirrigation behavior would also result in corresponding variation in SOD values on short time scales. In situ flow-through benthic metabolism chambers were used to measure SOD at a high temporal resolution in discrete sediment patches. Sediments with more macroinfauna had greater average SOD over the diel cycle, consistent with previous studies. Where more macroinfauna were present, they drove greater SOD during nightly low oxygen, presumably by enhancing their burrowing and irrigation activities. SOD was also more variable on a sub-diel timescale in sediments with more macroinfauna. Sediment oxygen demand is dynamic and highly sensitive both temporally, on very short timescales, and spatially, in terms of resident fauna, and their interaction produces heretofore unaccounted complexity in patterns of SOD particularly in shallow coastal systems. Extrapolations of temporally and spatially limited SOD measurements to a system-wide scale that do not account for the short-term and spatially variable effects of fauna may produce imprecise and misleading estimates of this critical ecosystem function. 

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2. Molecular oxygen generation from the reaction of water cations with oxygen atoms

   https://doi.org/10.1063/1.5102073  

   Fortenberry, Ryan C.; Trabelsi, Tarek; Westbrook, Brent R.; Del Rio, Weston A.; Francisco, Joseph S. (May 2019, The Journal of Chemical Physics)
3. Singlet oxygen quantum yields determined by oxygen consumption

   https://doi.org/10.1016/j.jphotochem.2019.04.029  

   Lutkus, Luke V.; Rickenbach, Sam S.; McCormick, Theresa M. (June 2019, Journal of Photochemistry and Photobiology A: Chemistry)
4. Geometrically flexible synthetic manganese-oxygen and calcium-manganese-oxygen cubane clusters as reactive biomimics of the oxygen evolving complex of photosystem II.

   https://doi.org/10.1021/scimeetings.0c03947  

   Michael J. Zdilla, Shivaiah Vaddypally (March 2020, ACS Spring 2020 National Meeting and Expo)

   The oxygen evolving complex (OEC) of photosystem II is responsible for the four-electron oxidation of water to dioxygen in oxygenic photosynthetic organisms. These organisms use light to drive this thermodynamically uphill process to harvest high-energy electrons from water for cellular energy, generating O2 as a byproduct. While numerous details of the operation of the OEC are well understood, the molecular mechanism of O=O formation remains under debate. Model complex chemistry from our group will be presented wherein we have prepared cluster systems with little or no terminal multidentate ligation in order to generate geometrically flexible and reactive clusters. Two systems will be presented: a series of Ca-Mn-O hemicubane clusters with variable calcium content, and their electrocatalytic activity in activation of water in oxidation reactions, and a Mn cubane cluster with a pendant Mn=O moiety that evolves dioxygen from an oxidation state analagous to the turnover state of the natural system 

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5. Oxygen suppression of macroscopic multicellularity

   https://doi.org/10.1038/s41467-021-23104-0  

   Bozdag, G. Ozan; Libby, Eric; Pineau, Rozenn; Reinhard, Christopher T.; Ratcliff, William C. (December 2021, Nature Communications)

   null (Ed.)

   Abstract Atmospheric oxygen is thought to have played a vital role in the evolution of large, complex multicellular organisms. Challenging the prevailing theory, we show that the transition from an anaerobic to an aerobic world can strongly suppress the evolution of macroscopic multicellularity. Here we select for increased size in multicellular ‘snowflake’ yeast across a range of metabolically-available O 2 levels. While yeast under anaerobic and high-O 2 conditions evolved to be considerably larger, intermediate O 2 constrained the evolution of large size. Through sequencing and synthetic strain construction, we confirm that this is due to O 2 -mediated divergent selection acting on organism size. We show via mathematical modeling that our results stem from nearly universal evolutionary and biophysical trade-offs, and thus should apply broadly. These results highlight the fact that oxygen is a double-edged sword: while it provides significant metabolic advantages, selection for efficient use of this resource may paradoxically suppress the evolution of macroscopic multicellular organisms. 

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