A new species of marine endolithic cyanophyte, Hyella pyxis Lukas and Hoffman (Order: Pleurocapsales), differs from other species of Hyella in its cell and filament dimensions, the manner in which its branches are initiated and the presence of gloeocapsin in the sheaths of colonies from the intertidal zone. Hyella pyxis colonies consist of a small cluster of coccoid cells located at the substrate surface and long, conspicuously branched filaments composed of cells that are longer than they are wide. Branches are initiated by the reorientation of the distal end of a filament cell or by the elongation of a filament cell, usually at one of its distal corners. Chromatic adaptation was not observed perhaps accounting for the relatively shallow depth limit of this species. Hyella pyxis was found within mollusk shells from the continental margin of eastern Florida to a depth of 50 m and carbonate rocks in the intertidal zone on Bermuda.
Freshwater content (FWC), generally characterized in the Arctic Ocean by salinities lower than 34.8 psu, has shifted in both quantity and distribution in recent decades in the Arctic Ocean. This has been largely driven by changes in the volume and salinity of freshwater sources and the direction and magnitude of major currents. In this study, we analyze the variability in FWC and other physical oceanographic variables from 1993 to 2021 in the Arctic Ocean and Beaufort Gyre (BG) using in situ and remote sensing observations and five ocean models and reanalysis products. Generally, ocean models and reanalysis products underestimate FWC in the BG when compared with observations. Modeled FWC and sea surface height (SSH) in the BG are well correlated during the time period and are similar to correlations of the observational data of these variables. ORAS5 compares best to EN4 salinity over the entire study period, although GLORYS12 agrees well pre-2007 and SODA post-2007. Outside the BG, consistency between modeled SSH, FWC, and limited observations varies between models. These comparisons help identify discrepancies in ocean model and reanalysis products while highlighting areas where future improvements are necessary to further our understanding of Arctic FWC. As observations are scarce in the Arctic, these products and their accuracy are important to studying this dynamic and vulnerable ocean.
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