In situ measurements of righting behavior in the common sea urchin Lytechinus variegatus: the importance of body size, substrate type, and covering material

Righting behavior has been used extensively in laboratory studies of sea urchins as an indicator of stress under various environmental conditions. In situ measurements of the natural righting response of sea urchins would serve to place such laboratory measurements in an ecological context as well as potentially validate laboratory control conditions. We investigated the righting response of the sea urchin Lytechinus variegatus in seagrass and sand bottom habitats of Saint Joseph’s Bay, Florida. Field-measured righting times (other than the exception mentioned below) in L. variegatus were similar to those measured in laboratory studies. Moreover, as seen in multiple sea urchin species in laboratory studies, smaller individuals exhibited significantly shorter righting times than larger individuals. Importantly, sea urchins lacking covering material (shell material, seagrass blades) that were placed on open sand patches took significantly longer to right than those with covering material placed on sand patches. Our field observations indicate the importance of sea urchin size, substrate type, and the presence or absence of covering materials when making righting measurements in the laboratory or the field. Our findings also suggest that higher water velocities facilitate righting, as at higher flows on sand patches, the presence/absence of covering material no longer significantly impacted righting time. These findings are ecologically important as they indicate that, under certain natural conditions (sand substrate, low availability of covering materials and low water velocities), L. variegatus that are displaced onto their aboral side are more vulnerable to predation

Role of carbonate burial in Blue Carbon budgets

Calcium carbonates (CaCO3) often accumulate in mangrove and seagrass sediments. As CaCO3 production emits CO2, there is concern that this may partially offset the role of Blue Carbon ecosystems as CO2 sinks through the burial of organic carbon (C-org). A global collection of data on inorganic carbon burial rates (C-inorg, 12% of CaCO3 mass) revealed global rates of 0.8 TgC(inorg) yr(-1) and 15-62 TgC(inorg) yr(-1) in mangrove and seagrass ecosystems, respectively. In seagrass, CaCO3 burial may correspond to an offset of 30% of the net CO2 sequestration. However, a mass balance assessment highlights that the C-inorg burial is mainly supported by inputs from adjacent ecosystems rather than by local calcification, and that Blue Carbon ecosystems are sites of net CaCO3 dissolution. Hence, CaCO3 burial in Blue Carbon ecosystems contribute to seabed elevation and therefore buffers sea-level rise, without undermining their role as CO2 sinks

Nightside clouds and disequilibrium chemistry on the hot Jupiter WASP-43b

This is the author accepted manuscript.Data Availability: The data used in this paper are associated with JWST DD-ERS program 1366 (PIs Batalha, Bean, and Stevenson; observation 11) and are publicly available from the Mikulski Archive for Space Telescopes (https://mast.stsci.edu). Additional intermediate and final results from this work are archived on Zenodo at https://zenodo.org/doi/10.5281/zenodo.10525170Hot Jupiters are among the best-studied exoplanets, but it is still poorly understood how their chemical composition and cloud properties vary with longitude. Theoretical models predict that clouds may condense on the nightside and that molecular abundances can be driven out of equilibrium by zonal winds. Here we report a phase-resolved emission spectrum of the hot Jupiter WASP-43b measured from 5–12 µm with JWST’s Mid-Infrared Instrument (MIRI). The spectra reveal a large day–night temperature contrast (with average brightness temperatures of 1524 ± 35 and 863 ± 23 Kelvin, respectively) and evidence for water absorption at all orbital phases. Comparisons with three-dimensional atmospheric models show that both the phase curve shape and emission spectra strongly suggest the presence of nightside clouds which become optically thick to thermal emission at pressures greater than ∼100 mbar. The dayside is consistent with a cloudless atmosphere above the mid-infrared photosphere. Contrary to expectations from equilibrium chemistry but consistent with disequilibrium kinetics models, methane is not detected on the nightside (2σ upper limit of 1–6 parts per million, depending on model assumptions).NASAEuropean Research Council (ERC)NSFNHFP Sagan Fellowship ProgramAustrian Science Fund (FWF)Science and Technology Facilities Council (STFC)KU LeuvenEuropean Union Horizon 2020FWOANRCentre National d’Etudes Spatiales (CNES