Explore the vast range of titles available.

Long-duration spaceflight induces changes to the brain and cerebrospinal fluid compartments and visual acuity problems known as spaceflight-associated neuro-ocular syndrome (SANS). The clinical relevance of these changes and whether they equally affect crews of different space agencies remain unknown. We used MRI to analyze the alterations occurring in the perivascular spaces (PVS) in NASA and European Space Agency astronauts and Roscosmos cosmonauts after a 6-mo spaceflight on the International Space Station (ISS). We found increased volume of basal ganglia PVS and white matter PVS (WM-PVS) after spaceflight, which was more prominent in the NASA crew than the Roscosmos crew. Moreover, both crews demonstrated a similar degree of lateral ventricle enlargement and decreased subarachnoid space at the vertex, which was correlated with WM-PVS enlargement. As all crews experienced the same environment aboard the ISS, the differences in WM-PVS enlargement may have been due to, among other factors, differences in the use of countermeasures and high-resistive exercise regimes, which can influence brain fluid redistribution. Moreover, NASA astronauts who developed SANS had greater pre- and postflight WM-PVS volumes than those unaffected. These results provide evidence for a potential link between WM-PVS fluid and SANS.

Long-duration spaceflight induces detrimental changes in human physiology. Its residual effects and mechanisms remain unclear. We prospectively investigated the changes in cerebrospinal fluid (CSF) volume of the brain ventricular regions in space crew by means of a region of interest analysis on structural brain scans. Cosmonaut MRI data were investigated preflight (n = 11), postflight (n = 11), and at long-term follow-up 7 mo after landing (n = 7). Post hoc analyses revealed a significant difference between preflight and postflight values for all supratentorial ventricular structures, i.e., lateral ventricle (mean % change ± SE = 13.3 ± 1.9), third ventricle (mean % change ± SE = 10.4 ± 1.1), and the total ventricular volume (mean % change ± SE = 11.6 ± 1.5) (all P < 0.0001), with higher volumes at postflight. At follow-up, these structures did not quite reach baseline levels, with still residual increases in volume for the lateral ventricle (mean % change ± SE = 7.7 ± 1.6; P = 0.0009), the third ventricle (mean % change ± SE = 4.7 ± 1.3; P = 0.0063), and the total ventricular volume (mean % change ± SE = 6.4 ± 1.3; P = 0.0008). This spatiotemporal pattern of CSF compartment enlargement and recovery points to a reduced CSF resorption in microgravity as the underlying cause. Our results warrant more detailed and longer longitudinal follow-up. The clinical impact of our findings on the long-term cosmonauts’ health and their relation to ocular changes reported in space travelers requires further prospective studies.

The Antarctic Slope Current (ASC) plays a crucial role in modulating the transport of warm Circumpolar Deep Water onto the continental shelves, influencing ice shelf melting and Antarctic ice sheet mass balance. However, our understandings of the ASC variability and its driving mechanisms remain limited due to observational constraints in the Antarctic region. This study investigates the seasonal variability of the ASC in the Cosmonaut Sea, East Antarctica, focusing on the observed spring weakening of the ASC and its underlying mechanisms. The spring weakening of the ASC is shown to be linked to reduced wind‐driven poleward Ekman transport, which induces a seesaw shift in sea surface height and a subsequent adjustment in the isopycnal structure across the continental slope. Our findings emphasize the importance of understanding the dynamical processes modulating the ASC's strength for assessing future Antarctic ice sheet mass loss and its contribution to global sea level rise.

Planktonic ciliates are important components of microzooplankton in marine pelagic ecosystems. However, the study of planktonic ciliate distribution in different water masses of the Southern Ocean was scarce. We investigated planktonic ciliate distribution in different water masses of the Cosmonaut and Cooperation Seas during December 6, 2019 to January 6, 2020. Tintinnids contributed 5.97% and 3.65% to total planktonic ciliate abundance and biomass, respectively. Both total planktonic ciliate and aloricate ciliate abundances were highest in the Winter Water (WW), while tintinnid abundance was highest in the Summer Surface Water (SSW). The biomasses of total planktonic ciliates and aloricate ciliates were highest in SSW, while that of tintinnids was highest in WW. The lowest values were all observed in the Circumpolar Deep Water (CDW). Fourteen tintinnid species were grouped into three types based on their distribution characteristics: Type I (Amphorellopsis quinquealata, Codonellopsis gaussi, Cymatocylis antarctica, Cymatocylis cf. calyciformis, Cymatocylis cf. convallaria, Salpingella faurei, and Salpingella sp.) species distributed in all the water masses; Type II species (Cymatocylis cf. cristallina, Cymatocylis cf. drygalskii, and Laackmanniella naviculaefera) were found in SSW and WW; and Type III species (Amphorides laackmanni, S. costata, S. laackmanni, and one undefined species) were restricted to WW and CDW. Our results characterize the distribution patterns and influencing factors of planktonic ciliates in different water masses in the Cosmonaut and Cooperation Seas, which will be helpful to understand the pelagic assemblage variation and constitute a baseline for studying the marine food web variation in the Antarctic Zone of the Southern Ocean.

For NASA astronauts Suni Williams and Butch Wilmore, the long wait to return to Earth is almost over. They went to the International Space Station last June in a Boeing Starliner spacecraft. They were supposed to return a week later, but because of problems with the Starliner, they've stayed at the station for over 250 days. Amna Nawaz discussed more with Williams, Wilmore and crewmate Nick Hague.

Myctophid fishes represent an important trophic link between zooplankton and higher trophic level predators in the oceanic ecosystems of the Southern Ocean. The Antarctic lanternfish (Electrona antarctica) is one of the most abundant myctophids in the Southern Ocean; however, information on their feeding habits is sparse, representing a key area of uncertainty in efforts to model Southern Ocean food web dynamics. Using a classification tree approach based on stomach content data, we explored the feeding strategy of E. antarctica in the Amundsen and Cosmonaut Seas during January and March 2021, as well as its variation in relation to ontogenetic stage and sampling area. An ontogenetic shift in the feeding preference of E. antarctica was identified in the Cosmonaut Sea: Fish smaller than 48 mm fed on ostracods and copepods, while larger fish (SL > 62 mm) relied primarily on krill. Conversely, there was no ontogenetic shift in the diet of E. antarctica in the Amundsen Sea, and this species feeds almost exclusively on Themisto gaudichaudii. The diet composition of E. antarctica presented spatial differences: Copepods (48% IRI) and krill (24% IRI) were consumed more in the Cosmonaut Sea, while amphipods (91% IRI) were consumed more in the Amundsen Sea. The spatial differences in the prey of E. antarctica are related to the oceanographic environment and the variety of plankton prey in different regions. We determined that the size of E. antarctica, sea surface temperature (SST), latitude, and chlorophyll-a concentration (Chl) were the most important variables associated with dietary differences. When the fish size is larger than 55 mm and the krill abundance is high, E. antarctica mainly preys on krill. Since E. antarctica occupies a key position in the mesopelagic fish community, increased knowledge of the trophic ecology of this fish would contribute to a comprehensive understanding of its response to environmental changes.

A free-fall baited camera lander was launched for the first time on the Cosmonaut Sea shelf of East Antarctica at a depth of 694 m during the 38th Chinese National Antarctic Research Expedition (CHINARE) in 2022. We identified 31 unique taxa (23 were invertebrates and eight were fish) belonging to eight phyla from 2403 pictures and 40 videos. The Antarctic jonasfish (Notolepis coatsi) was the most frequently observed fish taxa. Ten species of vulnerable marine ecosystem (VME) taxa were observed, accounting for 32% of all species. The maximum number (MaxN) of Natatolana meridionalis individuals per image frame was ten, and they were attracted to the bait. The macrobenthic community type were sessile suspension feeders with associated fauna (SSFA), which was shaped by the muddy substrata with scattered rocks. Rocks served as the best habitats for sessile fauna. The study reveals the megafauna community and their habitat by image survey in the Cosmonaut Sea for the first time. It helped us obtain Antarctic biodiversity baselines and monitoring data for future ecosystem health assessment and better protection.

The Cosmonaut Sea is an under-studied area and a “white spot” for macrobenthos research. Here, we report on the species diversity and community structure of macrobenthos collected using tringle trawls on the 38th Chinese National Antarctic Research Expedition (CHINARE) in the Cosmonaut Sea, East Antarctica. A total of 11 tringle trawls were deployed at different depths across the shelf, slope and seamount of the Cosmonaut Sea. A total of 275 macrobenthic species were found from 207 to 1994 m. The species richness per station varied from 23 to 89. Echinoderms (100 species), arthropods (48 species) and mollusks (36 species) were the most dominant groups. Echinoderms and arthropods dominated in abundance at seamount stations, and echinoderms, arthropods and polychaetes dominated in abundance at slope stations, while bryozoans, corals, ascidians and sponges were abundant on the Cosmonaut Sea shelf. Depth was the major driving force influencing the distribution of macrobenthos. The main components were two core communities. One was dominated by sessile suspension feeders and associated fauna. Variants of this community include sponges and bryozoans. The other core community was dominated by mobile deposit feeders, infauna and grazers–epifauna, which included arthropods and echinoderms. The results showed that the slope (40–50° E, 65–67° S) of the Cosmonaut Sea may be an important area with complex ecological processes. The results of this study contribute to the knowledge of species diversity and communities of macrobenthos in the Cosmonaut Sea and provide monitoring data for future ecosystem health assessments and better protection.

Studies on the demersal fish composition of the East Antarctic nearshore region are very scarce due to the harsh physical geography of the East Antarctic region, which is covered in ice and snow year round, leading to a scarcity of scientific surveys. Based on the data from the bottom trawl survey conducted by the 37–38th Chinese National Antarctic Research Expedition (CHINARE) program in the Cosmonaut Sea, East Antarctica, the species of demersal fishes were identified, and the demersal fish composition and the characteristics of depth distribution were examined and analyzed. The basic biological information of highly abundant species was analyzed. The results from 97 individuals sampled within 30–60° E, south of −65° S, indicate that the fishes belong to 5 orders, 11 families, 19 genera, and 23 species. Most of the species are found in Myctophidae and Bathydraconidae, and the most common species is Macrourus whitsoni (Macrouridae). Macrourus whitsoni and Prionodraco evansii have a high abundance in the survey. Macrourus whitsoni has body lengths of 144–662 mm and body weights of 17.3–1425.1 g, and Prionodraco evansii has body lengths of 90.18–134.33 mm and body weights of 4.9–20.7 g. The length–weight relationships for Macrourus whitsoni and Prionodraco evansii are y=0.00002x2.748 and y=0.000006x3.353, respectively. All the Macrourus whitsoni samples were found in waters deeper than 1000 m, with the highest number of individuals captured at depths of 1500–2000 m. Prionodraco evansii was found only at stations less than 250 m deep. These results complement the demersal fish composition and distribution data of the Cosmonaut Sea, East Antarctica. These data can provide valuable basic information for characterizing regional assemblages and delineating zoogeographic boundaries.