Recent  

The present study reported on diel variations of planktonic ciliate community structure in the nSCS and tWP, and ciliate do preformed diel vertical migrations. In both the nSCS and tWP, abundance proportions of large size-fraction aloricate ciliates in night were higher than in day. While for tintinnids, abundance proportion of large lorica oral diameter in night were lower than in day.

In order to better reconstruct the geologic history of the North Water Polynya, we provide modern validations and calibrations of lipid biomarker proxies in Baffin Bay. We find that sterols, rather than HBIs, most accurately capture the current extent of the North Water Polynya and will be a valuable tool to reconstruct its past presence/absence. Our local temperature calibrations for GDGTs and OH-GDGTs reduce the uncertainty present in global temperature calibrations.

Climate change is causing extensive permafrost degradation and nutrient releases into rivers with great ecological impacts on the Arctic Ocean. We focused on nitrogen (N) release from this degradation and associated cycling using N isotopes, an understudied area. Many N species are released at degradation sites with exchanges between species. N inputs from permafrost degradation and seasonal river nitrogen trends were identified using isotopes, helping to predict climate change impacts.

By monitoring the concentration and Δ¹⁷O of stream nitrate in three forested streams, the new nitrogen saturation index of forested catchments (M_atm / D_atm ratio) was estimated. We found that (1) the unprocessed atmospheric nitrate in our studied forested stream (FK1 catchment) was the highest ever reported in forested streams, (2) the M_atm / D_atm ratio can be used as a robust index for evaluating nitrogen saturation in forested catchments as the M_atm / D_atm ratio is independent of the precipitation.

Warming is expected to increase rates of microbial metabolism, but the effect of warming on nutrient demand is unclear. Our experiments demonstrate that microbial nutrient uptake increases less with temperature than metabolism, particularly when environmental nutrient concentrations are low. However, our simulation models suggest that warming may actually lead to declines in ecosystem-scale nutrient uptake as warming accelerates the depletion of carbon substrates required for microbial growth.

We determine the effect that years of extraction has on CO₂ and CH₄ emissions from an actively extracted peatland. Peatlands had high net C emissions in the first years after opening and then declined to half the initial value for several decades. Findings contribute to knowledge on the atmospheric burden that results from these activities, as well as being of use to industry in their life cycle reporting and government agencies responsible for GHG accounting and policy.

Chemical reactions in river sediments influence how clean the water is and how much greenhouse gas comes out of a river. Our study investigates why some sediments have higher rates of chemical reactions than others. We find that to achieve high rates, sediments need to have two things: only a few different kinds of molecules, but a lot of them. This result spans about 80 rivers such that it could be a general rule helpful for predicting the future of rivers and our planet.

The majority of river studies focuses on headwater or floodplain systems, while often neglecting intermediate river segments. Our study on the subalpine Sihl River bridges the gap between streams and lowlands and demonstrates that moderately steep river segments are areas of significant instream transformation, modulating the export of organic carbon over short distances.

The behaviour of natural systems is now very often represented through mathematical models. These models represent our understanding of how the nature works. Of course, the nature doesn't care about our understanding. Since our understanding is not perfect, evaluating models is challenging and there are uncertainties. This manuscript illustrates this uncertainty for land models and argues that evaluating models in the light of uncertainty in various components provides useful information.

Tundra wildfires are increasing in frequency and severity with climate change. We show using a combination of field measurements and computational modeling that tundra wildfires result in a positive feedback to climate change by emitting significant amounts of long-lived greenhouse gasses. With these effects, attention to tundra fires is necessary for mitigating climate change.

Mollusk shells are valuable recorders of climate and environmental changes of the past down to a daily resolution. To explore this potential, we measured changes in the composition of shells of two types of bivalves recorded at the hourly scale: The king scallop Pecten maximus, and giant clams (Tridacna) that have engage in photosymbiosis. We find that photosymbiosis produces more day-night fluctuation in shell chemistry, but that most of the variation is not periodic, perhaps recording weather.

Anthropogenic climate change will influence marine phytoplankton over the coming century. Here, we quantify the influence of anthropogenic climate change on marine phytoplankton variance using an Earth System Model ensemble, identifying a decline in global phytoplankton biomass variance with warming. Our results suggest that climate mitigation efforts that account for marine phytoplankton changes should also consider changes in phytoplankton variance driven by anthropogenic warming.

Social hibernation of animals is one of the most important physiological and ecological behaviours. The purpose of the study was the investigation of the influence of the roostsite climate parameters: temperature (T), humidity (Rh) and air flow velocity (v) on the clustering of the Barbastella barbastellus (western barbastelle) during hibernation. The quantile linear regression method was used for the statistical analysis of the results.

Fe and P are key factors controlling biogeography and activity of marine N₂-fixing microorganisms. We found lower abundance and activity of N₂ fixers in the northern South China Sea than around the western boundary of the North Pacific, and N₂ fixation rates switching from Fe-P co-limitation to P limitation. We hypothesize the importance of the Fe supply rates and its utilization strategies of each N₂ fixer in regulating spatial variability in community structure across the study area.

Quantifying the role of soils in nature-based solutions require accurate estimates of soil greenhouse gas (GHG) fluxes. We propose a novel optimization approach (i.e., temporal univariate Latin Hypercube sampling) that can be applied across ecosystems to improve monitoring efforts and reduce biased estimates across time. Our results have implications for assessing GHG fluxes from soils and consequently reduce uncertainty on the role of soils in nature-based solutions.

Experiments we conducted show that the carbonate inventory of Aegean seawater is in part not in exchange with atmospheric CO₂. This "background" reservoir makes up around 78 % of the total carbon in Aegean Seawater. This means that only 22 % of the dissolved inorganic carbon is in equilibrium with the atmosphere and is thus able to buffer anthropogenic CO₂. Based on our results it can be calculated that the buffer capacity for CO₂ in Aegean seawater will be reduced by 50 % by the year 2100.

The effects of sky conditions on ecosystem productivity over wetlands received little attention. Based on eddy covariance measurements during 2016–2020, we explored the impact of sky conditions on net ecosystem productivity (NEP) over an alpine marsh wetland in southwest China. We found diffuse radiation played a critical role in the variations of NEP, and gloomier sky condition was conducive to increasing apparent quantum yield and NEP.

Bacteria use extracellular enzymes to cut large organic matter to sizes small enough for uptake. We compared the enzymatic response of surface, midwater, and deep ocean bacteria to complex natural substrates. Bacteria in surface and mid-depth waters produced a much wider range of enzymes than those in the deep ocean, and may therefore consume a broader range of organic matter. The extent to which organic matter is recycled by bacteria depends in part on its residence time at different depths.

Recently, ocean alkalinity enhancement (OAE) has gained interest as a scalable way to address the urgent need for negative CO₂ emissions. In this paper we examine the capacity of different coastlines to tolerate alkalinity enhancement and the timescale of CO₂ uptake following the addition of a given quantity of alkalinity. The results suggest that OAE has significant potential and identify specific favorable and unfavorable coastlines for its deployment.

The oceans are both source and sink for trace gases important for atmospheric chemistry and marine ecology. Here, we quantified selected trace gases (including the biological metabolites DMS, methanethiol and isoprene) along a 2500 km transect from the north Atlantic to the Arctic Ocean. In context of phytoplankton and bacterial communities, our study suggests that methanethiol (rarely measured before) might substantially influence ocean-atmosphere cycling.

Ocean upwelling regions are highly productive. With ocean warming, severe changes in upwelling frequency and/or intensity and expansion of accompanying oxygen minimum zones are projected. In a field experiment off Peru, we investigated how different upwelling intensities affect the pelagic food web and found failed reproduction of dominant zooplankton. Therefore, changes projected could severely impact reproductive success of zooplankton communities and the pelagic food web in upwelling regions.

Water-soluble organic nitrogen (WSON) in marine aerosols is important for biogeochemical cycling of bioelements. Our shipboard measurements suggested that reactive nitrogen produced and exuded by nitrogen-fixing microorganisms in surface seawater, likely contributed to the formation of WSON aerosols in the subtropical North Pacific. This study provides new implications for the role of marine microbial activity in the formation of WSON aerosols in the ocean surface.

Organic matter (OM) turnover into dissolved inorganic carbon (DIC) was investigated by means of carbon isotope mass balances in Germany´s largest water reservoir. This includes a Metalimnetic Oxygen Minimum (MOM). Autochthonous particulate organic carbon (POC) was the main contributor to DIC, with rates that were highest for the MOM. Generally low turnover rates outline the environmental fragility of this water body in case OM loads increase by storm events or land use changes.

This is the first study conducted on monumental olive trees in a non-contaminated site of the MENA region and followed at a monthly basis over 18 months. Findings of our study indicate a higher uptake of Hg in the olive foliage compared other tissues and a remarkable Hg seasonal variation in foliage in the studied sites. The main source of foliage Hg is the atmospheric Hg and the main factor explaining the seasonality is due to the photosynthetic activity and stomatal conductance of olive.

The Changjiang is the main terrestrial source of nutrients to the East China Sea (ECS). Nutrient delivery to the ECS has been increasing since the 1960s resulting in low oxygen (hypoxia) during phytoplankton decomposition in summer. River phosphorus (P) has increased less than nitrogen and therefore, despite the large nutrient delivery, phytoplankton growth can be limited by the lack of P. Here, we investigate this link between P limitation, phytoplankton production/decomposition and hypoxia.