In recent years fish-kill events caused by oxygen deficit have been reported in Eckernförde Bight (Baltic Sea). This study sets out to understand the processes causing respective oxygen deficits by combining high-resolution coupled ocean circulation biogeochemical modeling, monitoring data, and artificial intelligence.

Using data collected during two expeditions to the South Atlantic Ocean, we investigated how the interaction between external sources and biological activity influenced the availability of the trace metals zinc and cobalt. This is important as both metals play essential roles in the metabolism and growth of phytoplankton and thus influence primary productivity of the oceans. We found seasonal changes in both processes that helped explain upper-ocean trace metal cycling.

The Gulf of Mexico deep waters are relatively poor in phytoplankton biomass due to low levels of nutrients in the upper layers. Using modeling techniques, we find that the long-living anticyclonic Loop Current eddies that are shed episodically from the Yucatan Channel strongly shape the distribution of phytoplankton and, more importantly, stimulate their growth. This results from the contribution of multiple mechanisms of physical–biogeochemical interactions discussed in this study.

Upwelling of nutrient-rich deep waters to the surface make eastern boundary upwelling systems hot spots of marine productivity. This leads to subsurface oxygen depletion and the transformation of bioavailable nitrogen into inert N₂. Here we quantify nitrogen loss processes following a simulated deep water upwelling. Denitrification was the dominant process, and budget calculations suggest that a significant portion of nitrogen that could be exported to depth is already lost in the surface ocean.

An alarming consequence of climate change is the oceanic primary production decline projected by Earth system models. These coarse-resolution models parameterize oceanic eddies. Here, idealized simulations of global warming with increasing resolution show that the decline in primary production in the eddy-resolved simulations is half as large as in the eddy-parameterized simulations. This stems from the high sensitivity of the subsurface nutrient transport to model resolution.

The bacteria carried by winds over the island of Sardinia in the Mediterranean Sea were collected, and their identities were investigated by reading DNA sequences. The sampling period was the factor that most determined the airborne species composition as its role was stronger than that of dust-carrying storms and of the geographical position of the sampling station. The bacteria found when the sampling was performed in September had more species variety than those collected in May.

Microbially produced methane can serve as a carbon source for freshwater macrofauna most likely through grazing on methane-oxidizing bacteria. This study investigates the contributions of different carbon sources to macrofaunal biomass. Our data suggest that the average contribution of methane-derived carbon is similar between different fauna but overall remains low. This is further supported by the low abundance of methane-cycling microorganisms.

We incorporate a new representation of the stable carbon isotope ¹³C in a global ocean biogeochemistry model. The model well reproduces the present-day ¹³C observations. We find a recent observation-based estimate of the oceanic ¹³C Suess effect (the decrease in ¹³C/¹²C ratio due to uptake of anthropogenic CO₂; ¹³C_SE) possibly underestimates ¹³C_SE by 0.1–0.26 per mil. The new model will aid in better understanding the past ocean state via comparison to ¹³C/¹²C measurements from sediment cores.

The formation of ice in clouds is critically important for the planet's climate. Hence, we need to know which aerosol types nucleate ice and how effectively they do so. Here we show that virus particles, with a range of architectures, nucleate ice when immersed in supercooled water. However, we also show that they only make a minor contribution to the ice-nucleating particle population in the terrestrial atmosphere, but we cannot rule them out as being important in the marine environment.

Satellite images show that the Amazon forest has greened up during past droughts. Measurements of tree stem growth and leaf litterfall upscaled using machine-learning algorithms show that leaf flushing at the onset of a drought results in canopy rejuvenation and green-up during drought while simultaneously trees excessively shed older leaves and tree stem growth declines. Canopy green-up during drought therefore does not necessarily point to enhanced tree growth and improved forest health.

We present an approach for ensuring the definitions of plant types in dynamic vegetation models are connected to the underlying ecological processes controlling community composition. Our approach can be applied regionally or globally. Robust resolution of community composition will allow us to use these models to address important questions related to future climate and management effects on plant community composition, structure, carbon storage, and feedbacks within the Earth system.