Non-photosynthetic lineages sibling to Cyanobacteria associate with eukaryotes in the open ocean.

Margulisbacteria are elusive uncultivated bacteria that have illuminated evolutionary transitions in the progenitor of Cyanobacteria, the latter being a critically important phylum that underpins oxygenic photosynthesis. The non-photosynthetic Margulisbacteria were discovered in a sulfidic spring and later in other habitats. Currently, this candidate phylum partitions into the Riflemargulisbacteria, primarily from sediments and groundwater, the Termititenax from insect gut microbiomes, and the Marinamargulisbacteria, from marine samples.

Past foraminiferal acclimatization capacity is limited during future warming.

Climate change affects marine organisms, causing migrations, biomass reduction and extinctions. However, the abilities of marine species to adapt to these changes remain poorly constrained on both geological and anthropogenic timescales. Here we combine the fossil record and a global trait-based plankton model to study optimal temperatures of marine calcifying zooplankton (foraminifera, Rhizaria) through time.

Resilience of Phytoplankton and Microzooplankton Communities under Ocean Alkalinity Enhancement in the Oligotrophic Ocean.

Ocean alkalinity enhancement (OAE) is currently discussed as a potential negative emission technology to sequester atmospheric carbon dioxide in seawater. Yet, its potential risks or cobenefits for marine ecosystems are still mostly unknown, thus hampering its evaluation for large-scale application. Here, we assessed the impacts OAE may have on plankton communities, focusing on phytoplankton and microzooplankton.

Strength and timing of austral winter Angolan coastal upwelling.

The tropical Angolan upwelling system (tAUS) is a highly productive ecosystem of great socio-economic importance. Productivity peaks in austral winter and is linked to the passage of remotely forced upwelling coastal trapped waves (CTWs), where the strength of the productivity peak is associated with the amplitude of the upwelling CTW. Here, we analyze the year-to-year variability in the timing and amplitude of the austral winter upwelling CTW by examining sea surface temperature, sea level anomaly, and wind fields.

Crustose coralline algae exhibit complex responses to breakage under current and future climate scenarios.

Rising pressures from local and global stressors on marine benthic habitats require understanding of their effects on habitat forming species like Crustose Coralline Algae (CCA), which play a crucial role in ecosystem diversity and structure. Here, the impact of mechanical damage and warming on the CCA species Lithophyllum stictiforme was investigated in the Mediterranean Sea using a manipulative field transplant experiment that takes advantage of temperature variations between depths of 35 m and 15 m as proxies for current and future climate scenarios. A significant effect of mechanical damage and warming on the growth angle of the thalli was detected, while no interactive effects on the other biological traits were observed.

Competing effects of wind and buoyancy forcing on ocean oxygen trends in recent decades.

Ocean deoxygenation is becoming a major stressor for marine ecosystems due to anthropogenic climate change. Two major pathways through which climate change affects ocean oxygen are changes in wind fields and changes in air-sea heat and freshwater fluxes. Here, we use a global ocean biogeochemistry model run under historical atmospheric forcing to show that wind stress is the dominant driver of year-to-year oxygen variability in most ocean regions.

Substantial trace metal input from the 2022 Hunga Tonga-Hunga Ha'apai eruption into the South Pacific.

The January 2022 eruption of the Hunga Tonga-Hunga Ha'apai (HTHH) volcano discharged 2,900 teragrams of ejecta, most of which was deposited in the South Pacific Ocean. Here we investigate its impact on the biogeochemistry of the South Pacific Gyre (SPG) using samples collected during the GEOTRACES cruise GP21 in February-April 2022. Surface water neodymium isotopes and rare earth element compositions showed a marked volcanic impact in the western SPG, potentially extending to the eastern region.

The interplay between host-specificity and habitat-filtering influences sea cucumber microbiota across an environmental gradient of pollution.

Environmental gradients can influence morpho-physiological and life-history differences in natural populations. It is unclear, however, to what extent such gradients can also modulate phenotypic differences in other organismal characteristics such as the structure and function of host-associated microbial communities. In this work, we addressed this question by assessing intra-specific variation in the diversity, structure and function of environmental-associated (sediment and water) and animal-associated (skin and gut) microbiota along an environmental gradient of pollution in one of the most urbanized coastal areas in the world.

Marine plankton community and net primary production responding to island-trapped waves in a stratified oligotrophic ecosystem.

The oligotrophic Adriatic Sea is characterized during a typical summer by low productivity caused by strong water column stratification, which inhibits vertical mixing and nutrient supply to the euphotic zone. These conditions can be disrupted by transient physical forcing, which enhances nutrient fluxes and creates localized hotspots of relatively high net primary production. In this study, plankton abundance and diversity were investigated in relation to the physical forcing and nutrient concentrations in an area affected by island-trapped waves (ITWs) near Lastovo Island (Adriatic Sea).

Temperature overshoot responses to ambitious forestation in an Earth System Model.

Despite the increasing relevance of temperature overshoot and the rather ambitious country pledges on Afforestation/Reforestation globally, the mitigation potential and the Earth system responses to large-scale non-idealized Afforestation/Reforestation patterns under a high overshoot scenario remain elusive. Here, we develop an ambitious Afforestation/Reforestation scenario by harnessing 1259 Integrated Assessment Model scenarios, restoration potential maps, and biodiversity constraints, reaching 595 Mha by 2060 and 935 Mha by 2100. We then force the Max Planck Institute's Earth System Model with this scenario which yields a reduction of peak temperature by 0.

Deciphering the variability in air-sea gas transfer due to sea state and wind history.

Understanding processes driving air-sea gas transfer and being able to model both its mean and variability are critical for studies of climate and carbon cycle. The air-sea gas transfer velocity ( ) is almost universally parameterized as a function of wind speed in large scale models-an oversimplification that buries the mechanisms controlling and neglects much natural variability. Sea state has long been speculated to affect gas transfer, but consistent relationships from in situ observations have been elusive.

Estimating the copepod biomass in the North West African upwelling system using a bi-frequency acoustic approach.

The Canary Current Large Marine Ecosystem (CCLME) is one of the most productive Large Marine Ecosystems worldwide. Assessing the abundance, biomass and distribution of zooplankton in the southern part of this system, off the coast of West Africa, remains challenging due to limited sampling efforts and data availability. However, zooplankton is of primary importance for pelagic ecosystem functioning.

Discovery of Lacto-N-Biosidases and a Novel N-Acetyllactosaminidase Activity in the CAZy Family GH20: Functional Diversity and Structural Insights.

The glycoside hydrolase family 20 (GH20) predominantly features N-acetylhexosaminidases (EC 3.2.1.

Detection and tracking of ocean layers using an AUV with UKF based extremum seeking control in the Baltic Sea.

Adaptive sampling and situational awareness are key features of modern autonomous underwater vehicles (AUVs) since data quality can be improved while operation time and cost can be reduced. An example for adaptive sampling in the marine environmental context is thermocline detection and tracking. The thermocline as horizontal ocean layer separates warm and cold water and is a key feature in many marine disciplines.

Discharge of ballast residual sediments during de-ballasting procedures: A more realistic estimate of propagule pressure.

Ship ballast residual sediments are an important vector of introduction for non-indigenous species. We evaluated the proportion of residual sediments and associated organisms released during de-ballasting operations of a commercial bulk carrier and estimated a total residual sediment accumulation of ∼13 t, with accumulations of up to 20 cm in some tank areas that had accumulated over 11 years. We observed interior hull-fouling (anemones, hydrozoans, and bryozoans) and high abundances of viable invertebrate resting stages and dinoflagellate cysts in sediments.

Customized digestion protocols for copepods, euphausiids, chaetognaths and fish larvae facilitate the isolation of ingested microplastics.

Degradation of oceanic plastic waste leads to the formation of microplastics that are ingested by a wide range of animals. Yet, the amounts that are taken up, especially by small zooplankton, are largely unknown. This is mostly due to the complex methodology that is required for isolating ingested microplastics from organisms.

Climate challenges for fish larvae: Interactive multi-stressor effects impair acclimation potential of Atlantic herring larvae.

Fish early life stages are particularly vulnerable and heavily affected by changing environmental factors. The interactive effects of multiple climate change-related stressors on fish larvae remain, however, largely underexplored. As rising temperatures can increase the abundance and virulence of bacteria, we investigated the combination of a spring heat wave and bacterial exposure on the development of Atlantic herring larvae (Clupea harengus).

Taking stock of global fisheries.

Current stock assessment models overestimate productivity and recovery trajectory.

Extreme erosion and bulking in a giant submarine gravity flow.

Sediment gravity flows are ubiquitous agents of transport, erosion, and deposition across Earth's surface, including terrestrial debris flows, snow avalanches, and submarine turbidity currents. Sediment gravity flows typically erode material along their path (bulking), which can dramatically increase their size, speed, and run-out distance. Hence, flow bulking is a first-order control on flow evolution and underpins predictive modeling approaches and geohazard assessments.

Tracking the distribution of persistent and mobile wastewater-derived substances in the southern and central North Sea using anthropogenic gadolinium from MRI contrast agents as a far-field tracer.

The use of the rare earth element gadolinium (Gd) in contrast agents for magnetic resonance imaging has led to a significant (micro-)contamination of riverine and coastal environments in many parts of the world. This study comprises a detailed investigation on the rare earth elements and yttrium inventory of the North Sea and also reports data for the major tributaries Thames, Rhine, Ems, Weser and Elbe. We show that large parts of the southern North Sea, including the Wadden Sea UNESCO Natural World Heritage site, are (micro)contaminated with Gd from Gd-based contrast agents (GBCA).