Picophytoplankton prevail year-round in the Elbe estuary.

Picophytoplankton are important primary producers, but not always adequately recognized, for example, due to methodological limitations. In this study, we combined flow cytometry and metabarcoding to investigate seasonal and spatial patterns of picophytoplankton abundance and community composition in the Elbe estuary. Due to the mixing of freshwater and seawater and the tidal currents this ecosystem is characterized by typical estuarine features such as salinity gradients and high turbidity.

Metabarcoding reveals potentially mixotrophic flagellates and picophytoplankton as key groups of phytoplankton in the Elbe estuary.

In estuaries, phytoplankton are faced with strong environmental forcing (e.g. high turbidity, salinity gradients).

Organic compounds drive growth in phytoplankton taxa from different functional groups.

Phytoplankton are usually considered autotrophs, but an increasing number of studies show that many taxa are able also to use organic carbon. Acquiring nutrients and energy from different sources might enable an efficient uptake of required substances and provide a strategy to deal with varying resource availability, especially in highly dynamic ecosystems such as estuaries. In our study, we investigated the effects of 31 organic carbon sources on the growth (proxied by differences in cell counts after 24 h exposure) of 17 phytoplankton strains from the Elbe estuary spanning four functional groups.

Water safety planning for healthcare facilities for extreme events.

Disasters such as the Ahr Valley flood in 2021 make us aware of the importance of functioning healthcare facilities. Their functionality depends on the availability of drinking water. Water safety planning is a long-established method to increase the safety of water utilities.

Digesters as heat storage: Effects of the digester temperature on the process stability, sludge liquor quality, and the dewaterability.

Variation of the digester temperature during the year enables the operation of digesters as seasonal heat storage contributing to a holistic heat management at water resource recovery facilities. Full- and lab-scale process data were conducted to examine the effect of the digester temperature on process stability, sludge liquor quality, and dewaterability. Both full- and lab-scale digesters show a stable anaerobic degradation process with a hydraulic retention time of more than 20 days and organic load rates up to 2.

Seasonality and Strain Specificity Drive Rapid Co-evolution in an Ostreococcus-Virus System from the Western Baltic Sea.

Marine viruses are a major driver of phytoplankton mortality and thereby influence biogeochemical cycling of carbon and other nutrients. Phytoplankton-targeting viruses are important components of ecosystem dynamics, but broad-scale experimental investigations of host-virus interactions remain scarce. Here, we investigated in detail a picophytoplankton (size 1 µm) host's responses to infections by species-specific viruses from distinct geographical regions and different sampling seasons.

Above and belowground traits impacting transpiration decline during soil drying in 48 maize (Zea mays) genotypes.

Background And Aims: Stomatal regulation allows plants to promptly respond to water stress. However, our understanding of the impact of above and belowground hydraulic traits on stomatal regulation remains incomplete. The objective of this study was to investigate how key plant hydraulic traits impact transpiration of maize during soil drying.

Prequalification of flotation sludge for a sustainable increase in biogas production and in regard of demand-driven feeding strategy.

Co-substrates can increase gas production in a digester significantly. The characteristic properties of substrates, depending on the amounts added, influence the processes in the digester reactor. As a consequence, they can have an impact on the buffer capacity, pH value, C:N ratio, dewaterability of the digested sludge and introduce contaminants to the digester among others.

Evolution of thermal tolerance and phenotypic plasticity under rapid and slow temperature fluctuations.

Global warming is associated with an increase in sea surface temperature and its variability. The consequences of evolving in variable, fluctuating environments are explored by a large body of theory: when populations evolve in fluctuating environments the frequency of fluctuations determines the shapes of tolerance curves (indicative of habitats that organisms can inhabit) and trait reaction norms (the phenotypes that organisms display across these environments). Despite this well-established theoretical backbone, predicting how trait and tolerance curves will evolve in organisms at the foundation of marine ecosystems remains a challenge.

Growth strategies of a model picoplankter depend on social milieu and CO.

Phytoplankton exist in genetically diverse populations, but are often studied as single lineages (single strains), so that interpreting single-lineage studies relies critically on understanding how microbial growth differs with social milieu, defined as the presence or absence of conspecifics. The properties of lineages grown alone often fail to predict the growth of these same lineages in the presence of conspecifics, and this discrepancy points towards an opportunity to improve our understanding of the factors that affect lineage growth rates. We demonstrate that different lineages of a marine picoplankter modulate their maximum lineage growth rate in response to the presence of non-self conspecifics, even when resource competition is effectively absent.

Determination of large microplastics: wet-sieving of dewatered digested sludge, co-substrates, and compost.

Dewatered digested sludge and compost may act as a conduit for microplastics (<5 mm) in terrestrial and subsequently aquatic systems. However, standardized methods for microplastics analyses are lacking. Thus, the aim is to demonstrate the applicability of wet-sieving as a way to quantify large microplastic particles (MPP, 1-5 mm) in dewatered digested sludge and compost.

Towards circular phosphorus: The need of inter- and transdisciplinary research to close the broken cycle.

Phosphorus (P) is an essential element to all living beings but also a finite resource. P-related problems center around broken P cycles from local to global scales. This paper presents outcomes from the 9th International Phosphorus Workshop (IPW9) held 2019 on how to move towards a sustainable P management.

Acclimation and adaptation to elevated pCO increase arsenic resilience in marine diatoms.

Arsenic pollution is a widespread threat to marine life, but the ongoing rise pCO levels is predicted to decrease bio-toxicity of arsenic. However, the effects of arsenic toxicity on marine primary producers under elevated pCO are not well characterized. Here, we studied the effects of arsenic toxicity in three globally distributed diatom species (Phaeodactylum tricornutum, Thalassiosira pseudonana, and Chaetoceros mulleri) after short-term acclimation (ST, 30 days), medium-term exposure (MT, 750 days), and long-term (LT, 1460 days) selection under ambient (400 µatm) and elevated (1000 and 2000 µatm) pCO.

Functional redundancy in natural pico-phytoplankton communities depends on temperature and biogeography.

Biodiversity affects ecosystem function, and how this relationship will change in a warming world is a major and well-examined question in ecology. Yet, it remains understudied for pico-phytoplankton communities, which contribute to carbon cycles and aquatic food webs year-round. Observational studies show a link between phytoplankton community diversity and ecosystem stability, but there is only scarce causal or empirical evidence.

Evolutionary temperature compensation of carbon fixation in marine phytoplankton.

The efficiency of carbon sequestration by the biological pump could decline in the coming decades because respiration tends to increase more with temperature than photosynthesis. Despite these differences in the short-term temperature sensitivities of photosynthesis and respiration, it remains unknown whether the long-term impacts of global warming on metabolic rates of phytoplankton can be modulated by evolutionary adaptation. We found that respiration was consistently more temperature dependent than photosynthesis across 18 diverse marine phytoplankton, resulting in universal declines in the rate of carbon fixation with short-term increases in temperature.

Residues from the dairy industry as co-substrate for the flexibilization of digester operation.

Water resource recovery facilities (WRRF) can make an important contribution to increase the share of renewable energies in Germany. In this context, it is important to utilize unused digester capacities on WRRF. In addition, a demand-orientated biogas production could synchronize electricity demand and electricity generation and improve the overall energetic balance of the WRRF.

Phytoplankton adaptation in ecosystem models.

We compare two different approaches to model adaptation of phytoplankton through trait value changes. Both consider mutation and selection (MuSe) but differ with respect to the underlying conceptual framework. The first one (MuSe-IBM) explicitly considers a population of individuals that are subject to random mutation during cell division.

Role of carbon allocation efficiency in the temperature dependence of autotroph growth rates.

Relating the temperature dependence of photosynthetic biomass production to underlying metabolic rates in autotrophs is crucial for predicting the effects of climatic temperature fluctuations on the carbon balance of ecosystems. We present a mathematical model that links thermal performance curves (TPCs) of photosynthesis, respiration, and carbon allocation efficiency to the exponential growth rate of a population of photosynthetic autotroph cells. Using experiments with the green alga, , we apply the model to show that the temperature dependence of carbon allocation efficiency is key to understanding responses of growth rates to warming at both ecological and longer-term evolutionary timescales.

Publisher Correction: Environmental fluctuations accelerate molecular evolution of thermal tolerance in a marine diatom.

The PDF version of this Article was updated shortly after publication following an error which resulted in the Φ symbol being omitted from the left hand side of equation 8. The HTML version was correct from the time of publication.

Environmental fluctuations accelerate molecular evolution of thermal tolerance in a marine diatom.

Diatoms contribute roughly 20% of global primary production, but the factors determining their ability to adapt to global warming are unknown. Here we quantify the capacity for adaptation to warming in the marine diatom Thalassiosira pseudonana. We find that evolutionary rescue under severe (32 °C) warming is slow, but adaptation to more realistic scenarios where temperature increases are moderate (26 °C) or fluctuate between benign and severe conditions is rapid and linked to phenotypic changes in metabolic traits and elemental composition.

Metabolic traits predict the effects of warming on phytoplankton competition.

Understanding how changes in temperature affect interspecific competition is critical for predicting changes in ecological communities with global warming. Here, we develop a theoretical model that links interspecific differences in the temperature dependence of resource acquisition and growth to the outcome of pairwise competition in phytoplankton. We parameterised our model with these metabolic traits derived from six species of freshwater phytoplankton and tested its ability to predict the outcome of competition in all pairwise combinations of the species in a factorial experiment, manipulating temperature and nutrient availability.

Temperature-driven selection on metabolic traits increases the strength of an algal-grazer interaction in naturally warmed streams.

Trophic interactions are important determinants of the structure and functioning of ecosystems. Because the metabolism and consumption rates of ectotherms increase sharply with temperature, there are major concerns that global warming will increase the strength of trophic interactions, destabilizing food webs, and altering ecosystem structure and function. We used geothermally warmed streams that span an 11°C temperature gradient to investigate the interplay between temperature-driven selection on traits related to metabolism and resource acquisition, and the interaction strength between the keystone gastropod grazer, Radix balthica, and a common algal resource.

The Temperature Dependence of Phytoplankton Stoichiometry: Investigating the Roles of Species Sorting and Local Adaptation.

The elemental composition of phytoplankton (C:N:P stoichiometry) is a critical factor regulating nutrient cycling, primary production and energy transfer through planktonic food webs. Our understanding of the multiple direct and indirect mechanisms through which temperature controls phytoplankton stoichiometry is however incomplete, increasing uncertainty in the impacts of global warming on the biogeochemical functioning of aquatic ecosystems. Here, we use a decade-long warming experiment in outdoor freshwater ponds to investigate how temperature-driven turnover in species composition and shifts in stoichiometric traits within species through local thermal adaptation contribute to the effects of warming on seston stoichiometry.

Adaptation of phytoplankton to a decade of experimental warming linked to increased photosynthesis.

Phytoplankton photosynthesis is a critical flux in the carbon cycle, accounting for approximately 40% of the carbon dioxide fixed globally on an annual basis and fuelling the productivity of aquatic food webs. However, rapid evolutionary responses of phytoplankton to warming remain largely unexplored, particularly outside the laboratory, where multiple selection pressures can modify adaptation to environmental change. Here, we use a decade-long experiment in outdoor mesocosms to investigate mechanisms of adaptation to warming (+4 °C above ambient temperature) in the green alga Chlamydomonas reinhardtii, in naturally assembled communities.