Multicentennial cycles in continental demography synchronous with solar activity and climate stability.

Human population dynamics and their drivers are not well understood, especially over the long term and on large scales. Here, we estimate demographic growth trajectories from 9 to 3 ka BP across the entire globe by employing summed probability distributions of radiocarbon dates. Our reconstruction reveals multicentennial growth cycles on all six inhabited continents, which exhibited matching dominant frequencies and phase relations.

Phytoplankton and particle size spectra indicate intense mixotrophic dinoflagellates grazing from summer to winter.

Mixotrophic dinoflagellates (MTD) are a diverse group of organisms often responsible for the formation of harmful algal blooms. However, the development of dinoflagellate blooms and their effects on the plankton community are still not well explored. Here we relate the species succession of MTD with parallel changes of phytoplankton size spectra during periods of MTD dominance.

Changing readiness to mitigate SARS-CoV-2 steered long-term epidemic and social trajectories.

Societal responses crucially shape the course of a pandemic, but are difficult to predict. Mitigation measures such as social distancing are here assumed to minimize a utility function that consists of two conflicting sub-targets, the disease related mortality and the multifaceted consequences of mitigation. The relative weight of the two sub-targets defines the mitigation readiness H, which entails the political, social, and psychological aspects of decision making.

Vertical migration by bulk phytoplankton sustains biodiversity and nutrient input to the surface ocean.

Phytoplankton subsumes the great variety of unicellular photoautotrophs that perform roughly half of Earth's primary production. They achieve this despite their challenging oceanic habitat, with opposing vertical gradients of nutrients (which often limit their growth near the surface) and light (which becomes limiting with increasing depth). Most phytoplankton species are commonly assumed to be incapable of moving actively between the zones of light and nutrient availability, which are separated vertically by from 30-120 m.

Physics or biology? Persistent chlorophyll accumulation in a shallow coastal sea explained by pathogens and carnivorous grazing.

One of the most striking patterns at the land-ocean interface is the massive increase of chlorophyll-a (CHL) from continental shelves towards the coast, a phenomenon that is classically linked to physical features. Here I propose that the coastal-offshore CHL gradient in a shallow sea has biological origins related to phytoplankton mortality that are neglected in state-of-the-art biogeochemical models. I integrate a trait-based ecosystem model into a modular coupling framework that is applied to the southern North Sea (SNS).

Effect of phytoplankton size diversity on primary productivity in the North Pacific: trait distributions under environmental variability.

While most biodiversity and ecosystem functioning (BEF) studies have found positive effects of species richness on productivity, it remain unclear whether similar patterns hold for marine phytoplankton with high local richness. We use the continuous trait-based modelling approach, which assumes infinite richness and represents diversity in terms of the variance of the size distribution, to investigate the effects of phytoplankton size diversity on productivity in a three-dimensional ocean circulation model driven by realistic physics forcing. We find a slightly negative effect of size diversity on primary production, which we attribute to several factors including functional trait-environment interactions, flexible stoichiometry and the saturation of productivity at low diversity levels.

Rapid aggregation of biofilm-covered microplastics with marine biogenic particles.

Ocean plastic pollution has resulted in a substantial accumulation of microplastics in the marine environment. Today, this plastic litter is ubiquitous in the oceans, including even remote habitats such as deep-sea sediments and polar sea ice, and it is believed to pose a threat to ecosystem health. However, the concentration of microplastics in the surface layer of the oceans is considerably lower than expected, given the ongoing replenishment of microplastics and the tendency of many plastic types to float.

Intermittency in processing explains the diversity and shape of functional grazing responses.

Central to theoretical studies of trophic interactions is the formulation of the consumer response to varying food availability. Response functions, however, are only rarely derived in mechanistic ways. As a consequence, the uncertainty in the functional representation of feeding remains large, as, e.

Predator-prey dynamics driven by feedback between functionally diverse trophic levels.

Neglecting the naturally existing functional diversity of communities and the resulting potential to respond to altered conditions may strongly reduce the realism and predictive power of ecological models. We therefore propose and study a predator-prey model that describes mutual feedback via species shifts in both predator and prey, using a dynamic trait approach. Species compositions of the two trophic levels were described by mean functional traits--prey edibility and predator food-selectivity--and functional diversities by the variances.

The economy of oil spills: direct and indirect costs as a function of spill size.

As a rational basis for addressing both ecological and economic consequences of oil spills, a combination of simulating and estimating methods is proposed in this paper. An integration of the state-of-the-art oil spill contingency simulation system OSCAR with economic assessment method leads to realistic oil spill scenarios including their biological and economic impacts and the effort taken for combat as well as to an estimate for the total oil spill costs. In order to derive a simple function of total costs depending on few spill characteristics such as size, a number of hypothetical scenarios are simulated and evaluated for the German North Sea area.

Willingness to pay among households to prevent coastal resources from polluting by oil spills: a pilot survey.

In many coastal regions oil spills can be considered to be one of the most important risks for the coastal environment. Efficient contingency management in responding to oil spills is critically important. Strategic priorities in contingency management highly depend upon the importance attributed to different economic and ecological resources such as beaches or birds.

Consensus oriented fuzzified decision support for oil spill contingency management.

Studies on multi-group multi-criteria decision-making problems for oil spill contingency management are in their infancy. This paper presents a second-order fuzzy comprehensive evaluation (FCE) model to resolve decision-making problems in the area of contingency management after environmental disasters such as oil spills. To assess the performance of different oil combat strategies, second-order FCE allows for the utilization of lexical information, the consideration of ecological and socio-economic criteria and the involvement of a variety of stakeholders.

Control of biogeochemical cycling by mobility and metabolic strategies of microbes in the sediments: an integrated model study.

An integrated modeling framework was developed to assess physical, biological and chemical processes in the sediment and at the sediment-water interface. Special focus is laid on the description of different functional groups of bacteria as defined according to their metabolic pathways, including fermentation, methanogenesis and oxidation of high and low molecular mass dissolved organic carbon, ammonium as well as other reduced compounds. The model is subjected to a new validation method which allows for an appropriate representation of remaining uncertainties.

Adaptive significance of C partitioning and regulation of specific leaf area in Betula pendula.

Carbon allocation and regulation of specific leaf area (sigma) define key processes underlying the adaptation of plants to varying habitats. In this study, the general principles governing adaptation and a dynamic optimality model of plant adaptation are reviewed. The central new elements of this model are: (i) differential root carbon costs for maintaining a defined nutrient status; (ii) a simple formula for optimal sigma at steady-state as a function of nitrogen (N) status and irradiance; and (iii) generic rules for the time propagation of adapting traits.

A generic model for changes in microbial kinetic coefficients.

Acclimation patterns in kinetic coefficients clearly demonstrate the limits of Monod's theory for the mathematical description of microbial growth. Focusing on E. coli grown under variable glucose levels, these patterns turn out to be highly diverse and sometimes even contradictory.