Thermal performance of planktonic ciliates differs between marine and freshwaters: A case study providing guidance for climate change studies

Predicting the performance of aquatic organisms in a future warmer climate depends critically on understanding how current temperature regimes affect the organisms’ growth rates. Using a meta-analysis for published experimental data, we calculated the activation energy (Ea) to parameterize the thermal sensitivity of marine and freshwater ciliates, major players in marine and freshwater food webs. We hypothesized that their growth rates increase with temperature but that ciliates dwelling in the immense, thermally stable ocean are closely adapted to their ambient temperature and have lower Ea than ciliates living in smaller, thermally more variable freshwater environments. The Ea was in the range known from other taxa but significantly lower for marine ciliates (0.390 ± 0.105 eV) than for freshwater ciliates (0.633 ± 0.060 eV), supporting our hypothesis. Accordingly, models aiming to predict the ciliate response to increasing water temperature should apply the environment-specific activation energies provided in this study

Functional ecology of aquatic phagotrophic protists - Concepts, limitations, and perspectives

Special issue Current trends in protistology – results from the VII ECOP - ISOP Joint Meeting 2015.-- 25 pages, 6 figures, 1 tableFunctional ecology is a subdiscipline that aims to enable a mechanistic understanding of patterns and processes from the organismic to the ecosystem level. This paper addresses some main aspects of the process-oriented current knowledge on phagotrophic, i.e. heterotrophic and mixotrophic, protists in aquatic food webs. This is not an exhaustive review; rather, we focus on conceptual issues, in particular on the numerical and functional response of these organisms. We discuss the evolution of concepts and define parameters to evaluate predator–prey dynamics ranging from Lotka–Volterra to the Independent Response Model. Since protists have extremely versatile feeding modes, we explore if there are systematic differences related to their taxonomic affiliation and life strategies. We differentiate between intrinsic factors (nutritional history, acclimatisation) and extrinsic factors (temperature, food, turbulence) affecting feeding, growth, and survival of protist populations. We briefly consider intraspecific variability of some key parameters and constraints inherent in laboratory microcosm experiments. We then upscale the significance of phagotrophic protists in food webs to the ocean level. Finally, we discuss limitations of the mechanistic understanding of protist functional ecology resulting from principal unpredictability of nonlinear dynamics. We conclude by defining open questions and identifying perspectives for future research on functional ecology of aquatic phagotrophic protistsHA was supported by grants from the German Research Foundation (DFG; AR 288/16) and from the Federal Ministry for Education and Research (BMBF: 03G0237B; 02WRM1364D). Project FERMI (CGL2014-59227-R) was awarded to AC from the Spanish Ministry of Economy and Competitiveness. RA was supported by the the European Union's Horizon 2020 research and innovation programme (Marie Sklodowska-Curie grant agreement No 658882). PJH was supported by the Danish Council for independent Reseach, project DDF-4181-00484. TW was financially supported by the Austrian Science Fund (FWF, projects P20118-B17 and P20360-B17). DJSM received no support for his efforts on this study, other than his salary provided by the University of LiverpoolPeer Reviewe

Sources, propagation and consequences of stochasticity in cellular growth

International audienceGrowth impacts a range of phenotypic responses. Identifying the sources of growth variation and their propagation across the cellular machinery can thus unravel mechanisms that underpin cell decisions. We present a stochastic cell model linking gene expression, metabolism and replication to predict growth dynamics in single bacterial cells. Alongside we provide a theory to analyse stochastic chemical reactions coupled with cell divisions, enabling efficient parameter estimation, sensitivity analysis and hypothesis testing. The cell model recovers population-averaged data on growth-dependence of bacterial physiology and how growth variations in single cells change across conditions. We identify processes responsible for this variation and reconstruct the propagation of initial fluctuations to growth and other processes. Finally, we study drug-nutrient interactions and find that antibiotics can both enhance and suppress growth heterogeneity. Our results provide a predictive framework to integrate heterogeneous data and draw testable predictions with implications for antibiotic tolerance, evolutionary and synthetic biology

The 1st Verified Software Competition, Extended Experience Report

We, the organizers and participants, report our experiences from the 1st Veried Software Competition, held in August 2010 in Edinburgh at the VSTTE 2010 conferenc

The 1st Verified Software Competition, Extended Experience Report

We, the organizers and participants, report our experiences from the 1st Veried Software Competition, held in August 2010 in Edinburgh at the VSTTE 2010 conferenc

Recent Change—North Sea

This chapter discusses past and ongoing change in the following physical variables within the North Sea: temperature, salinity and stratification; currents and circulation; mean sea level; and extreme sea levels. Also considered are carbon dioxide; pH and nutrients; oxygen; suspended particulate matter and turbidity; coastal erosion, sedimentation and morphology; and sea ice. The distinctive character of the Wadden Sea is addressed, with a particular focus on nutrients and sediments. This chapter covers the past 200 years and focuses on the historical development of evidence (measurements, process understanding and models), the form, duration and accuracy of the evidence available, and what the evidence shows in terms of the state and trends in the respective variables. Much work has focused on detecting long-term change in the North Sea region, either from measurements or with models. Attempts to attribute such changes to, for example, anthropogenic forcing are still missing for the North Sea. Studies are urgently needed to assess consistency between observed changes and current expectations, in order to increase the level of confidence in projections of expected future conditions