Streams of data from drops of water: 21st century molecular microbial ecology

Microorganisms are ubiquitous and represent a taxonomically and functionally diverse component of freshwater environments of significant ecological importance. The bacteria, archaea, and microbial eukarya in freshwater systems support a range of ecosystem processes and functions, including mediating all major biogeochemical cycles, and therefore regulate the flow of multiple ecosystem services. Yet relative to conspicuous higher taxa, microbial ecology remains poorly understood. As the anthropocene progresses, the demand for freshwater–ecosystem services is both increasing with growing human population density, and by association, increasingly threatened from multiple and often interacting stressors, such as climate change, eutrophication, and chemical pollution. Thus, it is imperative to understand the ecology of microorganisms and their functional role in freshwater ecosystems if we are to manage the future of these environments effectively. To do this, researchers have developed a vast array of molecular tools that can illuminate the diversity, composition, and activity of microbial communities. Within this primer, we discuss the history of molecular approaches in microbial ecology, and highlight the scope of questions that these methods enable researchers to address. Using some recent case studies, we describe some exemplar research into the microbial ecology of freshwater systems, and emphasize how molecular methods can provide novel ecological insights. Finally, we detail some promising developments within this research field, and how these might shape the future research landscape of freshwater microbial ecology

Production, Stability and Biodiversity of North Island New Zealand Kill Pastures

The relationship between pasture biomass and pasture stability with species diversity was derived for two low fertility, hill land sites. At one site, pasture production increased with an increased number of species contributing to biomass. The coefficient of variation in biomass, however, decreased with higher numbers of species. At a second site, pasture biomass was also found to increase with increasing species diversity, but the relationship between yield stability and species diversity was not as strong as at the first site. This suggested there were other factors that influenced the stability of pastures, which could include the substitution effect between species or the greater contribution of particular species to yield and stability

Combined measurement and QCD analysis of the inclusive e(+/-)p scattering cross sections at HERA

A combination is presented of the inclusive deep inelastic cross sections measured by the H1 and ZEUS Collaborations in neutral and charged current unpolarised e ± p scattering at HERA during the period 1994-2000. The data span six orders of magnitude in negative four-momentum-transfer squared, Q 2, and in Bjorken x. The combination method used takes the correlations of systematic uncertainties into account, resulting in an improved accuracy. The combined data are the sole input in a NLO QCD analysis which determines a new set of parton distributions, HERAPDF1.0, with small experimental uncertainties. This set includes an estimate of the model and parametrisation uncertainties of the fit result

A Measurement of the Q\u3csup\u3e2\u3c/sup\u3e, W and t Dependences of Deeply Virtual Compton Scattering at HERA

Deeply virtual Compton scattering, γ*p→γp has been measured in e+p collisions at HERA with the ZEUS detector using an integrated luminosity of 61.1 pb-1. Cross sections are presented as a function of the photon virtuality, Q2, and photon-proton centre-of-mass energy, W, for a wide region of the phase space, Q2 \u3e 1.5GeV2 and 40 \u3c W \u3c 170GeV. A subsample of events in which the scattered proton is measured in the leading proton spectrometer, corresponding to an integrated luminosity of 31.3 pb-1, is used for the first direct measurement of the differential cross section as a function of t, where t is the square of the four-momentum transfer at the proton vertex. © SISSA 2009