Effects of site‐selection bias on estimates of biodiversity change

Estimates of biodiversity change are essential for the management and conservation of ecosystems. Accurate estimates rely on selecting representative sites, but monitoring often focuses on sites of special interest. How such site‐selection biases influence estimates of biodiversity change is largely unknown. Site‐selection bias potentially occurs across four major sources of biodiversity data, decreasing in likelihood from citizen science, museums, national park monitoring, and academic research. We defined site‐selection bias as a preference for sites that are either densely populated (i.e., abundance bias) or species rich (i.e., richness bias). We simulated biodiversity change in a virtual landscape and tracked the observed biodiversity at a sampled site. The site was selected either randomly or with a site‐selection bias. We used a simple spatially resolved, individual‐based model to predict the movement or dispersal of individuals in and out of the chosen sampling site. Site‐selection bias exaggerated estimates of biodiversity loss in sites selected with a bias by on average 300–400% compared with randomly selected sites. Based on our simulations, site‐selection bias resulted in positive trends being estimated as negative trends: richness increase was estimated as 0.1 in randomly selected sites, whereas sites selected with a bias showed a richness change of −0.1 to −0.2 on average. Thus, site‐selection bias may falsely indicate decreases in biodiversity. We varied sampling design and characteristics of the species and found that site‐selection biases were strongest in short time series, for small grains, organisms with low dispersal ability, large regional species pools, and strong spatial aggregation. Based on these findings, to minimize site‐selection bias, we recommend use of systematic site‐selection schemes; maximizing sampling area; calculating biodiversity measures cumulatively across plots; and use of biodiversity measures that are less sensitive to rare species, such as the effective number of species. Awareness of the potential impact of site‐selection bias is needed for biodiversity monitoring, the design of new studies on biodiversity change, and the interpretation of existing data

Warming and oligotrophication cause shifts in freshwater phytoplankton communities

While there is a lot of data on interactive effects of eutrophication and warming, to date, we lack data to generate reliable predictions concerning possible effects of nutrient decrease and temperature increase on community composition and functional responses. In recent years, a wide‐ranging trend of nutrient decrease (re‐oligotrophication) was reported for freshwater systems. Small lakes and ponds, in particular, show rapid responses to anthropogenic pressures and became model systems to investigate single as well as synergistic effects of warming and fertilization in situ and in experiments. Therefore, we set up an experiment to investigate the single as well as the interactive effects of nutrient reduction and gradual temperature increase on a natural freshwater phytoplankton community, using an experimental indoor mesocosm setup. Biomass production initially increased with warming but decreased with nutrient depletion. If nutrient supply was constant, biomass increased further, especially under warming conditions. Under low nutrient supply, we found a sharp transition from initially positive effects of warming to negative effects when resources became scarce. Warming reduced phytoplankton richness and evenness, whereas nutrient reduction at ambient temperature had positive effects on diversity. Our results indicate that temperature effects on freshwater systems will be altered by nutrient availability. These interactive effects of energy increase and resource decrease have major impacts on biodiversity and ecosystem function and thus need to be considered in environmental management plans

Making the UN Ocean Decade work? The potential for, and challenges of, transdisciplinary research and real‐world laboratories for building towards ocean solutions

1. Due to the strong interconnectedness between the ocean and our societies worldwide, improved ocean governance is essential for sustainable development in the context of the UN Ocean Decade. However, a multitude of different perspectives—ecological, societal, political, economic—and relations between these have to be understood and taken into consideration to foster transformative pathways towards marine sustainability. 2. A core challenge that we are facing is that the ‘right’ response to complex societal issues cannot be known beforehand as abilities to predict complex systems are limited. Consequently, societal transformation is necessarily a journey towards the unknown and therefore requires experimental approaches that must enable the involvement of everyone with stakes in the future of our marine environment and its resources. 3. A promising transdisciplinary research method that fulfils both criteria—being participatory and experimental—are real-world laboratories. Here, we discuss how real-world labs can serve as an operational framework in the context of the Ocean Decade by facilitating and guiding successful knowledge exchange at the interface of science and society. The core element of real-world labs is transdisciplinary experimentation to jointly develop potential strategies leading to targeted real-world interventions, essential for achieving the proposed ‘Decade Outcomes’. 4. The authors specifically illustrate how deploying the concept of real-world labs can be advantageous when having to deal with multiple, overlapping challenges in the context of ocean governance and the blue economy. 5. Altogether, we offer a first major contribution to synthesizing knowledge on the potentials of marine real-world labs, considering how they act as a way of exploring options for sustainable ocean futures. Indeed, in the marine context, real-world labs are still under-explored but are a tangible way for addressing the societal challenges of working towards sustainability transformations over the coming UN Ocean Decade and beyond.BMBF CREATEBMBF MariscoVolkswagen Foundation ‘Niedersächsisches Vorab’BMBF ‘Innovation and structural change—WIR!’Peer Reviewe

Characterization of rubber particles and rubber chain elongation in Taraxacum koksaghyz

<p>Abstract</p> <p>Background</p> <p>Natural rubber is a biopolymer with exceptional qualities that cannot be completely replaced using synthetic alternatives. Although several key enzymes in the rubber biosynthetic pathway have been isolated, mainly from plants such as <it>Hevea brasiliensis</it>, <it>Ficus spec. </it>and the desert shrub <it>Parthenium argentatum</it>, there have been no <it>in planta </it>functional studies, e.g. by RNA interference, due to the absence of efficient and reproducible protocols for genetic engineering. In contrast, the Russian dandelion <it>Taraxacum koksaghyz</it>, which has long been considered as a potential alternative source of low-cost natural rubber, has a rapid life cycle and can be genetically transformed using a simple and reliable procedure. However, there is very little molecular data available for either the rubber polymer itself or its biosynthesis in <it>T. koksaghyz</it>.</p> <p>Results</p> <p>We established a method for the purification of rubber particles - the active sites of rubber biosynthesis - from <it>T. koksaghyz </it>latex. Photon correlation spectroscopy and transmission electron microscopy revealed an average particle size of 320 nm, and ¹³C nuclear magnetic resonance (NMR) spectroscopy confirmed that isolated rubber particles contain poly(<it>cis</it>-1,4-isoprene) with a purity >95%. Size exclusion chromatography indicated that the weight average molecular mass (<inline-formula><graphic file="1471-2091-11-11-i1.gif"/></inline-formula>w) of <it>T. koksaghyz </it>natural rubber is 4,000-5,000 kDa. Rubber particles showed rubber transferase activity of 0.2 pmol min^-1mg^-1. <it>Ex vivo </it>rubber biosynthesis experiments resulted in a skewed unimodal distribution of [1-¹⁴C]isopentenyl pyrophosphate (IPP) incorporation at a <inline-formula><graphic file="1471-2091-11-11-i1.gif"/></inline-formula>w of 2,500 kDa. Characterization of recently isolated <it>cis</it>-prenyltransferases (CPTs) from <it>T. koksaghyz </it>revealed that these enzymes are associated with rubber particles and are able to produce long-chain polyprenols in yeast.</p> <p>Conclusions</p> <p><it>T. koksaghyz </it>rubber particles are similar to those described for <it>H. brasiliensis</it>. They contain very pure, high molecular mass poly(<it>cis</it>-1,4-isoprene) and the chain elongation process can be studied <it>ex vivo</it>. Because of their localization on rubber particles and their activity in yeast, we propose that the recently described <it>T. koksaghyz </it>CPTs are the major rubber chain elongating enzymes in this species. <it>T. koksaghyz </it>is amenable to genetic analysis and modification, and therefore could be used as a model species for the investigation and comparison of rubber biosynthesis.</p

Patterns of Spatial Variation of Assemblages Associated with Intertidal Rocky Shores: A Global Perspective

Assemblages associated with intertidal rocky shores were examined for large scale distribution patterns with specific emphasis on identifying latitudinal trends of species richness and taxonomic distinctiveness. Seventy-two sites distributed around the globe were evaluated following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). There were no clear patterns of standardized estimators of species richness along latitudinal gradients or among Large Marine Ecosystems (LMEs); however, a strong latitudinal gradient in taxonomic composition (i.e., proportion of different taxonomic groups in a given sample) was observed. Environmental variables related to natural influences were strongly related to the distribution patterns of the assemblages on the LME scale, particularly photoperiod, sea surface temperature (SST) and rainfall. In contrast, no environmental variables directly associated with human influences (with the exception of the inorganic pollution index) were related to assemblage patterns among LMEs. Correlations of the natural assemblages with either latitudinal gradients or environmental variables were equally strong suggesting that neither neutral models nor models based solely on environmental variables sufficiently explain spatial variation of these assemblages at a global scale. Despite the data shortcomings in this study (e.g., unbalanced sample distribution), we show the importance of generating biological global databases for the use in large-scale diversity comparisons of rocky intertidal assemblages to stimulate continued sampling and analyses

Alzheimer's disease disrupts alpha and beta-band resting-state oscillatory network connectivity

Objective: Neuroimaging studies in Alzheimer’s disease (AD) yield conflicting results due to selective investigation. We conducted a comprehensive magnetoencephalography study of connectivity changes in AD and healthy ageing in the resting-state. Methods: We performed a whole-brain, source-space assessment of oscillatory neural signalling in multiple frequencies comparing AD patients, elderly and young controls. We compared eyes-open and closed group oscillatory envelope activity in networks obtained through temporal independent component analysis, and calculated whole-brain node-based amplitude and phase connectivity. Results: In bilateral parietotemporal areas, oscillatory envelope amplitude increased with healthy ageing, whereas both local amplitude and node-to-global connectivity decreased with AD. AD-related decreases were spatially specific and restricted to the alpha and beta bands. A significant proportion of the variance in areas of peak group difference was explained by cognitive integrity, in addition to group. None of the groups differed in phase connectivity. Results were highly similar for eyes-open and closed resting-state. Conclusions: These results support the disconnection syndrome hypothesis and suggest that AD shows distinct and unique patterns of disrupted neural functioning, rather than accelerated healthy ageing. Significance: Whole-brain assessments show that disrupted regional oscillatory envelope amplitude and connectivity in the alpha and beta bands play a key role in AD

Seasonality of Glacial Snow and Ice Microbial Communities

Blooms of microalgae on glaciers and ice sheets are amplifying surface ice melting rates, which are already affected by climate change. Most studies on glacial microorganisms (including snow and glacier ice algae) have so far focused on the spring and summer melt season, leading to a temporal bias, and a knowledge gap in our understanding of the variations in microbial diversity, productivity, and physiology on glacier surfaces year-round. Here, we investigated the microbial communities from Icelandic glacier surface snow and bare ice habitats, with sampling spanning two consecutive years and carried out in both winter and two summer seasons. We evaluated the seasonal differences in microbial community composition using Illumina sequencing of the 16S rRNA, 18S rRNA, and ITS marker genes and correlating them with geochemical signals in the snow and ice. During summer, Chloromonas, Chlainomonas, Raphidonema, and Hydrurus dominated surface snow algal communities, while Ancylonema and Mesotaenium dominated the surface bare ice habitats. In winter, algae could not be detected, and the community composition was dominated by bacteria and fungi. The dominant bacterial taxa found in both winter and summer samples were Bacteriodetes, Actinobacteria, Alphaproteobacteria, and Gammaproteobacteria. The winter bacterial communities showed high similarities to airborne and fresh snow bacteria reported in other studies. This points toward the importance of dry and wet deposition as a wintertime source of microorganisms to the glacier surface. Winter samples were also richer in nutrients than summer samples, except for dissolved organic carbon—which was highest in summer snow and ice samples with blooming microalgae, suggesting that nutrients are accumulated during winter but primarily used by the microbial communities in the summer. Overall, our study shows that glacial snow and ice microbial communities are highly variable on a seasonal basis

Mobilisation of organic compounds from reservoir rocks through the injection of CO₂ - comparison of baseline characterization and laboratory experiments

In the framework of CO₂ storage activities, the aim of our investigations is mainly to evaluate the effects of supercritical CO₂ (scCO₂) on the quantitative and qualitative extraction of organic compounds from reservoir rocks. Within the scope of the CO₂ storage project CO₂SINK the major task was to identify key mechanisms occurring in the reservoir as a result of the injection of CO₂ into a saline aquifer. Here, it is of special interest what types and amounts of organic matter will be extracted and mobilized from the reservoir rocks in conjunction with the injection of scCO₂. Thus, our investigations may help to evaluate the efficiency and reliability of the long-term storage of CO₂ in such a geological system. Here, we present compound-specific results from laboratory scCO₂-extraction experiments on reservoir rock samples from the CO₂ storage site in Ketzin, Germany. Low molecular weight organic acids (LMWOA) as well as polar lipid fatty acids (PLFA) extracted by scCO2 were analysed using ion chromatography and gas chromatography-mass spectrometry, respectively. Through the exposure to scCO₂ mainly formate and acetate, but also other LMWOA were released from the rock samples in varying amounts. PLFA profiles of scCO₂ extracts were dominated by saturated and unsaturated fatty acids with 16 and 18 carbon atoms of bacterial origin. The results of scCO₂ extraction are compared with the characterization of the organic inventory of pristine rock samples and fluid samples from observation wells of the Ketzin site to obtain information on quantitative and qualitative significance of the solvent potential of scCO₂

Bulk organic carbon and n-alkane composition data for leaf litter, soil, and floodplain sediment from the Rio Bermejo (Argentina) collected in 2015 - 2018

Endmember samples were collected and analyzed to determine the sources of organic material in the river suspended sediment. Endmembers include soil, leaf litter, and floodplain sediment. Soil and leaf litter samples were collected using an ethanol-cleaned hand trowel. Floodplain sediment samples were collected using an Edelman-type hand auger drilled down to a maximum of ~5 m. Samples were stored in paper bags, and then oven-dried at 40°C. n-alkanes were identified and quantified using an Agilent gas chromatograph (GC 7890-A) with flame ionization detection (FID) coupled to a single quadrupole mass spectrometer (MS 5975-C). We quantified n-alkane concentrations relative to the peak response of the internal standard, and then normalized the abundance to the sediment mass. We measured n-alkane d13C via GC-C-IRMS (gas chromatography/combustion/isotope-ratio mass spectrometry) with helium as a carrier gas (Agilent 7890N, ThermoFisher Delta V Plus). All compounds were measured in triplicate with a standard deviation of =0.5‰. Measurement quality was checked regularly by measuring n-alkane standards (nC15, nC20, nC25) with known isotopic composition (provided by Campro Scientific, Germany). d13C values were normalized to the Vienna Pee Dee Belemnite (VPDB) standard. We measured n-alkane d2H via GC-IRMS using a ThermoFisher Scientific Trace GC 1310 coupled to a Delta-V isotope ratio mass spectrometer. All d2H measurements were made in duplicate, and measurement quality was checked with d2H values were normalized to the Vienna Standard Mean Ocean Water (VSMOW) standard using an n-alkane standard mix with known d2H values (nC16 - nC30, from A. Schimmelman/Indiana University)