Institute of Environmental Biology

Utrecht, Netherlands

Institute of Environmental Biology

Utrecht, Netherlands

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Verbruggen F.,Institute of Environmental Biology | Heiri O.,Institute of Environmental Biology | Heiri O.,University of Bern | Reichart G.J.,Organic Geochemistry | And 3 more authors.
Limnology and Oceanography | Year: 2011

An understanding of modern relationships between the stable oxygen isotope composition (δd 18O) of lake water and aquatic invertebrates is essential for the interpretation of paleoclimate records based on δd 18O of organic remains of these organisms. We analyzed δd 18O of lake water and invertebrate remains, including head capsules of chironomid larvae and resting eggs (ephippia) of planktonic Cladocera, in surface sediments from 31 large, deep, and stratified lakes along a latitudinal transect through Europe. The δd 18O values measured for both lake water and aquatic invertebrate remains were compared to estimated δd 18O in precipitation. A strong linear relationship between mean annual air temperature and δd 18O of precipitation was observed along the north-south transect (r 5 0.97), whereas the relationship between precipitation δd 18O and lake-water δd 18O was weaker (r 5 0.80). A strong positive correlation was observed between δd 18O in lake water and aquatic invertebrates (r 5 0.95 and 0.94 for chironomids and cladocerans, respectively). Although slopes of linear regressions between lake-water δd 18O and δd 18O of both aquatic invertebrate groups are similar, a systematic offset between the absolute δd 18O values of chironomids and cladocerans was observed; chironomids were on average 2.4% heavier than Cladocera. We attribute this offset to differences in ecology, metabolism, and/or behavior between benthic chironomid larvae and planktonic Cladocera. δd 18O records based on subfossil chironomid and cladoceran remains have the potential to quantitatively characterize past lake-water δd 18O and, indirectly, past climatic changes. © 2011, by the Association for the Sciences of Limnology and Oceanography, Inc.


Yoshino H.,Tohoku University | Ando N.,Taisei Corporation | Kensuke H.,Kajima Corporation | Hasegawa K.,Akita Prefectural University | And 5 more authors.
Indoor and Built Environment | Year: 2014

In Japan, there is an increase in allergic diseases such as asthma, respiratory symptom, particularly prevailing among the young generation. The reasons why the prevalence is increasing are still not yet well understood. However, it is deemed that indoor environmental factors are one of the essential sources. Therefore, an epidemiology type of survey was investigated on the 4th and 5th grade school children in Japan. The survey was divided into three phases. Phase 1 was a preliminary cross-sectional questionnaire of the prevalence of health problems. Phase 2 was a cross-sectional questionnaire survey on housing characteristics and health. Phase 3 was a field measurement for case control. This paper describes the study protocol and the outcomes from Phase 1. The prevalence of current allergic symptoms was 49.9%. Asthma and rhinitis of the children were 12.5% and 33.3%, respectively. The prevalence of several allergic symptoms among boys was significantly higher than in girls. It indicated that the environmental factors such as pollen, indoor house dust and dust mites could influence allergic symptoms. This survey reveals the ratio of children allergic symptoms in Japan and the possibility of the association between adverse health effect and indoor environmental factors. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.


Verbruggen F.,Institute of Environmental Biology | Heiri O.,Institute of Environmental Biology | Reichart G.-J.,Organic Geochemistry | de Leeuw J.W.,Institute of Environmental Biology | And 3 more authors.
Journal of Paleolimnology | Year: 2010

Stable oxygen isotope measurements on fossil chironomid head capsules from lake sediments show that these chitinous remains can be used to reconstruct past lake water δ18O and, indirectly, past climate change. We examined the impact of chemical pretreatment procedures on the chemical and stable oxygen isotope composition, and morphology of chironomid cuticles. Use of alkali, acids, and sodium chlorite alters the chemical composition and the morphological structure of chironomid cuticles by selective removal of chitin or proteins. Gas chromatograms of pyrolyzates show that NaClO2 causes deproteination, whereas the combined use of HCl and HF results in partial chitin removal. Head capsules pretreated with KOH contained both chitin- and protein-derived moieties, although the concentration of protein was reduced, especially after KOH treatment at high concentration (28%) and temperature (100°C). Scanning electron microscopy confirmed that a proteinaceous matrix is still present in modern and fossil head capsules after KOH treatment. This matrix, however, is largely absent in head capsules pretreated with NaClO2. A change in the proportion of chitin and proteins in our samples was associated with differences in chironomid δ18O values. Our results suggest that deproteination results in a relative increase of chironomid δ18O, whereas removal of chitin leads to decreased δ18O values. We therefore discourage the use of acids or prolonged (≥1 h) exposure to hot alkali (70°C) prior to chironomid δ18O analysis. Chitin purification by sodium chlorite causes significant weight loss, which may preclude down-core chironomid δ18O measurements. Caution and standardization are required when pretreating samples for chironomid δ18O analysis to ensure reliable, comparable, and reproducible results. © 2009 The Author(s).


PubMed | German Center for Integrative Biodiversity Research iDiv Halle Jena Leipzig, Institute of Environmental Biology, Helmholtz Center for Environmental Research, Radboud University Nijmegen and 3 more.
Type: | Journal: The New phytologist | Year: 2016

Flooding is expected to increase in frequency and severity in the future. The ecological consequences of flooding are the combined result of species-specific plant traits and ecological context. However, the majority of past flooding research has focused on individual model species under highly controlled conditions. An early summer flooding event in a grassland biodiversity experiment in Jena, Germany, provided the opportunity to assess flooding responses of 60 grassland species in monocultures and 16-species mixtures. We examined plant biomass, species-specific traits (plant height, specific leaf area (SLA), root aerenchyma, starch content) and soil porosity. We found that, on average, plant species were less negatively affected by the flood when grown in higher-diversity plots in July 2013. By September 2013, grasses were unaffected by the flood regardless of plant diversity, and legumes were severely negatively affected regardless of plant diversity. Plants with greater SLA and more root aerenchyma performed better in September. Soil porosity was higher in higher-diversity plots and had a positive effect on plant performance. As floods become more frequent and severe in the future, growing flood-sensitive plants in higher-diversity communities and in soil with greater soil aeration may attenuate the most negative effects of flooding.


Poorter H.,Jülich Research Center | Poorter H.,Institute of Environmental Biology | Niinemets U.,Estonian University of Life Sciences | Walter A.,Jülich Research Center | And 2 more authors.
Journal of Experimental Botany | Year: 2010

In the past, biologists have characterized the responses of a wide range of plant species to their environment. As a result, phenotypic data from hundreds of experiments are publicly available now. Unfortunately, this information is not structured in a way that enables quantitative and comparative analyses. We aim to fill this gap by building a large database which currently contains data on 1000 experiments and 800 species. This paper presents methodology to generalize across different experiments and species, taking the response of specific leaf area (SLA; leaf area:leaf mass ratio) to irradiance as an example. We show how to construct and quantify a normalized mean light-response curve, and subsequently test whether there are systematic differences in the form of the curve between contrasting subgroups of species. This meta-analysis is then extended to a range of other environmental factors important for plant growth as well as other phenotypic traits, using >5300 mean values. The present approach, which we refer to as 'meta-phenomics', represents a valuable tool in understanding the integrated response of plants to their environment and could serve as a benchmark for future phenotyping efforts as well as for modelling global change effects on both wild species and crops. © 2010 The Author.


Ruhl M.,Institute of Environmental Biology | Veld H.,TNO | Kurschner W.M.,Institute of Environmental Biology
Earth and Planetary Science Letters | Year: 2010

The Triassic-Jurassic (T-J) boundary interval coincides with enhanced extinction rates in the marine realm and pronounced changes in terrestrial ecosystems on the continents. It is further marked by distinct negative excursions in the δ13Corg and δ13Ccarb signature that may represent strong perturbations of the global carbon cycle. We present integrated geochemical, stable-isotope and palynological data from the Kuhjoch section, the Global boundary Stratotype Section and Point (GSSP) for the base of the Jurassic (Northern Calcareous Alps, Austria). We show that the initial carbon isotope excursion (CIE), coinciding with the marine extinction interval and the formation of black shales in the western Tethys Eiberg Basin, is marked by only minor changes in kerogen type, which is mainly of terrestrial origin. Increased Total Organic Carbon (TOC) concentrations of 9% at the first half of the initial CIE coincide with Hydrogen Index (HI) values of over 600 mg HC/g TOC. The high correlation (with R2 = 0.93) between HI values and terrestrial Cheirolepidiaceaen conifer pollen suggests a terrestrial source for the hydrogen enriched organic compounds. The lack of major changes in source of the sedimentary organic matter suggests that changes in the δ13Corg composition are genuine and represent true disturbances of the global C-cycle. The sudden decrease in total inorganic carbon (TIC) concentrations likely represents the onset of a biocalcification crisis. It coincides with a 4.5‰ negative shift in δ13Corg values and possibly corresponds to the onset of CAMP related volcanic activity. The second half of the initial CIE is marked by the dramatic increase of green algae remains in the sediment. The simultaneous increase of the Corg/Ntot ratio suggests increased marine primary production at the final stage of black shale formation. © 2010 Elsevier B.V.


Verbruggen F.,Institute of Environmental Biology | Heiri O.,Institute of Environmental Biology | Heiri O.,University of Bern | Merilainen J.J.,University of Jyväskylä | Lotter A.F.,Institute of Environmental Biology
Freshwater Biology | Year: 2011

1. The distributions of subfossil remains of chironomid larvae in 28 large, deep and stratified lakes in Europe were examined in surface sediments along a latitudinal transect ranging from northern Sweden to southern Italy. 2. Canonical correspondence analysis (CCA) showed that summer surface water and July air temperature, as well as total phosphorus (TP) concentrations, hypolimnetic oxygen availability and conductivity were statistically significant (P<0.05) explanatory variables explaining between 11 and 14% of the variance in the chironomid data. 3. Owing to the spatial scale covered by our study, many environmental variables were covarying. Temperature, TP concentration and oxygen availability were positively or negatively correlated with the first axis of a detrended correspondence analysis (DCA) of chironomid assemblages, suggesting that climatic and trophic conditions influenced profundal chironomid assemblages either in a direct (food and oxygen) or in an indirect (temperature) way. Parameters related to local environmental conditions, lake morphology and bedrock geology, such as organic matter content of the sediment, maximum lake depth, Secchi depth and pH, were not significant in explaining the distribution of chironomid assemblages in our study lakes. 4. The strong relationship between chironomid assemblages and summer temperature may be related to the covariation of temperature with parameters, such as nutrient and oxygen availability, known to affect chironomid assemblages in deep, stratified lakes. However, summer temperature explained a statistically significant proportion of the variance in the chironomid assemblages even when effects of oxygen availability and TP concentrations were partialled out. This suggests that summer temperature has an effect on chironomid assemblages in deep lakes, which is not related to its covariation with trophic state. 5. The potential of fossil chironomid analysis for quantitatively reconstructing past nutrient conditions in deep, stratified lakes was examined by calculating the Benthic Quality Index (BQI) based on subfossil chironomids and by comparing BQI values with observed TP concentrations. BQI was linearly related to log-transformed TP. Applying this relationship to fossil chironomid assemblages from Lake Päijänne (Finland) produced a TP reconstruction in agreement with measured TP during the period 1970-1990, demonstrating that this approach can provide quantitative estimates of past nutrient concentrations in deep, stratified lakes. © 2010 Blackwell Publishing Ltd.


Nierop K.G.J.,University Utrecht | Speelman E.N.,University Utrecht | de Leeuw J.W.,University Utrecht | de Leeuw J.W.,Netherlands Institute for Sea Research | And 2 more authors.
Organic Geochemistry | Year: 2011

Several studies have reported the presence of large amounts of lignin in ubiquitously occurring species of the freshwater fern Azolla. Molecular analysis using flash pyrolysis and thermally assisted hydrolysis and methylation shows, however, that neither the leaves nor the roots of Azolla contain lignin. Instead, both contain polyphenolic constituents that have a close resemblance to condensed tannins, albeit with a slightly different composition than the common tannins of higher plants. © 2011 Elsevier Ltd.


Schoon P.L.,Netherlands Institute for Sea Research | Sluijs A.,Institute of Environmental Biology | Sinninghe Damste J.S.,Netherlands Institute for Sea Research | Sinninghe Damste J.S.,University Utrecht | And 2 more authors.
Paleoceanography | Year: 2011

The middle Paleocene through early Eocene long-term gradual warming was superimposed by several transient warming events, such as the Paleocene-Eocene Thermal Maximum (PETM) and Eocene Thermal Maximum 2 (ETM2). Both events show evidence for extreme global warming associated with a major injection of carbon into the ocean-atmosphere system, but the mechanisms of carbon injection and many aspects of the environmental response are still poorly understood. In this study, we analyzed the concentration and stable carbon isotopic (δ 13C) composition of several sulfur-bound biomarkers derived from marine photoautotrophs, deposited in the Arctic Ocean at ∼85N, during ETM2. The presence of sulfur-bound biomarkers across this event points toward high primary productivity and anoxic bottom water conditions. The previously reported presence of isorenieratene derivatives indicates euxinic conditions in the photic zone, likely caused by a combination of enhanced primary productivity and salinity stratification. The negative carbon isotope excursion measured at the onset of ETM2 for several biomarkers, ranges between 3‰ and 4.5‰, much larger than the ∼1.4‰ recorded in marine carbonates elsewhere, suggesting substantial enhanced isotopic fractionation by the primary producers likely due to a significant rise in pCO 2. In the absence of biogenic carbonates in the ETM2 section of our core we use coeval planktonic δ 13C from elsewhere to estimate surface water δ 13C in the Arctic Ocean and then apply the relation between isotopic fractionation and pCO 2, originally calibrated for haptophyte alkenones, to three selected organic biomarkers (i.e., S-bound phytane, C 35 hopane, and a C 25 highly branched isoprenoid). This yields pCO 2 values potentially in the range of four times preindustrial levels. However, these estimates are uncertain because of a lack of knowledge on the importance of pCO 2 on photosynthetic isotopic fractionation. Copyright 2011 by the American Geophysical Union.


Bonis N.R.,Institute of Environmental Biology | Ruhl M.,Institute of Environmental Biology | Kurschner W.M.,Institute of Environmental Biology
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2010

Several new Triassic-Jurassic boundary sections from the Eiberg Basin (Northern Calcareous Alps, Austria) have been studied at high resolution. We present integrated geochemical and biological proxy data from this western Tethys shelf basin. High-resolution correlation of Kuhjoch, the Global boundary Stratotype Section and Point (GSSP) for the base of the Jurassic, Hochalplgraben and Tiefengraben shows that the initial and main Carbon Isotope Excursions (CIE) are contemporaneous with first and last occurrences of boundary defining macro- and microfossils. We focus on the end-Triassic initial CIE at the transition from the limestones of the Kössen Formation to the marls of the Kendlbach Formation. This change coincides with a dramatically increased influx of conifer (Cheirolepidiaceae) pollen and increased total organic carbon (TOC) values, succeeded by an acme of green algae (Cymatiosphaera). We present a model in which increased terrestrial organic matter influx is related to enhanced seasonality and increased erosion of the hinterland. Reduced salinity of the surface waters led to the mass occurrence of green algae. Stratification of the water column may have caused anoxic bottom water conditions and black shale deposition during the initial CIE at the base of the Kendlbach Fm. © 2009 Elsevier B.V. All rights reserved.

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