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701.
Christofer Troedsson Jean-Marie Bouquet Carla M. Lobon Aliona Novac Jens C. Nejstgaard Sam Dupont Suncica Bosak Hans H. Jakobsen Nadezda Romanova Lene M. Pankoke Alejandro Isla Jörg Dutz Andrey F. Sazhin Eric M. Thompson 《Marine Biology》2013,160(8):2175-2187
Increasing pCO2 is hypothesized to induce shifts in plankton communities toward smaller cells, reduced carbon export rates and increased roles of gelatinous zooplankton. Appendicularians, among the most numerous pan-global “gelatinous” zooplankton, continuously produce filter-feeding houses, shortcutting marine food webs by ingesting submicron particles, and their discarded houses contribute significantly to carbon fluxes. We present a first mesocosm-scale study on the effects of temperature, pCO2 and bloom structures on the appendicularian, Oikopleura dioica. There were effects of temperature and nutrients on phytoplankton communities. No shifts in functional phytoplankton groups, nor changes in particle sizes/morphotypes, known to impact appendicularian feeding, were observed under manipulated pCO2 conditions. However, appendicularian abundance was positively correlated with increased pCO2, temperature and nutrient levels, consistent with hypotheses concerning gelatinous zooplankton in future oceans. This suggests appendicularians will play more important roles in marine pelagic communities and vertical carbon transport under projected ocean acidification and elevated temperature scenarios. 相似文献
702.
Franck?A.?HollanderEmail author Nicolas?Titeux Hans?Van?Dyck 《Behavioral ecology and sociobiology》2012,66(5):777-783
Preference measures are widely used in habitat selection studies to test an animal’s choice relative to particular habitat
features, but most measures are subject to criticism as they fail to indicate the underlying behavioral motivation. Order
of settlement on breeding sites has been proposed as an effective measure in migratory organisms, as it conceptually approaches
a choice experiment. We tested the assumption that early red-backed shrikes (Lanius collurio) are more willing to defend their territorial resource than individuals arriving later. We earlier showed that shrikes arriving
first settled in forest plantations that resulted in lower reproductive success compared to territories on farmland, suggesting
an ecological trap. Therefore, individuals are expected to place higher value on the lower quality sites in forests. Within
the context of resource valuation theory in animal contests, we used a simulated territorial intrusion experiment to measure
territorial defense and to evaluate the perceived value of the territory during the settlement phase in both habitat types.
Males arriving early were much more motivated to defend their territory than late birds. After correction for the disparity
in the timing of arrival between habitat types, shrikes also more vigorously defended their territories in the forest habitat
associated with the lowest reproductive returns. Although some resource valuation mechanisms remain unclear, our results show
that early and late-arriving individuals strongly differ in behavioral motivation to hold their territorial resources. This
study also demonstrates for the first time that organisms may exhibit a higher degree of territorial aggressiveness in a lower
quality habitat. 相似文献
703.
Measurements of resource capture by individuals, species, or functional groups coexisting in field stands improve our ability to investigate the ecophysiological basis of plant competition. But methodological and technical difficulties have limited the use of such measurements. Carbon capture, in particular, is difficult to asses in heterogeneous, dense field stands. Here we present a new approach to measure in situ daily gross carbon gain of individuals. It is based on measuring the 13C content of shoots after a few hours of continuous labeling of all assimilated CO2. The technique is simple and has few assumptions. A new, fully mobile facility was developed, capable of providing a labeling environment with a CO2 concentration close to atmospheric air and known, constant 13C-enrichment, while maintaining temperature and relative humidity within ambient values. This facility was used in seminatural grasslands of Germany and Argentina to explore the relationship between size and carbon gain of individuals of coexisting species growing in contrasting hierarchical positions, and to analyze the carbon gain of functional groups. In general, carbon gain per unit shoot mass increased with increasing size among small individuals, but it became independent of size among the largest ones. In consequence, competition appeared to be size asymmetric between subordinate individuals but size symmetric between dominant individuals. When comparing functional groups, the carbon gain per unit shoot mass of rosette dicots vs. grasses reflected not their relative contribution to stand biomass, but their hierarchical position: irrespectively of mass or growth form, being taller than neighbors was most important in determining carbon gain per unit shoot mass. We believe these results show that in situ measurements of carbon gain can provide valuable insight in field studies of plant competition. 相似文献
704.
Stefan Nickel Winfried Schröder Roman Schmalfuss Maike Saathoff Harry Harmens Gina Mills Marina V. Frontasyeva Lambe Barandovski Oleg Blum Alejo Carballeira Ludwig de Temmerman Anatoly M. Dunaev Antoaneta Ene Hilde Fagerli Barbara Godzik Ilia Ilyin Sander Jonkers Zvonka Jeran Pranvera Lazo Sebastien Leblond Siiri Liiv Blanka Mankovska Encarnación Núñez-Olivera Juha Piispanen Jarmo Poikolainen Ion V. Popescu Flora Qarri Jesus Miguel Santamaria Martijn Schaap Mitja Skudnik Zdravko Špirić Trajce Stafilov Eiliv Steinnes Claudia Stihi Ivan Suchara Hilde Thelle Uggerud Harald G. Zechmeister 《Environmental Sciences Europe》2018,30(1):53
Background
This paper aims to investigate the correlations between the concentrations of nine heavy metals in moss and atmospheric deposition within ecological land classes covering Europe. Additionally, it is examined to what extent the statistical relations are affected by the land use around the moss sampling sites. Based on moss data collected in 2010/2011 throughout Europe and data on total atmospheric deposition modelled by two chemical transport models (EMEP MSC-E, LOTOS-EUROS), correlation coefficients between concentrations of heavy metals in moss and in modelled atmospheric deposition were specified for spatial subsamples defined by ecological land classes of Europe (ELCE) as a spatial reference system. Linear discriminant analysis (LDA) and logistic regression (LR) were then used to separate moss sampling sites regarding their contribution to the strength of correlation considering the areal percentage of urban, agricultural and forestry land use around the sampling location. After verification LDA models by LR, LDA models were used to transform spatial information on the land use to maps of potential correlation levels, applicable for future network planning in the European Moss Survey.Results
Correlations between concentrations of heavy metals in moss and in modelled atmospheric deposition were found to be specific for elements and ELCE units. Land use around the sampling sites mainly influences the correlation level. Small radiuses around the sampling sites examined (5 km) are more relevant for Cd, Cu, Ni, and Zn, while the areal percentage of urban and agricultural land use within large radiuses (75–100 km) is more relevant for As, Cr, Hg, Pb, and V. Most valid LDA models pattern with error rates of <?40% were found for As, Cr, Cu, Hg, Pb, and V. Land use-dependent predictions of spatial patterns split up Europe into investigation areas revealing potentially high (=?above-average) or low (=?below-average) correlation coefficients.Conclusions
LDA is an eligible method identifying and ranking boundary conditions of correlations between atmospheric deposition and respective concentrations of heavy metals in moss and related mapping considering the influence of the land use around moss sampling sites.705.
Environmental Fluid Mechanics - Turbulent mixing processes in deep alpine Lake Garda (I) have not extensively been observed. Knowledge about drivers of turbulent fluxes are important for insights... 相似文献
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