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Ökologie

Die Stabilisotopenanalyse einer Vielzahl von Materialien im Bereich der Ökologie erlaubt es Forschern, Informationen zu gewinnen, die mit anderen analytischen Methoden nicht erzielt werden können. Stabile Isotope werden von Ökologen häufig als Tracer in biologischen Systemen eingesetzt, um Elementkreisläufe in einem Ökosystem nachzuvollziehen. Variationen in der Isotopensignatur in unterschiedlichen geographischen Regionen erlauben es, Isotopen als Tracer für Migration zu nutzen, während mit Hilfe des Prinzips der Isotopenfraktionierung biogeochemische Prozesse in einer solchen Detailgenauikgeit analysiert werden können, die von der Betrachtung der Elementzusammensetzung alleine nicht erreicht werden kann.

So können z.B. Kohlenstoffisotope genutzt werden, um die Primärenergiequelle in einem Ökosystem zu bestimmen, wohingegen Stickstoffisotope nützlich sind, um die trophische Ebene eines Organismus zu identifizieren. Schwefelisotope können benthische Produzenten von pelagischen unterscheiden, ebenso wie Sumpfpflanzen von Phytoplanktonproduzenten.

Die Entwicklung unseres Verständnisses dieser immanenten Beziehungen zwischen lebenden Organismen und ihrer Umgebung durch die Stabilisotopenanalyse unterstützt unseren sorgfältigen Umgang mit der natürlichen Welt um zu gewährleisten, dass künftige Generationen die gleichen Wunder erleben wie wir heute.

Publikationen zum Thema Ökologie mit unseren Geräten

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155 Ergebnisse:

Following the flow of ornithogenic nutrients through the Arctic marine coastal food webs
Journal of Marine Systems (2016)
Katarzyna Zmudczyńska-Skarbek, Piotr Balazy

Arctic colonial seabirds are recognized as effective fertilizers of terrestrial ecosystems by delivering marine-origin nutrients to the vicinities of their nesting sites. A proportion of this ornithogenic matter is then thought to return to the sea and, concentrated within a smaller area, locally provides additional nutrients for the nearshore marine communities. The aim of this study was to assess the presence and impact of local ornithogenic enrichment on two important elements of the Arctic coastal food web: (1) the planktonic pathway originating in the surface water, and (2) the benthic pathway based on benthic primary production. We sampled two areas in Isfjorden (Spitsbergen): one located below a coastal mixed breeding colony of guillemots and kittiwakes, and a control area not influenced by the colony. Slightly higher nitrogen stable isotope ratios (δ15N) were found in particulate organic matter suspended in the surface water (POM), sedimentary organic matter (SOM) from outside the zone of dense kelp forest, and the predatory/scavenging whelks Buccinum sp. collected below the seabird colony (the components recognized as following the planktonic path). In contrast, no ornithogenic isotopic enrichment was detected in the herbivorous gastropod Margarites helicinus or in SOM from the kelp zone (benthic path). The data are compatible with those obtained from the same location a year before, showing δ15N enrichment in predatory/scavenging hermit crabs Pagurus pubescens below the seabird, and no such changes in kelps Saccharina latissima or their presumed consumers, sea urchins Strongylocentrotus droebachiensis (Zmudczyńska-Skarbek et al., 2015a). The results suggest that, in the conditions of periodic, short-term pulses of ornithogenic nutrient inputs to the local marine environment, that typify the short High Arctic summer, planktonic organisms are the initial organisms to incorporate these nutrients, before transfer to the benthic food web via pelagic-benthic coupling. However, the supply of ornithogenic resources alone is insufficient to support benthic producers and the trophic pathways based on them. Overall, the ornithogenic subsidies are not a major nutrient source for marine organisms from below the seabird colony.
Schlagworte: carbon , nitrogen , ecol , elem

Following the flow of ornithogenic nutrients through the Arctic marine coastal food webs
Journal of Marine Systems (2016)
Katarzyna Zmudczyńska-Skarbek, Piotr Balazy

Arctic colonial seabirds are recognized as effective fertilizers of terrestrial ecosystems by delivering marine-origin nutrients to the vicinities of their nesting sites. A proportion of this ornithogenic matter is then thought to return to the sea and, concentrated within a smaller area, locally provides additional nutrients for the nearshore marine communities. The aim of this study was to assess the presence and impact of local ornithogenic enrichment on two important elements of the Arctic coastal food web: (1) the planktonic pathway originating in the surface water, and (2) the benthic pathway based on benthic primary production. We sampled two areas in Isfjorden (Spitsbergen): one located below a coastal mixed breeding colony of guillemots and kittiwakes, and a control area not influenced by the colony. Slightly higher nitrogen stable isotope ratios (δ15N) were found in particulate organic matter suspended in the surface water (POM), sedimentary organic matter (SOM) from outside the zone of dense kelp forest, and the predatory/scavenging whelks Buccinum sp. collected below the seabird colony (the components recognized as following the planktonic path). In contrast, no ornithogenic isotopic enrichment was detected in the herbivorous gastropod Margarites helicinus or in SOM from the kelp zone (benthic path). The data are compatible with those obtained from the same location a year before, showing δ15N enrichment in predatory/scavenging hermit crabs Pagurus pubescens below the seabird, and no such changes in kelps Saccharina latissima or their presumed consumers, sea urchins Strongylocentrotus droebachiensis (Zmudczyńska-Skarbek et al., 2015a). The results suggest that, in the conditions of periodic, short-term pulses of ornithogenic nutrient inputs to the local marine environment, that typify the short High Arctic summer, planktonic organisms are the initial organisms to incorporate these nutrients, before transfer to the benthic food web via pelagic-benthic coupling. However, the supply of ornithogenic resources alone is insufficient to support benthic producers and the trophic pathways based on them. Overall, the ornithogenic subsidies are not a major nutrient source for marine organisms from below the seabird colony.
Schlagworte: carbon , nitrogen , ecol , elem

Internal loading of phosphate in Lake Erie Central Basin
Science of The Total Environment (2016)
Adina Paytan, Kathryn Roberts, Sue Watson, Sara Peek, Pei-Chuan Chuang, Delphine Defforey, Carol Kendall

After significant reductions in external phosphorus (P) loads, and subsequent water quality improvements in the early 1980s, the water quality of Lake Erie has declined considerably over the past decade. The frequency and magnitude of harmful algal blooms (primarily in the western basin) and the extent of hypoxic bottom waters in the central basin have increased. The decline in ecosystem health, despite meeting goals for external P loads, has sparked a renewed effort to understand P cycling in the lake. We use pore-water P concentration profiles and sediment cores incubation experiments to quantify the P flux from Lake Erie central basin sediments. In addition, the oxygen isotopes of phosphate were investigated to assess the isotopic signature of sedimentary phosphate inputs relative to the isotopic signature of phosphate in lake water. Extrapolating the total P sediment flux based on the pore-water profiles to the whole area of the central basin ranged from 300 to 1250metric tons per year and using the flux based on core incubation experiments an annual flux of roughly 2400metric tons of P is calculated. These estimates amount to 8–20% of the total external input of P to Lake Erie. The isotopic signature of phosphate in the extractable fraction of the sediments (~18‰) can explain the non-equilibrium isotope values of dissolved phosphate in the deep water of the central basin of Lake Erie, and this is consistent with sediments as an important internal source of P in the Lake.

Internal loading of phosphate in Lake Erie Central Basin
Science of The Total Environment (2016)
Adina Paytan, Kathryn Roberts, Sue Watson, Sara Peek, Pei-Chuan Chuang, Delphine Defforey, Carol Kendall

After significant reductions in external phosphorus (P) loads, and subsequent water quality improvements in the early 1980s, the water quality of Lake Erie has declined considerably over the past decade. The frequency and magnitude of harmful algal blooms (primarily in the western basin) and the extent of hypoxic bottom waters in the central basin have increased. The decline in ecosystem health, despite meeting goals for external P loads, has sparked a renewed effort to understand P cycling in the lake. We use pore-water P concentration profiles and sediment cores incubation experiments to quantify the P flux from Lake Erie central basin sediments. In addition, the oxygen isotopes of phosphate were investigated to assess the isotopic signature of sedimentary phosphate inputs relative to the isotopic signature of phosphate in lake water. Extrapolating the total P sediment flux based on the pore-water profiles to the whole area of the central basin ranged from 300 to 1250metric tons per year and using the flux based on core incubation experiments an annual flux of roughly 2400metric tons of P is calculated. These estimates amount to 8–20% of the total external input of P to Lake Erie. The isotopic signature of phosphate in the extractable fraction of the sediments (~18‰) can explain the non-equilibrium isotope values of dissolved phosphate in the deep water of the central basin of Lake Erie, and this is consistent with sediments as an important internal source of P in the Lake.

Moon jellyfish, Aurelia aurita, in the Gulf of Gdansk: threatening predator or not?
BOREAL ENVIRONMENT RESEARCH (2016)
Dominika Bruli, Marcelina Zi, Stella Mudrak-cegio, Maciej Wo

The seasonal population dynamics and feeding preferences of the moon jellyfish, Aurelia aurita, in the Gulf of Gdansk (southern Baltic Sea) were investigated. Medusae were present in the water column from June to November, with maximum occurrence in August and September. The medusa bell diameter and weight increased during the study period reached maximum values in October. The relationship between bell diameter and wet weight was strong. No ephyrae were observed during the study period. Gastric content analysis revealed that the medusae fed mainly on copepods and cladocerans. Rotifers that dominated the water column throughout the study period were not found in the jellyfish guts, but the stable isotope signature indicated that they could have been a significant source of derived carbon. Low numbers of plankton prey and the lack of fish larvae in A. aurita guts suggest that the jellyfish is of minor relevance as a predator and competitor in the Gulf of Gdansk

Stable isotopes and digital elevation models to study nutrient inputs in high-arctic lakes
Rendiconti Lincei (2016)
Edoardo Calizza, Maria Letizia Costantini, David Rossi, Vittorio Pasquali, Giulio Careddu, Loreto Rossi

Five major factors control nutrient and organic matter inputs in high-Arctic lakes, all potentially affected by climate change: ice cover; run-off from the watershed; aquatic and terrestrial primary productivity; guano deposition from birds. Quantifying these controls is a key first step to understand what combination of factors underlies the biological productivity in Arctic lakes and drives their ecological response to climate change. Based on C and N elemental content and stable isotope analysis in sediments belonging to three lakes in North Spitsbergen (Svalbard), Digital Elevation Models and drainage maps, we propose an integrated approach for the analysis of nutrient and organic matter inputs in lakes and the role of catchment hydro-geomorphology in determining inter-lake differences in the isotopic composition of sediments. Given its high run-off and large catchment, organic deposits in Tvillingvatnet were dominated by terrestrial inputs, whereas inputs were mainly of aquatic origin in Storvatnet, a lowland lake characterised by low potential run-off. In Kolhamna, organic deposits seemed to be dominated by inputs from birds. Isotopic signatures were similar between samples within each lake, representing precise tracers for studies on the effect of climate change on biogeochemical cycles in lakes. The presented approach proved to be an effective research pathway for the identification of factors underlying nutrient and organic matter inputs within each water body, as well as for the modelling of expected changes in nutrient content associated with changes in isotopic composition of sediments.
Schlagworte: carbon , nitrogen , geol , ecol , elem

The main nitrate transporter of the dinoflagellate Lingulodinium polyedrum is constitutively expressed and not responsible for daily variations in nitrate uptake rates
Harmful Algae (2016)
Steve Dagenais Bellefeuille, David Morse

Dinoflagellates are unicellular eukaryotes capable of forming spectacular harmful algal blooms (HABs). Eutrophication of coastal waters by fertilizer runoff, nitrate in particular, has contributed to recent increases in the frequency, magnitude and geographic extent of HABs. Although physiological nitrate uptake and assimilation in dinoflagellates have often been measured in the field and in the laboratory, no molecular components involved in nitrate transport have yet been reported. This study reports the first identification and characterization of dinoflagellate nitrate transporters, found in the transcriptome of the bloom-forming Lingulodinium polyedrum. Of the 23 putative transporters found by BLAST searches, only members of the nitrate transporter 2 (NRT2) family contained all key amino acids known to be essential for nitrate transport. The dinoflagellate NRT2 sequences have 12 predicted transmembrane domains, as do the NRT2 sequences of bacteria, plants and fungi. The NRT2 sequences in Lingulodinium appear to have two different evolutionary origins, as determined by phylogenetic analyses. The most expressed transcript of all putative nitrate transporters was determined by RNA-Seq to be LpNRT2.1. An antibody raised against this transporter showed that the same amount of protein was found at different times over the light dark cycle and with different sources of N. Finally, global nitrate uptake was assessed using a 15N tracer, which showed that the process was not under circadian-control as previously suggested, but simply light-regulated.
Schlagworte: nitrogen , soil , ecol , elem

A small number of anadromous females drive reproduction in a brown trout ( Salmo trutta ) population in an English chalk stream
Freshwater Biology (2016)
Jill C. A. Goodwin, R. Andrew King, J. Iwan Jones, Anton Ibbotson, Jamie R. Stevens

Brown trout, Salmo trutta, exhibit one of the most highly variable and polytypic life-history strategies of all salmonids. Populations may be wholly freshwater-resident or almost exclusively migratory (anadromous), or fish of a single population may exhibit varying proportions of the two life-history strategies. Both anadromous and freshwater-resident trout freely interbreed to produce fertile offspring. We quantify maternal reproductive provisioning by anadromous and freshwater-resident brown trout to their offspring and assess relative parental fitness (in terms of number, size and time of emergence of offspring). Newly emerged juvenile trout (fry) were sampled (n = 119) over the emergence period in March–April 2007 in a lowland English chalk stream; samples of adult trout [anadromous (6F : 12M) and freshwater-resident (22F : 56M)], river-resident trout parr and macroinvertebrate prey were also collected. Using a novel combination of stable isotope analysis and microsatellite genotyping we demonstrate the overwhelming contribution of anadromous parents (both female and male) to fry production, despite the obvious presence and numerical dominance of resident adults. We unambiguously identify the maternal origins of 78% of juveniles sampled and show that maternal reproductive contribution to juvenile production in the river was higher for anadromous females (76%) than freshwater-resident fish (2.5%). Offspring of anadromous females emerged earlier and at a larger body size than offspring of resident females. Similarly, while the relative contribution of resident males (37%) was higher than that of resident females, anadromous males sired considerably more offspring (63%) than resident males. This is the first study of its kind to accurately assess the reproductive contribution of anadromous male trout. Overall, this study suggests that anadromous maternal traits provide offspring with an adaptive advantage and greater fitness in early ontogeny, and that a small number of anadromous females (six of 96 adults sampled) are the main drivers of reproduction in this system.
Schlagworte: carbon , nitrogen , ecol , elem

Resource subsidies from adfluvial fishes increase stream productivity
Freshwater Biology (2016)
Nicholas E. Jones, Robert W. Mackereth

Anadromous fishes are well known to shape the structure and function of recipient ecosystems by introducing nutrients and rich organic matter from the ocean. In contrast, the importance of potamodromous migrations, confined to freshwater, and the subsidies they provide to stream ecosystems has received much less attention. Our objective was to determine the importance of excretion, eggs, milt, and carcasses as nutrient and energy sources from a large population (82 449 suckers) of migrating longnose (Catostomus catostomus) and common white (Catostomus commersonii) suckers into a small (wetted width c. 10 m) oligotrophic river system. We hypothesise that the adfluvial suckers provide a large material subsidy that increased the productivity of the Cypress River and that this resource subsidy rivals or exceeds those delivered by other native and non-native fishes (e.g. Pacific salmonids). In total there was an estimated 5635 kg of eggs, 2025 kg of milt, and 1 kg of carcasses from suckers that spawn in the Cypress River. Relative to other mainly non-native fishes, suckers provided 92% of the annual egg biomass and 95% of the milt. Suckers, however, only provided <1% (1 kg) of the annual carcass biomass, whereas, pink salmon provided 50% (600 kg). Overall, suckers provided 84% and 78% of the annual subsidies of N and P, or 212 and 14 kg respectively. Ambient NH4 concentrations in the river were consistently below that predicted from excretion equations suggesting that microorganisms may have rapidly taken up much of the released ammonium. Downstream of the falls, epilithon biomass was over nine times more abundant, benthic invertebrate densities were approximately two times higher, and fish biomass was eight times greater compared to upstream. There were no upstream–downstream differences in substrate organic matter biomass. Fishes downstream of the falls had higher δ13C and δ15N values than biota upstream of the falls consistent with the anticipated effect of lake derived subsidies. Using stable isotopes values and a mixing model, we estimated that sucker eggs comprised 25–58% of the diet of stream fishes during the growing season. Suckers provided a large subsidy, greater than all other fishes, without mass mortality and significantly enhanced the productivity of the recipient river system. Stable isotopes revealed that subsidies were incorporated into the stream food web. Differences between salmon and sucker subsidies related to the type, magnitude, timing, and the life history of the donor highlight the potential importance of spawning migrations of adfluvial suckers, and other potamodromous fishes, in streams and rivers around the world.
Schlagworte: carbon , nitrogen , ecol , elem

Assessing filtration rates of exotic bivalves: dependence on algae concentration and seasonal factors
Hydrobiologia (2016)
Jonathan Marescaux, Elodie Falisse, Julien Lorquet, Karine Van Doninck, Jean-Nicolas Beisel, Jean-Pierre Descy

Due to their high filtration rates, exotic freshwater bivalves remove suspended organic matter from the water column, transferring resources to the sediment and increasing water clarity, which alters ecosystems. While there is a considerable amount of data on filtration rate of exotic bivalves, comparison between species is often invalid due to the utilization of different protocols for assessing filtration in experimental conditions. In this study, we quantified and compared for the first time the filtration rates of the zebra and quagga mussels and of two invasive Corbicula lineages (forms R and S) as a function of chlorophyll a concentration and season. The highest filtration rate observed was for the zebra mussel in fall and at high algal biomass. The incipient limiting level (ILL), defined as the chlorophyll a concentration at which the maximum filtration rate is observed, was observed in spring and summer in Corbicula species, and in summer and fall in Dreissena species. Overall, filtration rates presented a large range of variation, depending on chlorophyll a and season. Overall, Corbicula form S was observed as the best adapted to low food concentration. Moreover, Corbicula can switch to pedal feeding which gives them a competitive advantage at low chlorophyll a concentrations.
Schlagworte: carbon , ecol , gaschrom