10 results on '"Carola Winkelmann"'
Search Results
2. The very hungry amphipod: the invasive Dikerogammarus villosus shows high consumption rates for two food sources and independent of predator cues
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Susanne Worischka, Jochen Becker, Lisa Schwenkmezger, Luise Richter, Claudia Hellmann, and Carola Winkelmann
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0106 biological sciences ,Consumption (economics) ,Ecology ,010604 marine biology & hydrobiology ,Dikerogammarus villosus ,Biology ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Predation ,European bullhead ,Kairomone ,Ecosystem ,Predator ,Ecology, Evolution, Behavior and Systematics ,Cottus - Abstract
The invasion of the Ponto–Caspian amphipod Dikerogammarus villosus in European rivers is assumed to reduce macroinvertebrate diversity and to alter ecosystem functions. D. villosus shows an extraordinarily flexible feeding behavior including the ability to use various food sources. On the other hand, its response to predation risk seems to depend on environmental factors. To evaluate the ecological function of D. villosus, we estimated the daily food consumption for different food sources and analyzed potential effects of predator avoidance behavior on feeding. D. villosus consumption of willow leaves or chironomid larvae was quantified in 24-h laboratory experiments with and without kairomones of the European bullhead (Cottus gobio). Consumption rates were estimated based on gut content and gut evacuation rate under semi-natural laboratory conditions enabling the animals to feed over the whole time of the evacuation rate experiment. We observed very high evacuation rates and consequently high consumption rates up to 89% of body weight per day. Consumption rates differed significantly between food sources: D. villosus ingested more leaves than chironomid larvae. In contrast, predator cues did not affect the feeding of D. villosus. This might be explained by its strong refuge affinity and probably benefits its successful invasion. A comparison of the estimated consumption rates with results of an own consumption experiment (and other studies) under more artificial conditions indicated that more natural conditions result in higher consumption rates. Consequently, feeding rates from highly artificial experiments should be used with great caution to assess the ecosystem function of D. villosus. more...
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- 2017
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3. Larval growth and metabolic energy storage of Micropterna lateralis (Trichoptera: Limnephilidae) in an intermittent stream: glycogen dominates in final instars
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Steffen U. Pauls, Jochen Becker, Felicitas Hoppeler, and Carola Winkelmann
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0106 biological sciences ,Larva ,biology ,Glycogen ,Ecology ,010604 marine biology & hydrobiology ,media_common.quotation_subject ,fungi ,Voltinism ,Zoology ,Aquatic Science ,Diapause ,Limnephilidae ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,chemistry.chemical_compound ,Caddisfly ,chemistry ,Instar ,Metamorphosis ,media_common - Abstract
The caddisfly species Micropterna lateralis is an abundant representative of limnephilids in intermittent streams. Yet, its basic life history characteristics and adaptations related to environmental factors, such as stream drying, are comparatively understudied. Here, we investigated larval growth and metabolic energy reserves (glycogen, triglycerides) through development in their natural habitat. We concentrated on the larval development because this period represents the important phase of energy accumulation necessary for growth, metamorphosis and embryogenesis. Besides larval physiology, female adults were studied in terms of ovarian maturation. Our results indicate that adult females lack an imaginal diapause, which is otherwise often observed in intermittent stream-inhabiting Limnephilidae. Further, M. lateralis is univoltine and exhibits a relatively fast larval development with five distinct instars, of which four are characterised here (instars II–V). Accrual of biomass occurs in final instars, where a high amount of glycogen is accumulated. Lipid concentrations, on the other hand, are kept constant in final stages and slightly lower than in preceding instars. This dominance of glycogen in final instars found in M. lateralis is highly unusual in insects and of potential adaptive significance for the species’ ability to exploit intermittent habitats. more...
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- 2017
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4. River-specific effects of the invasive amphipod Dikerogammarus villosus (Crustacea: Amphipoda) on benthic communities
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Franz Schöll, Claudia Hellmann, Susanne Worischka, Jochen Becker, and Carola Winkelmann
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0106 biological sciences ,Amphipoda ,Ecology ,biology ,010604 marine biology & hydrobiology ,Biodiversity ,Community structure ,Dikerogammarus villosus ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Invasive species ,Mesocosm ,Benthic zone ,Dominance (ecology) ,Ecology, Evolution, Behavior and Systematics - Abstract
The invasive amphipod Dikerogammarus villosus is assumed to threaten native biodiversity in rivers. In spite of small-scale experiments and field observations, its impact on natural communities is largely unknown because it seems to be variable and long-term analyses are rare. We analysed long-term data from the Upper Elbe and Middle Rhine (Germany) for invasion patterns and changes in the community structure. In addition, mesocosm experiments were performed in both rivers to identify density effects of D. villosus on the communities. We assumed that D. villosus is a driver of changes in the macroinvertebrate community and that effects are river-specific due to differing benthic communities. We found two invasion patterns for D. villosus with fast invasion in the River Elbe and slower invasion in the River Rhine. The impact of D. villosus on the species composition was weak in both river communities. Invasion seems to have reduced taxa number and individuals and increased Shannon diversity in the River Rhine, but not in the River Elbe. The correlations between the densities of the invader and other taxa in the long-term data were mostly positive with the exception of two native taxa in the River Rhine, indicating a lack of strong negative species interactions. Also in the mesocosm experiments, the biomass gradient of D. villosus adults did not cause significant changes in the communities. The community in the River Rhine seemed to be more vulnerable to the D. villosus invasion than that in the River Elbe. This might be caused by a dominance of invasive species interacting positively with one another, as suggested by the ‘invasional meltdown’ theory. The study suggests that community-level effects of invasion may differ between rivers, probably due to differences in the community composition. more...
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- 2016
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5. Life Under Exceptional Conditions—Isotopic Niches of Benthic Invertebrates in the Estuarine Maximum Turbidity Zone
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Carola Winkelmann, René Gergs, Thomas Taupp, Markus A. Wetzel, and Claudia Hellmann
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0106 biological sciences ,Ecological niche ,Ecology ,010604 marine biology & hydrobiology ,media_common.quotation_subject ,Crangon crangon ,Detritivore ,Aquatic Science ,Biology ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Competition (biology) ,Benthos ,Benthic zone ,Ecology, Evolution, Behavior and Systematics ,media_common ,Isotope analysis ,Invertebrate - Abstract
The estuarine maximum turbidity zone (MTZ) can be assumed to be a stressful environment featuring special conditions of great biological importance with an excess of organic matter, high-deposition rates, large variations in salinity, and dredging activities. Under such harsh conditions, populations may remain below the carrying capacity and competition is assumed to be of little importance, as predicted by the stress-gradient hypothesis. Therefore, we hypothesized that invertebrates of similar feeding types may utilize the same resources. To test our hypothesis, we chose the three most abundant taxa classified in literature as deposit feeders (Bathyporeia pilosa, Boccardiella ligerica, Marenzelleria sp.) and two taxa classified as predominately predacious (Palaemon longirostris, Crangon crangon) and determined their isotopic niches based on a stable isotope analysis for the MTZ of the Elbe Estuary (Germany). We expected the isotopic niches of similar feeding types to show a clear overlap if our hypothesis was true. Our results showed that the isotopic niches of no two taxa overlapped within each feeding group, indicating different resource use and the absence of competition. The sediment analysis revealed that two of the deposit feeders inhabited significantly different mean grain sizes. The lack of overlap of isotopic niches within each feeding group may be due to differences in habitat and feeding behavior in the case of the deposit feeders and due to different migration behavior in the case of the predominately predacious species. However, competition may have occurred in the past, resulting in a divergence of feeding niches during evolution. more...
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- 2016
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6. Fish predation can induce mesohabitat-specific differences in food web structures in small stream ecosystems
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Claudia Hellmann, Susanne Worischka, Thomas U. Berendonk, and Carola Winkelmann
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Biomass (ecology) ,biology ,Habitat ,Ecology ,Gobio ,Aquatic Science ,biology.organism_classification ,Gobio gobio ,Ecology, Evolution, Behavior and Systematics ,Food web ,Intraguild predation ,Predation ,Apex predator - Abstract
Diverse benthic communities in streams include a wide variety of predators with different habitat preferences, e.g. for pools or riffles. We hypothesised that these preferences result in mesohabitat-specific predator community structures with quantitative differences concerning predation intensity by vertebrate and invertebrate predators, importance of intraguild predation, or top–down pressure. This hypothesis was evaluated for a small submontane stream by means of mesohabitat-specific quantification of prey consumption by two benthivorous fish species (Gobio gobio and Barbatula barbatula) and several invertebrate predators. The estimation was based on daily food rations and diet composition of predators and mesohabitat-specific predator biomass. We found clear differences between the two mesohabitat types. Predator food webs were less complex in pools than in riffles. Fish predation was more important than invertebrate predation in pools, and intraguild predation had a higher relative importance in these mesohabitats. These differences were probably caused by the mesohabitat use of G. gobio, the largest top predator, which preferred pools. Consequently, the predator food webs were more similar between the mesohabitats when fish were absent. Top–down pressure on primary consumers by all predators together was lowest in pools without fish, but the effect was not significant. Omnivory (including cannibalism) was intense, but its potentially destabilising effects were probably counterbalanced by mesohabitat connectivity. From the results of our experimental study, we conclude that even in small stream ecosystems, food web structures and predation pathways can differ between mesohabitats and that a mesohabitat-specific consideration will help to explain the variety of top–down effects on benthic communities. more...
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- 2014
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7. Correction to: Quantitative analysis of PET microplastics in environmental model samples using quantitative 1H-NMR spectroscopy: validation of an optimized and consistent sample clean-up method
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Carola Winkelmann, Nadine Peez, Christian B. Fischer, Sonja M. Ehlers, Wolfgang Imhof, Melanie Fritz, Jochen H. E. Koop, and Jochen Becker
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Matrix (chemical analysis) ,1h nmr spectroscopy ,Microplastics ,Chromatography ,Chemistry ,Sample preparation ,Organic matrix ,Biochemistry ,Quantitative analysis (chemistry) ,Analytical Chemistry ,Environmental model ,Clean-up - Abstract
Identification and quantification of microplastics (MP) in environmental samples is crucial for understanding the risk and distribution of MP in the environment. Currently, quantification of MP particles in environmental samples and the comparability of different matrices is a major research topic. Research also focusses on sample preparation, since environmental samples must be free of inorganic and organic matrix components for the MP analysis. Therefore, we would like to propose a new method that allows the comparison of the results of MP analysis from different environmental matrices and gives a MP concentration in mass of MP particles per gram of environmental sample. This is possible by developing and validating an optimized and consistent sample preparation scheme for quantitative analysis of MP particles in environmental model samples in conjunction with quantitative 1H-NMR spectroscopy (qNMR). We evaluated for the first time the effects of different environmental matrices on identification and quantification of polyethylene terephthalate (PET) fibers using the qNMR method. Furthermore, high recovery rates were obtained from spiked environmental model samples (without matrix ~ 90%, sediment ~ 97%, freshwater ~ 94%, aquatic biofilm ~ 95%, and invertebrate matrix ~ 72%), demonstrating the high analytical potential of the method. more...
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- 2019
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8. Reduced drift activity of two benthic invertebrate species is mediated by infochemicals of benthic fish
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Michael Schäffer, Carola Winkelmann, Jürgen Benndorf, and Claudia Hellmann
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Gammarus pulex ,Pulex ,biology ,Ecology ,Gammarus ,Kairomone ,Baetis ,Aquatic Science ,Nocturnal ,biology.organism_classification ,Gobio gobio ,Ecology, Evolution, Behavior and Systematics ,Predation - Abstract
Regulating mobility by actively entering the drift under imminent predation risk is an avoidance strategy employed by aquatic macroinvertebrate species that is widely accepted within the scientific community. This response was most evident with respect to diurnal predators that feed in the water column, such as many salmonids. We investigated the role of the nocturnal benthivorous gudgeon [Gobio gobio (L.)] on the drift activity of two macroinvertebrate species known to display this behaviour: Baetis rhodani (PICTET) and Gammarus pulex (L.). Laboratory drift experiments using gudgeon kairomones were conducted with the results determining significant altered activity in the presence of gudgeon kairomones for both macroinvertebrate species. B. rhodani showed reduced drift activity in the kairomone treatment compared to the kairomone-free control, with a distinct nocturnal pattern being observed for both. G. pulex shifted from a similar day/night movement pattern to a nocturnal movement pattern with decreased activity during the day. Reduce activity during the day, whilst maintaining normal activity at night would not reduce the probability of encountering a nocturnal predator under natural conditions and therefore appears to not be a meaningful anti-predator response. To assess the relevance of these findings under natural conditions, we compared the experimental results with drift measurements from field observations. These show a significant reduction in drift activity for G. pulex and slight tendencies for reduced night-time drift for B. rhodani, under seasonal variations. We conclude that the behaviour in response to the physical contact or the hydrodynamic stimuli of nocturnal predators is the most likely explanation for the differences between the results from our laboratory experiment and the field observation. We further discuss that the observed migration patterns might have different species specific consequences for density stabilisation on a population level. more...
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- 2013
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9. Physiological indicators of fitness in benthic invertebrates: a useful measure for ecological health assessment and experimental ecology
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Carola Winkelmann, Jochen H. E. Koop, Claudia Hellmann, Jochen Becker, and Christian Ortmann
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River ecosystem ,Resource (biology) ,Ecological health ,business.industry ,Ecology ,Ecology (disciplines) ,Environmental resource management ,Aquatic Science ,Biology ,Identification (biology) ,Relevance (information retrieval) ,Literature survey ,business ,Ecology, Evolution, Behavior and Systematics ,Organism - Abstract
Physiological indicators of fitness present a measure of an organism’s response to a changing environment. An analysis of how these organisms allocate and store their energy resources provides an understanding of how they cope with such environmental changes. Each individual has to balance the investment necessary to acquire a certain resource with the energy gained by it. This trade-off can be monitored by measuring several physiological indicators of fitness such as energy storage components, metabolic state or RNA/DNA ratio. Because environmental adaptations and ecological strategies of survival are best examined within the natural environment, our research has to rely on the physiological indicators that are easily accessible in the field. The physiological indicators presented here are significant for an individual’s fitness and in turn lead to reliable values in field-collected samples. Based on our own expertise and on a literature survey, the physiological relevance of the presented indicators is explained. Furthermore, some consideration to the analytical methods used to obtain the physiological indicators is given, and possible errors introduced at the sampling site and during the laboratory procedures are discussed. This work demonstrates that the integration of ecological and physiological expertise facilitates the identification of future ecological problems much earlier than separate approaches of both disciplines alone. more...
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- 2011
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10. Finding appropriate reference sites in large-scale aquatic field experiments
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Carola Winkelmann, Katja Kornek, Jochen H. E. Koop, Jürgen Benndorf, Marie König-Rinke, Markus A. Wetzel, and Susanne I. Schmidt
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Abiotic component ,Riffle ,River ecosystem ,Ecology ,Community structure ,Dominance (ecology) ,Ecosystem ,STREAMS ,Species richness ,Aquatic Science ,Biology ,Ecology, Evolution, Behavior and Systematics - Abstract
Defining the reference condition is one of the most critical aspects of ecosystem investigations since it describes the baseline against which the experimental sites will be evaluated and compared. In large-scale ecosystem experiments, this reference is ideally another ecosystem which is similar to the experimental system. We investigated two streams for their potential as experimental sites for a full-size pairwise ecosystem experiment. Temporal (2 years) and spatial (pool, riffle) variabilities of abiotic factors and as biotic element the structure of the macroinvertebrate communities were investigated. Criteria of similarity that we applied at the two streams were: (1) high similarity in abiotic factors, (2) only small differences in the faunal assemblages (abundance structures, composition, feeding types), and (3) that the differences between the two systems should not exceed the temporal and spatial differences within each system. Among the abiotic factors investigated, only the inorganic nutrients (nitrate and soluble reactive phosphorus), major ions (magnesium, calcium), electric conductivity, and pH showed significant differences between the two streams. Discharge rate, current velocity, temperature, and oxygen concentrations did not significantly differ between the streams. Also, the community structure did not differ in species richness, abundance, and biomass; and only small differences in dominance structure and feeding-type composition were observed. The differences between habitats within each stream were always higher than those between the streams. Thus, both the streams are characterized by a similar structure of the macroinvertebrate community, a main component of the stream food-web, which make them suitable for a full size pairwise ecosystem experiment. The present case study can form a basis for other full-size field experiments. more...
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- 2007
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