28 results on '"Carola Winkelmann"'
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2. Is The invasive amphipod Dikerogammarus villosus the main factor structuring the benthic community across different types of water bodies in the River Rhine system?
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Meike Koester, Maximilian Schneider, Jochen Becker, René Gergs, Claudia Hellmann, and Carola Winkelmann
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0106 biological sciences ,geography.geographical_feature_category ,biology ,Range (biology) ,Ecology ,010604 marine biology & hydrobiology ,Biodiversity ,Community structure ,Dikerogammarus villosus ,Aquatic Science ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Geography ,Habitat ,Benthos ,Benthic zone ,Tributary - Abstract
Dikerogammarus villosus, one of the most successful invaders in European river systems, is commonly regarded as a threat to native biodiversity and a main factor structuring the benthic community of invaded systems. The impact of D. villosus has been intensively studied in small-scale experiments and field observations, but its impact on natural communities on a larger scale remains unclear. Here, we investigated the benthic community structure at ten sites covering a broad range of habitats along the River Rhine (Central Europe) and its tributaries, to determine whether D. villosus is one of the main factors structuring the benthic community. Community composition was analysed using non-metric multidimensional scaling, distance-based redundancy analysis, and correlation analyses. D. villosus was one of nine relevant taxa present that altogether reflected a large part of the variation in the benthic samples, but further analyses indicated that the species might be less important for the community structure than other relevant taxa. Moreover, all nine relevant taxa together can explain only a similar amount of variation in our samples than the five relevant non-faunal environmental factors (water temperature, pH, conductivity, percentage of medium-sized gravel and macrophytes). Overall, our results suggested that rather a combination of non-faunal environmental factors than D. villosus mainly structure the benthic community composition on this larger spatial scale.
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- 2018
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3. Why are males more attractive after brood care? Proximate causes of enhanced sex pheromone emission in a burying beetle
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Ina S. Fujan, Johanna Chemnitz, Sandra Steiger, and Carola Winkelmann
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0106 biological sciences ,0301 basic medicine ,biology ,Physiology ,Zoology ,biology.organism_classification ,Pheromone trap ,Nicrophorus vespilloides ,010603 evolutionary biology ,01 natural sciences ,03 medical and health sciences ,030104 developmental biology ,Insect Science ,Sex pheromone ,Brood care ,Burying beetle ,Pheromone ,Carrion ,Paternal care ,Ecology, Evolution, Behavior and Systematics - Abstract
Recent studies demonstrate that pheromones can be costly to produce and emit and, therefore, the types and quantities that they express are likely to covary with individual condition. Previous experiments reveal that, when given the opportunity to breed and care for young, male burying beetles Nicrophorus vespilloides go on to produce a higher amount of their sex pheromone and attract more females than control males that do not exhibit parental care. This finding is surprising because parental care is usually assumed to be energetically costly, reducing the future capacity to invest in sexual signalling. However, burying beetles reproduce on dead vertebrates and the carrion meal might enable males to acquire resources that can subsequently be allocated to pheromone signalling. Alternatively, males might accumulate pheromone precursors because they do not emit their sex pheromone during brood care. To shed light on the mechanisms of enhanced pheromone emission after brood care, in the present study, we test the effect of diet quality, social condition during care (biparental versus uniparental care) and an experimentally enforced calling pause on subsequent male pheromone emission, body weight and energy storage components. The experimentally enforced calling pause and social condition during brood care demonstrate no impact on pheromone quantity. However, the results of the present study suggest that the vertebrate carrion meal during brood care partly explains enhanced pheromone release after care. Unravelling the biosynthetic pathways of the pheromone components and analyzing the impact of potential microbial symbionts on pheromone production represents a fruitful avenue for future research.
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- 2018
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4. Food consumption of the invasive amphipod Dikerogammarus villosus in field mesocosms and its effects on leaf decomposition and periphyton
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Luise Richter, Pavel Kratina, Jochen Becker, Carola Winkelmann, Claudia Hellmann, Susanne Worischka, and Anne Hänig
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0106 biological sciences ,0301 basic medicine ,biology ,Ecology ,010604 marine biology & hydrobiology ,Food consumption ,Dikerogammarus villosus ,Aquatic Science ,biology.organism_classification ,01 natural sciences ,Decomposition ,Mesocosm ,Fishery ,03 medical and health sciences ,030104 developmental biology ,Periphyton ,Water Science and Technology - Published
- 2018
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5. 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.
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- 2017
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6. 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.
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- 2017
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7. RNA/DNA ratio as a growth indicator of stream periphyton
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Carola Winkelmann, Sandra Spielvogel, and Daniela Mewes
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0106 biological sciences ,Biomass (ecology) ,010604 marine biology & hydrobiology ,Community structure ,RNA ,910 Geography & travel ,STREAMS ,Aquatic Science ,Biology ,010603 evolutionary biology ,01 natural sciences ,chemistry.chemical_compound ,Animal science ,chemistry ,Botany ,Nucleic acid ,Growth rate ,Periphyton ,DNA - Abstract
Summary The quantification of periphyton growth in situ poses numerous difficulties. The RNA/DNA ratio is widely used as a growth indicator in marine ecology. We tested its applicability as a growth indicator of periphyton in streams of different sizes. Periphyton-covered stones sampled from two different watercourses during two seasons were exposed in laboratory flumes to different light levels to induce different growth rates. The relationship between rate of biomass accrual and RNA/DNA ratio was analysed by measuring the chlorophyll-a content and the RNA and DNA content of total nucleic acid extract of the periphyton respectively. The RNA/DNA ratios showed a linear relationship with the biomass accrual at all sampling times. The slopes of these relationships varied significantly between the two watercourses, but not between seasons within the same watercourse. These results indicate that the RNA/DNA ratio can be used as a growth indicator for the periphyton studied here. We recommend that it be used to detect differences in growth rate of the same periphyton community either over time or between different treatments in ecological or ecotoxicological experiments. However, for long-term monitoring studies, we recommend taxonomic analyses of the assemblages because the observed differences in the relationship between the RNA/DNA ratio and growth rate might be attributed to community structure differences in the assemblages.
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- 2017
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8. Can top-down effects of cypriniform fish be used to mitigate eutrophication effects in medium-sized European rivers?
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Jörg Schneider, Madlen Gerke, Dirk Hübner, and Carola Winkelmann
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Environmental Engineering ,010504 meteorology & atmospheric sciences ,European chub ,010501 environmental sciences ,01 natural sciences ,Rivers ,Common nase ,Animals ,Environmental Chemistry ,Hyporheic zone ,Periphyton ,Waste Management and Disposal ,Ecosystem ,0105 earth and related environmental sciences ,Biomass (ecology) ,Biomanipulation ,biology ,Chlorophyll A ,Eutrophication ,biology.organism_classification ,Pollution ,Fishery ,Lakes ,Benthic zone ,Environmental science - Abstract
Eutrophication seriously threatens the ecological quality and biodiversity of running waters. In nutrient-enriched streams and shallow rivers, eutrophication leads to excessive periphyton growth and, in turn, biological clogging, oxygen depletion in the hyporheic zone and finally a reduction in the hyporheic habitat quality. Top-down control of the food-web by manipulating fish stocks, similar to the biomanipulation successfully applied in lakes, offers a promising approach to mitigating the effects of eutrophication in shallow rivers, especially those in which major reductions in nutrient input are not feasible. We conducted a reach-scale experiment over 4 years in a medium-sized eutrophic river to assess whether the top-down effects of two important large European cypriniform fish species, herbivorous common nase (Chondrostoma nasus) and omnivorous European chub (Squalius cephalus), would mitigate the effects of eutrophication. The enhancement of fish stocks was expected to reduce biological clogging, via the top-down control of periphyton by benthic grazing and enhanced bioturbation, thus increasing oxygen availability in the hyporheic zone as well as water exchange between the surface water and the hyporheic zone. As expected, enhancing the stocks of nase and chub increased both oxygen availability and vertical exchange flux of water in the upper layer of the hyporheic zone. However, periphyton biomass (chlorophyll a) was significantly reduced only in deeper pool habitat. Thus, while experimental biomanipulation in a shallow river significantly mitigated the effects of eutrophication in the hyporheic zone, top-down effects on periphyton biomass were rather small. Overall, to our knowledge, our results provide first evidence that the biomanipulation achieved by enhancing herbivorous and omnivorous fish stocks has the potential to mitigate the effects of eutrophication in medium-sized European rivers.
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- 2021
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9. 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.
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- 2016
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10. 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.
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- 2016
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11. The effects of fish kairomones and food availability on the predator avoidance behaviour of Gammarus pulex
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Franziska Szokoli, Susanne Worischka, Carola Winkelmann, and Thomas U. Berendonk
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Gammarus pulex ,Ecology ,Food availability ,Kairomone ,Zoology ,%22">Fish ,Predator avoidance ,Aquatic Science ,Biology ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics - Published
- 2015
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12. Selective predation by benthivorous fish on stream macroinvertebrates – The role of prey traits and prey abundance
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Susanne Worischka, Claudia Hellmann, Susanne I. Schmidt, and Carola Winkelmann
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biology ,Abundance (ecology) ,Ecology ,Stone loach ,Foraging ,Barbatula ,Aquatic Science ,biology.organism_classification ,Predator ,Gobio gobio ,Invertebrate ,Predation - Abstract
The prey selectivity of fish depends largely on traits of the prey and the predator. Preferable prey traits might be different for visual predators (such as drift-feeding salmonids) and rather non-visual predators (such as benthic feeders). We evaluated the explanatory power of five prey traits and prey long-term abundance for the prey selection of small benthivorous fish by analysing the macroinvertebrate community and the diet of gudgeon (Gobio gobio) and stone loach (Barbatula barbatula) in two small submontane streams. Fuzzy principal component analyses, as well as electivity indices, revealed that the fish fed selectively. Prey size and feeding type were the most descriptive variables for the fish diet, followed by mean abundance, whereas microhabitat preference, locomotion mode and current velocity preference were less important. The fish preferred prey that was both small and consistently abundant, grazers and sediment feeders. Larger prey and shredders were avoided. The selection patterns of both fish species differed from those of visual fish predators but strongly resembled each other. Supporting this, in gudgeon which feeds slightly more visually than the strictly nocturnal stone loach, selectivity concerning prey traits as well as prey mean abundance was slightly more pronounced. We analyzed also selectivity for prey clusters based on the three most important variables. The observed selectivity patterns concerning these clusters were less pronounced but supported the other results. The maximum (neutral) electivity index was that of gudgeon for small, abundant grazers or sediment feeders, including chironomids. We conclude that prey selection of benthivorous fish that forage mainly non-visually can largely be explained by a small number of prey traits which probably work in combination. The prey preferences of these predators seem to be closely connected to their active foraging mode and to depend partly on the ability to detect prey visually.
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- 2015
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13. 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.
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- 2014
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14. Flexibility in feeding periodicity of a grazing mayfly in response to different concentrations of benthivorous fish
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Jürgen Benndorf, Susanne Worischka, Jana Schneider, Carola Winkelmann, and Claudia Hellmann
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Mayfly ,biology ,Ecology ,Barbatula ,Foraging ,Aquatic Science ,Nocturnal ,biology.organism_classification ,Diel vertical migration ,Gobio gobio ,Predation ,Trophic level - Abstract
Flexibility is an important adaptive attribute of the feeding periodicity of grazing mayfly larvae because most natural environments offer a wide variation in local predation risk in terms of space, time or predator species. In this study any changes of diel feeding periodicity and consumption rates of Baetis rhodani (Ephemeroptera) were analysed in response to different densities of benthivorous fish ( Barbatula barbatula , Gobio gobio ) by quantifying gut fullness using the fluorescence of algal pigments. Laboratory experiments with the grazer species B. rhodani were conducted by using different concentrations of chemical fish cues. In order to assess the transferability of the results to a larger scale, the experimental results were compared with field observations in two second order streams using different densities of freely foraging benthivorous fish. During the presence of chemical fish cues in the laboratory experiments the feeding periodicity of the B. rhodani larvae were mostly diurnal while in the absence of fish chemicals nocturnal feeding was observed. The same patterns could be detected in the field during the experiments with the different fish densities. These findings indicate that the larvae were able to assess variations in the predation risk and to alter their feeding habits by making flexible behavioural adjustments. The results from the laboratory experiments further suggested that the behavioural response is controlled by fish density. Behavioural changes were observed for medium and high concentrations of the fish cues but not for a very low concentration. In the field however, the mere presence of fish seemed to be sufficient to induce the observed behavioural shifts. Although the presence of benthivorous fish seemed to cause a lower consumption rate of the B. rhodani larvae in the field, such a reduction could not be found in the laboratory experiments. A conclusion from this study is that the identification of behavioural modifications is an essential component needed for a better understanding of complex trophic interactions in benthic communities. Accurate evaluation and detailed observation of direct and indirect effects cannot be made without the consideration of such behavioural mechanisms.
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- 2014
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15. Top-down and bottom-up control of periphyton by benthivorous fish and light supply in two streams
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Susanne Worischka, Daniela Mewes, Jana Schneider, Jürgen Benndorf, Claudia Hellmann, Carola Winkelmann, and Susanne I. Schmidt
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geography ,Biomass (ecology) ,geography.geographical_feature_category ,Primary producers ,biology ,Ecology ,Stone loach ,Aquatic Science ,biology.organism_classification ,Gobio gobio ,Benthic zone ,Environmental science ,Periphyton ,Trophic cascade ,Riparian zone - Abstract
Summary We conducted a paired large-scale predation experiment over 32 months in two streams being seasonally shaded by deciduous riparian trees, using the benthivorous fish species gudgeon (Gobio gobio) and stone loach (Barbatula barbatula) as top predators. The biomass of benthic grazers and periphyton in the presence/absence of fish was measured and the periphyton production was compared with the consumption rates using a model-based approach. A three-level trophic cascade from benthivorous fish via benthic grazers to periphyton was evident from the field experiment. Integrated over the whole study period, fish reduced the biomass of benthic grazers and indirectly increased the periphyton biomass. Scenario analyses, using a simple dynamic model, indicated top-down control of periphyton to be strongest during autumn, when periphyton growth was light-limited, and weaker in the spring, when periphyton growth was not light-limited. The seasonal light supply variation was caused by shading due to deciduous riparian trees during the vegetation period. This asymmetry in temporal processes weakened the top-down control in a natural benthic community. Even though grazer biomass is naturally reduced in summer, due to the emergence of the most abundant species (mayflies), a grazer biomasses high enough to reduce the spring periphyton peak could not be sustained by the low summer periphyton growth. We suppose that the temporal decoupling of grazer biomass from periphyton biomass might be caused by the very short generation time of the primary producers (days) compared with the long generation time of the primary consumers (mostly 1 year).
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- 2013
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16. Omnivores as seasonally important predators in a stream food web
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Claudia Hellmann, Björn Wissel, and Carola Winkelmann
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Biomass (ecology) ,Ecology ,biology ,Aquatic Science ,biology.organism_classification ,Predation ,Gammarus pulex ,Benthic zone ,Ecosystem ,Omnivore ,Ecology, Evolution, Behavior and Systematics ,Trophic level ,Isotope analysis - Abstract
Omnivory is prevalent in terrestrial and aquatic food webs. However, the extent and seasonality of predatory feeding by omnivores in stream food webs is largely unknown. To understand better these aspects of omnivory in stream food webs, we investigated seasonal changes in the trophic positions of 2 omnivores in a small forested stream. We selected the amphipod, Gammarus pulex, and the caddisfly larvae, Hydropsyche spp., as key organisms because both taxa are common, reach high biomasses in many stream ecosystems, and have broad food spectra. We used stable-isotope analysis of the most prevalent taxa in the benthic macroinvertebrate community to assess the trophic positions of the 2 omnivorous taxa in different seasons. We estimated the degree of predatory feeding by quantifying the importance of different food resources with a stable-isotope mixing model (IsoSource). The predation capacity of omnivores, defined as the fraction of omnivore biomass associated with predation, was compared to the bio...
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- 2013
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17. 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.
- Published
- 2013
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18. Mate guarding in relation to seasonal changes in the energy reserves of two freshwater amphipods (Gammarus fossarumandG. pulex)
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Carola Winkelmann, Jochen Becker, Christian Ortmann, Jochen H. E. Koop, and Markus A. Wetzel
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biology ,Glycogen ,Bioenergetics ,Ecology ,Energy reserves ,Zoology ,Aquatic Science ,Seasonality ,biology.organism_classification ,medicine.disease ,chemistry.chemical_compound ,Gammarus pulex ,Pulex ,Dry weight ,chemistry ,Gammarus fossarum ,medicine - Abstract
Summary 1. We assessed sex-specific seasonal changes in major energy storage compounds (triglycerides, glycogen) in Gammarus fossarum and Gammarus pulex collected from the field, with respect to their reproductive activity. 2. The dynamics of stored energy followed a seasonal pattern in both species and sexes. Moreover, over a 4-year period, these changes were independent of the year in which they were investigated. Stored energy reached a peak in late winter, but was depleted in late summer and early autumn, coinciding with the reproductive periods. 3. Triglyceride (annual mean ± SD) accounted for 79.7 ± 11.9% of the total stored energy and was responsible for the seasonal pattern. In contrast, glycogen contributed a lesser percentage (20.3 ± 11.9%). Over the study period, the amount of stored energy ranged between 0.39 and 4.08 kJ g−1 dry mass (triglyceride: 0.19–3.69 kJ g−1 dry mass; glycogen: 0.14–0.80 kJ g−1 dry mass). 4. In both species, the energy reserves of males were drastically depleted shortly before the cessation of precopulatory mate guarding in the field, thus offering a bioenergetic explanation for the reproductive period in these two widespread species.
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- 2012
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19. Herbicide indirectly reduces physiological condition of a benthic grazer
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P. Bartels, Claudia Hellmann, D. Jungmann, Marcus Rybicki, and Carola Winkelmann
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Biomass (ecology) ,Ecology ,biology ,Physiological condition ,Aquatic Science ,Pesticide ,Oceanography ,biology.organism_classification ,Heptageniidae ,Freshwater ecosystem ,Aufwuchs ,Animal science ,Benthic zone ,Botany ,Microcosm ,Ecology, Evolution, Behavior and Systematics - Abstract
Freshwater ecosystems are polluted with various environmental chemicals. For example, pesticides enter the aquatic environment via spray drift or surface runoff from catchment areas used for industrialised agriculture. In the present study, we investigated the response of the grazeraufwuchs interaction when exposed to the herbicide terbutryn in a microcosm experiment. Terbutryn induced a trophic cascade with negative effects on grazers by inhibiting growth of pri- mary producers. We determined a no-observed-effect concentration (measured as particulate organic carbon, NOECPOC) of 0.21 µg l �1 for aufwuchs biomass and a lowest-observed-effect con- centration (LOECPOC) of 2.01 µg l �1 . Furthermore, a shift in the aufwuchs community was detected in all terbutryn treatments nearly 4 wk after exposure, and this shift persisted until the end of the experiment in the treatment with the highest terbutryn concentration. In addition, reduced energy stores (triglycerides, TG) of the grazer Rhithrogena semicolorata (Heptageniidae: Ephemeroptera) were found (NOECTG = 0.03 µg l �1 , LOECTG = 0.21 µg l �1 ), which was interpreted as an indication of moderate starvation during the experiment. While starvation did not result in reduced larval growth as might have been expected, the ob served reduction of TG content in larvae (24%) is consistent with results from a separate experiment in which starvation alone induced a 15% reduction of TG content as well as reduced emergence, reduced size at emergence, and reduced egg production.
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- 2012
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20. Habitat overlap between predatory benthic fish and their invertebrate prey in streams: the relative influence of spatial and temporal factors on predation risk
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Carola Winkelmann, Claudia Hellmann, Christoph Koebsch, and Susanne Worischka
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Habitat ,biology ,Benthic zone ,Ecology ,Stone loach ,Barbatula ,Foraging ,Aquatic Science ,biology.organism_classification ,Gobio gobio ,Spatial heterogeneity ,Predation - Abstract
Summary 1. The spatial heterogeneity of ecosystems as well as temporal activity patterns of organisms can have far-reaching effects on predator–prey relationships. We hypothesised that spatiotemporal constraints in mesohabitat use by benthic fish predators would reduce habitat overlap with benthic invertebrates and lead to mesohabitat-specific predation risks. 2. We analysed the spatiotemporal activity patterns of two small-bodied benthivorous fishes, gudgeon (Gobio gobio) and stone loach (Barbatula barbatula), and of benthic invertebrates in a small temperate stream during three 24-h field experiments. By applying a novel method of field video observation, we monitored the spatiotemporal foraging behaviour of the fish in their natural environment. A parallel analysis of invertebrate mesohabitat use by means of small area Hess sampling allowed a direct estimation of habitat overlap at a pool–riffle scale. 3. Gudgeon showed a dominant spatial activity pattern preferring pools at all times of day, whereas stone loach used both mesohabitats but with a distinct temporal (nocturnal) activity pattern. The patterns of residence were not identical with those of active foraging. Invertebrate community composition differed significantly between mesohabitats but not between times of day. More than half of the total dissimilarity between pools and riffles was accounted for by six invertebrate taxa. Five of these were subject to higher fish predation in pools than in riffles. The total prey consumption of the two fish species together in pools was about three times as high as in riffles. Trophic niche breadth of stone loach and thus its predation range was broader than that of gudgeon. 4. These results indicate that the potential predation risk for stream invertebrates depends on the combination of spatial and temporal patterns of both predator and prey. Given the distinct differences in predation risk found between pools and riffles, we conclude that spatial heterogeneity at the mesohabitat scale can influence mechanisms and consequences of selective predation. We also suggest that the analysis of spatiotemporal predator–prey relationships should not be based on the premise that the main residence habitat and active foraging habitat of a predator are identical.
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- 2012
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21. 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.
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- 2011
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22. Fish predation affects the structure of a benthic community
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Susanne Worischka, Thomas Petzoldt, Claudia Hellmann, Jürgen Benndorf, and Carola Winkelmann
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Biomass (ecology) ,Trout ,Gammarus pulex ,Riffle ,biology ,Benthic zone ,Ecology ,Aquatic Science ,biology.organism_classification ,Gobio gobio ,Food web ,Predation - Abstract
Summary 1. We conducted an experimental study of predation by benthivorous fish on a natural community of stream invertebrates using a reach-scale approach. Over a 2-year period (experimental phase), the benthic invertebrate community of a stretch containing two species of benthivorous fish was compared with a fishless stretch. Thereafter, all fish were removed and benthic community structure was analysed again to account for natural differences between the two stretches (reference phase). 2. Benthivorous fish at the moderate densities investigated did not affect total benthic biomass or density, but did alter species composition. In addition, the fish effect differed between pool and riffle habitats, with larger effects in the pools indicating a habitat-specific predation effect. In the reference phase, when all fish were removed from the stream, the difference between the two stretches was reduced. 3. The benthivorous fish reduced the densities of four taxa (Pisidium sp., Dugesia gonocephala, Gammarus pulex, Limoniidae), representing 29% of total biomass. It is possible that density reductions of other species were masked by prey migration despite the relatively large spatial scale. Indeed, higher drift activity in the upstream fishless stretch could have increased the density of Baetis rhodani in the fish stretch, as indicated by the results of a drift model. 4. Our results provide insights into stream food web ecology because fish predation showed effects even in a natural system where habitat complexity was high, environmental factors were highly variable and many predator and prey species interacted and because benthivorous fish were the focus, whereas the majority of previous predation experiments in streams have used drift-feeding trout.
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- 2011
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23. Benthic grazing in a eutrophic river: cascading effects of zoobenthivorous fish mask direct effects of herbivorous fish
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Jörg Schneider, Daniel Cob Chaves, Madlen Gerke, Carola Winkelmann, Dirk Hübner, Marc Richter, and Daniela Mewes
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0106 biological sciences ,Benthic grazing ,lcsh:Medicine ,Context (language use) ,Freshwater Biology ,010603 evolutionary biology ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Common nase ,Periphyton ,Top-down control ,Trophic cascade ,Biomass (ecology) ,Ecology ,biology ,Trophic cascades ,010604 marine biology & hydrobiology ,General Neuroscience ,Chondrostoma ,lcsh:R ,Indirect interactions ,General Medicine ,Eutrophication ,biology.organism_classification ,Fish ,Benthic zone ,Exclosure ,Aquaculture, Fisheries and Fish Science ,Environmental science ,General Agricultural and Biological Sciences - Abstract
Benthic grazing strongly controls periphyton biomass. The question therefore arises whether benthic grazing could be used as a tool to reduce excessive growth of periphyton in nutrient-enriched rivers. Although benthic invertebrate grazers reduce the growth of periphyton, this is highly context dependent. Here we assessed whether the only obligate herbivorous fish in European rivers, the common nase (Chondrostoma nasus L.), is able to reduce periphyton biomass in a eutrophic river. We conducted three consecutive in situ experiments at low, intermediate and high densities of nase in the river using standard tiles on the river bottom naturally covered with periphyton that were accessible to fish and tiles that excluded fish foraging with electric exclosures. The biomass of benthic invertebrate grazers was very low relative to nase. We hypothesised that nase would reduce periphyton biomass on accessible tiles and therefore expected higher periphyton biomass on the exclosure tiles, at least at intermediate and high densities of nase in the river. Contrary to our expectation, the impact of fish grazing was low even at high fish density, as judged by the significantly lower chlorophyll a concentration on exclosure tiles even though the ash-free dry mass on accessible and exclosure tiles did not differ. The lower chlorophyll a concentrations on exclosure tiles might be explained by a higher biomass of invertebrate grazers on the exclosure tiles, which would indicate that the effect of invertebrate grazers was stronger than that of herbivorous fish grazers. The high biomass of invertebrate grazers on exclosure tiles likely arose from the exclusion of zoobenthivorous fish, which occur in the river at high densities. The results of our small-scale experiments suggested that cascading top-down effects of zoobenthivorous fish have a higher impact on periphyton biomass than direct effects of herbivorous nase.
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- 2018
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24. 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.
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- 2007
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25. Physiological and behavioral responses of the invasive amphipod, Dikerogammarus villosus, to ammonia
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Carola Winkelmann, Jochen Becker, and Monika Normant-Saremba
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Male ,Time Factors ,Physiology ,Motor Activity ,Biochemistry ,Locomotor activity ,Ammonia ,chemistry.chemical_compound ,Animal science ,Mole ,Animals ,Amphipoda ,Molecular Biology ,Analysis of Variance ,biology ,Triglyceride ,Glycogen ,Dose-Response Relationship, Drug ,Dikerogammarus villosus ,Metabolism ,DNA ,biology.organism_classification ,chemistry ,Basal metabolic rate ,RNA ,Basal Metabolism ,Introduced Species - Abstract
We studied the physiological and behavioral responses of the Ponto-Caspian amphipod Dikerogammarus villosus during exposure to four total ammonia concentrations (NH3+NH4(+); TotAmm): 0.003 (control), 0.06, 1.6, and 7.0 mmol L(-1) (0.042, 0.84, 22.4, and 98.0 mg L(-1)) for a period of up to 12 h at 21 °C. During the transition period from the control to treatment concentration as well as during the first hour of exposure to 0.06 and 1.6 mmol L(-1), gammarids increased their locomotor activity, which was manifested in significantly higher routine metabolic rates compared to control conditions. At control conditions, the resting metabolic rate amounted to 0.98±0.26 mW g(-1) and significantly increased by 19 and 37% at 0.06 and 1.6 mmol L(-1), respectively. The highest examined [TotAmm] caused a rapid and significant increase in resting metabolic rate by 37% within the first 4 h of exposure before gammarids died. The exposure to elevated [TotAmm] also resulted in a significant decreased RNA:DNA ratio and significantly higher glycogen concentrations compared to the control. We conclude that even a short exposure to TotAmm of 0.06 mmol L(-1), which may occur in natural habitats, disturbs the physiology and behavior of D. villosus and leads to increased metabolic costs of the maintenance and reduced protein synthesis.
- Published
- 2015
26. The management of metabolic energy storage during the life cycle of mayflies: a comparative field investigation of the collector-gatherer Ephemera danica and the scraper Rhithrogena semicolorata
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Jochen H. E. Koop and Carola Winkelmann
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Male ,Insecta ,Physiology ,Swarming (honey bee) ,Zoology ,Biochemistry ,Mayfly ,chemistry.chemical_compound ,Endocrinology ,Species Specificity ,Animals ,Periphyton ,Ecology, Evolution, Behavior and Systematics ,Triglycerides ,Larva ,Life Cycle Stages ,Sex Characteristics ,biology ,Glycogen ,Ecology ,fungi ,Voltinism ,biology.organism_classification ,chemistry ,Instar ,Animal Science and Zoology ,Female ,Ephemera danica ,Energy Metabolism - Abstract
The concentration and seasonal dynamics of the major energy storage components, triglycerides and glycogen, were measured in two species of mayfly (Rhithrogena semicolorata and Ephemera danica) with contrasting life cycle strategies living in a small mountain stream. E. danica is a burrowing, semivoltine collector-gatherer; R. semicolorata is univoltine and scrapes periphyton from stones. This is the first publication which focuses on the role of metabolic energy sources during the larval life span of two mayfly species until the larvae emerge. Although triglycerides are the major energy reserve in both species (>84% of total energy storage) throughout the whole larval development their seasonal dynamic differed considerably. In R. semicolorata the triglyceride concentration declined during the last weeks prior to emergence in both sexes. The same pattern was found in female larvae of E. danica, but not in male E. danica. It is suggested that females use triglycerides in the last larval stages for egg maturation, which is completed in the last larval instar. In male E. danica the triglyceride concentrations remained high until emergence, presumably due to their high energy demands as adults for their swarming flights. Glycogen concentrations did not show such a difference between species and sexes. Its significance as a storage substrate for energy is rather low; however, concentrations decreased in both species and sexes prior to emergence.
- Published
- 2006
27. Predation effects of benthivorous fish on grazing and shredding macroinvertebrates in a detritus-based stream food web
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Jochen H. E. Koop, Jürgen Benndorf, Susanne Worischka, and Carola Winkelmann
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Gobio gobio ,Rhithrogena semicolorata ,Detritus ,biology ,Ecology ,Predation ,Aquatic Science ,biology.organism_classification ,Food web ,Gammarus pulex ,Pulex ,Benthic community ,Guild ,Top-down control ,Trophic level - Abstract
We investigated lethal and sublethal predation effects of the benthivorous gudgeon (Gobio gobio) on the grazing mayfly Rhithrogena semicolorata and the shredding amphipod Gammarus pulex over 21 months in a largely detritus-based small stream. We hypothesised that shredders are generally less vulnerable to fish predation and therefore less likely to be predation-controlled than grazers, because the latter are visible to the predators during their feeding on stone surfaces, while shredders may hide between leaves during foraging. The hypothesis was tested in two 400 m experimental reaches of a natural stream, which were manipulated in order to contain and to lack fish, respectively. Biomass of G. pulex was significantly reduced in the fish section while that of R. semicolorata was not. Since approximately 91% of the annual production of G. pulex but only 12% of R. semicolorata production was consumed by gudgeon, the observed biomass difference of G. pulex is likely due to a lethal predation effect. However, no sublethal predation effects such as reduced concentration of storage components (triglycerides, glycogen) or reduced reproductive success were observed for both species. Lower mean body length of the R. semicolorata larvae in the fish section did not result in a lower number of eggs in the abdomen of the last instar larvae. Hence, in contrast to our initial hypothesis, in the studied stream the shredder was top-down-controlled, while the grazer was not. It is concluded that top-down control depends on the ecological characteristics of a specific predator–prey pair rather than on trophic guild of the prey.
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28. Extended larval development compensates for sublethal effects of fish predation in a mayfly population (Rhithrogena semicolorata, Ephemeroptera)
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Claudia Hellmann, Susanne Worischka, Jürgen Benndorf, and Carola Winkelmann
- Subjects
education.field_of_study ,Rhithrogena semicolorata ,biology ,Ecology ,Stone loach ,Population ,Predation ,Emergence ,Aquatic Science ,Fecundity ,biology.organism_classification ,Gobio gobio ,Rhithrogena ,Sublethal effects ,Adaptive behaviour ,Mayfly ,Barbatula ,Fitness ,education ,Benthivorous fish - Abstract
Many predation experiments in streams are carried out in enclosures. Hence, the relevance of their results to predict population dynamics is often unclear due to the relatively small spatial and temporal scale of the experiments. To enhance the transferability of experimental results on the ecosystem scale the impact of fish predators on a prey population was observed in a reach scale approach over 2 years in a natural stream. A 400-m reach inhabited by the small benthivorous fishes gudgeon ( Gobio gobio ) and stone loach ( Barbatula barbatula ) was compared with a fishless reference reach. It was shown that fish predation may affect the population of the grazing mayfly Rhithrogena semicolorata on the ecosystem scale. Although the larvae grew slower in the fish reach than in the fishless reach, the adults reached the same size and fecundity because they emerged 2–3 weeks later. By this compensation, the prey species avoided a reduction of their individual fecundity. On the other hand, the extended exposure to the fish predators resulted in an enhanced mortality and a reduced density of adult mayflies. Thus, there was obviously a trade-off between maximising fecundity and minimising mortality from fish predation. The observed differences were almost certainly caused be fish predation and not by natural differences of the reaches. This was concluded from results gained after eliminating all benthivorous fish from the former fish reach. With the help of scenario analyses based on our empirical data and simple model assumptions we could demonstrate that compensating the potential loss in fecundity by extending development time led to higher average fitness of the prey population than emerging at an earlier fixed time to avoid additional predation losses. Therefore, we concluded that this strategy was adaptive in the presence of benthivorous fish.
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