Kooperativer Bibliotheksverbund

Berlin Brandenburg


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  • 1
    In: Journal of Animal Ecology, March 2006, Vol.75(2), pp.421-433
    Description: 1 We evaluated the effects of brown trout on boreal stream food webs using field surveys and enclosure/exclosure experiments. Experimental results were related to prey preference of uncaged trout in the same stream, as well as to a survey of macroinvertebrate densities in streams with vs. without trout. Finally, we assessed the generality of our findings by examining salmonid predation on three groups of macroinvertebrate prey (chironomid midges, epibenthic grazers, invertebrate predators) in a meta‐analysis. 2 In a preliminary experiment, invertebrate predators showed a strong negative response to trout, whereas chironomids benefited from trout presence. In the main experiment, trout impact increased with prey size. Trout had the strongest effect on invertebrate predators and cased caddis larvae, whereas Baetis mayfly and chironomid larvae were unaffected. Trout impact on the largest prey seemed mainly consumptive, because prey emigration rates were low and independent of fish presence. Despite strong effects on macroinvertebrates, trout did not induce a trophic cascade on periphyton. Uncaged trout showed a strong preference for the largest prey items (predatory invertebrates and aerial prey), whereas Baetis mayflies and chironomids were avoided by trout. 3 Densities of invertebrate predators were significantly higher in troutless streams. Baetis mayflies also were less abundant in trout streams, whereas densities of chironomids were positively, although non‐significantly, related to trout presence. Meta‐analysis showed a strong negative impact of trout on invertebrate predators, a negative but variable impact on mobile grazers (mainly mayfly larvae) and a slightly positive impact on chironomid larvae. 4 Being size‐selective predators, salmonid fishes have a strong impact on the largest prey types available, and this effect spans several domains of scale. Discrepancies between our experimental findings and those from the field survey and meta‐analysis show, however, that for most lotic prey, small‐scale experiments do not reflect fish impact reliably at stream‐wide scales. 5 Our findings suggest that small‐scale experiments will be useful only if the experimental results are evaluated carefully against natural history information about the experimental system and interacting species across a wide array of spatial scales.
    Keywords: Benthic Macroinvertebrates ; Brown Trout ; Size‐Selective Predation ; Spatial Scale ; Streams
    ISSN: 0021-8790
    E-ISSN: 1365-2656
    Source: John Wiley & Sons, Inc.
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  • 2
    In: Diversity and Distributions, September 2012, Vol.18(9), pp.931-941
    Description: Despite wide consensus that ecological patterns and processes should be studied at multiple spatial scales, the temporal component of diversity variation has remained poorly examined. Specifically, rare species may exhibit patterns of diversity variation profoundly different from those of dominant taxa. Southern Finland. We used multiplicative partitioning of true diversities (species richness, Shannon diversity) to identify the most important scale(s) of variation of benthic macroinvertebrate communities across several hierarchical scales, from individual samples to multiple littorals, lakes and years. We also assessed the among‐scale variability of benthic macroinvertebrate community composition by using measures of between‐ and within‐group distances at hierarchical scales. On average, a single benthic sample contained 23% of the total regional macroinvertebrate species pool. For both species richness and Shannon diversity, beta‐diversity was clearly the major component of regional diversity, with within‐littoral beta‐diversity (β) being the largest component of gamma‐diversity. The interannual component of total diversity was small, being almost negligible for Shannon index. Among‐sample (within‐littoral) diversity was related to variation of substratum heterogeneity at the same scale. By contrast, only a small proportion of rare taxa was found in an average benthic sample. Thus, dominant species among lakes and years were about the same, whereas rare species were mostly detected in a few benthic samples in one lake (or year). For rare species, the temporal component of diversity was more important than spatial turnover at most scales. While individual species occurrences and abundances, particularly those of rare taxa, may vary strongly through space and time, patterns of dominance in lake littoral benthic communities are highly predictable. Consequently, many rare species will be missed in temporally restricted samples of lake littorals. In comprehensive biodiversity surveys, interannual sampling of littoral macroinvertebrate communities is therefore needed.
    Keywords: Benthic Invertebrates ; Beta‐Diversity ; Humic Lakes ; Interannual Variability ; Multiplicative Diversity Partitioning ; Multiscale Surveys
    ISSN: 1366-9516
    E-ISSN: 1472-4642
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  • 3
    Language: English
    In: Environmetrics, 2013, Vol. 24(4), pp. 237-247
    Description: Reliable estimates of the nutrient fluxes carried by rivers from land-based sources to the sea are needed for efficient abatement of marine eutrophication. Although nutrient concentrations in rivers generally display large temporal variation, sampling and analysis for nutrients, unlike flow measurements, are rarely performed on a daily basis. The infrequent data calls for ways to reliably estimate the nutrient concentrations of the missing days. Here, we use the Gaussian state space models with daily water flow as a predictor variable to predict missing nutrient concentrations for four agriculturally impacted Finnish rivers. Via simulation of Gaussian state space models, we are able to estimate aggregated yearly phosphorus and nitrogen fluxes, and their confidence intervals.The effect of model uncertainty is evaluated through a Monte Carlo experiment, where randomly selected sets of nutrient measurements are removed and then predicted by the remaining values together with re-estimated parameters. Results show that our model performs well for rivers with long-term records of flow. Finally, despite the drastic decreases in nutrient loads on the agricultural catchments of the rivers over the last 25years, we observe no corresponding trends in riverine nutrient fluxes.
    Keywords: Simulation ; Sparse Data ; Interpolation ; Kalman Filter ; Kalman Smoother ; Phosphorus Load ; Finland ; Streams ; Series ; Natural Sciences ; Earth And Related Environmental Sciences ; Oceanography, Hydrology And Water Resources ; Naturvetenskap ; Geovetenskap Och Miljövetenskap ; Oceanografi, Hydrologi Och Vattenresurser
    ISSN: 1180-4009
    E-ISSN: 1099095X
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  • 4
    Language: English
    In: Water Research, 01 July 2018, Vol.138, pp.192-205
    Description: Assessment of ecological status for the European Water Framework Directive (WFD) is based on “Biological Quality Elements” (BQEs), namely phytoplankton, benthic flora, benthic invertebrates and fish. Morphological identification of these organisms is a time-consuming and expensive procedure. Here, we assess the options for complementing and, perhaps, replacing morphological identification with procedures using eDNA, metabarcoding or similar approaches. We rate the applicability of DNA-based identification for the individual BQEs and water categories (rivers, lakes, transitional and coastal waters) against eleven criteria, summarised under the headlines representativeness (for example suitability of current sampling methods for DNA-based identification, errors from DNA-based species detection), sensitivity (for example capability to detect sensitive taxa, unassigned reads), precision of DNA-based identification (knowledge about uncertainty), comparability with conventional approaches (for example sensitivity of metrics to differences in DNA-based identification), cost effectiveness and environmental impact. Overall, suitability of DNA-based identification is particularly high for fish, as eDNA is a well-suited sampling approach which can replace expensive and potentially harmful methods such as gill-netting, trawling or electrofishing. Furthermore, there are attempts to replace absolute by relative abundance in metric calculations. For invertebrates and phytobenthos, the main challenges include the modification of indices and completing barcode libraries. For phytoplankton, the barcode libraries are even more problematic, due to the high taxonomic diversity in plankton samples. If current assessment concepts are kept, DNA-based identification is least appropriate for macrophytes (rivers, lakes) and angiosperms/macroalgae (transitional and coastal waters), which are surveyed rather than sampled. We discuss general implications of implementing DNA-based identification into standard ecological assessment, in particular considering any adaptations to the WFD that may be required to facilitate the transition to molecular data. Source: .
    Keywords: Meta-Barcoding ; Edna ; Biological Quality Elements ; Rivers ; Lakes ; Transitional and Coastal Waters ; Engineering
    ISSN: 0043-1354
    E-ISSN: 1879-2448
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  • 5
    In: Freshwater Biology, August 2006, Vol.51(8), pp.1486-1495
    Description: 1. We investigated the diet and prey electivity of , a slow‐moving invertebrate predator capable of hunting in high‐flow microhabitats, and quantified the components of the predation sequence of fifth‐instar larvae foraging on mobile ( mayflies, stoneflies) versus semi‐sessile (larval blackflies) prey. 2. In the field, fifth‐instar consistently took more larval blackflies than more mobile prey. In behavioural trials, the number of attacks by differed significantly between prey types, mobile prey being attacked more often than blackflies. Capture success, by contrast, was highest for blackflies, whereas and were rarely captured. In mixed‐prey feeding trials, showed strong preference for blackflies and equally strong avoidance of and . 3. For mobile prey, the risk of being captured by this sluggish predator is very low, so they can afford to be in close contact with it. was almost unable to capture any other prey but blackflies, resulting in strong passive selection for blackflies. 4. Therefore, the diet of fifth‐instar can be predicted from laboratory observations and prey behaviour is the major determinant of the diet of this invertebrate predator.
    Keywords: Blackfly Larvae ; Invertebrate Predators ; Lotic Systems ; Prey Selection ; Rhyacophila
    ISSN: 0046-5070
    E-ISSN: 1365-2427
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  • 6
    In: Methods in Ecology and Evolution, October 2017, Vol.8(10), pp.1265-1275
    Description: DNA metabarcoding holds great promise for the assessment of macroinvertebrates in stream ecosystems. However, few large‐scale studies have compared the performance of DNA metabarcoding with that of routine morphological identification. We performed metabarcoding using four primer sets on macroinvertebrate samples from 18 stream sites across Finland. The samples were collected in 2013 and identified based on morphology as part of a Finnish stream monitoring program. Specimens were morphologically classified, following standardised protocols, to the lowest taxonomic level for which identification was feasible in the routine national monitoring. DNA metabarcoding identified more than twice the number of taxa than the morphology‐based protocol, and also yielded a higher taxonomic resolution. For each sample, we detected more taxa by metabarcoding than by the morphological method, and all four primer sets exhibited comparably good performance. Sequence read abundance and the number of specimens per taxon (a proxy for biomass) were significantly correlated in each sample, although the adjusted R2 values were low. With a few exceptions, the ecological status assessment metrics calculated from morphological and DNA metabarcoding datasets were similar. Given the recent reduction in sequencing costs, metabarcoding is currently approximately as expensive as morphology‐based identification. Using samples obtained in the field, we demonstrated that DNA metabarcoding can achieve comparable assessment results to current protocols relying on morphological identification. Thus, metabarcoding represents a feasible and reliable method to identify macroinvertebrates in stream bioassessment, and offers powerful advantage over morphological identification in providing identification for taxonomic groups that are unfeasible to identify in routine protocols. To unlock the full potential of DNA metabarcoding for ecosystem assessment, however, it will be necessary to address key problems with current laboratory protocols and reference databases.
    Keywords: Biomass Bias ; Ecological Status ; High‐Throughput Sequencing ; Macroinvertebrates ; Metabarcoding
    ISSN: 2041-210X
    E-ISSN: 2041-210X
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  • 7
    Language: English
    In: Genome, 2017, Vol.60(11), p.930(1)
    Description: Background: The Atlantic Forest in South America is one of the most biodiverse ecosystems on Earth, harboring around 7% of the species of our planet. Because this biodiversity hotspot possesses high rates of endemism and has been extremely disturbed, it is a priority for conservation efforts. Arthropods...
    Keywords: DNA Barcoding – Usage ; Animal Populations – Genetic Aspects
    ISSN: 0831-2796
    E-ISSN: 14803321
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  • 8
    Language: English
    In: Stochastic Environmental Research and Risk Assessment, 2016, Vol.30(7), pp.1981-2008
    Description: The percent model affinity ( PMA ) index is used to measure the similarity of two probability profiles representing, for example, an ideal profile (i.e. reference condition) and a monitored profile (i.e. possibly impacted condition). The goal of this work is to study the effects of sample size, evenness, true value of the index and number of classes on the statistical properties of the estimator of the PMA index. We derive and extend previous formulas of the expectation and variance of the estimator for estimated monitored profile and fixed reference profile. Using the obtained extension, we find that the estimator is asymptotically unbiased, converging faster when the profiles differ. When both profiles are estimated, we calculate the expectation using transformation rules for expectation and in addition derive the formula for the estimator’s variance. Since the computation of the probabilities in the variance formula is slow, we study the behavior of the variance with simulation experiments and assess whether it could be approximated with the variance for the fixed reference profile. Finally, we provide a set of recommendations for the users of the PMA index to avoid the most common caveats of the index.
    Keywords: Percent model affinity index ; Similarity measure ; Statistical properties ; Decision making ; Biomonitoring
    ISSN: 1436-3240
    E-ISSN: 1436-3259
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  • 9
    Language: English
    In: Limnologica, 2012, Vol.42(1), pp.19-30
    Description: Defining reference conditions for lakes situated in areas of human settlement and agriculture is rarely straightforward, and is especially difficult within easily eroding and nutrient rich watersheds. We used diatoms, cyanobaterial akinetes, remains of green algae and chironomid head capsules from sediment samples of Lake Kirmanjärvi, Finland, to assess its deviation from the initial ecological status. These site-specific records of change were compared to current type-specific ecological status assessment. All paleolimnological data indicated deviation from natural conditions and mirrored the current, monitoring-based assessment of “moderate” ecological lake status. However, the sediment data showed that the lake should be re-typified as a naturally eutrophic lake. Sediment records as well as current monitoring data indicated temporary improvement in water quality in response to extensive fish manipulation. Our results suggest that paleolimnological records can be used to derive site-specific reference conditions and that extensive restoration efforts can result in gradual, observable improvements of water quality and ecological status.
    Keywords: Water Framework Directive ; Sediment ; Chironomids ; Diatoms ; Cyanobacteria ; Green Algae ; Ecological Status Assessment ; Management ; Restoration ; Oceanography ; Ecology
    ISSN: 0075-9511
    E-ISSN: 1873-5851
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  • 10
    Language: English
    In: Frontiers in Plant Science, 01 August 2018, Vol.9
    Description: Species richness and spatial variation in community composition (i.e., beta diversity) are key measures of biodiversity. They are largely determined by natural factors, but also increasingly affected by anthropogenic factors. Thus, there is a need for a clear understanding of the human impact...
    Keywords: Biodiversity ; Beta Diversity ; Community Composition ; Eutrophication ; Human Impact ; Null Models Species Richness ; Botany
    E-ISSN: 1664-462X
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