Kooperativer Bibliotheksverbund

Berlin Brandenburg

and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Type of Medium
Language
Year
  • 1
    In: Nature Communications, 2015, Vol.6
    Description: Lakes are important habitats for biogeochemical cycling of carbon. The organization and structure of aquatic communities influences the biogeochemical interactions between lakes and the atmosphere. Understanding how trophic structure regulates ecosystem functions and influences greenhouse gas efflux from lakes is critical to understanding global carbon cycling and climate change. With a whole-lake experiment in which a previously fishless lake was divided into two treatment basins where fish abundance was manipulated, we show how a trophic cascade from fish to microbes affects methane efflux to the atmosphere. Here, fish exert high grazing pressure and remove nearly all zooplankton. This reduction in zooplankton density increases the abundance of methanotrophic bacteria, which in turn reduce CH4 efflux rates by roughly 10 times. Given that globally there are millions of lakes emitting methane, an important greenhouse gas, our findings that aquatic trophic interactions significantly influence the biogeochemical cycle of methane has important implications.
    Keywords: Biology;
    ISSN: 2041-1723
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    In: Ecology, December 2017, Vol.98(12), pp.3074-3085
    Description: The role of littoral habitats in lake metabolism has been underrated, especially in humic lakes, based on an assumption of low benthic primary production () due to low light penetration into water. This assumption has been challenged by recent recognition of littoral epiphyton dominance of whole‐lake in a small highly humic lake and of epiphyton as an important basal food source for humic lake biota. However, as these studies have mostly concerned single lakes, there is a need to test their wider generality. We studied the whole‐lake and community respiration () in eight small humic lakes in southern Finland during July 2015 using C incorporation to measure pelagic and the changes in dissolved inorganic carbon in light and dark in situ incubations to measure and littoral by epiphyton. Changes in O concentration in both pelagic and littoral surface water were measured periodically from each lake and, additionally, continuously with a data logger from one lake during the study period. The results revealed that the littoral dominated whole‐lake net primary production () in five of the eight lakes, which was supported by observed O supersaturation in the littoral surface water in most of the lakes. Calculated pelagic:littoral ratios by area correlated negatively with both littoral and littoral contribution to whole‐lake . Moreover, there was a significant positive relationship between littoral proportion of whole‐lake and the fraction of lake surface area covered by littoral aquatic vegetation. This demonstrates that increased aquatic littoral vegetation cover increases the overall importance of the littoral to whole‐lake in highly humic lakes. Littoral also correlated strongly with littoral O saturation, and the continuously measured O revealed substantial temporal variation in O saturation, particularly in the littoral zone. Whole‐lake gross primary production:community respiration (:) ratios revealed that accounting for littoral metabolism produced a marked shift towards lake metabolic balance, although all the eight lakes remained net heterotrophic. This study emphasizes that littoral metabolism needs to be accounted for when estimating whole‐lake C fluxes in all lakes, even in highly colored humic waters.
    Keywords: Boreal Lakes ; Community Respiration ; Epiphyton ; Lake Browning ; Lake Metabolism ; Whole‐Lake Primary Production
    ISSN: 0012-9658
    E-ISSN: 1939-9170
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Language: English
    In: Hydrobiologia, 2011, Vol.658(1), pp.383-388
    Description: We tested the impacts of most common sample preservation methods used for aquatic sample materials on the stable isotope ratios of carbon and nitrogen in clams, a typical baseline indicator organism for many aquatic food web studies utilising stable isotope analysis (SIA). In addition to common chemical preservatives ethanol and formalin, we also assessed the potential impacts of freezing on δ 13 C and δ 15 N values and compared the preserved samples against freshly dried and analysed samples. All preservation methods, including freezing, had significant impacts on δ 13 C and δ 15 N values and the effects in general were greater on the carbon isotope values (1.3–2.2‰ difference) than on the nitrogen isotope values (0.9–1.0‰ difference). However, the impacts produced by the preservation were rather consistent within each method during the whole 1 year experiment allowing these to be accounted for, if clams are intended for use in retrospective stable isotope studies.
    Keywords: Formalin ; Freezing ; Ethanol ; Preservation ; Stable isotope analysis
    ISSN: 0018-8158
    E-ISSN: 1573-5117
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: Ecology, 10/12/2015
    Description: Microbial communities play a key role in biogeochemical processes by degrading organic material and recycling nutrients, but can also be important food sources for upper trophic levels. Trophic cascades might modify microbial communities either directly via grazing or indirectly by inducing changes in other biotic or in abiotic factors (e.g., nutrients). We studied the effects of a tri‐trophic cascade on microbial communities during a whole‐lake manipulation in which European perch (Perca fluviatilis) were added to a naturally fishless lake divided experimentally into two basins. We measured environmental parameters (oxygen, temperature, and nutrients) and zooplankton biomass and studied the changes in the bacterial community using next generation sequencing of 16S rRNA genes and cell counting. Introduction of fish reduced the biomass of zooplankton, mainly Daphnia, which partly altered the bacterial community composition and affected the bacterial cell abundances. However, the microbial community composition was mainly governed by stratification patterns and associated vertical oxygen concentration. Slowly growing green sulfur bacteria (Chlorobium) dominated the anoxic water layers together with bacteria of the candidate division OD1. We conclude that alterations in trophic interactions can affect microbial abundance, but that abiotic factors seem to be more significant controls of microbial community composition in sheltered boreal lakes. ; p. 684-693.
    Keywords: Environmental Factors ; Oxygen ; Chlorobium ; Grazing ; Biomass ; Fish ; Genes ; Lakes ; Ribosomal Rna ; Trophic Relationships ; Daphnia ; Bacterial Communities ; Temperature ; High-Throughput Nucleotide Sequencing ; Nutrients ; Bacteria ; Basins ; Community Structure ; Zooplankton ; Perca Fluviatilis;
    ISSN: 0012-9658
    E-ISSN: 19399170
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Language: English
    In: PLoS ONE, 2016, Vol. 11(5)
    Description: Hydrogen stable isotopes (δ2H) have recently been used to complement δ13C and δ15N in food web studies due to their potentially greater power to separate sources of organic matter in aquatic food webs. However, uncertainties remain regarding the use of δ2H, since little is known about the potential variation in the amount of exchangeable hydrogen (Hex) among common sample materials or the patterns of δ2H when entire food webs are considered. We assessed differences in Hex among the typical sample materials in freshwater studies and used δ2H, δ13C and δ15N to compare their effectiveness in tracing allochthonous matter in food webs of two small temperate lakes. Our results showed higher average amounts of Hex in animal tissues (27% in fish and macroinvertebrates, 19% in zooplankton) compared to most plant material (15% in terrestrial plants and 8% in seston/periphyton), with the exception of aquatic vascular plants (23%, referred to as macrophytes). The amount of Hex correlated strongly with sample lipid content (inferred from C:N ratios) in fish and zooplankton samples. Overall, the three isotopes provided good separation of sources (seston, periphyton, macrophytes and allochthonous organic matter), particularly the δ2H followed by δ13C. Aquatic macrophytes revealed unexpectedly high δ2H values, having more elevated δ2H values than terrestrial organic matter with direct implications for estimating consumer allochthony. Organic matter from macrophytes significantly contributed to the food webs in both lakes highlighting the need to include macrophytes as a potential source when using stable isotopes to estimate trophic structures and contributions from allochthonous sources.
    Keywords: Natural Sciences ; Earth And Related Environmental Sciences ; Oceanography, Hydrology And Water Resources ; Naturvetenskap ; Geovetenskap Och Miljövetenskap ; Oceanografi, Hydrologi Och Vattenresurser
    ISSN: 1932-6203
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    In: Freshwater Biology, March 2016, Vol.61(3), pp.265-276
    Description: The prevailing view that many humic lakes are net heterotrophic is commonly based on pelagic measurements alone. Poor light conditions in humic lakes are assumed to constrain littoral primary production (PP), such that the littoral zone has been considered an insignificant contributor to whole‐lake PP. However, that assumption is based on models and inferences from pelagic processes which do not take littoral zone structure into account. Many lakes have an extensive ring of aquatic vegetation lying near the water surface, which provides substratum for epiphytic algae under well‐illuminated conditions. We measured both pelagic and littoral PP and community respiration (CR) in Mekkojärvi, a small, highly humic headwater lake, in southern Finland throughout the open water season in 2012. We used a 14C incorporation technique to measure pelagic PP, while littoral PP was determined using changes in dissolved inorganic carbon concentrations during in situ incubations. We then estimated whole‐lake PP and CR for both the littoral and pelagic zones. We found that littoral PP usually dominated whole‐lake PP, contributing 〉90% to total PP in summer. A mean pelagic production to respiration ratio (GPP : CR) of 0.4 clearly indicated strong net heterotrophy, but a value of 2.2 for the littoral zone indicated strong autotrophy. For both habitats combined, the mean whole lake GPP : CR was 1.6, indicating net autotrophy. We suggest that littoral PP can contribute significantly to whole‐lake PP even in highly humic lakes, and that the littoral contribution can shift some lakes which have been considered net heterotrophic to metabolic balance or even net autotrophy during the ice‐free period. Small humic lakes like Mekkojärvi with rings of littoral vegetation are widespread, especially in the boreal zone, and at least for similar lakes, evaluating lake metabolism from pelagic measurements alone is likely to be misleading.
    Keywords: Autotrophy ; Benthic Primary Production ; Dissolved Organic Carbon ; Heterotrophy ; Lake Metabolism
    ISSN: 0046-5070
    E-ISSN: 1365-2427
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: Ecology, 2013, Vol.95(6), pp.1496-1505
    Description: Lake ecosystems are strongly linked to their terrestrial surroundings by material and energy fluxes across ecosystem boundaries. However, the contribution of terrestrial particulate organic carbon (tPOC) from annual leaf fall to lake food webs has not yet been adequately traced and quantified. In this...
    Keywords: Natural Sciences ; Naturvetenskap
    ISSN: 0012-9658
    E-ISSN: 19399170
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: PLoS ONE, 01 January 2013, Vol.8(2), p.e56094
    Description: Stable isotope analyses are increasingly employed to characterise population niche widths. The convex hull area (TA) in a δ(13)C-δ(15)N biplot has been used as a measure of isotopic niche width, but concerns exist over its dependence on sample size and associated difficulties in among-population comparisons. Recently a more robust method was proposed for estimating and comparing isotopic niche widths using standard ellipse areas (SEA), but this approach has yet to be tested with empirical stable isotope data. The two methods measure different kind of isotopic niche areas, but both are now widely used to characterise isotopic niche widths of populations. We used simulated data and an extensive empirical dataset from two fish populations to test the influence of sample size on the observed isotopic niche widths (TA and SEA). We resampled the original datasets to generate 5000 new samples for different numbers of observations from 5 to 80 to examine the statistical distributions of niche area estimates for increasing sample size. Our results illustrate how increasing sample size increased the observed TA; even sample sizes much higher than n = 30 did not improve the precision for the TA method. SEA was less sensitive to sample size, but the natural variation in our empirical fish δ(13)C and δ(15)N data still resulted in considerable uncertainty around the mean estimates of niche width, reducing the precision particularly with sample sizes n〈30. These results confirm that the TA method is less appropriate for estimating population isotopic niche areas using small samples, especially when considerable population level isotope variation is expected. The results also indicate a need for caution when using SEA as a measure of trophic niche widths for consumers, particularly with low sample sizes and when the distribution and range for population isotope values are not known.
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    In: Oikos, February 2010, Vol.119(2), pp.409-416
    Description: Although some primary consumers such as chironomid larvae are known to exploit methane‐derived carbon via microbial consortia within aquatic food webs, few studies have traced the onward transfer of such carbon to their predators. The ruffe is a widespread benthivorous fish which feeds predominantly on chironomid larvae and is well adapted for foraging at lower depths than other percids. Therefore, any transfer of methanogenic carbon to higher trophic levels might be particularly evident in ruffe. We sampled ruffe and chironomid larvae from the littoral, sub‐littoral and profundal areas of Jyväsjärvi, Finland, a lake which has previously been shown to contain chironomid larvae exhibiting the very low stable carbon isotope ratios indicative of methane exploitation. A combination of fish gut content examination and stable isotope analysis was used to determine trophic linkages between fish and their putative prey. Irrespective of the depth from which the ruffe were caught, their diet was dominated by chironomids and pupae although the proportions of taxa changed. Zooplankton made a negligible contribution to ruffe diet. A progressive decrease in δC and δN values with increasing water column depth was observed for both chironomid larvae and ruffe, but not for other species of benthivorous fish. Furthermore, ruffe feeding at greater depths were significantly larger than those feeding in the littoral, suggesting an ontogenetic shift in habitat use, rather than diet, as chironomids remained the predominant prey item. The outputs from isotope mixing models suggested that the incorporation of methane‐derived carbon to larval chironomid biomass through feeding on methanotrophic bacteria increased at greater depth, varying from 0% in the littoral to 28% in the profundal. Using these outputs and the proportions of littoral, sub‐littoral or profundal chironomids contributing to ruffe biomass, we estimated that 17% of ruffe biomass in this lake was ultimately derived from chemoautotrophic sources. Methanogenic carbon thus supports considerable production of higher trophic levels in lakes.
    Keywords: Physical sciences -- Physics -- Microphysics ; Biological sciences -- Biology -- Zoology ; Physical sciences -- Chemistry -- Chemical compounds ; Physical sciences -- Earth sciences -- Geography ; Biological sciences -- Biology -- Marine biology ; Biological sciences -- Ecology -- Biomass ; Physical sciences -- Chemistry -- Chemical elements ; Biological sciences -- Biology -- Zoology ; Biological sciences -- Biology -- Developmental biology ; Biological sciences -- Biology -- Developmental biology;
    ISSN: 0030-1299
    E-ISSN: 1600-0706
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    In: Oikos, July 2018, Vol.127(7), pp.960-969
    Description: Aquatic and terrestrial ecosystems are linked by fluxes of carbon and nutrients in riparian areas. Processes that alter these fluxes may therefore change the diet and composition of consumer communities. We used stable carbon isotope (δC) analyses to test whether the increased abundance of aquatic prey observed in a previous study led to a dietary shift in riparian consumers in areas illuminated by artificial light at night (ALAN). We measured the contribution of aquatic‐derived carbon to diets in riparian arthropods in experimentally lit and unlit sites along an agricultural drainage ditch in northern Germany. The δC signature of the spider (Tetragnathidae) was 0.7‰ lower in the ALAN‐illuminated site in summer, indicating a greater assimilation of aquatic prey. Bayesian mixing models also supported higher intake of aquatic prey under ALAN in spring (34% versus 21%). In contrast, isotopic signatures for (0.3‰) and (0.7‰) indicated a preference for terrestrial prey in the illuminated site in spring. Terrestrial prey intake increased in spring for under ALAN (from 70% to 74%) and in spring and autumn for (from 68% to 77% and from 67% to 72%) and Opiliones (from 68% to 72%; 68% to 75%). This was despite most of the available prey (up to 80%) being aquatic in origin. We conclude that ALAN changed the diet of riparian secondary consumers by increasing the density of both aquatic and terrestrial prey. Dietary changes were species‐ and season‐specific, indicating that the effects of ALAN may interact with phenology and feeding strategy. Because streetlights can occur in high density near freshwaters, ALAN may have widespread effects on aquatic–terrestrial ecosystem linkages.
    Keywords: Spiders ; Food Web ; Alan ; Predator–Prey ; Stable Isotopes ; Siar ; Feeding Strategies
    ISSN: 0030-1299
    E-ISSN: 1600-0706
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages