TY - JOUR A1 - Weyhenmeyer, G. A. A1 - Adrian, Rita A1 - Gaedke, Ursula A1 - Livingstone, D. M. A1 - Maberly, Stephen C. T1 - Response of phytoplankton in European lakes to a change in the North Atlantic Oscillation Y1 - 2002 SN - 0368-0770 ER - TY - BOOK A1 - Gaedke, Ursula A1 - Seifried, Angelika A1 - Adrian, Rita T1 - Biomass size spectra and plankton diversity in a shallow eutrophic lake N2 - Biomass size spectra collate structural and functional attributes of plankton communities enabling standardised temporal and cross-system comparisons and may be rapidly obtained by automated particle counters. To examine how differences in plankton communities from highly eutrophic and more oligotrophic lakes are reflected in size spectra, a three-year time series of biomass size spectra was established for polymictic, eutrophic Lake Müggelsee, based on approximately weekly sampling and microscopic enumeration. The continuous but often bumpy size spectra reflected appropriately the seasonal and trophy-related variations in the plankton composition and growth conditions and the potential impact of daphnids on smaller plankton. We tested the hypothesis that more diverse plankton communities have smoother size spectra than impoverished ones. The spectra of L. Müggelsee and other more less eutrophic lakes covaried roughly with the functional diversity in total plankton composition but were unrelated to taxonomical diversity within the phyto- or mesozooplankton. The slopes of the normalised size spectra of Lake Müggelsee were generally more negative than -1, exhibited a recurrent seasonal pattern, and were strongly correlated with crustacean biomass. In contrast to less eutrophic systems, slopes could not be used to quantify energy fluxes within the foodweb due to highly variable algal P/B ratios and frequently bumpy size distributions. The latter indicated stronger deviations from the ideal concept of a steady energy flow along the size gradient than found in e. g. large, mesotrophic Lake Constance. Y1 - 2004 SN - 1434-2944 ER - TY - JOUR A1 - Boëchat, Iola G. A1 - Weithoff, Guntram A1 - Krüger, Angela A1 - Gücker, Björn A1 - Adrian, Rita T1 - A biochemical explanation for the success of the mixotrophy in the flagellate Ochromonas sp. N2 - We report the influence of different nutritional modes-autotrophy, mixotrophy, and heterotrophy-on the fatty acid and sterol composition of the freshwater flagellate Ochromonas sp. and discuss the ecological significance of our results with respect to the resource competition theory (rct). Polyunsaturated fatty acids (PUFAs) are the most efficient biochemical variable distinguishing between nutritional modes of Ochromonas sp. Decreasing concentrations of PUFAs were observed in the order autotrophs, mixotrophs, heterotrophs. In mixotrophs and heterotrophs, concentrations of saturated fatty acids were higher than those of monounsaturated fatty acids and PUFAs as a result of bacterivory. Stigmasterol was the main sterol in Ochromonas sp., regardless of nutritional mode. Mixotrophs showed higher growth rates than heterotrophs, which could not be explained by rct. Heterotrophs, in turn, exhibited higher growth rates than autotrophs, which were cultured under the same light conditions as mixotrophs. Mixotrophs can synthesize PUFAs, which are important for many physiological functions such as membrane permeability and growth. Thus, mixotrophy facilitated efficient growth as well as the ability to synthesize complex and essential biomolecules. These strong synergetic effects are due to the combination of biochemical benefits of heterotrophic and autotrophic metabolic pathways and cannot be predicted by rct. Y1 - 2007 UR - http://www.aslo.org/lo/ U6 - https://doi.org/10.4319/lo.2007.52.4.1624 SN - 0024-3590 ER - TY - INPR A1 - Walz, Norbert A1 - Adrian, Rita A1 - Gilbert, John J. A1 - Monaghan, Michael T. A1 - Weithoff, Guntram A1 - Zimmermann-Timm, Heike T1 - Preface T2 - Hydrobiologia : acta hydrobiologica, hydrographica, limnologica et protistologica Y1 - 2011 U6 - https://doi.org/10.1007/s10750-010-0514-2 SN - 0018-8158 VL - 662 IS - 1 SP - 1 EP - 4 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Sommer, Ulrich A1 - Adrian, Rita A1 - Domis, Lisette Nicole de Senerpont A1 - Elser, James J. A1 - Gaedke, Ursula A1 - Ibelings, Bas A1 - Jeppesen, Erik A1 - Lurling, Miquel A1 - Molinero, Juan Carlos A1 - Mooij, Wolf M. A1 - van Donk, Ellen A1 - Winder, Monika ED - Futuyma, DJ T1 - Beyond the Plankton Ecology Group (PEG) Model mechanisms driving plankton succession JF - Annual review of ecology, evolution, and systematics JF - Annual Review of Ecology Evolution and Systematics N2 - The seasonal succession of plankton is an annually repeated process of community assembly during which all major external factors and internal interactions shaping communities can be studied. A quarter of a century ago, the state of this understanding was described by the verbal plankton ecology group (PEG) model. It emphasized the role of physical factors, grazing and nutrient limitation for phytoplankton, and the role of food limitation and fish predation for zooplankton. Although originally targeted at lake ecosystems, it was also adopted by marine plankton ecologists. Since then, a suite of ecological interactions previously underestimated in importance have become research foci: overwintering of key organisms, the microbial food web, parasitism, and food quality as a limiting factor and an extended role of higher order predators. A review of the impact of these novel interactions on plankton seasonal succession reveals limited effects on gross seasonal biomass patterns, but strong effects on species replacements. KW - lakes KW - oceans KW - seasonal patterns KW - pelagic zone KW - light KW - overwintering KW - grazing KW - parasitism KW - food quality Y1 - 2012 SN - 978-0-8243-1443-9 U6 - https://doi.org/10.1146/annurev-ecolsys-110411-160251 SN - 1543-592X VL - 43 IS - 2-4 SP - 429 EP - 448 PB - Annual Reviews CY - Palo Alto ER - TY - JOUR A1 - Schmidt, Silke Regina A1 - Gerten, Dieter A1 - Hintze, Thomas A1 - Lischeid, Gunnar A1 - Livingstone, David M. A1 - Adrian, Rita T1 - Temporal and spatial scales of water temperature variability as an indicator for mixing in a polymictic lake JF - Inland waters : journal of the International Society of Limnology N2 - We applied coarse spectral analysis to more than 2 decades of daily near-surface water temperature (WT) measurements from Muggelsee, a shallow polymictic lake in Germany, to systematically characterize patterns in WT variability from daily to yearly temporal scales. Comparison of WT with local air temperature indicates that the WT variability patterns are likely attributable to both meteorological forcing and internal lake dynamics. We identified seasonal patterns of WT variability and showed that WT variability increases with increasing Schmidt stability, decreasing Lake number and decreasing ice cover duration, and is higher near the shore than in open water. We introduced the slope of WT spectra as an indicator for the degree of lake mixing to help explain the identified temporal and spatial scales of WT variability. The explanatory power of this indicator in other lakes with different mixing regimes remains to be established. KW - Lake number KW - polymictic lakes KW - Schmidt stability KW - seasonality KW - spectral analysis KW - variability Y1 - 2018 U6 - https://doi.org/10.1080/20442041.2018.1429067 SN - 2044-2041 SN - 2044-205X VL - 8 IS - 1 SP - 82 EP - 95 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - JOUR A1 - Schmidt, Silke Regina A1 - Lischeid, Gunnar A1 - Hintze, Thomas A1 - Adrian, Rita T1 - Disentangling limnological processes in the time-frequency domain JF - Limnology and oceanography N2 - State variables in lake ecosystems are subject to processes that act on different time scales. The relative importance of each of these processes changes over time, e.g., due to varying constraints of physical, biological, and biogeochemical processes. Correspondingly, continuous automatic measurements at high temporal resolution often reveal intriguing patterns that can rarely be directly ascribed to single processes. In light of the rather complex interplay of such processes, disentangling them requires more powerful methods than researchers have applied up to this point. For this reason, we tested the potential of wavelet coherence, based on the assumption that different processes result in correlations between different variables, on different time scales and during different time windows across the seasons. The approach was tested on a set of multivariate hourly data measured between the onset of an ice cover and a cyanobacterial summer bloom in the year 2009 in the Muggelsee, a polymictic eutrophic lake. We found that processes such as photosynthesis and respiration, the growth and decay of phytoplankton biomass, dynamics in the CO2-carbonate system, wind-induced resuspension of particles, and vertical mixing all occasionally served as dominant drivers of the variability in our data. We therefore conclude that high-resolution data and a method capable of analyzing time series in both the time and the frequency domain can help to enhance our understanding of the time scales and processes responsible for the high variability in driver variables and response variables, which in turn can lay the ground for mechanistic analyses. Y1 - 2018 U6 - https://doi.org/10.1002/lno.11049 SN - 0024-3590 SN - 1939-5590 VL - 64 IS - 2 SP - 423 EP - 440 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Rusak, James A. A1 - Tanentzap, Andrew J. A1 - Klug, Jennifer L. A1 - Rose, Kevin C. A1 - Hendricks, Susan P. A1 - Jennings, Eleanor A1 - Laas, Alo A1 - Pierson, Donald C. A1 - Ryder, Elizabeth A1 - Smyth, Robyn L. A1 - White, D. S. A1 - Winslow, Luke A. A1 - Adrian, Rita A1 - Arvola, Lauri A1 - de Eyto, Elvira A1 - Feuchtmayr, Heidrun A1 - Honti, Mark A1 - Istvanovics, Vera A1 - Jones, Ian D. A1 - McBride, Chris G. A1 - Schmidt, Silke Regina A1 - Seekell, David A1 - Staehr, Peter A. A1 - Guangwei, Zhu T1 - Wind and trophic status explain within and among-lake variability of algal biomass JF - Limnology and oceanography letters / ASLO, Association for the Sciences of Limnology and Oceanography N2 - Phytoplankton biomass and production regulates key aspects of freshwater ecosystems yet its variability and subsequent predictability is poorly understood. We estimated within-lake variation in biomass using high-frequency chlorophyll fluorescence data from 18 globally distributed lakes. We tested how variation in fluorescence at monthly, daily, and hourly scales was related to high-frequency variability of wind, water temperature, and radiation within lakes as well as productivity and physical attributes among lakes. Within lakes, monthly variation dominated, but combined daily and hourly variation were equivalent to that expressed monthly. Among lakes, biomass variability increased with trophic status while, within-lake biomass variation increased with increasing variability in wind speed. Our results highlight the benefits of high-frequency chlorophyll monitoring and suggest that predicted changes associated with climate, as well as ongoing cultural eutrophication, are likely to substantially increase the temporal variability of algal biomass and thus the predictability of the services it provides. Y1 - 2018 U6 - https://doi.org/10.1002/lol2.10093 SN - 2378-2242 VL - 3 IS - 6 SP - 409 EP - 418 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Perkins, Daniel M. A1 - Perna, Andrea A1 - Adrian, Rita A1 - Cermeno, Pedro A1 - Gaedke, Ursula A1 - Huete-Ortega, Maria A1 - White, Ethan P. A1 - Yvon-Durocher, Gabriel T1 - Energetic equivalence underpins the size structure of tree and phytoplankton communities JF - Nature Communications N2 - The size structure of autotroph communities - the relative abundance of small vs. large individuals - shapes the functioning of ecosystems. Whether common mechanisms underpin the size structure of unicellular and multicellular autotrophs is, however, unknown. Using a global data compilation, we show that individual body masses in tree and phytoplankton communities follow power-law distributions and that the average exponents of these individual size distributions (ISD) differ. Phytoplankton communities are characterized by an average ISD exponent consistent with three-quarter-power scaling of metabolism with body mass and equivalence in energy use among mass classes. Tree communities deviate from this pattern in a manner consistent with equivalence in energy use among diameter size classes. Our findings suggest that whilst universal metabolic constraints ultimately underlie the emergent size structure of autotroph communities, divergent aspects of body size (volumetric vs. linear dimensions) shape the ecological outcome of metabolic scaling in forest vs. pelagic ecosystems. Y1 - 2019 U6 - https://doi.org/10.1038/s41467-018-08039-3 SN - 2041-1723 VL - 10 PB - Nature Publ. Group CY - London ER -