TY - JOUR A1 - Berger, S.A. A1 - Diehl, S. A1 - Stibor, H. A1 - Trommer, G. A1 - Ruthestroth, M. A1 - Wild, A. A1 - Weigert, A. A1 - Jäger, Christoph G. A1 - Striebel, M. T1 - Water temperature and mixing depth affect timing and magnitude of events during spring succession of the plankton JF - Oecologia N2 - In many lakes, the most conspicuous seasonal events are the phytoplankton spring bloom and the subsequent clear-water phase, a period of low-phytoplankton biomass that is frequently caused by mesozooplankton (Daphnia) grazing. In Central European lakes, the timing of the clear-water phase is linked to large-scale climatic forcing, with warmer winters being followed by an earlier onset of the clear-water phase. Mild winters may favour an early build-up of Daphnia populations, both directly through increased surface temperatures and indirectly by reducing light limitation and enhancing algal production, all being a consequence of earlier thermal stratification. We conducted a field experiment to disentangle the separate impacts of stratification depth (affecting light supply) and temperature on the magnitude and timing of successional events in the plankton. We followed the dynamics of the phytoplankton spring bloom, the clear-water phase and the spring peak in Daphnia abundance in response to our experimental manipulations. Deeper mixing delayed the timing of all spring seasonal events and reduced the magnitudes of the phytoplankton bloom and the subsequent Daphnia peak. Colder temperatures retarded the timing of the clear-water phase and the subsequent Daphnia peak, whereas the timing of the phytoplankton peak was unrelated to temperature. Most effects of mixing depth (light) and temperature manipulations were independent, effects of mixing depth being more prevalent than effects of temperature. Because mixing depth governs both the light climate and the temperature regime in the mixed surface layer, we propose that climate-driven changes in the timing and depth of water column stratification may have far-reaching consequences for plankton dynamics and should receive increased attention. KW - Algal spring bloom KW - Clear-water phase KW - Daphnia hyalina KW - Enclosure experiment KW - Phytoplankton KW - Zooplankton Y1 - 2007 UR - https://doi.org/10.1007/s00442-006-0550-9 VL - 150 IS - 4 SP - 643 EP - 654 ER - TY - JOUR A1 - Weitere, Markus A1 - Altenburger, Rolf A1 - Anlanger, Christine A1 - Baborowski, Martina A1 - Bärlund, Ilona A1 - Beckers, Liza-Marie A1 - Borchardt, Dietrich A1 - Brack, Werner A1 - Brase, Lisa A1 - Busch, Wibke A1 - Chatzinotas, Antonis A1 - Deutschmann, Björn A1 - Eligehausen, Jens A1 - Frank, Karin A1 - Graeber, Daniel A1 - Griebler, Christian A1 - Hagemann, Jeske A1 - Herzsprung, Peter A1 - Hollert, Henner A1 - Inostroza, Pedro A. A1 - Jäger, Christoph G. A1 - Kallies, René A1 - Kamjunke, Norbert A1 - Karrasch, Bernhard A1 - Kaschuba, Sigrid A1 - Kaus, Andrew A1 - Klauer, Bernd A1 - Knöller, Kay A1 - Koschorreck, Matthias A1 - Krauss, Martin A1 - Kunz, Julia V. A1 - Kurz, Marie J. A1 - Liess, Matthias A1 - Mages, Margarete A1 - Müller, Christin A1 - Muschket, Matthias A1 - Musolff, Andreas A1 - Norf, Helge A1 - Pöhlein, Florian A1 - Reiber, Lena A1 - Risse-Buhl, Ute A1 - Schramm, Karl-Werner A1 - Schmitt-Jansen, Mechthild A1 - Schmitz, Markus A1 - Strachauer, Ulrike A1 - von Tümpling, Wolf A1 - Weber, Nina A1 - Wild, Romy A1 - Wolf, Christine A1 - Brauns, Mario T1 - Disentangling multiple chemical and non-chemical stressors in a lotic ecosystem using a longitudinal approach JF - Science of the Total Environment N2 - Meeting ecological and water quality standards in lotic ecosystems is often failed due to multiple stressors. However, disentangling stressor effects and identifying relevant stressor-effect-relationships in complex environmental settings remain major challenges. By combining state-of-the-art methods from ecotoxicology and aquatic ecosystem analysis, we aimed here to disentangle the effects of multiple chemical and non-chemical stressors along a longitudinal land use gradient in a third-order river in Germany. We distinguished and evaluated four dominant stressor categories along this gradient: (1) Hydromorphological alterations: Flow diversity and substrate diversity correlated with the EU-Water Framework Directive based indicators for the quality element macroinvertebrates, which deteriorated at the transition from near-natural reference sites to urban sites. (2) Elevated nutrient levels and eutrophication: Low to moderate nutrient concentrations together with complete canopy cover at the reference sites correlated with low densities of benthic algae (biofilms). We found no more systematic relation of algal density with nutrient concentrations at the downstream sites, suggesting that limiting concentrations are exceeded already at moderate nutrient concentrations and reduced shading by riparian vegetation. (3) Elevated organic matter levels: Wastewater treatment plants (WWTP) and stormwater drainage systems were the primary sources of bioavailable dissolved organic carbon. Consequently, planktonic bacterial production and especially extracellular enzyme activity increased downstream of those effluents showing local peaks. (4) Micropollutants and toxicity-related stress: WWTPs were the predominant source of toxic stress, resulting in a rapid increase of the toxicity for invertebrates and algae with only one order of magnitude below the acute toxic levels. This toxicity correlates negatively with the contribution of invertebrate species being sensitive towards pesticides (SPEARpesticides index), probably contributing to the loss of biodiversity recorded in response to WWTP effluents. Our longitudinal approach highlights the potential of coordinated community efforts in supplementing established monitoring methods to tackle the complex phenomenon of multiple stress. KW - Multiple stress KW - Running waters KW - Indicators KW - Ecological functions KW - Effect based analyses Y1 - 2021 UR - https://doi.org/10.1016/j.scitotenv.2020.144324 VL - 769 SP - 144324 ER -