@article{BergerDiehlStiboretal.2007, author = {Berger, S.A. and Diehl, S. and Stibor, H. and Trommer, G. and Ruthestroth, M. and Wild, A. and Weigert, A. and J{\"a}ger, Christoph G. and Striebel, M.}, title = {Water temperature and mixing depth affect timing and magnitude of events during spring succession of the plankton}, series = {Oecologia}, volume = {150}, journal = {Oecologia}, number = {4}, pages = {643 -- 654}, year = {2007}, abstract = {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.}, language = {en} } @article{WeitereAltenburgerAnlangeretal.2021, author = {Weitere, Markus and Altenburger, Rolf and Anlanger, Christine and Baborowski, Martina and B{\"a}rlund, Ilona and Beckers, Liza-Marie and Borchardt, Dietrich and Brack, Werner and Brase, Lisa and Busch, Wibke and Chatzinotas, Antonis and Deutschmann, Bj{\"o}rn and Eligehausen, Jens and Frank, Karin and Graeber, Daniel and Griebler, Christian and Hagemann, Jeske and Herzsprung, Peter and Hollert, Henner and Inostroza, Pedro A. and J{\"a}ger, Christoph G. and Kallies, Ren{\´e} and Kamjunke, Norbert and Karrasch, Bernhard and Kaschuba, Sigrid and Kaus, Andrew and Klauer, Bernd and Kn{\"o}ller, Kay and Koschorreck, Matthias and Krauss, Martin and Kunz, Julia V. and Kurz, Marie J. and Liess, Matthias and Mages, Margarete and M{\"u}ller, Christin and Muschket, Matthias and Musolff, Andreas and Norf, Helge and P{\"o}hlein, Florian and Reiber, Lena and Risse-Buhl, Ute and Schramm, Karl-Werner and Schmitt-Jansen, Mechthild and Schmitz, Markus and Strachauer, Ulrike and von T{\"u}mpling, Wolf and Weber, Nina and Wild, Romy and Wolf, Christine and Brauns, Mario}, title = {Disentangling multiple chemical and non-chemical stressors in a lotic ecosystem using a longitudinal approach}, series = {Science of the Total Environment}, volume = {769}, journal = {Science of the Total Environment}, pages = {144324}, year = {2021}, abstract = {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.}, language = {en} }