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32 results on '"Nejstgaard, Jens"'

3. Freshwater salinisation: a research agenda for a saltier world

Author

Cunillera-Montcusí, David, Beklioğlu, Meryem, Cañedo-Argüelles, Miguel, Jeppesen, Erik, Ptacnik, Robert, Amorim, Cihelio A., Arnott, Shelley E., Berger, Stella A., Brucet, Sandra, Dugan, Hilary A., Gerhard, Miriam, Horváth, Zsófia, Langenheder, Silke, Nejstgaard, Jens C., Reinikainen, Marko, Striebel, Maren, Urrutia-Cordero, Pablo, Vad, Csaba F., Zadereev, Egor, and Matias, Miguel

Published
2022
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4. Characterizing and Implementing the Hamamatsu C12880MA Mini-Spectrometer for Near-Surface Reflectance Measurements of Inland Waters.

Author

Jechow, Andreas, Bumberger, Jan, Palm, Bert, Remmler, Paul, Schreck, Günter, Ogashawara, Igor, Kiel, Christine, Kohnert, Katrin, Grossart, Hans-Peter, Singer, Gabriel A., Nejstgaard, Jens C., Wollrab, Sabine, Berger, Stella A., and Hölker, Franz

Subjects
BODIES of water, PROXIMITY detectors, SENSOR networks, REMOTE sensing, REFLECTANCE measurement
Abstract

In recent decades, inland water remote sensing has seen growing interest and very strong development. This includes improved spatial resolution, increased revisiting times, advanced multispectral sensors and recently even hyperspectral sensors. However, inland waters are more challenging than oceanic waters due to their higher complexity of optically active constituents and stronger adjacency effects due to their small size and nearby vegetation and built structures. Thus, bio-optical modeling of inland waters requires higher ground-truthing efforts. Large-scale ground-based sensor networks that are robust, self-sufficient, non-maintenance-intensive and low-cost could assist this otherwise labor-intensive task. Furthermore, most existing sensor systems are rather expensive, precluding their employability. Recently, low-cost mini-spectrometers have become widely available, which could potentially solve this issue. In this study, we analyze the characteristics of such a mini-spectrometer, the Hamamatsu C12880MA, and test it regarding its application in measuring water-leaving radiance near the surface. Overall, the measurements performed in the laboratory and in the field show that the system is very suitable for the targeted application. [ABSTRACT FROM AUTHOR]

Published
2024
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8. Design and implementation of an illumination system to mimic skyglow at ecosystem level in a large-scale lake enclosure facility

Author

Jechow, Andreas, Schreck, Günther, Kyba, Christopher C. M., Berger, Stella A., Bistarelli, Lukas Thuile, Bodenlos, Matthias, Gessner, Mark O., Grossart, Hans-Peter, Kupprat, Franziska, Nejstgaard, Jens C., Pansch, Andreas, Penske, Armin, Sachtleben, Michael, Shatwell, Tom, Singer, Gabriel A., Stephan, Susanne, Walles, Tim J. W., Wollrab, Sabine, Zielinska-Dabkowska, Karolina M., and Hölker, Franz

Published
2021
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9. Lake browning counteracts cyanobacteria responses to nutrients: Evidence from phytoplankton dynamics in large enclosure experiments and comprehensive observational data

Author

Lyche Solheim, Anne, primary, Gundersen, Hege, additional, Mischke, Ute, additional, Skjelbred, Birger, additional, Nejstgaard, Jens C., additional, Guislain, Alexis L. N., additional, Sperfeld, Erik, additional, Giling, Darren P., additional, Haande, Sigrid, additional, Ballot, Andreas, additional, Moe, S. Jannicke, additional, Stephan, Susanne, additional, Walles, Tim J. W., additional, Jechow, Andreas, additional, Minguez, Laetitia, additional, Ganzert, Lars, additional, Hornick, Thomas, additional, Hansson, Truls Hveem, additional, Stratmann, Cleo N., additional, Järvinen, Marko, additional, Drakare, Stina, additional, Carvalho, Laurence, additional, Grossart, Hans‐Peter, additional, Gessner, Mark O., additional, and Berger, Stella A., additional

Published
2023
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11. Deepwater dissolved oxygen shows little ecological memory between lake phenological seasons

Author

Pilla, Rachel M., primary, Williamson, Craig E., additional, Overholt, Erin P., additional, Rose, Kevin C., additional, Berger, Stella A., additional, Couture, Raoul-Marie, additional, de Wit, Heleen A., additional, Granados, Ignacio, additional, Grossart, Hans-Peter F., additional, Kirillin, Georgiy B., additional, Laas, Alo, additional, Nejstgaard, Jens C., additional, Rusak, James A., additional, Swinton, Mark W., additional, Toro, Manuel, additional, and Yao, Huaxia, additional

Published
2023
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12. Lake browning counteracts cyanobacteria responses to nutrients: Evidence from phytoplankton dynamics in large enclosure experiments and comprehensive observational data.

Author

Lyche Solheim, Anne, Gundersen, Hege, Mischke, Ute, Skjelbred, Birger, Nejstgaard, Jens C., Guislain, Alexis L. N., Sperfeld, Erik, Giling, Darren P., Haande, Sigrid, Ballot, Andreas, Moe, S. Jannicke, Stephan, Susanne, Walles, Tim J. W., Jechow, Andreas, Minguez, Laetitia, Ganzert, Lars, Hornick, Thomas, Hansson, Truls Hveem, Stratmann, Cleo N., and Järvinen, Marko

Subjects
EXTREME weather, CYANOBACTERIAL blooms, PHYTOPLANKTON, HUMUS, MICROCYSTIS, LAKES, CYANOBACTERIA
Abstract

Lakes worldwide are affected by multiple stressors, including climate change. This includes massive loading of both nutrients and humic substances to lakes during extreme weather events, which also may disrupt thermal stratification. Since multi‐stressor effects vary widely in space and time, their combined ecological impacts remain difficult to predict. Therefore, we combined two consecutive large enclosure experiments with a comprehensive time‐series and a broad‐scale field survey to unravel the combined effects of storm‐induced lake browning, nutrient enrichment and deep mixing on phytoplankton communities, focusing particularly on potentially toxic cyanobacterial blooms. The experimental results revealed that browning counteracted the stimulating effect of nutrients on phytoplankton and caused a shift from phototrophic cyanobacteria and chlorophytes to mixotrophic cryptophytes. Light limitation by browning was identified as the likely mechanism underlying this response. Deep‐mixing increased microcystin concentrations in clear nutrient‐enriched enclosures, caused by upwelling of a metalimnetic Planktothrix rubescens population. Monitoring data from a 25‐year time‐series of a eutrophic lake and from 588 northern European lakes corroborate the experimental results: Browning suppresses cyanobacteria in terms of both biovolume and proportion of the total phytoplankton biovolume. Both the experimental and observational results indicated a lower total phosphorus threshold for cyanobacterial bloom development in clearwater lakes (10–20 μg P L−1) than in humic lakes (20–30 μg P L−1). This finding provides management guidance for lakes receiving more nutrients and humic substances due to more frequent extreme weather events. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Interactive effects of nitrogen and phosphorus on growth and stoichiometry of lake phytoplankton

Author

Frost, Paul C., primary, Pearce, Nolan J. T., additional, Berger, Stella A., additional, Gessner, Mark O., additional, Makower, A. Katharina, additional, Marzetz, Vanessa, additional, Nejstgaard, Jens C., additional, Pralle, Aljona, additional, Schälicke, Svenja, additional, Wacker, Alexander, additional, Wagner, Nicole D., additional, and Xenopoulos, Marguerite A., additional

Published
2023
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14. Environmental variability in aquatic ecosystems : Avenues for future multifactorial experiments

Author

Gerhard, Miriam, Koussoroplis, Apostolos-Manuel, Raatz, Michael, Pansch, Christian, Fey, Samuel B., Vajedsamiei, Jahangir, Calderó-Pascual, Maria, Cunillera-Montcusí, David, Juvigny-Khenafou, Noël P. D., Polazzo, Francesco, Thomas, Patrick K., Symons, Celia C., Beklioğlu, Meryem, Berger, Stella A., Chefaoui, Rosa M., Ger, Kemal Ali, Langenheder, Silke, Nejstgaard, Jens C., Ptacnik, Robert, Striebel, Maren, Gerhard, Miriam, Koussoroplis, Apostolos-Manuel, Raatz, Michael, Pansch, Christian, Fey, Samuel B., Vajedsamiei, Jahangir, Calderó-Pascual, Maria, Cunillera-Montcusí, David, Juvigny-Khenafou, Noël P. D., Polazzo, Francesco, Thomas, Patrick K., Symons, Celia C., Beklioğlu, Meryem, Berger, Stella A., Chefaoui, Rosa M., Ger, Kemal Ali, Langenheder, Silke, Nejstgaard, Jens C., Ptacnik, Robert, and Striebel, Maren

Abstract

The relevance of considering environmental variability for understanding and predicting biological responses to environmental changes has resulted in a recent surge in variability-focused ecological research. However, integration of findings that emerge across studies and identification of remaining knowledge gaps in aquatic ecosystems remain critical. Here, we address these aspects by: (1) summarizing relevant terms of variability research including the components (characteristics) of variability and key interactions when considering multiple environmental factors; (2) identifying conceptual frameworks for understanding the consequences of environmental variability in single and multifactorial scenarios; (3) highlighting challenges for bridging theoretical and experimental studies involving transitioning from simple to more complex scenarios; (4) proposing improved approaches to overcome current mismatches between theoretical predictions and experimental observations; and (5) providing a guide for designing integrated experiments across multiple scales, degrees of control, and complexity in light of their specific strengths and limitations.

Published
2023
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15. Environmental variability in aquatic ecosystems: Avenues for future multifactorial experiments

Author

Gerhard, Miriam, primary, Koussoroplis, Apostolos‐Manuel, additional, Raatz, Michael, additional, Pansch, Christian, additional, Fey, Samuel B., additional, Vajedsamiei, Jahangir, additional, Calderó‐Pascual, Maria, additional, Cunillera‐Montcusí, David, additional, Juvigny‐Khenafou, Noël P. D., additional, Polazzo, Francesco, additional, Thomas, Patrick K., additional, Symons, Celia C., additional, Beklioğlu, Meryem, additional, Berger, Stella A., additional, Chefaoui, Rosa M., additional, Ger, Kemal Ali, additional, Langenheder, Silke, additional, Nejstgaard, Jens C., additional, Ptacnik, Robert, additional, and Striebel, Maren, additional

Published
2022
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16. Population response of pelagic fishes (ciscoes, Coregonusspp.) to rapidly accelerated eutrophication of an originally oligotrophic deep lake

Author

Mehner, Thomas, Wollrab, Sabine, Gonsiorczyk, Thomas, and Nejstgaard, Jens

Abstract

ABSTRACTNot much is known about early responses of pelagic fish populations to rapidly increasing nutrient concentrations in originally oligotrophic lakes. Here we report on population parameters of a pair of pelagic ciscoes (Coregonusspp.) exposed to accelerating eutrophication of the deep (69.5 m) and stratified Lake Stechlin (northeast Germany), in which total phosphorus (TP) concentration increased from ∼15 to >60 mg m−3within 10 years. With increasing TP concentrations, lower Secchi depths, declining oxygen concentrations in deeper water layers, higher phytoplankton, and higher zooplankton biomass were observed. Correlation analyses supported strong bottom-up directed effects of higher TP concentrations on primary and secondary producers and negative effects of TP on water quality parameters. Annual hydroacoustic records and midwater trawling showed an increase in average individual fish size. No temporal trend was found in fish biomass, but we observed cyclic annual biomass fluctuations. Diel vertical migration amplitudes of ciscoes declined, primarily by the occurrence of more fish in shallower waters than in previous years during daytime. We propose that release from density-dependent food limitation, due to increased plankton food abundances, resulted in increased individual sizes for both cisco species, which in turn increasingly blurs species discrimination because length distributions of both species are no longer substantially different. Our data show the value of long-term lake monitoring, including fish population surveys, to understand the initially subtle changes in biotic communities that may precede more drastic, potentially irreversible changes from anthropogenic pressures.

Published
2023
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17. Brownification reduces oxygen gross primary production and community respiration and changes the phytoplankton community composition: An in situ mesocosm experiment with high‐frequency sensor measurements in a North Atlantic bay

Author

Soulié, Tanguy, Stibor, Herwig, Mas, Sébastien, Braun, Benjamin, Knechtel, Johanna, Nejstgaard, Jens C., Sommer, Ulrich, Vidussi, Francesca, Mostajir, Behzad, Soulié, Tanguy, Stibor, Herwig, Mas, Sébastien, Braun, Benjamin, Knechtel, Johanna, Nejstgaard, Jens C., Sommer, Ulrich, Vidussi, Francesca, and Mostajir, Behzad

Abstract

In recent decades, the increase in terrestrial inputs to freshwater and coastal ecosystems, especially occurring at northern latitudes, has led to a process of water color darkening known as “brownification.” To assess how brownification affects plankton community composition and functioning in northern coastal areas, an in situ mesocosm experiment using a highly colored humic substance to simulate a brownification event was performed in a North Atlantic bay (Hopavågen, Norway) in August 2019. Manual sampling for analyses of nutrient concentrations, phytoplankton pigments and zooplankton abundances was combined with high-frequency (every 15 min) monitoring of key environmental variables to investigate the response of the plankton community in terms of oxygen metabolism and community composition. In response to brownification, the oxygen gross primary production (GPP) and community respiration (R) slowed down significantly, by almost one-third. However, GPP and R both decreased to the same extent; thus, the oxygen metabolic balance was not affected. Moreover, the chlorophyll-a concentration significantly decreased under brownification, by 9% on average, and the chemotaxonomic pigment composition of the phytoplankton changed, indicating their acclimation to the reduced light availability. In addition, brownification seemed to favor appendicularians, the dominant mesozooplankton group in the mesocosms, which potentially contributed to lowering the phytoplankton biomass. In conclusion, the results of this in situ mesocosm experiment suggest that brownification could induce significant changes in phytoplankton and zooplankton community composition and significantly alter the overall oxygen metabolism of plankton communities in a northern Atlantic bay.

Published
2022
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18. Food web structure and intraguild predation affect ecosystem functioning in an established plankton model

Author

Prowe, A. E. Friederike, Su, Bei, Nejstgaard, Jens C., Schartau, Markus, Prowe, A. E. Friederike, Su, Bei, Nejstgaard, Jens C., and Schartau, Markus

Abstract

Understanding how marine microbial food webs and their ecosystem functions are changing is crucial for projections of the future ocean. Often, simplified food web models are employed and their solutions are only evaluated against available observations of plankton biomass. With such an approach, it remains unclear how different underlying trophic interactions affect interpretations of plankton dynamics and functioning. Here, we quantitatively compare four hypothetical food webs to data from an existing mesocosm experiment using a refined version of the Minimum Microbial Food Web model. Food web representations range from separated food chains to complex food webs featuring additional trophic links including intraguild predation (IGP). Optimization against observations and taking into account model complexity ensures a fair comparison of the different food webs. Although the different optimized model food webs capture the observations similarly well, projected ecosystem functions differ depending on the underlying food web structure and the presence or absence of IGP. Mesh-like food webs dominated by the microbial loop yield higher recycling and net primary production (NPP) than models dominated by the classical diatom-copepod food chain. A high degree of microzooplankton IGP increases NPP and organic matter recycling, but decreases trophic transfer efficiency (TTE) to copepods. Copepod production, the trophic role of copepods, and TTE are more sensitive to initial biomass changes in chain-like than in complex food webs. Measurements resolving trophic interactions, in particular those quantifying IGP, remain essential to reduce model uncertainty and allow sound conclusions for ecosystem functioning in plankton ecosystems.

Published
2022
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19. A global agenda for advancing freshwater biodiversity research

Author

Maasri, Alain, Jähnig, Sonja C., Adamescu, Mihai C., Adrian, Rita, Baigun, Claudio, Baird, Donald J., Batista-Morales, Angelica, Bonada, Núria, Brown, Lee E., Cai, Qinghua, Campos-Silva, Joao V., Clausnitzer, Viola, Contreras-MacBeath, Topiltzin, Cooke, Steven J., Datry, Thibault, Delacámara, Gonzalo, De Meester, Luc, Dijkstra, Klaus-Douwe B., Tu Do, Van, Domisch, Sami, Dudgeon, David, Erös, Tibor, Freitag, Hendrik, Freyhof, Joerg, Friedrich, Jana, Friedrichs-Manthey, Martin, Geist, Juergen, Gessner, Mark O., Goethals, Peter, Gollock, Matthew, Gordon, Christopher, Grossart, Hans-Peter, Gulemvuga, Georges, Gutiérrez-Fonseca, Pablo E., Haase, Peter, Hering, Daniel, Hahn, Hans Jürgen, Hawkins, Charles P., He, Fengzhi, Heino, Jani, Hermoso, Virgilio, Hogan, Zeb, Hölker, Franz, Jeschke, Jonathan M., Jiang, Meilan, Johnson, Richard K., Kalinkat, Gregor, Karimov, Bakhtiyor K., Kasangaki, Aventino, Kimirei, Ismael A., Kohlmann, Bert, Kuemmerlen, Mathias, Kuiper, Jan J., Kupilas, Benjamin, Langhans, Simone D., Lansdown, Richard, Leese, Florian, Magbanua, Francis S., Matsuzaki, Shin-ichiro S., Monaghan, Michael T., Mumladze, Levan, Muzon, Javier, Mvogo Ndongo, Pierre A., Nejstgaard, Jens C., Nikitina, Oxana, Ochs, Clifford, Odume, Oghenekaro Nelson, Opperman, Jeffrey J., Patricio, Harmony, Pauls, Steffen U., Raghavan, Rajeev, Ramírez, Alonso, Rashni, Bindiya, Ross-Gillespie, Vere, Samways, Michael J., Schäfer, Ralf B., Schmidt-Kloiber, Astrid, Seehausen, Ole, Shah, Deep Narayan, Sharma, Subodh, Soininen, Janne, Sommerwerk, Nike, Stockwell, Jason D., Suhling, Frank, Tachamo Shah, Ram Devi, Tharme, Rebecca E., Thorp, James H., Tickner, David, Tockner, Klement, Tonkin, Jonathan D., Valle, Mireia, Vitule, Jean, Volk, Martin, Wang, Ding, Wolter, Christian, Worischka, Susanne, Maasri, Alain, Jähnig, Sonja C., Adamescu, Mihai C., Adrian, Rita, Baigun, Claudio, Baird, Donald J., Batista-Morales, Angelica, Bonada, Núria, Brown, Lee E., Cai, Qinghua, Campos-Silva, Joao V., Clausnitzer, Viola, Contreras-MacBeath, Topiltzin, Cooke, Steven J., Datry, Thibault, Delacámara, Gonzalo, De Meester, Luc, Dijkstra, Klaus-Douwe B., Tu Do, Van, Domisch, Sami, Dudgeon, David, Erös, Tibor, Freitag, Hendrik, Freyhof, Joerg, Friedrich, Jana, Friedrichs-Manthey, Martin, Geist, Juergen, Gessner, Mark O., Goethals, Peter, Gollock, Matthew, Gordon, Christopher, Grossart, Hans-Peter, Gulemvuga, Georges, Gutiérrez-Fonseca, Pablo E., Haase, Peter, Hering, Daniel, Hahn, Hans Jürgen, Hawkins, Charles P., He, Fengzhi, Heino, Jani, Hermoso, Virgilio, Hogan, Zeb, Hölker, Franz, Jeschke, Jonathan M., Jiang, Meilan, Johnson, Richard K., Kalinkat, Gregor, Karimov, Bakhtiyor K., Kasangaki, Aventino, Kimirei, Ismael A., Kohlmann, Bert, Kuemmerlen, Mathias, Kuiper, Jan J., Kupilas, Benjamin, Langhans, Simone D., Lansdown, Richard, Leese, Florian, Magbanua, Francis S., Matsuzaki, Shin-ichiro S., Monaghan, Michael T., Mumladze, Levan, Muzon, Javier, Mvogo Ndongo, Pierre A., Nejstgaard, Jens C., Nikitina, Oxana, Ochs, Clifford, Odume, Oghenekaro Nelson, Opperman, Jeffrey J., Patricio, Harmony, Pauls, Steffen U., Raghavan, Rajeev, Ramírez, Alonso, Rashni, Bindiya, Ross-Gillespie, Vere, Samways, Michael J., Schäfer, Ralf B., Schmidt-Kloiber, Astrid, Seehausen, Ole, Shah, Deep Narayan, Sharma, Subodh, Soininen, Janne, Sommerwerk, Nike, Stockwell, Jason D., Suhling, Frank, Tachamo Shah, Ram Devi, Tharme, Rebecca E., Thorp, James H., Tickner, David, Tockner, Klement, Tonkin, Jonathan D., Valle, Mireia, Vitule, Jean, Volk, Martin, Wang, Ding, Wolter, Christian, and Worischka, Susanne

Abstract

Global freshwater biodiversity is declining dramatically, and meeting the challenges of this crisis requires bold goals and the mobilisation of substantial resources. While the reasons are varied, investments in both research and conservation of freshwater biodiversity lag far behind those in the terrestrial and marine realms. Inspired by a global consultation, we identify 15 pressing priority needs, grouped into five research areas, in an effort to support informed stewardship of freshwater biodiversity. The proposed agenda aims to advance freshwater biodiversity research globally as a critical step in improving coordinated actions towards its sustainable management and conservation.

Published
2022
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20. Environmental variability in aquatic ecosystems: Avenues for future multifactorial experiments

Author

Gerhard, Miriam, Koussoroplis, Apostolos‐Manuel, Raatz, Michael, Pansch, Christian, Fey, Samuel B., Vajedsamiei, Jahangir, Calderó‐Pascual, Maria, Cunillera‐Montcusí, David, Juvigny‐Khenafou, Noël P. D., Polazzo, Francesco, Thomas, Patrick K., Symons, Celia C., Beklioğlu, Meryem, Berger, Stella A., Chefaoui, Rosa M., Ger, Kemal Ali, Langenheder, Silke, Nejstgaard, Jens C., Ptacnik, Robert, Striebel, Maren, Gerhard, Miriam, Koussoroplis, Apostolos‐Manuel, Raatz, Michael, Pansch, Christian, Fey, Samuel B., Vajedsamiei, Jahangir, Calderó‐Pascual, Maria, Cunillera‐Montcusí, David, Juvigny‐Khenafou, Noël P. D., Polazzo, Francesco, Thomas, Patrick K., Symons, Celia C., Beklioğlu, Meryem, Berger, Stella A., Chefaoui, Rosa M., Ger, Kemal Ali, Langenheder, Silke, Nejstgaard, Jens C., Ptacnik, Robert, and Striebel, Maren

Abstract

The relevance of considering environmental variability for understanding and predicting biological responses to environmental changes has resulted in a recent surge in variability-focused ecological research. However, integration of findings that emerge across studies and identification of remaining knowledge gaps in aquatic ecosystems remain critical. Here, we address these aspects by: (1) summarizing relevant terms of variability research including the components (characteristics) of variability and key interactions when considering multiple environmental factors; (2) identifying conceptual frameworks for understanding the consequences of environmental variability in single and multifactorial scenarios; (3) highlighting challenges for bridging theoretical and experimental studies involving transitioning from simple to more complex scenarios; (4) proposing improved approaches to overcome current mismatches between theoretical predictions and experimental observations; and (5) providing a guide for designing integrated experiments across multiple scales, degrees of control, and complexity in light of their specific strengths and limitations.

Published
2022
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21. Spatial and seasonal patterns of water isotopes in northeastern German lakes

Author

Aichner, Bernhard, primary, Dubbert, David, additional, Kiel, Christine, additional, Kohnert, Katrin, additional, Ogashawara, Igor, additional, Jechow, Andreas, additional, Harpenslager, Sarah-Faye, additional, Hölker, Franz, additional, Nejstgaard, Jens Christian, additional, Grossart, Hans-Peter, additional, Singer, Gabriel, additional, Wollrab, Sabine, additional, and Berger, Stella Angela, additional

Published
2022
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22. Using UV-Fluorescence Fingerprints to Assess Lake Browning Effects - A Mesocosm Experiment in Lake Stechlin, Germany

Author

Clercin, Nicolas, Vinçon Leite, Brigitte, Ogashawara, Igor, Kiel, Christine, Wollrab, Sabine, Berger, Stella, Nejstgaard, Jens, and Vinçon-Leite, Brigitte

Subjects
[SDE] Environmental Sciences, aquatic mesocosms, water browning, Dissolved organic matter, Fluorescence
Abstract

During the summer of 2021, a browning experiment was conducted at the LakeLab mesocosm facility at Lake Stechlin, Germany, as part of the AQUACOSM Transnational Access program. From mid-July to mid-August, a total of 10 sampling campaigns in 16 enclosures was run to assess the effects of artificial browning (HuminFeed® addition) on water clarity and light penetration in the epilimnion. Four different treatments: control (CC), +nutrients (CN), control +browning (BC) and +nutrients +browning (BN) were applied to a subset of 4 enclosures; additional control measurements were taken at different locations in Lake Stechlin. Each sample aliquot was analyzed with a fluorescence spectrophotometer (Hitachi F-7000) to obtain its spectral fingerprint. Commonfluorescence peaks were measured and their respective behaviors analyzed throughout the study period. The results indicate that all fluorescence peaks and fluorescence-based indicators were attenuated and remained low after addition of artificial humic substances. Only peak C fluorescence, reflecting humic-like compounds in water, increased in enclosures BC and BN that received the browning treatment; thus highlighting the specific HuminFeed® signature. Interestingly, after a 2-week lag phase, fluorescence of peaks B and T (tyrosine- and tryptophan-like compounds) and BIX, the Biological Index characterizing the biological production of DOM, increased significantly in enclosures CN and BC. These observations may be linked to phytoplankton growth which did not occur in photic zones of BN enclosures. Spectral signatures of CC enclosures mimicked those from lake controls and none demonstrated significant fluorescence variations.

Published
2022

23. Can space-for-time-substitution surveys represent zooplankton biodiversity patterns and their relationship to environmental drivers?

Author

Stockwell, Jason, Ivanick, Lia, Chiapella, Ariana, Vichi, Cecilia, Grossart, Hans-Peter, Zagarese, Horacio, Diovisalvi, Nadia, Odriozola, Mariana, Gideon, Gal, Geraldes, Ana Maria, Christoffersen, Kirsten Seestern, Sarvala, Jouko, Blank, Kätlin, Beklioğlu, Meryem, Kainz, Martin, Bruel, Rosalie, Ger, Kemal Ali, Matsuzaki, Shin-Ichiro, Khan, Samiullah, Nejstgaard, Jens, Znachor, Petr, Seda, Jaromír, Obertegger, Ulrike, Salmaso, Nico, García-Girón, Jorge, Leoni, Barbara, Jeppesen, Erik, Tavşanoğlu, Ülkü Nihan, Rusanovskaya, Olga O., Tartarotti, Barbara, Dur, Gaël, Kuczyńska-Kippen, Natalia, Dondajewska-Pielka, Renata, Eyto, Elvira de, Thackeray, Stephen, Garcia de Souza, Javier R., Rusak, James A., Moe, Jannicke, Figary, Stephanie, May, Linda, Gunn, Iain, Doubek, Jonathan, Symons, Celia C., Burnet, Sarah, Lepori, Fabio, Alcocer, Javier, Fernández, Rocío, Oseguera, Luis A., Verburg, Piet, and Fontanarrosa, María Soledad

Subjects
Space-for-Time-Substitution, Lago di Tovel, Zooplancton, Space for time, Settore BIO/07 - ECOLOGIA
Abstract

Space-for-Time-Substitution surveys (SFTS) are commonly used to describe zooplankton community dynamics and to determine lake ecosystem health. SFTS surveys typically combine single point observations from many lakes to evaluate the response of zooplankton community structure and dynamics (e.g., species abundance and biomass, diversity, demographics and modeled rate processes) to spatial gradients in hypothesized environmental drivers (e.g., temperature, nutrients, predation), in lieu of tracking such responses over long time scales. However, the reliability and reproducibility of SFTS zooplankton surveys have not yet been comprehensively tested against empirically-based community dynamics from longterm monitoring efforts distributed worldwide. We use a recently compiled global data set of more than 100 lake zooplankton time series to test whether SFTS surveys can accurately capture zooplankton diversity, and the hypothesized relationship with temperature, using simulated SFTS surveys of the time series data. Specifically, we asked: (1) to what degree can SFTS surveys capture observed biodiversity dynamics; (2) how does timing and duration of sampling affect detected biodiversity patterns; (3) does biodiversity ubiquitously increase with temperature across lakes, or vary by climate zone or lake type; and (4) do results from SFTS surveys produce comparable biodiversity-temperature relationship(s) to empirical data within and among lakes? Testing biodiversity-ecosystem function (BEF) relationships, and the drivers of such relationships, requires a solid data basis. Our work provides a global perspective on the design and usefulness of (long-term) zooplankton monitoring programs and how much confidence we can place in the zooplankton biodiversity patterns observed from SFTS surveys. info:eu-repo/semantics/publishedVersion

Published
2022

25. Brownification reduces oxygen gross primary production and community respiration and changes the phytoplankton community composition: An in situ mesocosm experiment with high‐frequency sensor measurements in a North Atlantic bay

Author

Soulié, Tanguy, primary, Stibor, Herwig, additional, Mas, Sébastien, additional, Braun, Benjamin, additional, Knechtel, Johanna, additional, Nejstgaard, Jens C., additional, Sommer, Ulrich, additional, Vidussi, Francesca, additional, and Mostajir, Behzad, additional

Published
2022
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27. Cover Image

Author

Maasri, Alain, primary, Jähnig, Sonja C., additional, Adamescu, Mihai C., additional, Adrian, Rita, additional, Baigun, Claudio, additional, Baird, Donald J., additional, Batista‐Morales, Angelica, additional, Bonada, Núria, additional, Brown, Lee E., additional, Cai, Qinghua, additional, Campos‐Silva, Joao V., additional, Clausnitzer, Viola, additional, Contreras‐MacBeath, Topiltzin, additional, Cooke, Steven J., additional, Datry, Thibault, additional, Delacámara, Gonzalo, additional, De Meester, Luc, additional, Dijkstra, Klaus‐Douwe B., additional, Do, Van Tu, additional, Domisch, Sami, additional, Dudgeon, David, additional, Erös, Tibor, additional, Freitag, Hendrik, additional, Freyhof, Joerg, additional, Friedrich, Jana, additional, Friedrichs‐Manthey, Martin, additional, Geist, Juergen, additional, Gessner, Mark O., additional, Goethals, Peter, additional, Gollock, Matthew, additional, Gordon, Christopher, additional, Grossart, Hans‐Peter, additional, Gulemvuga, Georges, additional, Gutiérrez‐Fonseca, Pablo E., additional, Haase, Peter, additional, Hering, Daniel, additional, Hahn, Hans Jürgen, additional, Hawkins, Charles P., additional, He, Fengzhi, additional, Heino, Jani, additional, Hermoso, Virgilio, additional, Hogan, Zeb, additional, Hölker, Franz, additional, Jeschke, Jonathan M., additional, Jiang, Meilan, additional, Johnson, Richard K., additional, Kalinkat, Gregor, additional, Karimov, Bakhtiyor K., additional, Kasangaki, Aventino, additional, Kimirei, Ismael A., additional, Kohlmann, Bert, additional, Kuemmerlen, Mathias, additional, Kuiper, Jan J., additional, Kupilas, Benjamin, additional, Langhans, Simone D., additional, Lansdown, Richard, additional, Leese, Florian, additional, Magbanua, Francis S., additional, Matsuzaki, Shin‐ichiro S., additional, Monaghan, Michael T., additional, Mumladze, Levan, additional, Muzon, Javier, additional, Mvogo Ndongo, Pierre A., additional, Nejstgaard, Jens C., additional, Nikitina, Oxana, additional, Ochs, Clifford, additional, Odume, Oghenekaro Nelson, additional, Opperman, Jeffrey J., additional, Patricio, Harmony, additional, Pauls, Steffen U., additional, Raghavan, Rajeev, additional, Ramírez, Alonso, additional, Rashni, Bindiya, additional, Ross‐Gillespie, Vere, additional, Samways, Michael J., additional, Schäfer, Ralf B., additional, Schmidt‐Kloiber, Astrid, additional, Seehausen, Ole, additional, Shah, Deep Narayan, additional, Sharma, Subodh, additional, Soininen, Janne, additional, Sommerwerk, Nike, additional, Stockwell, Jason D., additional, Suhling, Frank, additional, Tachamo Shah, Ram Devi, additional, Tharme, Rebecca E., additional, Thorp, James H., additional, Tickner, David, additional, Tockner, Klement, additional, Tonkin, Jonathan D., additional, Valle, Mireia, additional, Vitule, Jean, additional, Volk, Martin, additional, Wang, Ding, additional, Wolter, Christian, additional, and Worischka, Susanne, additional

Published
2022
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29. A global agenda for advancing freshwater biodiversity research

Author

Maasri, Alain, primary, Jähnig, Sonja C., additional, Adamescu, Mihai C., additional, Adrian, Rita, additional, Baigun, Claudio, additional, Baird, Donald J., additional, Batista‐Morales, Angelica, additional, Bonada, Núria, additional, Brown, Lee E., additional, Cai, Qinghua, additional, Campos‐Silva, Joao V., additional, Clausnitzer, Viola, additional, Contreras‐MacBeath, Topiltzin, additional, Cooke, Steven J., additional, Datry, Thibault, additional, Delacámara, Gonzalo, additional, De Meester, Luc, additional, Dijkstra, Klaus‐Douwe B., additional, Do, Van Tu, additional, Domisch, Sami, additional, Dudgeon, David, additional, Erös, Tibor, additional, Freitag, Hendrik, additional, Freyhof, Joerg, additional, Friedrich, Jana, additional, Friedrichs‐Manthey, Martin, additional, Geist, Juergen, additional, Gessner, Mark O., additional, Goethals, Peter, additional, Gollock, Matthew, additional, Gordon, Christopher, additional, Grossart, Hans‐Peter, additional, Gulemvuga, Georges, additional, Gutiérrez‐Fonseca, Pablo E., additional, Haase, Peter, additional, Hering, Daniel, additional, Hahn, Hans Jürgen, additional, Hawkins, Charles P., additional, He, Fengzhi, additional, Heino, Jani, additional, Hermoso, Virgilio, additional, Hogan, Zeb, additional, Hölker, Franz, additional, Jeschke, Jonathan M., additional, Jiang, Meilan, additional, Johnson, Richard K., additional, Kalinkat, Gregor, additional, Karimov, Bakhtiyor K., additional, Kasangaki, Aventino, additional, Kimirei, Ismael A., additional, Kohlmann, Bert, additional, Kuemmerlen, Mathias, additional, Kuiper, Jan J., additional, Kupilas, Benjamin, additional, Langhans, Simone D., additional, Lansdown, Richard, additional, Leese, Florian, additional, Magbanua, Francis S., additional, Matsuzaki, Shin‐ichiro S., additional, Monaghan, Michael T., additional, Mumladze, Levan, additional, Muzon, Javier, additional, Mvogo Ndongo, Pierre A., additional, Nejstgaard, Jens C., additional, Nikitina, Oxana, additional, Ochs, Clifford, additional, Odume, Oghenekaro Nelson, additional, Opperman, Jeffrey J., additional, Patricio, Harmony, additional, Pauls, Steffen U., additional, Raghavan, Rajeev, additional, Ramírez, Alonso, additional, Rashni, Bindiya, additional, Ross‐Gillespie, Vere, additional, Samways, Michael J., additional, Schäfer, Ralf B., additional, Schmidt‐Kloiber, Astrid, additional, Seehausen, Ole, additional, Shah, Deep Narayan, additional, Sharma, Subodh, additional, Soininen, Janne, additional, Sommerwerk, Nike, additional, Stockwell, Jason D., additional, Suhling, Frank, additional, Tachamo Shah, Ram Devi, additional, Tharme, Rebecca E., additional, Thorp, James H., additional, Tickner, David, additional, Tockner, Klement, additional, Tonkin, Jonathan D., additional, Valle, Mireia, additional, Vitule, Jean, additional, Volk, Martin, additional, Wang, Ding, additional, Wolter, Christian, additional, and Worischka, Susanne, additional

Published
2021
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30. Application of species-specific primers to estimate the in situ diet of Bythotrephes [Cladocera, Onychopoda] in its native European range via molecular gut content analysis.

Author

Pichler, Arthur, Walters, Tina L, Frischer, Marc E, Nejstgaard, Jens C, and Ptáčníková, Radka

Subjects
CYTOCHROME oxidase, CLADOCERA, DNA primers, CONTENT analysis, ANIMAL nutrition, POLYMERASE chain reaction, DAPHNIA
Abstract

The study of invasive species often focuses on regions of recent introduction rather than native habitats. Understanding an invasive species in its natural environment, however, can provide important insights regarding the long-term outcome of invasions. In this study we investigated the diet of the invasive spiny water flea, Bythotrephes longimanus , in two Austrian perialpine lakes, where it is native. The gut contents of wild-caught Bythotrephes individuals were estimated by quantitative polymerase chain reaction, targeting species-specific fragments of the barcoding region of the cytochrome c oxidase I gene of potential prey. The observed prey spectrum of Bythotrephes in the study lakes consisted primarily of Eudiaptomus gracilis and Diaphanosoma brachyurum. The Daphnia longispina complex, Leptodora kindtii and Mesocyclops leuckarti also contributed to the diet. Results indicate that Bythotrephes is a generalist feeder with a preference for epilimnetic prey. [ABSTRACT FROM AUTHOR]

Published
2021
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31. Chlorophyll-a determinations in mesocosms under varying nutrient and temperature treatments: in-situ fluorescence sensors versus in-vitro measurements.

Author

Levi EE, Jeppesen E, Nejstgaard JC, and Davidson TA

Abstract

Harmful algal blooms (HABs) are a significant threat to freshwater ecosystems, and monitoring for changes in biomass is therefore important. Fluorescence in-situ sensors enable rapid and high frequency real-time data collection and have been widely used to determine chlorophyll- a (Chla) concentrations that are used as an indicator of the total algal biomass. However, conversion of fluorescence to equivalent Chla concentrations is often complicated due to biofouling, phytoplankton composition and the type of equipment used. Here, we validated measurements from 24 Chla and 12 phycocyanin (cyanobacteria indicator) fluorescence in-situ sensors (Cyclops-7F, Turner Designs) against spectrophotometrically (in-vitro) determined Chla and tested a data-cleaning procedure for eliminating data errors and impacts of non-photochemical quenching. The test was done across a range of freshwater plankton communities in 24 mesocosms (i.e. experimental tanks) with a 2x3 (high and low nutrient x ambient, IPCC-A2 and IPCC-A2+50% temperature scenarios) factorial design. For most mesocosms (tanks), we found accurate (r 2 ≥ 0.7) calibration of in-situ Chla fluorescence data using simple linear regression. An exception was tanks with high in-situ phycocyanin fluorescence, for which multiple regressions were employed, which increased the explained variance by >16%. Another exception was the low Chla concentration tanks (r 2 < 0.3). Our results also show that the high frequency in-situ fluorescence data recorded the timing of sudden Chla variations, while less frequent in-vitro sampling sometimes missed these or, when recorded, the duration of changes was inaccurately determined. Fluorescence in-situ sensors are particularly useful to detect and quantify sudden phytoplankton biomass variations through high frequency measurements, especially when using appropriate data-cleaning methods and accounting for factors that can impact the fluorescence readings. Nevertheless, corroborating these data with in-vitro Chla assessments would provide additional validation for the early warnings provided by sensor data., Competing Interests: No competing interests were disclosed., (Copyright: © 2024 Levi EE et al.)

Published
2024
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32. A global agenda for advancing freshwater biodiversity research.

Author

Maasri A, Jähnig SC, Adamescu MC, Adrian R, Baigun C, Baird DJ, Batista-Morales A, Bonada N, Brown LE, Cai Q, Campos-Silva JV, Clausnitzer V, Contreras-MacBeath T, Cooke SJ, Datry T, Delacámara G, De Meester L, Dijkstra KB, Do VT, Domisch S, Dudgeon D, Erös T, Freitag H, Freyhof J, Friedrich J, Friedrichs-Manthey M, Geist J, Gessner MO, Goethals P, Gollock M, Gordon C, Grossart HP, Gulemvuga G, Gutiérrez-Fonseca PE, Haase P, Hering D, Hahn HJ, Hawkins CP, He F, Heino J, Hermoso V, Hogan Z, Hölker F, Jeschke JM, Jiang M, Johnson RK, Kalinkat G, Karimov BK, Kasangaki A, Kimirei IA, Kohlmann B, Kuemmerlen M, Kuiper JJ, Kupilas B, Langhans SD, Lansdown R, Leese F, Magbanua FS, Matsuzaki SS, Monaghan MT, Mumladze L, Muzon J, Mvogo Ndongo PA, Nejstgaard JC, Nikitina O, Ochs C, Odume ON, Opperman JJ, Patricio H, Pauls SU, Raghavan R, Ramírez A, Rashni B, Ross-Gillespie V, Samways MJ, Schäfer RB, Schmidt-Kloiber A, Seehausen O, Shah DN, Sharma S, Soininen J, Sommerwerk N, Stockwell JD, Suhling F, Tachamo Shah RD, Tharme RE, Thorp JH, Tickner D, Tockner K, Tonkin JD, Valle M, Vitule J, Volk M, Wang D, Wolter C, and Worischka S

Subjects
Biodiversity, Fresh Water, Conservation of Natural Resources, Ecosystem
Abstract

Global freshwater biodiversity is declining dramatically, and meeting the challenges of this crisis requires bold goals and the mobilisation of substantial resources. While the reasons are varied, investments in both research and conservation of freshwater biodiversity lag far behind those in the terrestrial and marine realms. Inspired by a global consultation, we identify 15 pressing priority needs, grouped into five research areas, in an effort to support informed stewardship of freshwater biodiversity. The proposed agenda aims to advance freshwater biodiversity research globally as a critical step in improving coordinated actions towards its sustainable management and conservation., (© 2021 The Authors. Ecology Letters published by John Wiley & Sons Ltd.)

Published
2022
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