https://hdl.handle.net/10481/46989 2026-04-05T21:13:22Z https://hdl.handle.net/10481/109679 Browning, nutrient inputs, and fast vertical mixing from simulated extreme rainfall and wind stress alter estuarine phytoplankton productivity Helbling, E. W.; Banaszak, A. T.; Valiñas, M. S.; Vizzo, J. I.; Villafañe, V. E.; Jabalera Cabrerizo, Marco Browning and nutrient inputs from extreme rainfall, together with increased vertical mixing due to strong winds, are more frequent in coastal ecosystems; however, their interactive effects on phytoplankton are poorly understood. We conducted experiments to quantify how brown- ing, together with different mixing speeds (fluctuating radiation), and a nutrient pulse alter primary productivity and photosynthetic efficiency in estuarine phytoplankton communities. Phytoplankton communities (grazers excluded) were exposed simultaneously to these dri- vers, and key photosynthetic targets were quantified: oxygen production, electron transport rates (ETRs), and carbon fixation immediately following collection and after a 2-d acclima- tion/adaptation period. Increasing mixing speeds in a turbid water column (e.g. browning) significantly decreased ETRs and carbon fixation in the short term. Acclimation/adaptation to this condition for 2 d resulted in an increase in nanoplanktonic diatoms and a community that was photosyntheti- cally more efficient; however, this did not revert the decreasing trend in carbon fixation with increased mixing speed. The observed interactive effects (resulting from extreme rainfall and strong winds) may have profound implications in the trophodynamics of highly productive system such as the Southwest Atlantic Ocean due to changes in the size structure of the community and reduced productivity. https://hdl.handle.net/10481/109670 Temperature fluctuation attenuates the effects of warming in estuarine microbial plankton communities Jabalera Cabrerizo, Marco; Marañón, Emilio; Fernández-González, Cristina; Alonso-Núñez, Adrián; Larsson, Henrik; Aranguren-Gassis, María Sea surface warming has the potential to alter the diversity, trophic organization and productivity of marine communities. However, it is unknown if temperature fluctuations that ecosystems naturally experience can alter the predicted impacts of warming. We address this uncertainty by exposing a natural marine plankton community to warming conditions (C3◦C) under a constant vs. fluctuating (±3◦C) temperature regime using an experimental mesocosm approach. We evaluated changes in stoichiometry, biomass, nutrient uptake, taxonomic composition, species richness and diversity, photosynthetic performance, and community metabolic balance. Overall, warming had a stronger impact than fluctuating temperature on all biological organization levels considered. As the ecological succession progressed toward post-bloom, the effects of warming on phytoplankton biomass, species richness, and net community productivity intensified, likely due to a stimulated microzooplankton grazing, and the community metabolic balance shifted toward a CO2 source. However, fluctuating temperatures reduced the negative effects of warming on photosynthetic performance and net community productivity by 40%. Our results demonstrate that temperature fluctuations may temper the negative effect of warming on marine net productivity. These findings highlight the need to consider short-term thermal fluctuations in experimental and modeling approaches because the use of constant warming conditions could lead to an overestimation of the real magnitude of climate change impacts on marine ecosystems. This study was supported by a Transnational Access granted to MJC through AQUACOSM project, by European Union’s Horizon 2020 Research and Innovation Programme through project “Tropical and South Atlantic climate-based marine ecosystem predictions for sustainable management” (TRIATLAS, grant agreement no. 731065), and by Ministerio de Ciencia, Innovación y Universidades (MICINN) through project “Responses of marine phytoplankton to environmental variability across levels of biological organization” (POLARIS, grant number PGC2018-094553-B-I00) to EM. MJC was supported by Juan de la Cierva-Formación (FJCI2017-32318) and Incorporación (ICJ2019-040850-I) postdoctoral contracts from MICINN, MA-G by a postdoctoral contract from Xunta de Galicia (Tipo B) and by the Retención de Talento program from Universidade de Vigo, and CF-G by a predoctoral contract from Xunta de Galicia (ED481-2017/342). https://hdl.handle.net/10481/109668 Warming and CO2 effects under oligotrophication on temperate phytoplankton communities Jabalera Cabrerizo, Marco; Álvarez-Manzaneda Salcedo, María Inmaculada; León Palmero, Elizabeth; Guerrero-Jiménez, Gerardo; De Senerpont Domis, Lisette N. ; Teurlincx, Sven; González Olalla, Juan Manuel Eutrophication, global warming, and rising carbon dioxide (CO2) levels are the three most prevalent pressures impacting the biosphere. Despite their individual effects are well-known, it remains untested how oligotrophication (i.e. nutrients reduction) can alter the planktonic community responses to warming and elevated CO2 levels. Here, we performed an indoor mesocosm experiment to investigate the warming × CO2 interaction under a nutrient reduction scenario (40%) mediated by an in-lake management strategy (i.e. addition of a commercial solid-phase phosphorus sorbent -Phoslock®) on a natural freshwater plankton community. Biomass production increased under warming × CO2 relative to present-day conditions; however, a Phoslock®-mediated oligotrophication reduced such values by 30–70%. Conversely, the warming × CO2 × oligotrophication interaction stimulated the photosynthesis by 20% compared to ambient nutrient conditions, and matched with higher resource use efficiency (RUE) and nutrient demand. Surprisingly, at a group level, we found that the multi-stressors scenario increased the photosynthesis in eukaryotes by 25%, but greatly impaired in cyanobacteria (ca. −25%). This higher cyanobacterial sensitivity was coupled with a reduced light harvesting efficiency and compensation point. Since Phoslock®-induced oligotrophication unmasked a strong negative warming × CO2 effect on cyanobacteria, it becomes crucial to understand how the interplay between climate change and nutrient abatement actions may alter the, ecosystems functioning. With an integrative understanding of these processes, policy makers will design more appropriate management strategies to improve the ecological status of aquatic ecosystems without compromising their ecological attributes and functioning. This study was partly funded by a Transnational Access granted to MJC through AQUACOSM project, and by the European Comision EU H2020-INFRAIA-project (No. 731065), and by NIOO’s own funding. MJC was supported by a Juan de la Cierva-Formación contract (FJCI-2017-32318) funded by Ministerio de Ciencia, Innovación y Universidades. MIAM was funded by a Ministerio de Economía y Competitividad PhD contract (MINECO, CTM2013-46951-R), ELP and JMGO were supported by a “Formación de Profesorado Universitario” contract from the Ministerio de Educación, Cultura y Deporte (FPU14/02917 and FPU14/00977, respectively), and GGJ by a PhD fellowship from the National Council of Science and Techonology of Mexico (CONACyT). https://hdl.handle.net/10481/103745 Multi-interacting global-change drivers reduce photosynthetic and resource use efficiencies and prompt a microzooplankton-phytoplankton uncoupling in estuarine communities Jabalera Cabrerizo, Marco; Villafañe, Virginia E.; Helbling, E. Walter; Blum, R.; Vizzo, Juan I.; Gadda, A.; Valiñas, Macarena S. Plankton communities are subjected to multiple global change drivers; however, it is unknown how the interplay between them deviates from predictions based on single-driver studies, in particular when trophic interactions are explicitly considered. We investigated how simultaneous manipulation of temperature, pH, nutrient availability and solar radiation quality affects the carbon transfer from phytoplankton to herbivorous protists and their potential consequences for ecosystem functioning. Our results showed that multiple interacting global-change drivers reduced the photosynthetic (gross primary production-to-electron transport rates ratios, from 0.2 to 0.6–0.8) and resource use efficiencies (from 9 to 1 μg chlorophyll a (Chl a) μmol nitrogen−1) and prompted uncoupling between microzooplankton grazing (m) and phytoplankton growth (μ) rates (μ > m). The altered trophic interaction could be due to enhanced intra-guild predation or to microzooplankton growing at suboptimal temperatures compared to their prey. Because phytoplankton-specific loss rates to consumers grazing are the most significant uncertainty in marine biogeochemical models, we stress the need for experimental approaches quantifying it accurately to avoid bias in predicting the impacts of global change on marine ecosystems. https://hdl.handle.net/10481/100621 A shifting balance: responses of mixotrophic marine algae to cooling and warming under UVR Jabalera Cabrerizo, Marco; González Olalla, Juan Manuel; Hinojosa-López, Víctor J.; Peralta Cornejo, Francisco José; Carrillo Lechuga, Presentación Mixotrophy is a dominant metabolic strategy in ecosystems worldwide. Shifts in temperature (T) and light (i.e. the ultraviolet portion of spectrum (UVR)) are key abiotic factors that modulate the conditions under which an organism is able to live. However, whether the interaction between both drivers alters mixotrophy in a global-change context remains unassessed. To determine the T × UVR effects on relative electron transport rates, nonphotochemical quenching, bacterivory, and bacterial production, we conducted an experiment with Isochrysis galbana populations grown mixotrophically, which were exposed to 5°C of cooling and warming with respect to the control (19°C) with (or without) UVR over light–dark cycles and different timescales. At the beginning of the experiment, cooling inhibited the relative electron transport and bacterivory rates, whereas warming depressed only bacterivory regardless of the radiation treatment. By the end of the experiment, warming and UVR conditions stimulated bacterivory. These reduced relative electron transport rates (c. 50% (warming) and > 70% (cooling)) were offset by increased (35%) cumulative bacterivory rates under warming and UVR conditions. We propose that mixotrophy constitutes an energy-saving and a compensatory mechanism to gain carbon (C) when photosynthesis is impaired, and highlight the need to consider the natural environmental changes affecting the populations when we test the impacts of interacting global-change drivers.