An evaluation of freshwater monitoring programs in ILTER nodes and mountain national parks: identifying key variables to monitor global change effects

Acknowledgements This study was funded by the European Commission, under the LIFE Nature and Biodiversity program, as part of the project LIFE-DIVAQUA (Proyecto LIFE18 NAT/ES/000121). We also like to thank all the Spanish government agencies and research institutions who provided information, answered the questionnaires and participated in the workshop “Synthesis of the monitoring programs of global change in aquatic ecosystems SMNP: Autonomous Organism of National Parks, MAPAMA-Dir. Gral. Agua, Universidad de Granada, Instituto Universitario de Investigación del Agua, (IdeA-UGR), Universidad Politécnica de Madrid, CISE-P.N. Sierra de Guadarrama, Fundación Biodiversidad, CEAB-CSIC, IGME, MNCN-CSIC, Universidad de Córdoba, Universidad de Barcelona and ICTA-UAB. We also like to thank the 28 European Nation Parks who responded our query. The authors finally thank the support provided by Christoph Wohner in the use of the DEIMS-SDR.Electronic supplementary material The online version contains supplementary material available at https://doi.org/10.1007/s10531-022-02466-x.Data Availability The datasets used to review the monitoring programs at the Global scale conducted in the ILTER nodes that are included in Rivers (ILTER-Rivers) or Lakes (ILTER-Lakes) are available at the DEIMS dataset registry (DEIMS-SDR) (for more details see: Wohner et al. 2019; https://deims.org/). The datasets used to review the monitoring programs at the European scale conducted in the EMNP are available by requesting them via email to the corresponding EMNP. The datasets used to review the monitoring programs at the National scale conducted in the five SMNP are mostly included in this article and it supplementary information file. In addition, meteorological data recorded by the Spanish Global Change Monitoring Network in available at the Meteorological data download web application (https://www.miteco.gob.es/es/redparques- nacionales/red-seguimiento/acceso-datos.aspx). Further and more detailed information is available from the corresponding author on reasonable request.Funding This study was carried out with the financial support of the EU LIFE programme, as part of the project LIFE-DIVAQUA (Proyecto LIFE18 NAT/ES/000121). The information showed in this publication only reflects the point of view of the authors. The European Comission and CINEA cannot be held responsible for any use which be made of the information contained here. Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.Identifying and quantifying global change impacts on biotic and abiotic components of ecosystems is critical to promote an effective adaptation that increases the success of conservation strategies. To achieve this goal, global and regional assessment efforts require certain degree of harmonization on local monitoring programs to establish relevant comparisons at different spatio-temporal scales. Otherwise, the lack of harmonization might hinder the detection and assessment on the effects of human impacts. In this work we have compiled information on freshwater monitoring programs located in areas of intensive research and conservation interest: International Long Term Ecological Research (ILTER) nodes and mountain National Parks. We aimed at evaluating the quality and robustness of these programs to assess the impact of global change, addressing from the worldwide to the European and Spanish national scale. Results highlighted that freshwater monitoring programs lack a common strategy to monitor these ecosystems. Even at the continental and national scales, contrasting strategies and level of detail have been historically applied. Water quality, habitat and biodiversity are more commonly monitored than community structure and ecosystem functioning. Monitoring efforts on the Spanish Mountain National parks indicated differences on the targeted aquatic ecosystems. Rivers and lakes received a higher attention, while mires were rarely considered. Our results provide evidence that greater efforts should be directed towards constructing a coordinated strategy to monitor freshwater ecosystems at national, continental, and global scales. This strategy should involve a shared backbone of biophysical and biogeochemical variables for each habitat type on agreed protocols that are implemented across regions and administrative borders. Achieving this will support a substantial advance on the ecological research to further delineate proper conservation strategies to face the challenges imposed by global change.European Commission LIFE18 NAT/ES/00012

Uncoupled phytoplanktonbacterioplankton relationship by multiple drivers interacting at diferent temporal scales in a highmountain Mediterranean lake

Global-change stressors act under diferent timing, implying complexity and uncertainty in the study of interactive efects of multiple factors on planktonic communities. We manipulated three types of stressors acting in diferent time frames in an in situ experiment: ultraviolet radiation (UVR); phosphorus (P) concentration; temperature (T) in an oligotrophic Mediterranean high-mountain lake. The aim was to examine how the sensitivity of phytoplankton and bacterioplankton to UVR and their trophic relationship change under nutrient acclimation and abrupt temperature shifts. Phytoplankton and bacteria showed a common pattern of metabolic response to UVR× P addition interaction, with an increase in their production rates, although evidencing an inhibitory UVR efect on primary production (PP) but stimulatory on bacterial production (HBP). An abrupt T shift in plankton acclimated to UVR and P addition decreased the values of PP, evidencing an inhibitory UVR efect, whereas warming increased HBP and eliminated the UVR efect. The weakening of commensalistic and predatory relationship between phyto- and bacterioplankton under all experimental conditions denotes the negative efects of present and future global-change conditions on planktonic food webs towards impairing C fux within the microbial loop

Multiple interacting environmental drivers reduce the impact of solar UVR on primary productivity in Mediterranean lakes

Increases in rainfall, continental runoff, and atmospheric dust deposition are reducing water transparency in lakes worldwide (i.e. higher attenuation Kd). Also, ongoing alterations in multiple environmental drivers due to global change are unpredictably impacting phytoplankton responses and lakes functioning. Although both issues demand urgent research, it remains untested how the interplay between Kd and multiple interacting drivers affect primary productivity ( Pc). We manipulated four environmental drivers in an in situ experiment—quality of solar ultraviolet radiation (UVR), nutrient concentration (Nut), CO2 partial pressure ( CO2), and light regime (Mix)—to determine how the Pc of nine freshwater phytoplankton communities, found along a Kd gradient in Mediterranean ecosystems, changed as the number of interacting drivers increased. Our findings indicated that UVR was the dominant driver, its effect being between 3–60 times stronger, on average, than that of any other driver tested. Also, UVR had the largest difference in driver magnitude of all the treatments tested. A future UVR × CO2 × Mix × Nut scenario exerted a more inhibitory effect on Pc as the water column became darker. However, the magnitude of this synergistic effect was 40–60% lower than that exerted by double and triple interactions and by UVR acting independently. These results illustrate that although future global-change conditions could reduce Pc in Mediterranean lakes, multiple interacting drivers can temper the impact of a severely detrimental driver (i.e. UVR), particularly as the water column darkens.Ministerio de Economía y Competividad (MINECO)European Union (EU) MICROSENSCGL2011-23681 METAS-CGL2015-67682-RMedio Ambiente, Rural, y Marino PN2009/067Junta de Andalucía CVI-02598 P09-RNM-5376Fundación Playa Unión (Argentina)Juan de la Cierva-Formacion from the Ministerio de Ciencia, Innovación y Universidades FJCI2017-32318Postdoctoral contract "Contrato Puente" from Plan Propio (FP7/2017) of the University of GranadaMETAS projec

Saharan dust inputs and high UVR levels jointly alter the metabolic balance of marine oligotrophic ecosystems

The metabolic balance of the most extensive bioma on the Earth is a controversial topic of the global-change research. High ultraviolet radiation (UVR) levels by the shoaling of upper mixed layers and increasing atmospheric dust deposition from arid regions may unpredictably alter the metabolic state of marine oligotrophic ecosystems. We performed an observational study across the south-western (SW) Mediterranean Sea to assess the planktonic metabolic balance and a microcosm experiment in two contrasting areas, heterotrophic nearshore and autotrophic open sea, to test whether a combined UVR × dust impact could alter their metabolic balance at mid-term scales. We show that the metabolic state of oligotrophic areas geographically varies and that the joint impact of UVR and dust inputs prompted a strong change towards autotrophic metabolism. We propose that this metabolic response could be accentuated with the global change as remote-sensing evidence shows increasing intensities, frequencies and number of dust events together with variations in the surface UVR fluxes on SW Mediterranean Sea. Overall, these findings suggest that the enhancement of the net carbon budget under a combined UVR and dust inputs impact could contribute to boost the biological pump, reinforcing the role of the oligotrophic marine ecosystems as CO2 sinks.This work was funded by the Ministerio Español de Ciencia e Innovación (CGL2011–23681 and CGL2015-67682-R), and Campus de Excelencia Internacional del Mar (CeiMar). M.J.C. and J.M.G.-O. were supported by the Spanish Government Fellowship “Formación de Profesorado Universitario” (FPU12/01243 and FPU14/00977, respectively)

Synergistic effects of UVR and simulated stratification on commensalistic phytoplankton–bacteria relationship in two optically contrasting oligotrophic Mediterranean lakes

An indirect effect of global warming is a reduction in the depth of the upper mixed layer (UML) causing organisms to be exposed to higher levels of ultraviolet (UVR, 280–400 nm) and photosynthetically active radiation (PAR, 400–700 nm). This can affect primary and bacterial production as well as the commensalistic phytoplankton–bacteria relationship. The combined effects of UVR and reduction in the depth of the UML were assessed on variables related to the metabolism of phytoplankton and bacteria, during in situ experiments performed with natural pico- and nanoplankton communities from two oligotrophic lakes with contrasting UVR transparency (high-UVR versus low-UVR waters) of southern Spain. The negative UVR effects on epilimnetic primary production (PP) and on heterotrophic bacterial production (HBP), intensified under increased stratification, were higher in the low-UVR than in the high-UVR lake, and stronger on the phytoplanktonic than on the heterotrophic bacterial communities. Under UVR and increased stratification, the commensalistic phytoplankton–bacteria relationship was strengthened in the high-UVR lake where excretion of organic carbon (EOC) rates exceeded the bacterial carbon demand (BCD; i.e., BCD : EOC(%) ratio 100). The greater UVR damage to phytoplankton and bacteria and the weakening of their commensalistic interaction found in the low-UVR lake indicates that these ecosystems would be especially vulnerable to UVR and increased stratification as stressors related to global climate change. Thus, our findings may have important implications for the carbon cycle in oligotrophic lakes of the Mediterranean region.This study was supported by the Ministerio Español de Medio Ambiente, Rural y Marino (PN2009/067), Ciencia e Innovación (CGL2011-23681), Junta de Andalucía (Excelencia CVI-02598 and P09-RNM-5376), Consejo Nacional de Investigaciones Científicas y Técnicas – CONICET (PIP no. 112-201001-00228), and Fundación Playa Unión. G. Herrera and C. Durán were supported by a Formación de Profesorado Universitario grant from the Spanish government. The authors are indebted to the staff of Sierra Nevada National Park and Lagunas de Ruidera Natural Park for permission to work, to E. Jiménez-Coll for the bacterial production analysis, and to D. Nesbitt for writing assistance in English

The effects of UV radiation on photosynthesis estimated as chlorophyll fluorescence in Zygnemopsis decussata (Chlorophyta) growing in a high mountain lake (Sierra Nevada, Southern Spain)

The effect of increased UV radiation on photosynthesis estimated as in vivo chlorophyll fluorescence i.e. optimal quantum yield (Fv/Fm) and electron transport rate (ETR) in the green filamentous alga Zygnemopsis decussata (Streptophyta, Zygnematales) growing in the high mountain lake "La Caldera" (Sierra Nevada, Spain) at 3050 m altitude was evaluated. Two sets of in situ experiments were conducted: (1) On July 2006, Fv/Fm was measured throughout the day at different depths (0.1, 0.25, 0.5 and 1 m) and in the afternoon, ETR and phenolic compounds were determined. In addition, in order to analyze the effect of UV radiation, Fv/Fm was determined in algae incubated for 3 days at 0.5m under three different light treatments: PAR+UVA+UVB (PAB), PAR+UVA (PA) and PAR (P). (2) On August 2007, Fv/Fm was determined under PAB, PA and P treatments and desiccation/rehydration conditions. Fv/Fm decreased in algae growing in surface waters (0.1 m) but also at 1 m depth compared to that at 0.5 m depth. The decrease of Fv/Fm at noon due to photoinhibition was small (less than 10%) except in algae growing at 1 m depth (44%). The maximal electron transport rate was 3.5-5 times higher in algae growing at 0.25-0.5 m respectively than that at 0.1 and 1 m depth. These results are related to the accumulation of phenolic compounds: i.e. the algae at 0.25-0.5 m presented respectively about a 3-5 times higher concentration of phenolic compounds than that of algae at 0.1-1 m depth. The protection mechanisms seem to be stimulated by UVB radiation, since Fv/Fm was higher in the presence of UVB (PAB treatment) compared to PA or P treatments. UVA exerts the main photoinhibitory effect, not only at midday, but also in the afternoon. UVB radiation also had a protective effect in algae grown under desiccation conditions for three days. During re-hydration, the rapid increase of Fv/Fm (after 1 h) was higher in the UVB-grown algae than in algae grown under UVA radiation. After 5 h, Fv/Fm values were similar in algae submitted to desiccation/rehydration under PAB and P treatments as they were in the control (submerged algae). The combined effect of desiccation and UVA produced the greatest decrease of photosynthesis in Z. decussata. Thus UVB, in contrast to other species, may support the recovery process. Z. decussata can acclimate to severe stress conditions in this high mountain lake by the photoprotection mechanism induced by UVB radiation through dynamic photoinhibition and the accumulation of phenolic compounds (UV screen and antioxidant substances).This research was supported by the Spanish Ministries of Environment (PN2003/25) and Education and Science (CGL2005/01564, AGL2005/02655, CGL 2008/01127, CGL 2008/05407) and Consejería de Innovación, Ciencia y Empresa, Junta de Andalucía (Excelencia project P07-CVI-02598)

Interactive effects of vertical mixing, nutrients and ultraviolet radiation: in situ photosynthetic responses of phytoplankton from high mountain lakes in Southern Europe

Global change, together with human activities, has resulted in increasing amounts of organic material (including nutrients) that water bodies receive. This input further attenuates the penetration of solar radiation, leading to the view that opaque lakes are more "protected" from solar ultraviolet radiation (UVR) than clear ones. Vertical mixing, however, complicates this view as cells are exposed to fluctuating radiation regimes, for which the effects have, in general, been neglected. Furthermore, the combined impacts of mixing, together with those of UVR and nutrient inputs are virtually unknown. In this study, we carried out complex in situ experiments in three high mountain lakes of Spain (Lake Enol in the National Park Picos de Europa, Asturias, and lakes Las Yeguas and La Caldera in the National Park Sierra Nevada, Granada), used as model ecosystems to evaluate the joint impact of these climate change variables. The main goal of this study was to address the question of how short-term pulses of nutrient inputs, together with vertical mixing and increased UVR fluxes modify the photosynthetic responses of phytoplankton. The experimentation consisted in all possible combinations of the following treatments: (a) solar radiation: UVR + PAR (280–700 nm) versus PAR (photosynthetically active radiation) alone (400–700 nm); (b) nutrient addition (phosphorus (P) and nitrogen (N)): ambient versus addition (P to reach to a final concentration of 30 μg P L−1, and N to reach N:P molar ratio of 31); and (c) mixing: mixed (one rotation from surface to 3 m depth (speed of 1 m 4 min−1, total of 10 cycles)) versus static. Our findings suggest that under ambient nutrient conditions there is a synergistic effect between vertical mixing and UVR, increasing phytoplankton photosynthetic inhibition and excretion of organic carbon (EOC) from opaque lakes as compared to algae that received constant mean irradiance within the epilimnion. The opposite occurs in clear lakes where antagonistic effects were determined, with mixing partially counteracting the negative effects of UVR. Nutrient input, mimicking atmospheric pulses from Saharan dust, reversed this effect and clear lakes became more inhibited during mixing, while opaque lakes benefited from the fluctuating irradiance regime. These climate change related scenarios of nutrient input and increased mixing, would not only affect photosynthesis and production in lakes, but might also further influence the microbial loop and trophic interactions via enhanced EOC under fluctuating UVR exposure.This work was supported by Ministerio Español de Medio Ambiente, Rural y Marino (PN2009/067) and Ciencia e Innovación (GLC2008-01127/BOS and CGL2011-23681), Junta de Andalucía (Excelencia CVI-02598), Agencia Nacional de Promoción Científica y Tecnológica (PICT 2007-1651) and Fundación Playa Unión; GH and CD were supported by the Spanish Government – Formación de Profesorado Universitario Grant

Análisis de las interacciones tróficas en el plancton de un sistema oligotrófico

En este trabajo se aborda el estudio de las interacciones tróficas fitoplancton-zooplancton, mediante el análisis experimental "in situ" utilizando microcosmos. Se ha ensayado el efecto de diferentes variables sobre la comunidad fitoplanctónica, entre las que destacamos a) presión de pastoreo o "grazing", mediante manipulación de las densidades de predadores, b) composición específica de la comunidad zooplanctónica, realizando los experimentos en momentos del periodo libre de hielo en los que se desarrollan distintas especies o diferentes estadios de desarrollo de la especie dominante mixodiaptomus laciniatus; y c) volumen del microcosmos, utilizando dos tamaños de encerramientos (15 l o 350 l de capacidad). De los resultados obtenidos destacamos: la desaparición de las especies flageladas de todos los encerramientos de pequeño volumen y su diferente desarrollo en las de mayor tamaño es una evidencia a favor de su comportamiento migratorio, seguramente como mecanismo de defensa a un clima de luz inhibidor. La respuesta específica a la manipulación de la comunidad de zooplancton no es homogénea. Las especies de flagelados son preferentemente consumidas por los predadores, a la vez que un aumento en la concentración de calanoides estimula su desarrollo. (Entre las células no móviles, cyanarcus sp, se puede considerar como "resistente" a la digestión. Su paso a través del conducto gastrointestinal, le permite un acceso directo a los nutrientes limitantes que determina una tasa de crecimiento superior en encerramientos con animales.) En medios oligotróficos, contrariamente a lo expuesto por mcqueen et al, (1986), la regulación "top-down" no se encuentra reforzada. El mecanismo "consimidor-controlador" depende en mayor grado de la naturaleza de las especies consumidoras que de la biomasa predadora. Esto indica que los mecanismos descendentes de regulación tienen una respuesta estacional. Los calanoides estimulan el crecimiento del fitoplancton, un efecto que se manifiesta fundamentalmente por el incremento en la concentración de clorofila como medida de la producción primaria potencial y en los valores de la tasa de crecimiento de las diferentes especies, así como del conjunto de la comunidad. Los grandes cladoceros (daphnia pulex) ejercen un efecto depresor neto de las celulas algales.) El tamaño del encerramiento afecta a los valores absolutos de las tasas de crecimiento de la comunidad de fitoplancton asi como a los de la tasa de alimentación del conjunto del zooplacton. En bolsas pequeñas (15 1), dichos valores son de un orden de magnitud inferior a los obtenidos en encerramientos de mayor volumen (350 1). Sin embargo, el patrón general de respuesta de las poblaciones a la presión de "grazing" impuesta por el zooplancton, se mantiene en ambos tamaños de bolsasUniversidad de Granada, Facultad de Ciencias. Leída el 18-12-8

Housekeeping in the Hydrosphere: Microbial Cooking, Cleaning, and Control under Stress

Who’s cooking, who’s cleaning, and who’s got the remote control within the waters blanketing Earth? Anatomically tiny, numerically dominant microbes are the crucial “homemakers” of the watery household. Phytoplankton’s culinary abilities enable them to create food by absorbing sunlight to fix carbon and release oxygen, making microbial autotrophs top-chefs in the aquatic kitchen. However, they are not the only bioengineers that balance this complex household. Ubiquitous heterotrophic microbes including prokaryotic bacteria and archaea (both “bacteria” henceforth), eukaryotic protists, and viruses, recycle organic matter and make inorganic nutrients available to primary producers. Grazing protists compete with viruses for bacterial biomass, whereas mixotrophic protists produce new organic matter as well as consume microbial biomass. When viruses press remote-control buttons, by modifying host genomes or lysing them, the outcome can reverberate throughout the microbial community and beyond. Despite recognition of the vital role of microbes in biosphere housekeeping, impacts of anthropogenic stressors and climate change on their biodiversity, evolution, and ecological function remain poorly understood. How trillions of the smallest organisms in Earth’s largest ecosystem respond will be hugely consequential. By making the study of ecology personal, the “housekeeping” perspective can provide better insights into changing ecosystem structure and function at all scales.National Science Foundation (NSF) EAR1637093 OCE 2346958National Aeronautics and Space Administration-Michigan Space Grant Consortium Graduate Fellowships NNX15AJ20HSpanish Government FEDER-CGL2015-67682-RFondo Europeo de Desarrollo Regional Project FEDER-CGL2015-67682-RJunta de Andalucía P12-RNM 327Spanish Government Fellowship "Formacion de Profesorado Universitario" Grant FPU14/0097

Microbial plankton responses to multiple environmental drivers in marine ecosystems with different phosphorus limitation degrees

We thank R/V UCÁDIZ crew, and Eulogio Corral by their help during seawater sampling. Cristina Estevan-Pardo is acknowledged by her collaboration during the experiments, and David Nesbitt for the English proofreading. Comments and suggestions by the Associated Editor Dr. Blasco and three anonymous reviewers are deeply acknowledged. This research was funded by ‘convocatoria de proyectos de jóvenes investigadores CEIMAR 2018’ from Campus de Excelencia Internacional del Mar (MIXOCOST, CEIJ-008 to MJC), and by Ministerio de Economía y Competitividad and Fondo Europeo de Desarrollo regional (FEDER) (METAS, CGL2015-67682-R to PC and JMM-S). MJC was supported by Juan de la Cierva-Formación ( FJCI2017-32318 ) and Incorporación ( IJC2019-040850-I ) grants from Ministerio de Ciencia, Innovación y Universidades . JMG-O was supported by University of Granada through programa de promoción y empleo joven from Junta de Andalucía and FEDER ( PEJ2018-003106-A ), and DS-G by METAS project.Multiple drivers are threatening the functioning of the microbial food webs and trophic interactions. Our understanding about how temperature, CO2, nutrient inputs, and solar ultraviolet radiation (UVR) availability interact to alter ecosystem functioning is scarce because research has focused on single and double interactions. Moreover, the role that the degree of in situ nutrient limitation could play in the outcome of these interactions has been largely neglected, despite it is predominant in marine ecosystems. We address these uncertainties by combining remote-sensing analyses, and a collapsed experimental design with natural microbial communities from Mediterranean Sea and Atlantic Ocean exposed to temperature, nutrients, CO2, and UVR interactions. At the decade scale, we found that more intense and frequent (and longer lasting) Saharan dust inputs (and marine heatwaves) were only coupled with reduced phytoplankton biomass production. When microbial communities were concurrently exposed to future temperature, CO2, nutrient, and UVR conditions (i.e. the drivers studied over long-term scales), we found shifts from net autotrophy [primary production:respiration (PP:R) ratio > 1] towards a metabolic equilibrium (PP:R ratio ~ 1) or even a net heterotrophy (PP:R ratio < 1), as P-limitation degree was higher (i.e. Atlantic Ocean). These changes in the metabolic balance were coupled with a weakened phytoplankton-bacteria interaction (i.e. bacterial carbon demand exceeded phytoplankton carbon supply. Our work reveals that an accentuated in situ P limitation may promote reductions both in carbon uptake and fluxes between trophic levels in microbial plankton communities under global-change conditions. We show that considering long-term series can aid in identifying major local environmental drivers (i.e. temperature and nutrients in our case), easing the design of future global-change studies, but also that the abiotic environment to which microbial plankton communities are acclimated should be taken into account to avoid biased predictions concerning the effects of multiple interacting global-change drivers on marine ecosystems.Campus de Excelencia Internacional del MarFondo Europeo de DesarrolloIncorporación IJC2019-040850-IMETASMIXOCOST CEIJ-008Ministerio de Ciencia, Innovación y UniversidadesMinisterio de Economía y CompetitividadUniversidad de GranadaEuropean Regional Development Fund CGL2015-67682-R, FJCI2017-32318Junta de Andalucía PEJ2018-003106-