Gerçek Zamanlı Otomatik Göl İzleme Sistemi ile Göl Metabolizması ve Fitoplankton Biyokütlesinin Uç Olaylar ve Çevresel Değişkenlere Göre Değişiminin Araştırılması

TÜBİTAK ÇAYDAG15.01.2018Ocak 2015 - Ocak 2018 dönemini kapsayan üç yıllık 4 is paketinden (IP) olusan TUBITAKprojesinin 1. IP si olan Eymir Gölü?nde yüksek frekanslı otomatik izleme istasyonun (YFOII)kurulması 2015 Haziran ayı itibari ile gerçeklestirilmistir. IP2 kapsamında planlanan çevrimiçiveri transferi ise ODTÜ, Limnoloji Laboratuvarında tahsis edilen bilgisayara uygun yazılımlararacılıgı ile aktarılmıstır. IP3, YFOII?den alınan verilerin kontrolü ve takibi, manuel su kaliteörneklemesi, YFOII verileri ile metabolizma hesabı, bu verilerin birincil üretim ve uç olaylarlailiskilendirilmesini kapsamaktadır. IP3 paketinden elde edilen sonuçlar ile Eymir Gölü?nünötrofik bir göl olmasına ragmen yılın çogu zamanı heterotrofik (Net Ekosistem Üretimi (NEP)0'dan küçük) özellikte oldugu yani atmosfere karbon salınımı yaptıgı tespit edilmistir.Fitoplankton asırı artıslarına ise genellikle Agustos ve Eylül aylarında su girisinin olmadıgı gölsuyunun durgun, hava sıcaklıgının yüksek oldugu dönemlerde rastlanılmıstır. Bu dönemlerdegöl metabolizmasının ototrofik (NEP 0'dan büyük) oldugu yani ekosistemin karbon tuttugutespit edilmistir. Bu durumun uzun yıllarca yürütülen restorasyon amaçlı evsel atıksuuzaklastırılması ve biyomanipulasyonun olumlu etkisi oldugu düsünülmektedir. Bunların yanısıra Eymir Gölü ani meteorolojik ve çevresel degisimlerden hızlıca etkilenmektedir. Özelliklerüzgar göldeki sıcaklık tabakalasmasını degistirmekte ve epilimnion tabakasındametabolizmanın salınımlar göstermesine sebep olmaktadır. Ancak bu degiskenlerin eskidegerlerine dönmesi ile sistem kendini kısa sürede toparlayabilmektedir.Ayrıca yine projenin 4. IP si kapsamında, ortaokul ögrencilerinin bilimsel süreçle tanısması,doga ve göl ekolojisi bilincinin ve duyarlılıgının gelismesini amaçlayan ?Eymir Gölü Elçileri?egitim paketi gelistirilmesi hedeflenmistir. Proje kapsamında gelistirilen egitim programı ODTÜAnkara Gelistirme Vakfı Ortaokulu ve Gölbası Cemil Yıldırım Ortaokulundan 5. ve 7. sınıfögrencilerine uygulanmıstır. Ayrıca proje çıktıları www.lem.bio.metu.edu.tr adresinden güncelolarak paylasılmıstır. Toplanan verilerin ilgili kurumlarla paylasılması içinde site içerisinde sifreile girilen bir sekme açılmıstır. Yine bilgiyi yayma kapsamında 9 Mart 2018 tarihinde ilgilibirimlerin davet edildigi mini-çalıstay düzenlenmistir.The establishment of a high-frequency automated monitoring station (HFAMS) was carried out inJune 2015 in Lake Eymir as the first work package (WP1) with four WPs in the TÜBİTAK project(project number: 114Y415) which covered the period of January 2015 to January 2018. Theonline data transfer planned within the scope of the second WP was provided through the propersoftware embedded in a computer allocated to Limnology Laboratory, METU. WP 3 included amanuel of water quality sampling to control and monitor data from HFAMS, further data qualitycontrol and assurance of the HFAMS, metabolism estimates from, and relating these data to netprimary productivity and extreme events. According to data from HFAMS obtained in WP 3, LakeEymir was determined to be heterotrophic (net ecosystem production (NEP) 0). Moreover. Lake Eymir wasrapidly subjected to the sudden meteorological and environmental changes. In particular, highwind speeds destroyed the lake stratification and caused instant fluctuations in metabolism inthe epilimnion layer. However, when wind speed returned to their previous phases, the systemwas restored back in a short period of time.Within the scope of the WP 4, it is aimed at devising a training package called “Lake EymirAmbassadors” for secondary school students with the purpose of having them recognizescientific processes and developing their awareness and sensitivity about nature and lakeecology. This training programme was applied to students of the fifth and seventh grades ofODTÜ Ankara Geliştirme Vakfı (ODTÜ GVO) and Gölbaşı Cemil Yıldırım secondary schools.Project outputs and data have been shared and updated online from this address(www.lem.bio.metu.edu.tr). Also, a mini-workshop to disseminate information was organized on9 March 2018 by which people from the relevant departments were invited.Keywords: Environmental factors, real-time automated water quality monitoring system, lakemetabolism, climate change, meteorological extreme events, citizen science, data transfe

Effects of water temperature on summer periphyton biomass in shallow lakes: a pan-European mesocosm experiment

Periphyton communities play an important role in shallow lakes and are controlled by direct forces such as temperature, light, nutrients, and invertebrate grazing, but also indirectly by planktivorous fish predation. We performed a pan-European lake mesocosm experiment on periphyton colonization covering five countries along a north/south geographical/temperature gradient (Estonia, Germany, Czech Republic, Turkey, and Greece). Periphyton biomass on artificial polypropylene strips exposed at 50 cm water depth at low and high nutrient regimes (with mean total phosphorus concentration of 20 and 65 µg L−1, respectively) was compared during mid-summer. No significant effect of nutrient loading on periphyton biomass was observed as nutrient concentrations in the mesocosms were generally above limiting values. Water temperature significantly enhanced summer periphyton biomass development. Additionally, direct and indirect top-down control of snails and fish emerged as a significant factor in periphyton biomass control

Effects of trophic status, water level, and temperature on shallow lake metabolism and metabolic balance: A standardized pan‐European mesocosm experiment

Important drivers of gross primary production (GPP) and ecosystem respiration (ER) in lakes are temperature, nutrients, and light availability, which are predicted to be affected by climate change. Little is known about how these three factors jointly influence shallow lakes metabolism and metabolic status as net heterotrophic or autotrophic. We conducted a pan‐European standardized mesocosm experiment covering a temperature gradient from Sweden to Greece to test the differential temperature sensitivity of GPP and ER at two nutrient levels (mesotrophic or eutrophic) crossed with two water levels (1 m and 2 m) to simulate different light regimes. The findings from our experiment were compared with predictions made according the metabolic theory of ecology (MTE). GPP and ER were significantly higher in eutrophic mesocosms than in mesotrophic ones, and in shallow mesocosms compared to deep ones, while nutrient status and depth did not interact. The estimated temperature gains for ER of ~ 0.62 eV were comparable with those predicted by MTE. Temperature sensitivity for GPP was slightly higher than expected ~ 0.54 eV, but when corrected for daylight length, it was more consistent with predictions from MTE ~ 0.31 eV. The threshold temperature for the switch from autotrophy to heterotrophy was lower under mesotrophic (~ 11°C) than eutrophic conditions (~ 20°C). Therefore, despite a lack of significant temperature‐treatment interactions in driving metabolism, the mesocosm's nutrient level proved to be crucial for how much warming a system can tolerate before it switches from net autotrophy to net heterotrophy

Multi-proxy palaeoecological responses to water-level fluctuations in three shallow Turkish lakes

Natural or human-induced water-level fluctuations influence the structure and function of shallow lakes, especially in semi-arid to arid climate regions. In order to reliably interpret the effect of water-level changes from sedimentary remains in the absence of historical data, it is crucial to understand the variation in sedimentary proxies in relation to water level measurements. Here, we took advantage of existing water surface elevation data on three large shallow lakes in Turkey to elucidate the impact of lake-level changes on benthic-pelagic primary production over the last 50-100 years. Sub-fossil cladocerans, diatoms, plant remains and pigments were investigated as biological variables; X-ray fluorescence (XRF) and loss on ignition (LOI) analyses were conducted as geochemical-physical variables on a set of Pb-210 and Cs-137 dated cores. Dating of the cores were robust, with the exception of uncertainties in Lake Marmara littoral core due to low unsupported 210Pb activities and high counting errors. Results indicated that Lake Marmara was dominated by benthic species throughout the sediment record, while Lakes Beysehir and Uluabat shifted from a littoral-dominated system to one with increased pelagic species abundance. In all cores there was a stronger response to longer-term (decadal) and pronounced water-level changes than to short-term (annual-biennial) and subtle changes. It was also noted that degree of alteration in proxies differed between lakes, through time and among pelagic-littoral areas, likely emphasising differences in depositional environments and/or resolution of sampling and effects of other stressors such as eutrophication. Our results highlight lake-specific changes associated with water-level fluctuations, difficulties of conducting studies at required resolution in lakes with rather mixed sediment records and complexity of palaeolimnological studies covering recent periods where multiple drivers are in force. They further emphasise the need to include instrumental records when interpreting effects of recent water-level changes from sediment core data in large shallow lakes

Phytoplankton Community Response to Nutrients, Temperatures, and a Heat Wave in Shallow Lakes: An Experimental Approach

Phytoplankton usually responds directly and fast to environmental fluctuations, making them useful indicators of lake ecosystem changes caused by various stressors. Here, we examined the phytoplankton community composition before, during, and after a simulated 1-month heat wave in a mesocosm facility in Silkeborg, Denmark. The experiment was conducted over three contrasting temperature scenarios (ambient (A0), Intergovernmental Panel on Climate Change A2 scenario (circa +3 degrees C, A2) and A2+ %50 (circa +4.5 degrees C, A2+)) crossed with two nutrient levels (low (LN) and high (HN)) with four replicates. The facility includes 24 mesocosms mimicking shallow lakes, which at the time of our experiment had run without interruption for 11 years. The 1-month heat wave effect was simulated by increasing the temperature by 5 degrees C (1 July to 1 August) in A2 and A2+, while A0 was not additionally heated. Throughout the study, HN treatments were mostly dominated by Cyanobacteria, whereas LN treatments were richer in genera and mostly dominated by Chlorophyta. Linear mixed model analyses revealed that high nutrient conditions were the most important structuring factor, which, regardless of temperature treatments and heat waves, increased total phytoplankton, Chlorophyta, Bacillariophyta, and Cyanobacteria biomasses and decreased genus richness and the grazing pressure of zooplankton. The effect of temperature was, however, modest. The effect of warming on the phytoplankton community was not significant before the heat wave, yet during the heat wave it became significant, especially in LN-A2+, and negative interaction effects between nutrient and A2+ warming were recorded. These warming effects continued after the heat wave, as also evidenced by Co-inertia analyses. In contrast to the prevailing theory stating that more diverse ecosystems would be more stable, HN were less affected by the heat wave disturbance, most likely because the dominant phytoplankton group cyanobacteria is adapted to high nutrient conditions and also benefits from increased temperature. We did not find any significant change in phytoplankton size diversity, but size evenness decreased in HN as a result of an increase in the smallest and largest size classes simultaneously. We conclude that the phytoplankton community was most strongly affected by the nutrient level, but less sensitive to changes in both temperature treatments and the heat wave simulation in these systems, which have been adapted for a long time to different temperatures. Moreover, the temperature and heat wave effects were observed mostly in LN systems, indicating that the sensitivity of phytoplankton community structure to high temperatures is dependent on nutrient availability

Macroecological patterns of resilience inferred from a multinational, synchronized experiment

The likelihood of an ecological system to undergo undesired regime shifts is expected to increase as climate change effects unfold. To understand how regional climate settings can affect resilience; i.e., the ability of an ecosystem to tolerate disturbances without changing its original structure and processes, we used a synchronized mesocosm experiment (representative of shallow lakes) along a latitudinal gradient. We manipulated nutrient concentrations and water levels in a synchronized mesocosm experiment in different climate zones across Europe involving Sweden, Estonia, Germany, the Czech Republic, Turkey and Greece. We assessed attributes of zooplankton communities that might contribute to resilience under different ecological configurations. We assessed four indicator of relative ecological resilience (cross-scale, within-scale structures, aggregation length and gap size) of zooplankton communities, inferred from discontinuity analysis. Similar resilience attributes were found across experimental treatments and countries, except Greece, which experienced severe drought conditions during the experiment. These conditions apparently led to a lower relative resilience in the Greek mesocosms. Our results indicate that zooplankton community resilience in shallow lakes is marginally affected by water level and the studied nutrient range unless extreme drought occurs. In practice, this means that drought mitigation could be especially challenging in semi-arid countries in the future

The future depends on what we do today – projecting Europe’s surface water quality into three different future scenarios

There are infinite possible future scenarios reflecting the impacts of anthropogenic multiple stress on our planet. These impacts include changes in climate and land cover, to which aquatic ecosystems are especially vulnerable. To assess plausible developments of the future state of European surface waters, we considered two climate scenarios and three storylines describing land use, management and anthropogenic development (‘Consensus’, ‘Techno’ and ‘Fragmented’, which in terms of environmental protection represent best-, intermediate- and worst-case, respectively). Three lake and four river basins were selected, representing a spectrum of European conditions through a range of different human impacts and climatic, geographical and biological characteristics. Using process-based and empirical models, freshwater total nitrogen, total phosphorus and chlorophyll-a concentrations were projected for 2030 and 2060. Under current conditions, the water bodies mostly fail good ecological status. In future predictions for the Techno and Fragmented World, concentrations further increased, while concentrations generally declined for the Consensus World. Furthermore, impacts were more severe for rivers than for lakes. Main pressures identified were nutrient inputs from agriculture, land use change, inadequately managed water abstractions and climate change effects. While the basins in the Continental and Atlantic regions were primarily affected by land use changes, in the Mediterranean/Anatolian the main driver was climate change. The Boreal basins showed combined impacts of land use and climate change and clearly reflected the climate-induced future trend of agricultural activities shifting northward. The storylines showed positive effects on ecological status by classical mitigation measures in the Consensus World (e.g. riparian shading), technical improvements in the Techno World (e.g. increasing wastewater treatment efficiency) and agricultural extensification in the Fragmented World. Results emphasize the need for implementing targeted measures to reduce anthropogenic impacts and the importance of having differing levels of ambition for improving the future status of water bodies depending on the societal future to be expected

Impacts of multiple stressors on freshwater biota across spatial scales and ecosystems

Climate and land-use change drive a suite of stressors that shape ecosystems and interact to yield complex ecological responses (that is, additive, antagonistic and synergistic effects). We know little about the spatial scales relevant for the outcomes of such interactions and little about effect sizes. These knowledge gaps need to be filled to underpin future land management decisions or climate mitigation interventions for protecting and restoring freshwater ecosystems. This study combines data across scales from 33 mesocosm experiments with those from 14 river basins and 22 cross-basin studies in Europe, producing 174 combinations of paired-stressor effects on a biological response variable. Generalized linear models showed that only one of the two stressors had a significant effect in 39% of the analysed cases, 28% of the paired-stressor combinations resulted in additive effects and 33% resulted in interactive (antagonistic, synergistic, opposing or reversal) effects. For lakes, the frequencies of additive and interactive effects were similar for all spatial scales addressed, while for rivers these frequencies increased with scale. Nutrient enrichment was the overriding stressor for lakes, with effects generally exceeding those of secondary stressors. For rivers, the effects of nutrient enrichment were dependent on the specific stressor combination and biological response variable. These results vindicate the traditional focus of lake restoration and management on nutrient stress, while highlighting that river management requires more bespoke management solutions.Additional co-authors: Tuba Bucak, Anthonie D. Buijse, Ana Cristina Cardoso, Raoul-Marie Couture, Fabien Cremona, Dick de Zwart, Christian K. Feld, M. Teresa Ferreira, Heidrun Feuchtmayr, Mark O. Gessner, Alexander Gieswein, Lidija Globevnik, Daniel Graeber, Wolfram Graf, Cayetano Gutiérrez-Cánovas, Jenica Hanganu, Uğur Işkın, Marko Järvinen, Erik Jeppesen, Niina Kotamäki, Marijn Kuijper, Jan U. Lemm, Shenglan Lu, Anne Lyche Solheim, Ute Mischke, S. Jannicke Moe, Peeter Nõges, Tiina Nõges, Steve J. Ormerod, Yiannis Panagopoulos, Leo Posthuma, Sarai Pouso, Christel Prudhomme, Katri Rankinen, Jes J. Rasmussen, Jessica Richardson, Alban Sagouis, José Maria Santos, Ralf B. Schäfer, Rafaela Schinegger, Stefan Schmutz, Susanne C. Schneider, Lisa Schülting, Pedro Segurado, Kostas Stefanidis, Bernd Sures, Stephen J. Thackeray, Jarno Turunen, María C. Uyarra, Markus Venohr, Peter Carsten von der Ohe & Daniel Herin

Environmental variability in aquatic ecosystems: Avenues for future multifactorial experiments

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

Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.Peer reviewe