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Kirje Eesti aasta muld 2025 on Klibumuld(Eesti Maaülikool, 2025) Kõlli, Raimo; Kauer, KarinFor the Year 2025 Soil of Estonia by the Estonian Soil Science Society (ESSS) was elected Skeletic Regosol (as named by World Reference Base for Soil Resources (WRB)), which is one of subspecies of Coarse Rich Ryhky Soils (by Estonian Soil Classification (ESC)). Although these soils form less than 0,2% from the whole soil cover of Estonia, they merit an attention from the aspect of peculiarities of their forming, which have been taken place on narrow coastal area on the border between sea and mainland. Skeletic Regosols have been formed only on these littoral areas, which is rich mainly in coarse calcareous earth materials as limestone or dolomite containing also small stones (ryhk, pebble, shingle) and large stones. Besides that, these soils are as well rich in different kind of eruptive rocks of the size of small and large stones. The most part of Skeletal Regosols’ coarse fraction was formed under the influence of breaking waves, which were induced by strong sea winds. The main criteria of Ryhky Soils’ identification after ESC are the content and shape of small stones (Ø 1‒10 cm), water regime of soil cover, and fabric of soil profiles. Ryhky soils are divided into subspecies by the by the shape of small stones. In ryhky soils among others the ryhk fraction is dominated, but in Pebble soils the pebble and in Shingly soils the shingle fractions are dominating. In the development of Skeletic Regosols or of Shingle soils two development stages is separated. During the first Skeletic Regosols’ abnormal development stage only the primitive shingle rich parent material for these soils have been formed on the border area between mainland and sea. But during this period the soil forming processes are practically absent. During the second development stage of Skeletic Regosols development ie. after with draw of sea water the normal soil forming processes are taken place. As a result of this are formed humus horizons and activated biological cycling on chemical elements and others. In the article the soil forming conditions, coarse earth’s fractions shape and size, development stages of soil profiles, as well soils productivity, humus status, distribution, and agrochemical properties are treated.Kirje Eesti aasta 2024 mullaks valitud leostunud gleimulla tutvustus(Eesti Maaülikool, 2024) Kõlli, Raimo; Tõnutare, TõnuThe name of Estonian year 2024 soil by Estonian soil classification is the Leached gley soil, but by the WRB system Mollic Gleysol. By its properties the Leached gley soil belongs to the permanently wet with calcareous subsoil mineral soils group. The typical its profile fabric’s formula is (O)–AT–BwG–CG. On natural areas these soils’ humus covers (or humipedons) belong by the local classification to the wet forest-mull type, on the base of which on drained arable areas mostly the humus covers with eutrophic raw humuous type were formed. In diminishing order of these soils textures is - loams 44% > sands 22% > loamy sands 17% > clays 17%. The position of Leached gley soils among other soil species is analysed by mean of Estonian normally developed soil matrix. The Leached gley soils form approximately 13% from the total Estonian soil cover and 40% from the total area of wet soils. Most of Leached gley soils with loamy texture were drained and are used in quality of arable lands. Besides the analysis of Leached gley soil profiles’ fabric, humus status and texture, the different chemical-physical properties separately for forest and arable soils are presented. By the comparative analysis of arable and forest soils’ properties and pedo-ecological functioning regularities, the changes happened with land use changes in Leached gley soils are elucidated. It reveals that formed on Leached gley soils’ forests and grasslands plant cover composition depends in great extent from the properties of soils. Consequently in the management of arable Leached gley soils their suitability for agricultural crops should be taken also into account.Kirje Eesti mullateaduse arengust kaasaegse Eesti Mullateaduse Seltsi rajamise eelsel ja järgsel ajal(Eesti Maaülikool, 2024) Kõlli, Raimo; Astover, AlarEesti Mullateaduse Selts (EMTS) on mullateadusest (muldade uurimine, mullastikukaardid, andmebaasid jms), taimede toitumisest (väetised, agrokeemia jms), muldade ökoloogiast (mullaelustik, talitlemine jt), muldade keskkonnasõbralikust kasutamisest ja muldade kaitsest (potentsiaalsetele võimetele vastava hea seisundi hoidmisest) huvitatud üksikisikute ja organisatsioonide mittetulunduslik ühendus. Eesti mullateadlaste seltsiline tegevus taaselustati Eesti Maaülikooli (EMÜ) mullateaduse õppetooli eestvõttel 2009. aastal ning selle presidendiks valiti Alar Astover. EMTS-i kompetents võimaldab seltsil olla mullastikualaste teadmiste levitaja põllu- ja metsamajandusliku maakasutuse alal, osaleda mullateaduse alase teadustöö, hariduse ja teadlikkuse tõstmise edendamisel ühiskonnas ning selgitada muldkatete rolli olulisust ümbritseva keskkonna kestlikult hea talitlemisseisundi tagamisel. EMTS on arenenud mitmekülgseks ja toimekaks tänu koostööle ja teabevahetusele teiste riikide sama eriala seltside, mullateadusele lähedaste erialaseltside ja Rahvusvahelise Mullateaduste Liiduga (IUSS), mis moodustati 1924. a. Itaalias. EMTS kuulub Euroopa Mullaseltside Konföderatsiooni (ECSSS) ning esindab Eestit Euroopa Mullakaitse Seltsis (ESSC) ja Ülemaailmse Mulla- ja Veekaitse Ühingus (WASWAC). Eesti muldkatte majandamine alates primitiivsest põlluharimisest kuni tänapäevase teaduslikel alustel muldade majandamiseni on olnud keerukas vaheldunud riigikordade erinevate põllu- ja metsamaade majandamise poliitikate tõttu. Muldade praktilist käitlust ja kodumaise mullateaduse arengut on edendavalt toetanud erialaseltside sünergiline mõju ning ülikoolide mullateaduse õppetoolide ja teiste maa- ja looduskasutusega seotud teadusliku uurimise instituutide ja riigiasutuste tegevused. Taolisi koostöös toimunud arenguid käsitlemegi käesolevas loos ühisel ajateljel, millega on suhestunud nii mullateaduse arengusse olulise panuse teinud teadlased kui ka praktiline majandustegevus. Meie käsitluses on see ajatelg jaotatud perioodideks riigikorra poliitiliste erisuste (kui mullaväliste nähtuste) alusel. Arenguloo erilise tähtsusega verstapostiks meie jaoks on Eesti Vabariigi sünd 1918. aastal. Käsitlus hõlmab nii iseseisvuse perioodile eelnenud kui ka järgnenud, erinevate riiklike majanduspoliitikatega perioode. Üldreeglina on areng ajajoonel esitatud perioodide kaupa ja isikute nimed ilma tiitliteta. Käesoleva Eesti mullateaduse ajalugu käsitleva tagasivaate koostamist ajendas IUSS-i jõudmine oma 100. aastapäevani (Horn jt, 2024). Käesolev ülevaade on sellele sündmusele pühendatud lühikese ingliskeelse artikli (Kõlli, Astover, 2024) Eesti lugejale suunatud mahukam versioon. Kirjanduslikke allikaid oleme esitanud kahel viisil ja eesmärgil. Selgitavas tekstis on viited tehtud kirjanduslike allikate autori(te) ja ilmumisaasta alusel. Enamus nendest on tagasivaated eelnenud ajale, mistõttu nende publitseerimine on reeglina lükkunud mõnele järgnevale ajaperioodile. Olles oma tagasivaates fookustanud mullateaduse alaste temaatikate arengu, temaatikaid edasiviinud isikud ja tegevuste katus-asutused, oleme pidanud tõdema, et enam kui sajandi jooksul tehtut on võimatu mahutada soovitud detailsusega ühte artiklisse. Sellest lähtudes on tagasivaate lisas 1 esitatud sama eriala harrastavate teadlaste poolt koostatud erinevaid perioode ja temaatikaid või asutuste ajalugu käsitlevate artiklite bibliograafiline loend [AL01‒19]. Loodetavasti võimaldavad toodud allikad täpsustada Eesti mullateaduse arengu tervikpilti. Lisas 2 on aga esitatud mõnede meile teadaolevate mullateadlaste personaal-bibliograafiad [PB1‒11]. Üldreeglina on lisadele viidatud vaid erandkordadel. Kokkuvõttena saab öelda, et oleme ajatelje suhtes saanud esitada ennekõike perioodide olulisemad uurimisteemad, põhitegijad ja -tegevused, ala eest vastutavad juhid ning tähtsündmused. Suhteliselt tagasihoidlikult oleme saanud käsitleda koostöid mullateadusega piirnevate teiste loodusteaduste tegevustega.Kirje Eesti maismaa-ökosüsteemid rohepöörde tõmbetuultes(Eesti Maaülikool, 2023) Kõlli, RaimoEuroopa Komisjon on algatanud loodusliku keskkonnaga harmoonilisse sei- sundisse juhtiva majanduse tegevuskava, milles on oluline roll ka muldadel (Montanarella ja Panagos, 2021). Ambitsioonikas rohepööre loodetakse ellu viia suhteliselt lühikese aja jooksul, jõudes kliimaneutraalsuseni aastaks 2050 (EK, 2019). Detailsete lahenduste leidmine on jäetud iga eraldiseisva riigi juhtivorganite, teadlaste, asjatundjate, vastavat ressurssi majandavate ettevõ- tete ja kohalike elanike pädevusse. Meie arvates on rohepöördeliste muutmiste üheks võimaluseks reguleerivat mõju taluvate ökoloogiliste protsesside teadus- põhine suunamine loodusele ja inimkonnale võimalikult soodsasse kestlikult toimivasse seisundisse. Eestile on meie arvates nii looduslike kui kultuurökosüsteemide majandamise edukuse võtmeks lähtumine tänapäevaks väljakujunenud põllu- ja metsa- majandusliku maakasutuse praktikast, võttes arvesse ennekõike teiste sarnaste tingimustega regioonide edulood (Valgepea jt, 2021). Oluline on õigete vali- kute tegemine, suhtudes samas kriitiliselt meile mittesobivate, praktikas tões- tamata soovituste kasutamisse. Rohetootmise arendamisel tuleks arvesse võtta lokaalseid mullastiku tingimusi, meile sobivaid tegevusi soovitatud uutest stra- teegilistest suundadest ning seni hästi toiminud tehnoloogiaid ja masinaparke, hõlmates vastava ala asjatundjaid ja andmebaase. Käesoleva artikli ülesandeks on analüüsida Eesti põllu-, metsa- ja rohumaa- ökosüsteemide seisundite ja majandamise kooskõla mullastiku omadustega (EPP, 1978, 1983, 1985) ning leida uusi võimalusi rohepoliitika edendamiseks. Meie arvates ei ole nutulaul Euroopa looduse halva seisundi kohta samaväärselt kehtiv Eesti maismaaökosüsteemide seisundi kohta.Kirje Muldkate kui ökosüsteemi seisundi ja rohetootmisvõime määraja(Eesti Maaülikool; Maaelu Teadmuskeskus, 2024) Kõlli, RaimoInseparable constituent of each terrestrial ecosystem is a soil cover, which determines the fabric and functioning peculiarities of plant cover and via its the development of most other components of ecosystems and as well the functioning of whole ecosystem. In actual work the role of arable, forest and grassland ecosystems’ mineral soil covers are treated in the light of European Green Deal. It seems to us, that the importance of soil cover in the further harmonized natural development plans have been up to actual day clearly underestimated. For precising the role of soils in ecosystems’ functioning, the soils’ influence was analysed in following diminishing levels as ‒ soil-plant subsystem -> soil cover -> humus cover, where each following is the constituent of previous. The discussion part enfolds more than dozen problems, among them recommendations of European Commission, availability of information on Estonian soil resources, management of soil organic carbon, soil quality and protection, species richness, restoration of soil-plant systems, innovation in soil science and others.Kirje Eutrophication and Geochemistry Drive Pelagic Calcite Precipitation in Lakes(MDPI, 2021) Khan, Hares; Laas, Alo; Marcé, Rafael; Sepp, Margot; Obrador, Biel; Centre for LimnologyPelagic calcification shapes the carbon budget of lakes and the sensitivity of dissolved inorganic carbon (DIC) responses to lake metabolism. This process, being tightly linked to primary production, needs to be understood within the context of summer eutrophication which is increasing due to human stressors and global change. Most lake carbon budget models do not account for calcification because the conditions necessary for its occurrence are not well constrained. This study aims at identifying ratios between calcification and primary production and the drivers that control these ratios in freshwater. Using in situ incubations in several European freshwater lakes, we identify a strong relationship between calcite saturation and the ratio between calcification and net ecosystem production (NEP) (p-value < 0.001, R2 = 0.95). NEP-induced calcification is a short-term process that is potentiated by the increase in calcite saturation occurring at longer time scales, usually reaching the highest levels in summer. The resulting summer calcification event has effects on the DIC equilibria, causing deviations from the metabolic 1:1 stoichiometry between DIC and dissolved oxygen (DO). The strong dependency of the ratio between NEP and calcification on calcite saturation can be used to develop a suitable parameterization to account for calcification in lake carbon budgets.Kirje A proposed order-level classification in Oligochaeta (Annelida, Clitellata)(Magnolia Press, 2021) Schmelz, Rüdiger M.; Erséus, Christer; Martin, Patrick; Van Haaren, Ton; Timm, Tarmo; Centre for LimnologyThe purpose of our contribution is to propose a robust and practical order-level classification of the families of Oligochaeta, that is, non-leech Clitellata. The order level is mandatory in Linnaean rank-based classification and is also required in many internet-based biodiversity databases. However, it has received little attention in oligochaete systematics, and the few available order-level classifications of Oligochaeta no longer represent phylogenetic relationships adequately. Our proposal is based on corroborated molecular phylogenetic evidence and takes as benchmarks class level for Clitellata, subclass level for Oligochaeta and Hirudinea, and order level for Crassiclitellata, the monophylum that includes most of the earthworm taxa. As a result, eleven orders are proposed: A lluroididA Timm & Martin, 2015; CApilloventridA Timm, n. ordo; CrAssiClitellAtA Jamieson, 1988; enChytrAeidA Kasprzak, 1984; hAplotAxidA Brinkhurst & Jamieson, 1971; lumbriCulidA Brinkhurst & Jamieson, 1971; moniligAstridA Brinkhurst & Jamieson, 1971; nArApidA Timm, n. ordo; pArvidrilidA Timm, n. ordo; rAndiellidA Jamieson, 1988; tubifiCidA Jamieson, 1978. This order-level classification is robust and easily adaptable to future insights into phylogenetic relationships.Kirje Detecting Climate Driven Changes in Chlorophyll-a Using High Frequency Monitoring: The Impact of the 2019 European Heatwave in Three Contrasting Aquatic Systems(MDPI, 2021) Free, Gary; Bresciani, Mariano; Pinardi, Monica; Giardino, Claudia; Alikas, Krista; Kangro, Kersti; Rõõm, Eva-Ingrid; Vaičiūtė, Diana; Bučas, Martynas; Tiškus, Edvinas; Hommersom, Annelies; Laanen, Marnix; Peters, Steef; Chair of Hydrobiology and FisheryThe frequency of heatwave events in Europe is increasing as a result of climate change. This can have implications for the water quality and ecological functioning of aquatic systems. We deployed three spectroradiometer WISPstations at three sites in Europe (Italy, Estonia, and Lithuania/Russia) to measure chlorophyll-a at high frequency. A heatwave in July 2019 occurred with record daily maximum temperatures over 40 ◦C in parts of Europe. The effects of the resulting storm that ended the heatwave were more discernable than the heatwave itself. Following the storm, chlorophyll-a concentrations increased markedly in two of the lakes and remained high for the duration of the summer while at one site concentrations increased linearly. Heatwaves and subsequent storms appeared to play an important role in structuring the phenology of the primary producers, with wider implications for lake functioning. Chlorophyll-a peaked in early September, after which a wind event dissipated concentrations until calmer conditions returned. Synoptic coordinated high frequency monitoring needs to be advanced in Europe as part of water management policy and to improve knowledge on the implications of climate change. Lakes, as dynamic ecosystems with fast moving species-succession, provide a prism to observe the scale of future change.Kirje Distribution of Phosphorus Forms Depends on Compost Source Material(MDPI, 2021) Lanno, Marge; Kriipsalu, Mait; Shanskiy, Merrit; Silm, Maidu; Kisand, AnuComposting is a sustainable method for recovering nutrients from various organic wastes, including food waste. Every input waste has different nutrient contents, in turn, suggesting that every compost has different fertilizer and/or soil improvement values. The phosphorus (P) concentration and relative distribution of P forms is related to the original organic material. The relative distribution of P forms determines how readily plants can absorb P from the compost-amended soil. The aim of this study was to investigate the content and relative share of P forms in composts made from fish waste, sewage sludge, green waste, and horse manure. Six forms of P (labile; bound to reducible metals; bound to non-reducible metals; bound to easily degradable organic material; and bound to calcium) were determined using sequential extraction method. The results indicated that fish waste compost had relatively high proportion of labile P, suggesting good biological availability. In comparison, sewage sludge compost contained the highest overall P concentration per dry weight unit, while labile P constituted only 6% of summary of P forms. The results indicate that the evaluation of composts as alternative P sources in agriculture should rely on the relative distribution of P forms in the compost in addition to the typically recognized value of the total P.Kirje Synergy between Satellite Altimetry and Optical Water Quality Data towards Improved Estimation of Lakes Ecological Status(MDPI, 2021) Ansper-Toomsalu, Ave; Alikas, Krista; Nielsen, Karina; Tuvikene, Lea; Kangro, Kersti; Chair of Hydrobiology and FisheryEuropean countries are obligated to monitor and estimate ecological status of lakes under European Union Water Framework Directive (2000/60/EC) for sustainable lakes’ ecosystems in the future. In large and shallow lakes, physical, chemical, and biological water quality parameters are influenced by the high natural variability of water level, exceeding anthropogenic variability, and causing large uncertainty to the assessment of ecological status. Correction of metric values used for the assessment of ecological status for the effect of natural water level fluctuation reduces the signal-to-noise ratio in data and decreases the uncertainty of the status estimate. Here we have explored the potential to create synergy between optical and altimetry data for more accurate estimation of ecological status class of lakes. We have combined data from Sentinel-3 Synthetic Aperture Radar Altimeter and Cryosat-2 SAR Interferometric Radar Altimeter to derive water level estimations in order to apply corrections for chlorophyll a, phytoplankton biomass, and Secchi disc depth estimations from Sentinel-3 Ocean and Land Color Instrument data. Long-term in situ data was used to develop the methodology for the correction of water quality data for the effects of water level applicable on the satellite data. The study shows suitability and potential to combine optical and altimetry data to support in situ measurements and thereby support lake monitoring and management. Combination of two different types of satellite data from the continuous Copernicus program will advance the monitoring of lakes and improves the estimation of ecological status under European Union Water Framework Directive.Kirje Effect of changing in weather conditions on Eastern Mediterranean coastal lagoon fishery(Elsevier, 2021) Cerim, Hasan; Özdemir, Nedim; Cremona, Fabien; Öglü, Burak; Chair of Hydrobiology and FisheryClimate change shows itself in many different ways on marine life. The fishery is also a part of marine life and affected by climate change-driven weather conditions directly or indirectly. In the present study, relationships between commercial species (grey mullet -≈90% of total capture- and gilthead seabream) that were captured from lagoon traps in Köyceğiz lagoon (Turkey) and local weather conditions were analysed. The machine learning method Random Forests (RF) was used to pre-select the model predictors. RF results showed that while temperature-related parameters, cloudy days, and wind speed were the most effective parameters, precipitation-parameters were the least important parameters for these two species catch. Generalized linear models (GLMs) were applied to each fish species with the best pre-selected parameters, with the resulting equation being used for future prediction of the two fish species. Future prediction of predictors was calculated by monthly autoregressive integrated moving average (ARIMA) and 20th/80th percentile intervals were used as the scenarios. Simulations showed that an increase in some weather parameters (wind speed, seawater temperature, maximum air temperature, cloudy days) lead to an increase in grey mullet and (wind speed) gilthead seabream catch. Models proved that the impact of the weather parameters differs for those two targeted fish species although they live in the same environment. We recommend that individual fish species (and/or catch) should be used in the models, not the whole fish yield. Moreover, the model can also be used for non-commercial species in ecosystem-based studies. Changes in weather parameters due to climate change should be monitored to make proper decision on fishery management.Kirje Environmental drivers and abrupt changes of phytoplankton community in temperate lake Lielais Svetinu, Eastern Latvia, over the last Post-Glacial period from 14.5 kyr(Elsevier, 2021) Tõnno, Ilmar; Talas, Liisi; Freiberg, Rene; Kisand, Anu; Belle, Simon; Stivrins, Normunds; Alliksaar, Tiiu; Heinsalu, Atko; Veski, Siim; Kisand, Veljo; Chair of Hydrobiology and FisheryUnderstanding the long-term dynamics of ecological communities on the centuries-to-millennia scale is important for explaining the emergence of present-day biodiversity patterns and for predicting possible future scenarios. Fossil pigments and ancient DNA present in various sedimentary deposits can be analysed to study long-term changes in ecological communities. We analysed recent compilations of data, including fossil pigments, microfossils, and molecular inventories from the sedimentary archives, to understand the impact of gradual versus abrupt climate changes on the ecosystem status of a regional model lake over the last ~14.5 kyr. Such long and complete paleo-archives are scarce in North-Eastern Europe. The study site lies in a sensitive area, both climatically and in respect to vegetation. Namely the maritime-continentality line runs west to east in the central Baltic area to NE Europe and its south- north transect lies within the gradual decay of the nemoral forest into a boreal environment. Therefore, the selected location is an ideal sampling point to decipher long term environmental changes in the temperate climate zone. The main objective of the present study was to find out external factors influencing phototroph dynamics at temperate Lake Lielais Sv etin ̧ u over the post-glacial period (~14.5 kyr). We were able to model climate change together with vegetation change and the appearance of anthropogenic forcing, either as a gradual change or as abrupt events that influenced the phototrophs, which are keystone groups within the lacustrine ecosystem. Most interestingly, the gradual increase of species richness of phototrophs was linked to similar increase in fungal parasites of the same group e phototrophs. Abrupt climate change in the Late Glacial period caused abrupt events in the ecosystem but equally abrupt events were caused by gradual changes during the stable period of the Holocene Thermal Maximum (HTM). In addition, we highlight the increased frequency and degree of perturbation in pristine lakes due to low impact human activity over a larger region. Both observations demonstrate an impaired relationship between gradual external drivers and ecosystem response and apply to future scenarios of climate warming and increased human impact in north-eastern Europe.Kirje Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer(ASLO, 2021) Donis, Daphne; Mantzouki, Evanthia; McGinnis, Daniel F.; Vachon, Dominic; Gallego, Irene; Grossart, Hans‐Peter; Senerpont Domis, Lisette N.; Teurlincx, Sven; Seelen, Laura; Lürling, Miquel; Verstijnen, Yvon; Maliaka, Valentini; Fonvielle, Jeremy; Visser, Petra M.; Verspagen, Jolanda; Herk, Maria; Antoniou, Maria G.; Tsiarta, Nikoletta; McCarthy, Valerie; Perello, Victor C.; Machado‐Vieira, Danielle; Oliveira, Alinne Gurjão; Maronić, Dubravka Špoljarić; Stević, Filip; Pfeiffer, Tanja Žuna; Vucelić, Itana Bokan; Žutinić, Petar; Udovič, Marija Gligora; Plenković‐Moraj, Anđelka; Bláha, Luděk; Geriš, Rodan; Fránková, Markéta; Christoffersen, Kirsten Seestern; Warming Trine Perlt; Feldmann, Tõnu; Laas, Alo; Panksep, Kristel; Tuvikene, Lea; Kangro, Kersti; Koreivienė, Judita; Karosienė, Jūratė; Kasperovičienė, Jūratė; Savadova‐Ratkus, Ksenija; Vitonytė, Irma; Häggqvist, Kerstin; Salmi, Pauliina; Arvola, Lauri; Rothhaupt, Karl; Avagianos, Christos; Kaloudis, Triantafyllos; Gkelis, Spyros; Panou, Manthos; Triantis, Theodoros; Zervou, Sevasti‐Kiriaki; Hiskia, Anastasia; Obertegger, Ulrike; Boscaini, Adriano; Flaim, Giovanna; Salmaso, Nico; Cerasino, Leonardo; Haande, Sigrid; Skjelbred, Birger; Grabowska, Magdalena; Karpowicz, Maciej; Chmura, Damian; Nawrocka, Lidia; Kobos, Justyna; Mazur‐Marzec, Hanna; Alcaraz‐Párraga, Pablo; Wilk‐Woźniak, Elżbieta; Krztoń, Wojciech; Walusiak, Edward; Gagala‐Borowska, Ilona; Mankiewicz‐Boczek, Joana; Toporowska, Magdalena; Pawlik‐Skowronska, Barbara; Niedźwiecki, Michał; Pęczuła, Wojciech; Napiórkowska‐Krzebietke, Agnieszka; Dunalska, Julita; Sieńska, Justyna; Szymański, Daniel; Kruk, Marek; Budzyńska, Agnieszka; Goldyn, Ryszard; Kozak, Anna; Rosińska, Joanna; Szeląg‐Wasielewska, Elżbieta; Domek, Piotr; Jakubowska‐Krepska, Natalia; Kwasizur, Kinga; Messyasz, Beata; Pełechata, Aleksandra; Pełechaty, Mariusz; Kokocinski, Mikolaj; Madrecka‐Witkowska, Beata; Kostrzewska‐Szlakowska, Iwona; Frąk, Magdalena; Bańkowska‐Sobczak, Agnieszka; Wasilewicz, Michał; Ochocka, Agnieszka; Pasztaleniec, Agnieszka; Jasser, Iwona; Antão‐Geraldes, Ana M.; Leira, Manel; Vasconcelos, Vitor; Morais, Joao; Vale, Micaela; Raposeiro, Pedro M.; Gonçalves, Vítor; Aleksovski, Boris; Krstić, Svetislav; Nemova, Hana; Drastichova, Iveta; Chomova, Lucia; Remec‐Rekar, Spela; Elersek, Tina; Hansson, Lars‐Anders; Urrutia‐Cordero, Pablo; Bravo, Andrea G.; Buck, Moritz; Colom‐Montero, William; Mustonen, Kristiina; Pierson, Don; Yang, Yang; Richardson, Jessica; Edwards, Christine; Cromie, Hannah; Delgado‐Martín, Jordi; García, David; Cereijo, Jose Luís; Gomà, Joan; Trapote, Mari Carmen; Vegas‐Vilarrúbia, Teresa; Obrador, Biel; García‐Murcia, Ana; Real, Monserrat; Romans, Elvira; Noguero‐Ribes, Jordi; Duque, David Parreño; Fernández‐Morán, Elísabeth; Úbeda, Bárbara; Gálvez, José Ángel; Catalán, Núria; Pérez‐Martínez, Carmen; Ramos‐Rodríguez, Eloísa; Cillero‐Castro, Carmen; Moreno‐Ostos, Enrique; Blanco, José María; Rodríguez, Valeriano; Montes‐Pérez, Jorge Juan; Palomino, Roberto L.; Rodríguez‐Pérez, Estela; Hernández, Armand; Carballeira, Rafael; Camacho, Antonio; Picazo, Antonio; Rochera, Carlos; Santamans, Anna C.; Ferriol, Carmen; Romo, Susana; Soria, Juan Miguel; Özen, Arda; Karan, Tünay; Demir, Nilsun; Beklioğlu, Meryem; Filiz, Nur; Levi, Eti; Iskin, Uğur; Bezirci, Gizem; Tavşanoğlu, Ülkü Nihan; Çelik, Kemal; Ozhan, Koray; Karakaya, Nusret; Koçer, Mehmet Ali Turan; Yilmaz, Mete; Maraşlıoğlu, Faruk; Fakioglu, Özden; Soylu, Elif Neyran; Yağcı, Meral Apaydın; Çınar, Şakir; Çapkın, Kadir; Yağcı, Abdulkadir; Cesur, Mehmet; Bilgin, Fuat; Bulut, Cafer; Uysal, Rahmi; Latife, Köker; Akçaalan, Reyhan; Albay, Meriç; Alp, Mehmet Tahir; Özkan, Korhan; Sevindik, Tuğba Ongun; Tunca, Hatice; Önem, Burçin; Paerl, Hans; Carey, Cayelan C.; Ibelings, Bastiaan W.To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phos- phorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L 1 ), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chloro- phyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4 C) and showed a signifi- cant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature.Kirje Effects of environmental stressors and their interactions on zooplankton biomass and abundance in a large eutrophic lake(Springer, 2021) Cremona, Fabien; Blank, Kätlin; Haberman, Juta; Chair of Hydrobiology and FisheryWe assessed long-term impacts of multi- ple stressors and their interaction on the zooplankton community of the large, eutrophic, cyanobacteria- dominated Lake Peipsi (Estonia, Russia). Stressor dataset consisted in time series (1997–2018) of temperature, nutrients, pH, water transparency, phy- toplankton biomass and taxonomic richness. The best predictors were selected with random forests machine- learning algorithms and the subsequent models were constructed with generalized linear modeling. We also aimed to identify graphical thresholds representing non-linear, marked responses of abundance or bio- mass to stressors. Temperature was the dominant stressor for explaining zooplankton abundance and biomass, followed by cyanobacteria biomass, total nitrogen concentration and water transparency. The effect of water temperature was positive, whereas the effect of cyanobacteria became negative after their biomass exceeded a threshold of * 2 mg l-1 . How- ever, the two stressors together had antagonistic effects on zooplankton, causing a decrease in biomass and abundance. For zooplankton, critical thresholds of total nitrogen (* 700 lg l-1 ), total phosphorus (* 70 lg l-1 ), and water transparency (* 1.4 m) after which zooplankton metrics changed drastically, were determined. These findings show that although lake warming alone could be positive for zooplankton, the necessity of reducing interacting stressors that influence harmful cyanobacteria growth and biomass, especially nitrogen loads, must be considered.Kirje Model-based decomposition of environmental, spatial and species-interaction effects on the community structure of common fish species in 772 European lakes(Wiley, 2021) Mehner, Thomas; Argillier, Christine; Hesthagen, Trygve; Holmgren, Kerstin; Jeppesen, Erik; Kelly, Fiona; Krause, Teet; Olin, Mikko; Volta, Pietro; Winfield, Ian J.; Brucet, SandraAim: We tested whether there is a strong effect of species interactions on assembly of local lake fish communities, in addition to environmental filters and dispersal. Location: Seven hundred and seventy-two European lakes and reservoirs. Time period: 1993–2012. Major taxa studied: Nineteen species of freshwater fishes. Methods: We applied a latent variable approach using Bayesian Markov chain Monte Carlo algorithms (R package “BORAL”). We compared the contributions of six environmental predictors and the spatial organization of 772 European lakes in 209 river basins on the presence/absence of the 19 most frequent fish species and on the biomass and mean mass of the six dominant species. We inspected the residual correlation matrix for positive and negative correlations between species. Results: Environmental (50%) and spatial (10%) predictors contributed to the presence/absence assembly of lake fish communities, whereas lake size and productivity contributed strongly to the biomass and mean mass structures. We found highly significant negative correlations between predator and prey fish species pairs in the presence/absence, biomass and mean mass datasets. There were more significantly positive than negative correlations between species pairs in all three datasets. In addition, unmeasured abiotic predictors might explain some of the correlations between species. Main conclusions: Strong effects of species interactions on assembly of lake fish communities are very likely. We admit that our approach is of a correlational nature and does not generate mechanistic evidence that interactions strongly shape fish community structures; however, the results fit with present knowledge about the interactions between the most frequent fish species in European lakes and they support the assumption that, in particular, the mean masses of fish species in lakes are modified by species interactions.Kirje Both climate trends and short-term fluctuations affected algae–zooplankton interactions in a boreal lake during the late Holocene(Wiley, 2021) Belle, Simon; Tõnno, Ilmar; Vrede, Tobias; Freiberg, Rene; Nilsson, Jenny L.; Goedkoop, Willem1. Most studies aiming to explore the response of algae and zooplankton trophic interactions to climate variability have only been focused on unidirectional and very shortterm trends in temperature changes. As a result, the non-stationary aspect of climate change (warming and cooling periods, frequencies) remains completely unstudied. 2. We studied elemental and stable isotope composition of sedimentary organic matter, photosynthetic pigments, and carbon stable isotope composition of Cladocera resting eggs in a sediment record covering the last c. 2,600 years. We examined how past climate change acting at different timescales affected algal biomass and community composition, and carbon assimilation by zooplankton in a boreal lake. 3. Our study revealed major effects of both long-term climate trends and shorter term fluctuations on algae–zooplankton interactions in a boreal lake. We found the main climate trends, in particular the Little Ice Age, induced algal biomass and community composition changes and drastic changes in carbon assimilation by zooplankton. Interestingly, we found that temperature fluctuations could also contribute to regulating algae–zooplankton interactions. Specifically, we observed drastic changes in sedimentary markers and stable isotope composition of zooplankton remains during the most recent period, suggesting a strong influence of ongoing anthropogenic change on algae–zooplankton interactions. 4. Our study confirms previous findings showing close long-term linkage between the temporal dynamics of zooplankton diet and planktonic algae, and that both climate trends and short-term fluctuations are key in regulating consumer– resource trophic interactions. 5. Novel approaches that combine high temporal resolution paleolimnological reconstructions and contemporary monitoring studies are needed to better understand climate change effects on algae–zooplankton interactions and lake food webs.Kirje Sea foams are ephemeral hotspots for distinctive bacterial communities contrasting sea-surface microlayer and underlying surface water(Oxford University Press, 2021) Rahlff, Janina; Stolle, Christian; Giebel, Helge-Ansgar; Mustaffa, Nur Ili Hamizah; Wurl, Oliver; Herlemann, Daniel P.R.; Chair of Hydrobiology and FisheryThe occurrence of foams at oceans’ surfaces is patchy and generally short-lived, but a detailed understanding of bacterial communities inhabiting sea foams is lacking. Here, we investigated how marine foams differ from the sea-surface microlayer (SML), a <1-mm-thick layer at the air–sea interface, and underlying water from 1 m depth. Samples of sea foams, SML and underlying water collected from the North Sea and Timor Sea indicated that foams were often characterized by a high abundance of small eukaryotic phototrophic and prokaryotic cells as well as a high concentration of surface-active substances (SAS). Amplicon sequencing of 16S rRNA (gene) revealed distinctive foam bacterial communities compared with SML and underlying water, with high abundance of Gammaproteobacteria. Typical SML dwellers such as Pseudoalteromonas and Vibrio were highly abundant, active foam inhabitants and thus might enhance foam formation and stability by producing SAS. Despite a clear difference in the overall bacterial community composition between foam and SML, the presence of SML bacteria in foams supports the previous assumption that foam is strongly influenced by the SML. We conclude that active and abundant bacteria from interfacial habitats potentially contribute to foam formation and stability, carbon cycling and air–sea exchange processes in the ocean.Kirje Genome analysis of the monoclonal marbled crayfish reveals genetic separation over a short evolutionary timescale(Springer Nature, 2021) Maiakovska, Olena; Andriantsoa, Ranja; Tönges, Sina; Legrand, Carine; Gutekunst, Julian; Hanna, Katharina; Pârvulescu, Lucian; Novitsky, Roman; Weiperth, András; Sciberras, Arnold; Deidun, Alan; Ercoli, Fabio; Kouba, Antonin; Lyko, Frank; Chair of Hydrobiology and FisheriesThe marbled crayfish (Procambarus virginalis) represents a very recently evolved parthenogenetic freshwater crayfish species that has invaded diverse habitats in Europe and in Madagascar. However, population genetic analyses have been hindered by the homogeneous genetic structure of the population and the lack of suitable tools for data analysis. We have used whole-genome sequencing to characterize reference specimens from various known wild populations. In parallel, we established a whole-genome sequencing data analysis pipeline for the population genetic analysis of nearly monoclonal genomes. Our results provide evidence for systematic genetic differences between geographically separated populations and illustrate the emerging differentiation of the marbled crayfish genome. We also used mark-recapture population size estimation in combination with genetic data to model the growth pattern of marbled crayfish populations. Our findings uncover evolutionary dynamics in the marbled crayfish genome over a very short evolutionary timescale and identify the rapid growth of marbled crayfish populations as an important factor for ecological monitoring.Kirje Migrating silver eels return from the sea to the river of origin after a false start(The Royal Society, 2021) Tambets, Meelis; Kärgenberg, Einar; Järvalt, Ain; Økland, Finn; Kristensen, Martin Lykke; Koed, Anders; Bernotas, Priit; Chair of Hydrobiology and FisheryThe European eel’s singular spawning migration from European waters towards the Sargasso Sea remains elusive, including the early phase of migration at sea. During spawning migration, the movement of freshwater resident eels from river to sea has been thought to be irreversible. We report the first recorded incidents of eels returning to the river of origin after spending up to a year in the marine environment. After migrating to the Baltic Sea, 21% of the silver eels, tagged with acoustic transmitters, returned to the Narva River. Half returned 11–12 months after moving to the sea, with 15 km being the long- est upstream movement. The returned eels spent up to 33 days in the river and migrated to the sea again. The fastest specimen migrated to the outlet of the Baltic Sea in 68 days after the second start—roughly 1300 km. The surprising occurrence of returning migrants has implications for sustainable management and protection of this critically endangered species.Kirje Biodiversity and functional trait effects on copper toxicity in a proof-of-concept multispecies microalgal assay(Elsevier, 2021) Joonas, Elise; Olli, Kalle; Kahru, Anne; Aruoja, VillemThis study aimed to elucidate biodiversity effects on algal biomass production under toxicant stress and to increase environmental realism in ecotoxicological testing by exposing artificial algal communities to Cu2+. All 15 possible combinations of four functionally distinct microalgal species (green algae Chlamydomonas reinhardtii and Raphidocelis subcapitata, diatom Fistulifera pelliculosa and cyanobacterium Synechocystis sp.) were exposed to 0.01 and 0.02 mg Cu2+ l 1 in a modified algal growth inhibition assay (OECD 201). Compared to monocultures, the replicability of assays in multispecies communities decreased. Copper-induced inhibition of the biomass yield of individual species did not change due to interactions between species in multispecies tests, indicating that Cu toxicity was the driver of competitive outcomes. Biomass yield was increased at higher species richness in controls and Cu-exposed treatments. Selection effect is considered to prevail over trait complementarity in our experiments, because functional diversity, that expresses species trait variability and equality in species’ occurrence, had a negative effect on algal biomass yield, while species richness increased the yield. Algal functional traits related to cell size were the best predictors of microalgal biomass production. Species identity was identified as an important determinant of community-level outcomes.