Fütoplankton järvede seisundi indikaatorina

A Thesis for applying for the degree of Doctor of Philosophy in Environmental Sciences and Applied Biology.Väitekiri filosoofiadoktori kraadi taotlemiseks keskkonnateaduste ja rakendusbioloogia erialal.According to Water Framework Directive (WFD), phytoplankton abundance, composition and bloom metrics should be used in lake ecological quality assessment. Phytoplankton is highly sensitive to environmental changes and can serve as an early warning parameter in water quality assessment. To quantify the response of phytoplankton communities to nutrient pressure, the metric should be robust. Still numerous confounding factors and even the adaptational plasticity of phytoplankton can compromise its indicator value and increase the uncertainty of assessment results. Therefore, the final assessment of the ecological quality needs to be based on multifaceted analysis of phytoplankton ecology. The aims of this study were to ascertain the main environmental factors determining the distribution and biomass of dominant phytoplankton species in the EU lakes, to analyze the suitability and strength of phytoplankton parameters and metrics for estimating the ecological status of lakes in EU lakes, and to exemplify the evaluation of phytoplankton metrics through uncertainty analyses of their response to eutrophication. Substantial effort was made within the EU 7th Framework Programme project WISER to collect consistent phytoplankton data across European lakes. These data was used in the present study to elaborate the best sampling procedures for lakes, test metrics in use, develop a common metric and study parameters which influence the distribution of dominant phytoplankton species and algal classes. The CCA ranked water colour, total phosphorous (TP) and alkalinity as the most important factors determining the large-scale distribution patterns of lake phytoplankton dominants in European lakes. During this study, strict sampling procedure was tested, wherein appeared, that single open water sampling location is generally sufficient for assessment of ecological quality of lakes. In this study three robust metrics are provided to assess the impact of eutrophication pressures.Euroopa Liidu Veepoliitika Raamdirektiivi (VRD) nõuete kohaselt tuleks veekogude ökoloogilise seisundi hindamisel kasutada fütoplanktoni näitajaid, mis iseloomustavad tema hulka ja koosseisu ning veeõitsengute sagedust ja intensiivsust. Fütoplankton on tundlik ja reageerib kiiresti veekogus toimuvatele muutustele. Survetegurite mõju hindamiseks peaks nende seos fütoplanktoni näitajatega olema piisavalt tugev ja stabiilne. Mitmed kõrvaltegurid ja koguni fütoplanktoni kohastumisvõime võivad seda seost häirida, mis suurendab määramatust ja vähendab fütoplanktoni indikaatorväärtust. Seetõttu peab järve seisundile antav lõpphinnang tuginema igakülgsele fütoplanktoni ökoloogia arvestamisele. Doktoritöö eesmärgiks oli välja selgitada peamised tegurid, mis mõjutavad fütoplanktoni dominantliikide levikut EL järvedes, analüüsida fütoplanktoni parameetrite sobivust ja tugevust hindamaks järvede ökoloogilist seisundit, ja testida eutrofeerumist iseloomustavaid fütoplanktoni näitajaid. EL 7. raamprogrammi projekti WISER raames koguti Euroopa järvedest kindla juhendi alusel suurel hulgal uusi fütoplanktoni andmeid. Nende andmete põhjal töötati käesolevas töös välja parim veeproovide kogumise kord, testiti näitajaid, mis olid juba varasemalt kasutusel, töötati välja ühine indeks ja uuriti dominantliikide, perekondade ja muude rühmade esinemist mõjutavaid tegureid. Üle-euroopalistel andmetel põhinev kanooniline korrespondentsanalüüs näitas, et kõige enam mõjutavad fütoplanktoni dominantliikide esinemist üldfosfori sisaldus vees, vee värvus ja üldaluselisus. Selle uurimuse käigus töötati välja kindel proovivõtu protokoll, mille käigus jõuti järeldusele, et üks avavee proov järves on tavaliselt hinnangu andmiseks piisav. Selles töös pakume välja kolm surveteguritest oluliselt sõltuvat indeksit, mida võiks kasutada veekogude seisundi hindamisel.Publication of this thesis is supported by the Estonian University of Life Sciences

Nitrogen in Estonian lakes – the trends and impacts on Cyanobacteria

• The relative role of N&P to control eutrophication in lakes is continuously debated (Schindler et al. 2008). • Estonian limnologists have been P-believers as the post-socialist sharp reduction of N loading brought back cyanobacterial blooms in Lake Peipsi (Nõges et al. 2005) • The long debate has not discredited the importance of P-Control, but displayed evidence on the significance of N reduction to recover lake ecosystems (Paerl et al. 2016) • Chemically reduced N forms, such as NH4 + and urea favour non-N-fixing cyanobacteria (McCarthy et al. 2009)This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 951963. Eesti Teadusagentuur / Estonian Research Council PRG 709, PRG 1167. Horizon 2020, European Union Funding fof Research & Innovation. Twinning CSA 951963.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 951963. Eesti Teadusagentuur / Estonian Research Council PRG 709, PRG 1167. Horizon 2020, European Union Funding fof Research & Innovation. Twinning CSA 951963

Kliimamuutuste mõju uuring Eesti väikejärvedele

Ilmastikumuutused on väga laiahaardelised ja mõjutavad kõiki Maa ökosüsteeme. Ühe põhilise kasvuhoonegaasi, süsihappegaasi (CO2), kontsentratsioon võib 2050. aastateks kahekordistuda, ületades 700 ppm (George 2010) ning IPCC (Intergovernmental Panel of Climate Change 2018) andmetel võib selle sajandi lõpuks õhutemperatuur tõusta kuni 7 kraadi (Nõges, Nõges 2011), mis tähendab olulist survet nii maismaa kui ka vee ökosüsteemidele. Riigid seisavad silmitsi üha enam süvenevate probleemidega, kus kliimasurve ühelt poolt muudab kvaliteedinäitajate dünaamikaid ja teisalt raskendab veekogude hea ökoloogilise seisundi saavutamist. Mitmete stressorite koosmõju mõjutab tugevalt magevee ökosüsteeme, see kandub edasi toiduahela kaudu, mõjutades otseselt ökosüsteemi funktsioneerimist, dünaamikat ja struktuuri (Li et al. 2019). Eesti järvi on uuritud üle saja aasta, mis sobiks kliimast tingitud muutuste jälgimiseks ja selgitamiseks. Paraku tuleb aru saada, et järjepidevat aegrida uuringuandmetest saaks koostada ehk meie suurjärvede kohta. Pikem aegrida on ka Ülemiste kohta. Selle järve haldamine on erafirma käes ja andmete kasutamine teatavate piirangutega. Hiljuti valmis meie asutuse poolt tehtud Ülemiste järve käsitlev uurimus („Ülemiste järve limnoloogiline eksperthinnang“), mis sobib hästi antud projekti konteksti ja soovitame sellekohaseid tulemusi küsida aktsiaseltsilt Tallinna Vesi. Enamuse väikejärvede kohta on andmeid küll üsna varajasest ajast, st inventuurides möödunud sajandi 1920ndaist ja 1930ndaist, kuid enamasti on andmeid vaid ühekordsetest vaatlustest kasvuperioodil. Põhjalikke kompleksseid uuringuid tehti alates 1951. aastast, kuid taas uuriti erinevatel aastatel erinevaid järvi ja enamasti korra suvel. Väikejärvede püsivaatlusi alustati alles 1992. aastal hüdrobioloogilise seire käigus. Tollest ajast on siiani pidevas uurimises ainult kuus järve. Sellises olukorras saame teha ülevaateid suhteliselt lühikese aja jooksul ja väheste järvede kohta. See tähendab, et pigem saame käsitleda ilma mõju veekogudele ja saame esitada ekspertarvamusi kliima mõju kohta. Hindasime kliima ja ilma mõju kuue erineva väikejärve keemilise ja bioloogilise seisundi kujunemisele kasutades väikejärvede hüdrobioloogilise ja hüdrokeemilise varasemate uuringute raames kogutud andmeid ja uurimistulemusi. Järvede füüsikalis-keemiliste parameetrite ja elustiku dünaamika muutuste selgitamiseks kasutati väikejärvede hüdrobioloogilise ja hüdrokeemilise seire käigus kogutud andmeid ja eksperthinnanguid. Ilmastiku mõju hindamiseks kasutati Riigi Ilmateenistuse ajaloolisi andmeid õhutemperatuuri ja sademete kohta. Peamised küsimused, millele püüdsime vastust leida: - Millised on kliima ja ilma muutumise (keskmine õhutemperatuur, sademed ja neist tulenevad näitajad) otsesed ja kaudsed mõjud väikejärve ökosüsteemi funktsioneerimisele? - Muutuste ja põhjuste selgitamine ning tulevikustsenaariumite kirjeldamine. - Ettepanekute tegemine väikejärvede seisundi säilitamiseks. Võimalusel tehakse prognoose järvede kliimamuutustega kohanemiseks

Nitrogen and its expected impacts in Estonian lakes : [poster]

• The relative role of N&P to control eutrophication in lakes is continuously debated (Schindler et al. 2008). • Estonian limnologists have been P-believers as the post- socialist sharp reduction of N loading brought back cyanobacterial blooms in Lake Peipsi (Nõges et al. 2005) • The long debate has not discredited the importance of P- control, but displayed evidence on the significance of N reduction to recover lake ecosystems (Paerl et al. 2016) • Chemically reduced N forms, such as NH4+ and urea favour non-N-fixing Cyanos (McCarthy et al. 2009) • Agriculture has intensified and the application of mineral fertilisers in Estonia has increased in the recent decade (Nõges et al. 2022)The presentation took place at the 11th International Shallow Lakes Conference.This study was funded by the Estonian Research Council grants PRG709, and PRG1167. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 951963.This study was funded by the Estonian Research Council grants PRG709, and PRG1167. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 951963

Lake Peipsi 2019 (Phytoplankton samples)

Method: Phytoplankton samples were preserved in Lugol’s (acidified iodine) solution and counted under an inverted microscope (Utermöhl, 1958). 3-10 ml of preserved sample was settled overnight and counted in random fields or transects. Biovolumes of algal cells, colonies and/or filaments were calculated using assigned geometric shapes dimensions, and converted to biomass assuming the specific density of 1 g cm-3 in accordance with Edler (1979). Approved by CEN on 14 July 2006 “Water quality - Guidance standard on the enumeration of phytoplankton using inverted microscopy (Utermöhl technique)” (CEN 15204, 2006) European Standard EN 15204:2006 Utermöhl, H., 1958. Zur Vervollkommnung der quantitativen Phytoplankton-Methodik. Mitteilungen der Internationale Vereinigung für Theoretische und Angewandte Limnologie 9, 1- 38. Edler, L. (ed.), 1979. Recommendations on methods for marine biological studies in the Baltic Sea. Phytoplankton and chlorophyll. Baltic Marine Biologists WG 9. Leg: K. Blank, K. Palmik-Das, L. Tuvikene, A. Tuvikene; det: K. Maileh

Järvede seisundi parandamiseks vajalike uuringute teostamine ja meetmekavade väljatöötamine : projekti lõpparuanne : Pullijärve meetme- ja tegevuskava

Euroopa Liidu Veepoliitika Raamdirektiiv (VRD) reguleerib vee kasutamise ja selle hea seisundi säilitamisega seotud seaduseid ning regulatsioone liikmesriikides. Vesi on hindamatu ressurss, mistõttu nõuab dokument liikmesriikidelt pingutusi ja tegevusi, et saavutada pinnavete hea keemiline ja ökoloogiline seisund. Pullijärv1 on pehme ja heleda veega eutrofeerunud oligotroofne järv ning siin elavad mitmed haruldased looduskaitsealused liigid. Lisaks on järv olulise rekreatsioonilise väärtusega kohalike seas. Viimaste uuringute käigus on järve ökoloogiline seisund olnud kesine ja mitmed kvaliteedinäitajad on oluliselt halvenenud. Seetõttu on vajalik uurida “mittehea” seisundi põhjuseid ja töötada välja tõhusad meetmed järve seisundi parandamiseks. Eesti Maaülikool esitas Keskkonnainvesteeringute Keskuse (KIK) poolt läbiviidud taotlusvooru projekti nr 14705 “Järvede seisundi parandamiseks vajalike uuringute teostamine ja meetmekavade väljatöötamine” taotluse, mis rahastati pooles mahus. Läbirääkimiste tulemusel kooskõlastati uus lähteülesanne Keskkonnaameti poolt 28.09.2018. a (nr 7-18/18/3808-6). Uus lähteülesanne keskendub Pullijärve (VEE2155200) mittehea seisundi põhjuste väljaselgitamisele. Uuringute käigus selgitati olemasolevate andmete alusel Pullijärve seisundi dünaamikat alates 1950. aastatest tänapäevani, uuriti sise- ja väliskoormust ning pakuti välja meetmed järve seisundi parandamiseks. Uurimismeetodid, mida kasutati hüdrokeemilistel analüüsidel ja elustiku uuringutel, on standardiseeritud või interkalibreeritud ja vastavad seadustes äratoodud nõuetele ning nendega on võimalik tutvuda põhjalikumalt töö metoodika peatükkides. Parameetrite seisundi klassipiirid pärinevad keskkonnaministri määrusest nr 44 (Pinnaveekogumite…, 2009). Töö eesmärk on välja töötada meetme- ja tegevuskava Pullijärve hea ökoloogilise seisundi saavutamiseks järgmise veemajanduskava perioodi jooksul (2020-2027). Uuringu lõpparuanne koosneb kahest osast: Esimeses osas (järve seisundi dünaamika) antakse ülevaade Pullijärve funktsioneerimisest ja kvaliteedielementide dünaamikast. Esitatakse välis- ja sisekoormuse uuringute tulemused. Teises osas (meetme- ja tegevuskava) kirjeldatakse kliima mõju pehme- ja heledaveelisele järvele, antakse ülevaade ökosüsteemiteenustest ning pakutakse välja meetme- ja tegevuskava koos ajakavaga. Uuringut viisid läbi ja aruande koostasid Eesti Maaülikooli Põllumajandus- ja keskkonnainstituudi Hüdrobioloogia ja kalanduse õppetooli teadlased: prof. Ingmar Ott, Ph.D. (vastutav täitja), M.Sc. Ronald Laarmaa, M.Sc. Kairi Maileht, Ph.D. Sirje Vilbaste, Ph.D. Margot Sepp, M.Sc. Katrin Saar, Ph.D Henn Timm, M.Sc. Anu Palm ja Katrin Ott

Disentangling the effects of land use and geo-climatic factors on diversity in European freshwater ecosystems

International audienceLand use effects are considered among the main stressors on freshwater biodiversity, with up to 80% of land in Europe under intensive use. Here, we address the impact of arable and urban landscapes on taxon richness, Shannon–Wiener diversity, taxon rareness and taxonomic distinctness of eleven organ- ism groups encompassing vertebrates, invertebrates and plants, occurring in five freshwater ecosystem types across Europe: rivers, floodplains, lakes, ponds and groundwater. In addition, nine geo-climatic descriptors (e.g. latitude, longitude, precipitation) were used to disentangle land use effects from those of natural drivers of biodiversity. Using a variance partitioning scheme based on boosted regression trees and generalised linear regression modelling, we sought: (i) to partition the unique, shared and unex- plained variation in the metrics explained by both groups of descriptor variables, (ii) to quantify the contribution of each descriptor variable to biodiversity variation in the most parsimonious regression model and (iii) to identify interactions of land use and natural descriptors. The variation in biodiver- sity uniquely described by land use was consistently low across both ecosystem types and organism groups. In contrast, geo-climatic descriptors uniquely, and jointly with land use, explained significantly more variance in all 39 biodiversity metrics tested. Regression models revealed significant interactions between geo-climatic descriptors and land use for a third of the models, with interactions accounting for up to 17% of the model’s deviance. However, no consistent patterns were observed related to the type of biodiversity metric and organism group considered. Subdividing data according to the strongest geo-climatic gradient in each dataset aimed to reduce the strength of natural descriptors relative to land use. Although data sub-setting can highlight land use effects on freshwater biodiversity, sub-setting our data often failed to produce stronger land use effects. There was no increase in spatial congruence in the subsets, suggesting that the observed land use effects were not dependent on the spatial extent of the subsets. Our results confirm significant joint effects of, and interactions between, land use and natural environmental descriptors on freshwater biodiversity, across ecosystem types and organism groups. This has implications for biodiversity monitoring. First, the combined analysis of anthropogenic and natural descriptors is a prerequisite for the analysis of human threats to biodiversity. Second, geo-climatically, but not necessarily geographically more homogeneous datasets can help unmask the role of anthropogenic descriptors. And third, whole community-based biodiversity metrics (including taxon richness) are not ideal indicators of anthropogenic effects on biodiversity at broad scales

Strength and uncertainty of lake phytoplankton metrics for assessing eutrophication impacts in lakes.

Phytoplankton constitutes a diverse array of short-lived organisms which derive their nutrients from the water column of lakes. These features make this community the most direct and earliest indicator of the impacts of changing nutrient conditions on lake ecosystems. It also makes them particularly suitable for measuring the success of restoration measures following reduction in nutrient loads. This paper integrates a large volume of work on a number of measures, or metrics, developed or using phytoplankton to assess the ecological status of European lakes, as required for the Water Framework Directive (WFD). It examines the indicator strenght of these metrics, specifically in relation to representing the impacts of eutrophication. It also examines how these measures vary naturally at different locations within a lake, as well as between lakes, and how much variability is associated with different replicate samples, different months within a year and between years. On the basis of this analysis, three of the strongest metrics (chlorophyll-a, Phytoplankton Trophic Index (PTI) and cyanobacterial biovolume) are recommended for use as robust measures for assessing the ecological quality of lakes in relation to nutrient enrichment pressures and a minimum recommended sampling frequency is provided for these three metrics.JRC.H.1-Water Resource

Water colour, phosphorus and alkalinity are the major determinants of the dominant phytoplankton species in European lakes

Analysis of phytoplankton data from about 1,500 lakes in 20 European countries has revealed that two-thirds of the species that dominate lakes during the summer are dominant right across Europe. Using Canonical Correspondence Analyses, we have examined how both habitat conditions within lakes and environmental factors over broad geographical scales explained the distribution of the 151 most common summer dominant species. The distributions of these species were best explained by water colour and latitude, although alkalinity and total phosphorus also appeared to be important explanatory factors. Contrary to our original hypothesis, summer water temperatures had a negligible impact on the distribution of dominants, although, due to the restricted summer season we examined, only a limited temperature gradient was present in the dataset. Cryptophytes occurred more frequently among dominants in Northern Europe whereas cyanobacteria and dinophytes dominated more in Central and Southern Europe. Our analyses suggest that besides nutrient concentrations, other water chemistry variables, such as alkalinity and the content of humic substances, have at least as important a role in determining the distribution of the dominant phytoplankton species in European lakes

Quantifying uncertainties in biologically-based water quality assessment: a pan-European analysis of lake phytoplankton community metrics

Lake phytoplankton are adopted world-wide as a sensitive indicator of water quality. European environmental legislation, the EU Water Framework Directive (WFD), formalises this, requiring the use of phytoplankton to assess the ecological status of lakes and coastal waters. Here we provide a rigorous assessment of a number of proposed phytoplankton metrics for assessing the ecological quality of European lakes, specifically in response to nutrient enrichment, or eutrophication, the most widespread pressure affecting lakes. To be useful indicators, metrics must have a small measurement error relative to the eutrophication signal we want them to represent among lakes of different nutrient status. An understanding of variability in metric scores among different locations around a lake, or due to sampling and analytical variability can also identify how best this measurement error is minimised. To quantify metric variability, we analyse data from a multi-scale field campaign of 32 European lakes, resolving the extent to which seven phytoplankton metrics (including chlorophyll a, the most widely used metric of lake quality) vary among lakes, among sampling locations within a lake and through sample replication and processing. We also relate these metrics to environmental variables, including total phosphorus concentration as an indicator of eutrophication. For all seven metrics, 65–96% of the variance in metric scores was among lakes, much higher than variability occurring due to sampling/sample processing. Using multi-model inference, there was strong support for relationships between among-lake variation in three metrics and differences in total phosphorus concentrations. Three of the metrics were also related to mean lake depth. Variability among locations within a lake was minimal (<4%), with sub-samples and analysts accounting for much of the within-lake metric variance. This indicates that a single sampling location is representative and suggests that sub-sample replication and standardisation of analyst procedures should result in increased precision of ecological assessments based upon these metrics. For three phytoplankton metrics being used in the WFD: chlorophyll a concentration, the Phytoplankton Trophic Index (PTI) and cyanobacterial biovolume, >85% of the variance in metric scores was among-lakes and total phosphorus concentration was well supported as a predictor of this variation. Based upon this study, we can recommend that these three proposed metrics can be considered sufficiently robust for the ecological status assessment of European lakes in WFD monitoring schemes