Phytoplankton quantity as an indicator of eutrophication in Finnish coastal waters : applications within the Water Framework Directive

The tackling of coastal eutrophication requires water protection measures based on status assessments of water quality. The main purpose of this thesis was to evaluate whether it is possible both scientifically and within the terms of the European Union Water Framework Directive (WFD) to assess the status of coastal marine waters reliably by using phytoplankton biomass (ww) and chlorophyll a (Chl) as indicators of eutrophication in Finnish coastal waters. Empirical approaches were used to study whether the criteria, established for determining an indicator, are fulfilled.The first criterion (i) was that an indicator should respond to anthropogenic stresses in a predictable manner and has low variability in its response. Summertime Chl could be predicted accurately by nutrient concentrations, but not from the external annual loads alone, because of the rapid affect of primary production and sedimentation close to the loading sources in summer. The most accurate predictions were achieved in the Archipelago Sea, where total phosphorus (TP) and total nitrogen (TN) alone accounted for 87% and 78% of the variation in Chl, respectively. In river estuaries, the TP mass-balance regression model predicted Chl most accurate when nutrients originated from point-sources, whereas land-use regression models were most accurately in cases when nutrients originated mainly from diffuse sources. The inclusion of morphometry (e.g. mean depth) into nutrient models improved accuracy of the predictions.The second criterion (ii) was associated with the WFD. It requires that an indicator should have type-specific reference conditions, which are defined as “conditions where the values of the biological quality elements are at high ecological status”. In establishing reference conditions, the empirical approach could only be used in the outer coastal waters types, where historical observations of Secchi depth of the early 1900s are available. Most accurate prediction was achieved in the Quark. However, the average reference values in the outer coastal types are underestimated in sites near the zone of the inner coastal waters. In the inner coastal water types, reference Chl, estimated from present monitoring data, are imprecise - not only because of the less accurate estimation method - but also because the intrinsic characteristics, described for instance by morphometry, vary considerably inside these extensive inner coastal types. As for phytoplankton biomass, the reference values were less accurate than in the case of Chl, because it was possible to estimate reference conditions for biomass only by using the reconstructed Chl values, not the historical Secchi observations. An paleoecological approach was also applied to estimate reference conditions for Chl. In Laajalahti, an urban embayment off Helsinki, strongly loaded by municipal waste waters until 1986, reference conditions prevailed in the mid- and late 1800s. The recovery of the bay from pollution has delayed as a consequence of benthic release of nutrients. Laajalahti will probably not achieve the good quality objectives of the WFD on time.The third criterion (iii) was associated with coastal management including the resources it has available. Analyses of Chl are cheap and fast to carry out compared to the analyses of phytoplankton biomass and species composition; the fact which has an effect on number of samples to be taken and thereby on the reliability of assessments. However, analyses on phytoplankton biomass and species composition provide more metrics for ecological classification, the metrics which reveal various aspects of eutrophication contrary to what Chl alone does

Rannikkovesien ekologisen luokittelun perusteita – yhteenveto eurooppalaisista tyypittelyn, luokittelun ja seurannan ohjeistuksista

Raportissa esitellään EU:n vesipuitedirektiivin myötä kehitettävän ekologisen luokittelun taustaa ja perusteita rannikkovesien osalta. Tekstissä tarkastellaan sekä direktiivissä annettuja määritelmiä että EU:n asettamien, yhteistä lähestymistapaa (Common Implementation Startegy, CIS) työstäneiden työryhmien näkemyksiä ja tulkintoja direktiivin tekstistä. Raportissa käydään läpi direktiivissä rannikkovesien luokitteluun sisällytetyt laatutekijät, sekä selitetään vertailuolosuhteet ja ekologinen laatusuhde (ecological quality ratio, EQR). Siinä esitellään myös direktiivissä esitetyt menetelmät vertailuolosuhteiden määrittämiseksi, ja pohditaan niiden käyttökelpoisuutta. Raportissa tarkastellaan sekä direktiivissä lueteltuja että työryhmien ohjeistuksissaan esittämiä kriteereitä luokittelussa käytettävien laatutekijöiden ja muuttujien valitsemiseksi. Lisäksi esitellään lyhyesti vaihtoehtoisia menetelmiä luokkarajojen asettamiseksi. Lopuksi tarkastellaan biologisten tekijöiden ja niitä tukevien fysikaalis-kemiallisten ja hydrologis-morfologisten tekijöiden suhdetta luokittelussa ja annetaan katsaus interkalibrointiprosessista, jonka avulla on tarkoitus varmistaa eri maiden luokittelutulosten vertailukelpoisuus

Interaction between the land and the sea : sources and patterns of nutrients in the scattered coastal zone of a eutrophied sea

A long-term trophic development of three geographical transects—including a river mouth, an estuary, and an archipelago—were studied in the southern Finnish coast in the Baltic Sea. Each transect was studied to clarify how far off the coast the land-based nutrient sources (catchment factor, CF) had a decisive role in shaping the wintertime regimes of dissolved inorganic nitrogen and dissolved inorganic phosphorus and where the marine processes (marine factor, MF) start to play a major role. Generally, CF controlled the nutrient regime from the coast to the outer brink of the inner coastal area, after which MF started to dominate. The estuaries exhibited steep vertical nutrient gradients, above which the riverine input dominated the nutrient regime. The extent of the area where CF dominated the nutrient regime was therefore decisively dependent on estuarine stratification, i.e., whether the conclusions were drawn based on the surface layer data, including the riverine impact, or on the data beneath that layer, including the marine impact. This result deviates from the current consensus that the trophic regime of the sea is most directly assessed by the surface layer nutrient content. The estuarine nutrient regime is unrepresentative to that of a typical coastal water body due to the strong land-based impact on the estuary. Therefore, any generalization of the trophic condition of an estuary to represent areas farther off the coast should be done cautiously. The estuaries should also be defined as belonging to transitional waters according to the typology related to European Marine Legislation

Influence of EU policy on agricultural nutrient losses and the state of receiving surface waters in Finland

In Finland, the first large-scale efforts to control nutrient loading from agriculture got under way with the introduction of the EU Agri-Environmental Program in 1995. We examined whether these efforts have decreased agricultural nutrient losses and improved the quality of receiving waters. To do so we used monitoring data on fluxes of nutrients and total suspended solids in agricultural catchments in 1990–2004 and on the water quality of agriculturally loaded rivers, lakes and estuaries in 1990–2005. No clear reduction in loading or improvement in water quality was detected. Hydrological fluctuations do not seem to have eclipsed the effects of the measures taken, since there was no systematic pattern in runoff in the period studied. The apparent inefficiency of the measures taken may be due to the large nutrient reserves of the soil, which slowed down nutrient reductions within the period studied. Simultaneous changes in agricultural production (e.g. regional specialisation) and in climate may also have counteracted the effects of agri-environmental measures. The actions to reduce agricultural loading might have been more successful had they focused specifically on the areas and actions that contribute most to the current loading

Participatory operations model for cost-efficient monitoring and modeling of river basins — A systematic approach

AbstractThe worldwide economic downturn and the climate change in the beginning of 21st century have stressed the need for cost efficient and systematic operations model for the monitoring and management of surface waters. However, these processes are still all too fragmented and incapable to respond these challenges. For example in Finland, the estimation of the costs and benefits of planned management measures is insufficient. On this account, we present a new operations model to streamline these processes and to ensure the lucid decision making and the coherent implementation which facilitate the participation of public and all the involved stakeholders. The model was demonstrated in the real world management of a lake. The benefits, pitfalls and development needs were identified. After the demonstration, the operations model was put into operation and has been actively used in several other management projects throughout Finland

Nitraattidirektiivin täytäntöönpano Suomessa : Raportointijakso 2016–2019

Vuonna 1991 hyväksytty neuvoston direktiivi vesien suojelemisesta maataloudesta peräisin olevien nitraattien aiheuttamalta pilaantumiselta, eli ns. nitraattidirektiivi (91/676/EEC) on olennainen osa Euroopan unionin vesien suojeluun liittyvää sääntelyä ja sidoksissa vesipuitedirektiiviin. Sen tarkoituksena on vähentää maataloudesta peräisin olevaa nitraattien aiheuttamaa vesien pilaantumista. Euroopan unionin jäsenvaltioiden on raportoitava neljän vuoden välein nitraattidirektiivin velvoittamana komissiolle maatalouden aiheuttama vesistökuormitus, pinta-, pohja- ja rannikkovesien nitraattipitoisuudet ja niiden trendit sekä toimintaohjelmien toteutuminen. Suomessa raportoinnin toteuttaa Suomen ympäristökeskus yhdessä ympäristöministeriön kanssa. Suomen osalta raportointi toteutettiin nyt kuudennen kerran. Nitraattidirektiivin raportointijaksolla 2016–2019 nitraatin pitoisuudet nousivat kahdeksassa Etelä-Suomen maatalousvaltaisten alueiden joessa ajoittain lähelle tai ylittivät direktiivin asettaman raja-arvon, 25 mg/l nitraattia. Vuodesta 1996 lähtien pintavesien nitraattipitoisuudet ovat pysyneet pääosin vakaina tai laskeneet lievästi. Raportoinnissa tarkastellaan myös jokien, järvien ja rannikkovesien rehevyystasoa. Pohjavesille asetettu raja-arvo, 50 mg/l nitraattia, ylittyi jaksolla 2016–2019 neljällä maa- ja metsätalouden kuormittamalla alueella. Valtaosin pitoisuudet olivat alle 25 mg/l ja muutossuunta edelliseen raportointijaksoon verrattuna vakaa puolessa kohteista ja lievästi laskeva noin viidesosalla kohteista

Diazotrophic cyanobacteria in planktonic food webs

Blooms of cyanobacteria are recurrent phenomena in coastal estuaries. Their maximum abundance coincides with the productive period of zooplankton and pelagic fish. Experimental studies indicate that diazotrophic, i.e. dinitrogen (N2)-fixing cyanobacterial (taxonomic order Nostocales) blooms affect zooplankton, as well as other phytoplankton. We used multidecadal monitoring data from one archipelago station (1992–2013) and ten open sea stations (1979–2013) in the Baltic Sea to explore the potential bottom-up connections between diazotrophic and non-diazotrophic cyanobacteria and phyto- and zooplankton in natural plankton communities. Random forest regression, combined with linear regression analysis showed that the biomass of cyanobacteria (both diazotrophic and non-diazotrophic) was barely connected to any of the phytoplankton and zooplankton variables examined. Instead, physico-chemical variables (salinity, temperature, total phosphorus), as well as spatial and temporal variability seemed to have more significant connections to both phytoplankton and zooplankton variables. Zooplankton variables were also connected to the biomass of phytoplankton groups other than cyanobacteria (such as chrysophytes, cryptophytes and prymnesiophytes), and phytoplankton variables had connections with the biomass of different zooplankton groups, especially copepods. Overall, negative relationships between cyanobacteria and other plankton taxa were scarcer than expected based on previous experimental studies.​​​​​​​</ul

Diazotrophic cyanobacteria in planktonic food webs

Blooms of cyanobacteria are recurrent phenomena in coastal estuaries. Their maximum abundance coincides with the productive period of zooplankton and pelagic fish. Experimental studies indicate that diazotrophic, i.e. dinitrogen (N2)-fixing cyanobacterial (taxonomic order Nostocales) blooms affect zooplankton, as well as other phytoplankton. We used multidecadal monitoring data from one archipelago station (1992–2013) and ten open sea stations (1979–2013) in the Baltic Sea to explore the potential bottom-up connections between diazotrophic and non-diazotrophic cyanobacteria and phyto- and zooplankton in natural plankton communities. Random forest regression, combined with linear regression analysis showed that the biomass of cyanobacteria (both diazotrophic and non-diazotrophic) was barely connected to any of the phytoplankton and zooplankton variables examined. Instead, physico-chemical variables (salinity, temperature, total phosphorus), as well as spatial and temporal variability seemed to have more significant connections to both phytoplankton and zooplankton variables. Zooplankton variables were also connected to the biomass of phytoplankton groups other than cyanobacteria (such as chrysophytes, cryptophytes and prymnesiophytes), and phytoplankton variables had connections with the biomass of different zooplankton groups, especially copepods. Overall, negative relationships between cyanobacteria and other plankton taxa were scarcer than expected based on previous experimental studies