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Teekkarikylä, Finland

Raateoja M.,Finnish Environment Institute | Kuosa H.,University of Helsinki | Flinkman J.,Finnish Environment Institute | Paakkonen J.-P.,City of Helsinki Environment Center | Perttila M.,Finnish Meteorological Institute
Journal of Marine Systems

The frequently observed, but commonly ignored hydrographic characteristic of the Baltic Sea, the oxygen minimum zone (OMiZ) above and within the summertime thermocline, was studied during the 6-yr monitoring programme encompassing the Gulfs of Bothnia and Finland in the northern Baltic Sea. A temperature-anomaly-driven density gradient was found to be a prerequisite for the existence of the OMiZ. We determined the magnitude of the apparently utilized O2 in the OMiZ by combining graphical analysis and empirical modelling. A sound criterion for distinguishing the cases in which the OMiZ had a biological origin, and not only a hydrodynamic one, was the accompanying ammonium maximum zone (AMaZ). Of a total of 46 stations visited, a density gradient was found at every station, an accompanying OMiZ at 37 stations, and an accompanying AMaZ at 20 stations. This suggests that biological activity is an essential factor in forming the OMiZ. We investigated to what extent the OMiZ was a manifestation of microbial decomposition of autochthonous organic matter, as zooplankton respiration was also a factor. As a study average, ~ 80% of the apparently utilized O2 was consumed by the microbial decomposition process and ~ 20% of it by mesozooplankton respiration. According to the O2 quota consumed in the process, the microbial community in the OMiZ of the Gulf of Finland decomposed, on average, 14% of all the organic matter settling from the euphotic zone in the time frame of mid-June to early August. A pronounced allochthonous organic carbon pool in the Gulf of Bothnia hinders a prompt estimation of a corresponding share for that basin. © 2009 Elsevier B.V. All rights reserved. Source

Nevalainen L.,Austrian Academy of Sciences | Nevalainen L.,City of Helsinki Environment Center

Distribution of benthic microcrustacean (Crustacea: Cladocera) was investigated with paleolimnological approach by using their fossil surface sediment assemblages within a thermally extreme lake in the Niedere Tauern, Austrian Alps. The results from 20 surface sediment samples suggested that the spatial distribution of chydorids is clearly heterogeneous along the water depth gradient (1.8-6.1. m);. Alona quadrangularis dominated in shallow (warm, minerogenic) habitats,. Chydorus sphaericus-type succeeded at intermediate depths, and. Alona affinis dominated in deep (cold, organic) sites. Apparently, these benthic cladocerans exhibit clear habitat and resource segregation. The distributional patterns revealed local community thresholds at approximately 2.5 and 4.5. m water depths and these thresholds were likely to be forced by variances in habitat quality (minerogenic-organic), food resources (periphyton/detritus), thermal properties (warm-cold), and UV-exposure (high-low). The results emphasize the usability of the paleolimnological approach in distributional investigations and its applicability in providing information on species-environmental relationships for environmental change evaluations and paleoecological interpretations. © 2011 Elsevier GmbH. Source

Nummi P.,University of Helsinki | Vaananen V.-M.,University of Helsinki | Pakarinen R.,City of Helsinki Environment Center | Pienmunne E.,University of Helsinki
Ornis Fennica

Human actions, such as increasing recreational activity at lakes, have resulted in a deterioration in the quality of diver breeding grounds.We studied the breeding success of Redthroated Divers during 1994-2011 in Nuuksio National park in Southern Finland. We conducted an experiment in which we used peat hummocks to build floating nesting sites for the focal species.We used a population in Evo, South-Central Finland, as our control (i.e., nomanagement).We found that the Nuuksio population increased steadily, and that the birds had a relatively high breeding success (pairs with a brood 73%, juveniles/pair 1.04). The index of juveniles per pair did not suggest density-dependence in the Nuuksio population. All except one nesting attempt at Nuuksio and Evo failed in mainland shoreline mire margins. Our results indicate that artificial nesting sites increase the breeding success of the Red-throated Diver.We assume that the mitigation of the effects of disturbance with management can improve brood production in the species. Source

Kultti S.,University of Helsinki | Nevalainen L.,Austrian Academy of Sciences | Nevalainen L.,City of Helsinki Environment Center | Luoto T.P.,University of Helsinki | And 2 more authors.

Chydorids (Cladocera, Chydoridae) have two reproductive strategies: asexual reproduction that prevails during favorable environmental conditions and sexual reproduction that is induced by environmental stimuli associated with seasonal or aperiodic environmental stresses. These modes of reproduction can be recognized in the subfossil sedimentary records as parthenogenetic shells of females (asexual reproduction) and by ephippia (sexual reproduction). We studied the interrelations between subfossil chydorid ephippia and environmental variables by analyzing surface sediment samples obtained from 76 Finnish lakes across a latitudinal gradient (60-70°N). The results showed that the total chydorid ephippia (TCE) increases along the climate gradient from ~2 to 3% in the south to ~25% in the north and suggested a significant dependence (r ~ -0. 8, P < 0. 001) with several climate factors, especially that of mean July air temperature. We used this relationship to create a model for reconstructing past mean July air temperatures. A linear regression of the log10 transformed TCE as a single independent variable explained 76% (SE ± 0. 76°C) of the variance of the observed mean July air temperatures. Accordingly, we propose that this novel tool may be highly suitable for reconstructing paleotemperatures in cold-temperate environments. © 2011 Springer Science+Business Media B.V. Source

Talvitie J.,Aalto University | Heinonen M.,Helsinki Region Environmental Services Authority HSY | Paakkonen J.-P.,City of Helsinki Environment Center | Vahtera E.,City of Helsinki Environment Center | And 3 more authors.
Water Science and Technology

This study on the removal of microplastics during different wastewater treatment unit processes was carried out at Viikinmäki wastewater treatment plant (WWTP). The amount of microplastics in the influent was high, but it decreased significantly during the treatment process. The major part of the fibres were removed already in primary sedimentation whereas synthetic particles settled mostly in secondary sedimentation. Biological filtration further improved the removal. A proportion of the microplastic load also passed the treatment and was found in the effluent, entering the receiving water body. After the treatment process, an average of 4.9 (±1.4) fibres and 8.6 (±2.5) particles were found per litre of wastewater. The total textile fibre concentration in the samples collected from the surface waters in the Helsinki archipelago varied between 0.01 and 0.65 fibres per litre, while the synthetic particle concentration varied between 0.5 and 9.4 particles per litre. The average fibre concentration was 25 times higher and the particle concentration was three times higher in the effluent compared to the receiving body of water. This indicates that WWTPs may operate as a route for microplastics entering the sea. © IWA Publishing 2015. Source

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