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Kai Piirsoo Sirje Vilbaste Jaak Truu Peeter Pall Tiiu Trei Arvo Tuvikene Malle Viik 《Aquatic Ecology》2007,41(2):183-194
Information on the structure of microalgal assemblages in the epiphyton and epilithon is necessary to understand the origin
of phytoplankton in lowland rivers. To this end, we carried out concurrent investigations on phytoplankton, epiphyton and
epilithon in 18 reaches of three Estonian rivers during the midsummers of 2002 and 2003. A total of 251 taxa was recorded,
of which 192 were epiphyton species, 158 were epilithon species and 150 were phytoplankton species. Canonical correspondence
analysis (CCA), based on the 31 most abundant taxa, indicated differences in the structure of the algal assemblages between
the different biotopes (phytoplankton, epiphyton and epilithon) as well as between the studied rivers. The composition of
the phytoplankton clearly differed from that of the other biotopes, with prevailing small flagellates, a chrysophyte (Synura uvella) and cryptophytes (Rhodomonas lacustris and Cryptomonas erosa). The epiphyton was characterized by a large number of diatoms, while the epilithic community contained filamentous cyanobacteria
(Phormidium tergestinum and Planktolyngya sp.) and a green alga (Stigeoclonium tenue) in addition to diatoms. Based on redundancy analysis (RDA), phosphorous was the most relevant parameter determining the
distribution of species in the phytoplankton assemblages. Shading by trees on the river bank, dissolved oxygen concentration
and water temperature as well as river width determined the distribution of species in the epiphyton. The data set on the
epilithon did not reveal any significant relationships between species distribution and the measured environmental parameters. 相似文献
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Laura M. E. Sutcliffe Pter Batry Urs Kormann Andrs Bldi Lynn V. Dicks Irina Herzon David Kleijn Piotr Tryjanowski Iva Apostolova Raphaël Arlettaz Ainars Aunins Stphanie Aviron Ligita Baleentien Christina Fischer Lubos Halada Tibor Hartel Aveliina Helm Iordan Hristov Sven D. Jelaska Mitja Kaligari
Johannes Kamp Sebastian Klimek Pille Koorberg Jarmila Kostiukov Anik Kovcs‐Hostynszki Tobias Kuemmerle Christoph Leuschner Regina Lindborg Jacqueline Loos Simona Maccherini Riho Marja Orsolya Mth Inge Paulini Vnia Proena Jos Rey‐Benayas F. Xavier Sans Charlotte Seifert Jarosaw Stalenga Johannes Timaeus Pter Trk Chris van Swaay Eneli Viik Teja Tscharntke 《Diversity & distributions》2015,21(6):722-730
A large proportion of European biodiversity today depends on habitat provided by low‐intensity farming practices, yet this resource is declining as European agriculture intensifies. Within the European Union, particularly the central and eastern new member states have retained relatively large areas of species‐rich farmland, but despite increased investment in nature conservation here in recent years, farmland biodiversity trends appear to be worsening. Although the high biodiversity value of Central and Eastern European farmland has long been reported, the amount of research in the international literature focused on farmland biodiversity in this region remains comparatively tiny, and measures within the EU Common Agricultural Policy are relatively poorly adapted to support it. In this opinion study, we argue that, 10 years after the accession of the first eastern EU new member states, the continued under‐representation of the low‐intensity farmland in Central and Eastern Europe in the international literature and EU policy is impeding the development of sound, evidence‐based conservation interventions. The biodiversity benefits for Europe of existing low‐intensity farmland, particularly in the central and eastern states, should be harnessed before they are lost. Instead of waiting for species‐rich farmland to further decline, targeted research and monitoring to create locally appropriate conservation strategies for these habitats is needed now. 相似文献
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F. Cremona T. Kõiv P. Nõges P. Pall E.-I. Rõõm T. Feldmann M. Viik T. Nõges 《Hydrobiologia》2014,731(1):109-123
To study the role of large and shallow hemiboreal lakes in carbon processing, we calculated a 3-year carbon mass balance for Lake Võrtsjärv (Estonia) based on in situ measurements. This balance took into account hydrological and biogeochemical processes affecting dissolved inorganic (DIC), dissolved organic (DOC) and particulate organic (POC) carbon species. Accumulation varied greatly on a seasonal and yearly basis. The lake exported carbon during most of the year except during spring floods and in late autumn. In-lake processes were responsible for exporting POC and storing DOC while DIC switched between storage and export. The carbon cycle was alternatively dominated in 2009 by biogeochemical processes and in 2011 by riverine fluxes, whereas in 2010 the two process types were of the same magnitude. These results suggest that the role of large shallow lakes like Võrtsjärv in the global C cycle is equally driven by hydrological factors, in particular seasonal water level changes, and by biogeochemical in-lake reactions. 相似文献
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Tuomo Nieminen Rami Lehtinen Jari Viik Terho Lehtimäki Kari Niemelä Kjell Nikus Mari Niemi Janne Kallio Tiit Kööbi Väinö Turjanmaa Mika Kähönen 《BMC cardiovascular disorders》2006,6(1):1-8
Background
The occurrence of variations in the spectrum of cardiovascular disease between different regions of the world and ethnic groups have been the subject of great interest. This study report the 24-h variation of myocardial infarction (MI) occurrence in patients recruited from CCU located in Argentina and Uruguay.Methods
A cohort of 1063 patients admitted to the CCU within 24 h of the onset of symptoms of an acute MI was examined. MI incidence along the day was computed in 1 h-intervals.Results
A minimal MI incidence between 03:00 and 07:00 h and the occurrence of a first maximum between 08:00 and 12:00 h and a second maximum between 15:00 and 22:00 h were verified. The best fit curve was a 24 h cosinor (acrophase ~ 19:00 h, accounting for 63 % of variance) together with a symmetrical gaussian bell (maximum at ~ 10:00 h, accounting for 37 % of variance). A similar picture was observed for MI frequencies among different excluding subgroups (older or younger than 70 years; with or without previous symptoms; diabetics or non diabetics; Q wave- or non-Q wave-type MI; anterior or inferior MI location). Proportion between cosinor and gaussian probabilities was maintained among most subgroups except for older patients who had more MI at the afternoon and patients with previous symptoms who were equally distributed among the morning and afternoon maxima.Conclusion
The results support the existence of two maxima (at morning and afternoon hours) in MI incidence in the Argentine and Uruguayan population. 相似文献
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