排序方式: 共有4条查询结果,搜索用时 171 毫秒
1
1.
Primary production of aquatic macrophytes and their epiphytes in two shallow lakes (Peipsi and Võrtsjärv) in Estonia 总被引:1,自引:0,他引:1
In shallow lakes with large littoral zones, epiphytes and submerged macrophytes can make an important contribution to the total annual primary production. We investigated the primary production (PP) of phytoplankton, submerged macrophytes, and their epiphytes, from June to August 2005, in two large shallow lakes. The production of pelagic and littoral phytoplankton and of the dominant submerged macrophytes in the littoral zone (Potamogeton perfoliatus in Lake Peipsi and P. perfoliatus and Myriopyllum spicatum in Lake Võrtsjärv) and of their epiphytes was measured using a modified 14C method. The total PP of the submerged macrophyte area was similar in both lakes: 12.4 g C m?2 day?1 in Peipsi and 12.0 g C m?2 day?1 in Võrtsjärv. In Peipsi, 84.2% of this production was accounted for by macrophytes, while the shares of phytoplankton and epiphytes were low (15.6 and 0.16%, respectively). In Võrtsjärv, macrophytes contributed 58%, phytoplankton 41.9% and epiphytes 0.1% of the PP in the submerged macrophyte area. Epiphyte production in both lakes was very low in comparison with that of phytoplankton and macrophytes: 0.01, 5.04, and 6.97 g C m?2 day?1, respectively, in Võrtsjärv, and 0.02, 1.93, and 10.5 g C m?2 day?1, respectively, in Peipsi. The PP of the littoral area contributed 10% of the total summer PP of Lake Peipsi sensu stricto and 35.5% of the total summer PP of Lake Võrtsjärv. 相似文献
2.
Maria Kahlert Raino-Lars Albert Eeva-Leena Anttila Roland Bengtsson Christian Bigler Tiina Eskola Veronika Gälman Steffi Gottschalk Eva Herlitz Amelie Jarlman Jurate Kasperoviciene Mikołaj Kokociński Helen Luup Juha Miettinen Ieva Paunksnyte Kai Piirsoo Isabel Quintana Janne Raunio Bernt Sandell Heikki Simola Irene Sundberg Sirje Vilbaste Jan Weckström 《Journal of applied phycology》2009,21(4):471-482
The goal of this study was a harmonization of diatom identification and counting among diatomists from the Scandinavian and
Baltic countries to improve the comparison of diatom studies in this geographical area. An analysis of the results of 25 diatomists
following the European standard EN 14407 during an intercalibration exercise showed that a high similarity was achieved by
harmonization and not because of a long experience with diatoms. Sources of error were wrong calibration scales, overlooking
of small taxa, especially small Navicula s.l., misidentifications (Eunotia rhomboidea was mistaken for Eunotia incisa) and unclear separation between certain taxa in the identification literature. The latter was discussed during a workshop
with focus on the Achnanthes minutissima group, the separation of Fragilaria capucina var. gracilis from F. capucina var. rumpens, and Nitzschia palea var. palea from N. palea var. debilis. The exercise showed also that the Swedish standard diatom method tested here worked fine with acceptable error for the indices
IPS (Indice de Polluo-sensibilité Spécifique) and ACID (ACidity Index for Diatoms) when diatomists with a low similarity (Bray–Curtis
<60%) with the auditor in at least one of the samples are excluded. 相似文献
3.
Nõges Peeter Tuvikene Lea Feldmann Tõnu Tõnno Ilmar Künnap Helen Luup Helen Salujõe Jaana Nõges Tiina 《Hydrobiologia》2003,506(1-3):567-573
Hydrobiologia - The hydrochemical regime and the biota in two lakes of Vooremaa landscape protection area, Central Estonia, were studied in 2000–2001 within the frames of the EC project... 相似文献
4.
Biostratigraphic diatom analyses were carried out on a short sediment core from the large shallow-water Lake Võrtsjärv, Estonia, in order to relate the diatom composition to the instrumental water level record. We dated the sediment core by radiometric methods (210Pb, 137Cs, 241Am) and spheroidal fly-ash particle abundance chronology and evaluated the statistical significance of the relationships between the percentage of planktonic diatoms and the water level continuously monitored since 1871. Before the 1960s, the percentage of planktonic diatoms in the sediment showed quite strong positive relationship to water level. The impact of eutrophication after the 1960s presumably masked the influence of water level changes on the diatom community. In addition, statistical analysis of the upper part of the sediment core (1970—present day) together with measured limnological parameters of the lake showed that water transparency had the strongest influence on diatoms, while temperature, pH and alkalinity had lesser impacts. Our study shows that the planktonic:periphytic diatom ratio in the sediment can be used to track overall trends of the lake-level changes in Lake Võrtsjärv before the onset of cultural eutrophication; however, the results have to be interpreted carefully, taking into consideration other possible limnological factors such as water transparency, nutrients and wind. 相似文献
1