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SUSANNA BJÖRK-RAMBERG 《Freshwater Biology》1985,15(2):175-183
SUMMARY.
- 1 The uptake of phosphate and inorganic nitrogen by sediment and phytoplankton was studied under natural conditions (1977) and during lake fertilization with phosphorus and nitrogen (1978–79) in Lake Gunillajaure, a small, stratified, subarctic lake in northern Sweden. The experiments were performed in situ in plexiglass cylinders, to which additions of nutrients were made, and the uptake followed by consecutive sampling and analysis of the water phase.
- 2 Additions of HgCl2 to the experimental vessels reduced the phosphate uptake to the sediment to less than 10% and it could therefore be concluded that the sediment uptake was mainly of biological nature.
- 3 Dark assimilation was 30–40% of that in light. Since light clearly stimulated the sediment uptake the epipelic algae were probably responsible.
- 4 The phosphate uptake to the sediment could be described by Michaelis-Menten kinetics and the calculated constants (Vmax, ks) were very alike in 1977 and 1978 but appeared to have increased in 1979.
- 5 The sediment uptake of ammonium and nitrate was very slow indrcating that the epipelic algae were not nitrogen starved.
- 6 Even though the epipelic algae had a potential for efficient uptake of phosphorus, the phytoplankton took up 92–96% of the phosphate added to the lake on each fertilization occasion due to the relatively large water volume in the epilimnion in relation to the bottom area available for the epipelic algae.
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New records of marine Tardigrada in the Mediterranean Sea 总被引:1,自引:0,他引:1
SANTIAGO VILLORA-MORENO SUSANNA DE ZIO GRIMALDI 《Zoological Journal of the Linnean Society》1996,116(1-2):149-166
Meiofauna from Chafarinas archipelago (western Mediterranean, N. Africa) were studied, and marine Tardigrada were identified to species level. A total of 15 species, belonging to families Stygarctidae, Halechiniscidac (Subfamilies Halechiniscinae, Florarctinae, Styraconyxinae and Tanarctinae), Batillipedidae, and Echiniscoididae, were found for the first time from the Alboran Sea and southwestern Mediterranean area. Four species and one subspecies are new records for the Mediterranean Sea: I'ioractus acer, F. asper, P. stellatus, Actinarctus doryphorus and Echiniscoides sigismundi hispaniensis. The male of Floractus stellatus , previously unknown to science, is described. Many species have been recorded for the first time in different sedimentary environments, such as midlittoral pools, very shallow gravels, pools in a mixed rocky environment or between Posidonia oceanica meadows, 'Amphioxus' gravels, and coastal detritic. 相似文献
3.
ALFONSO SUSANNA NÚRIA GARCIA-JACAS ROSER VILATERSANA TERESA GARNATJE JOAN VALLÈS SEYED MAHMOOD GHAFFARI 《Botanical journal of the Linnean Society. Linnean Society of London》2003,143(4):411-418
Twenty chromosome counts are reported in the genus Cousinia and the monotypic genus Schmalhausenia , which are part of the Arctium group, from Armenia, Iran, Kazakhstan and Uzbekistan. Twelve are new and eight provide confirmation of scarce or disputable previous data. The correlation between karyological data, pollen type and molecular phylogeny is very close, and on this basis two main groups can be defined. One is the arctioid group, which comprises the genera Arctium and Schmalhausenia , and a small part of the genus Cousinia , with x = 18. The other is the genus Cousinia s.s. , with a dysploid series ranging from x = 13–11. Some considerations on the chromosomal evolution in the group are made. © 2003 The Linnean Society of London, Botanical Journal of the Linnean Socety , 2003, 143 , 411–418. 相似文献
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SUSANNA BORONAT NATÀLIA GARCIA-REYERO ROGER FONTS PILAR FERNÁNDEZ JOAN O. GRIMALT BENJAMIN PIÑA 《Freshwater Biology》2009,54(12):2543-2554
1. Sediment extracts from 63 European remote lakes were tested for the presence of ligands of the aryl hydrocarbon receptor (AhR), using a yeast-based bioassay. The lakes belong to different European mountain regions in Central Norway, Scotland, Piedmont (Italy), Tyrol (Austria and Italy) and the Julian Alps (Slovenia).
2. AhR ligand activity varied about 40-fold among the examined lakes, with Scotland having the highest proportion of lakes with high AhR ligand activity, whereas samples with low AhR ligand activity predominate in the Julian Alps.
3. AhR ligand activity in sediment samples correlated with the concentration of several environmentally relevant compounds, including polycyclic aromatic hydrocarbons, hexachlorobenzene and several polychlorobiphenyl ether congeners. These correlations suggest an anthropogenic origin for the detected AhR ligands, rather than being generated from natural processes.
4. We conclude that pollutants deposited in remote lakes by atmospheric processes are active AhR ligands at the concentrations found in these lakes. Given the high toxicity associated with ectopic activation of AhR in different animal systems, this activity may represent a significant risk for the exposed fauna. 相似文献
2. AhR ligand activity varied about 40-fold among the examined lakes, with Scotland having the highest proportion of lakes with high AhR ligand activity, whereas samples with low AhR ligand activity predominate in the Julian Alps.
3. AhR ligand activity in sediment samples correlated with the concentration of several environmentally relevant compounds, including polycyclic aromatic hydrocarbons, hexachlorobenzene and several polychlorobiphenyl ether congeners. These correlations suggest an anthropogenic origin for the detected AhR ligands, rather than being generated from natural processes.
4. We conclude that pollutants deposited in remote lakes by atmospheric processes are active AhR ligands at the concentrations found in these lakes. Given the high toxicity associated with ectopic activation of AhR in different animal systems, this activity may represent a significant risk for the exposed fauna. 相似文献
6.
KONSTANTYN ROMASCHENKO KUDDISI ERTURUL ALFONSO SUSANNA NÚRIA GARCIA-JACAS TUNA UYSAL EMINE ARSLAN 《Botanical journal of the Linnean Society. Linnean Society of London》2004,145(3):345-352
Twenty-seven chromosome counts are reported in 23 species of the genus Centaurea , mostly eastern endemic species of the Jacea group, which has become the core of the re-defined genus Centaurea . Twenty reports are new, one is a correction of a previous count, one is a confirmation of limited previous data and one represents a new basic number in the Centaureinae. The prevalence of the basic chromosome number x = 9 among the Eastern sections of the Jacea group is confirmed, together with the close correlation between karyological data and classification of the genus. Two alternative hypotheses on the aberrant chromosome number (for the Centaureinae) found in C. behen are proposed. One of them, if verified, would confirm that a cycle of polyploidy and descending dysploidy is a key mechanism in the speciation of the group. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 145 , 345–352. 相似文献
7.
TUNA UYSAL KUDDISI ERTUĞRUL ALFONSO SUSANNA NÚRIA GARCİA‐JACAS 《Botanical journal of the Linnean Society. Linnean Society of London》2009,159(2):280-286
Twenty‐two chromosome counts are reported in 16 species, four subspecies and two varieties of the genus Centaurea. These are mostly Turkish local endemics of section Cheirolepis, a complicated group from the Eastern clade of the Jacea group. Twenty‐one reports are new. Prevalence of the basic chromosome number x = 9 among the eastern sections of the Jacea group is confirmed. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 280–286. 相似文献
8.
Most long-distance passerine migrants in Sweden moult on breeding grounds before leaving on autumn migration to winter quarters. However, birds laying second or replacement clutches, or just breeding late, have too little time for a normal moult on the breeding grounds. When time is limited the birds may respond by making various adjustments to the moult, for example by moulting more quickly or by suspending the moult. In this study, the relationship between the performance of post-nuptial remex moult in Common Whitethroats breeding on Gotland, southeast Sweden, and autumn migration departure was investigated. The majority (77%) of the birds had interrupted moult in either the primaries or secondaries. Interruption of moult was more common among birds with a later onset date, as was asymmetry in moult between wings. The interruption of moult led to a significant time gain and moult completion was, consequently, more synchronized than moult onset. The results from this study indicate, in accordance with other data, that an early start of autumn migration is important. An early start may be crucial to facilitate the crossing of the Sahara Desert once the dry season has begun. 相似文献
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ABSTRACT The anatomy of five endolithic lichens (Acrocordia conoidea, Petractis clausa, Rinodina immersa, Verrucaria baldensis, and V. marmorea) from the Trieste Karst (north-eastern Italy) was thoroughly investigated. Samples already used in previous ecophysiological studies were examined by histological and mineralogical techniques, and by SEM. Biomineralisation products were searched for by X-ray diffractometry, X-ray microdiffractometry, and Fourier Transformed Infrared spectrophotometry. The results confirm that the photobiont layer is located approximately at the same depth in the substratum, although the species occur in habitats with strongly different light regimes; the thallus development is relatively constant within populations of a single species, but differs considerably among species. Several peculiarities of each species were revealed, such as the presence of large clews of hyphae in the inner layer of P. clausa, forming large voids in the substratum, or the development of morphologically different oil-hyphae. Calcium oxalate crystals were not detected. Some terms currently used to describe the anatomy of endolithic lichens are critically discussed, and the new term “lithocortex” and “pseudo-medulla” are introduced. 相似文献