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Author |
Bischof, K; Peralta, G; Kräbs, G; van de Poll, WH; Perez-Llorens, JL; Breeman, AM |
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Title  |
Effects of solar UV-B radiation on canopy structure of Ulva communities from southern Spain |
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Journal Article |
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Year |
2002 |
Publication |
Journal of Experimental Botany |
Abbreviated Journal |
J Exp Bot |
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Volume |
53 |
Issue |
379 |
Pages |
2411-2421 |
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Keywords |
canopy formation; photosynthesis; ultraviolet radiation; Ulva rotundata |
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Abstract |
Within the sheltered creeks of Cádiz bay, Ulva thalli form extended mat-like canopies. The effect of solar ultraviolet radiation on photosynthetic activity, the composition of photosynthetic and xanthophyll cycle pigments, and the amount of RubisCO, chaperonin 60 (CPN 60), and the induction of DNA damage in Ulva aff. rotundata Bliding from southern Spain was assessed in the field. Samples collected from the natural community were covered by screening filters, generating different radiation conditions. During daily cycles, individual thalli showed photoinhibitory effects of the natural solar radiation. This inhibition was ev
en more pronounced in samples only exposed to photosynthetically active radiation (PAR). Strongly increased heat dissipation in these samples indicated the activity of regulatory mechanisms involved in dynamic photoinhibition. Adverse effects of UV-B radiation on photosynthesis were only observed in combination with high levels of PAR, indicating the synergistic effects of the two wavelength ranges. In samples exposed either to PAR+UV-A or to UV-B+UV-A without PAR, no inhibition of photosynthetic quantum yield was found in the course of the day. At the natural site, the top layer of the mat-like canopies is generally completely bleached. Artificially designed Ulva canopies exhibited fast bleaching of the top layer under the natural solar radiation conditions, while this was not observed in canopies either shielded from UV or from PAR. The bleached first layer of the canopies acts as a selective UV-B filter, and thus prevents subcanopy thalli from exposure to harmful radiation. This was confirmed by the diff
erences in photosynthetic activity, pigment composition, and the concentration of RubisCO in thalli with different positions within the canopy. In addition, the induction of the stress protein CPN 60 under UV exposure and the low accumulation of DNA damage indicate the presence of physiological protection mechanisms against harmful UV-B. A mechanism of UV-B-induced inhibition of photosynthesis under field conditions is proposed. |
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Oxford University Press |
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English |
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English |
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southern Spain |
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no |
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Call Number |
refbase @ user @ |
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12 |
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Author |
Amon, RMW; Budéus, G; Meon, B |
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Title |
Dissolved organic carbon distribution and origin in the Nordic Seas: Exchanges with the Arctic Ocean and the North Atlantic |
Type |
Journal Article |
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Year |
2003 |
Publication |
Journal of Geophysical Research |
Abbreviated Journal |
J Geophys Res |
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Volume |
108 |
Issue |
C7 |
Pages |
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Keywords |
dissolved organic matter; dissolved organic carbon; chromophoric dissolved organic matter; fluorescence; vertical carbon transport |
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Abstract |
Dissolved organic carbon (DOC) and in situ fluorescence were measured along with hydrographic parameters in the Greenland, Iceland, and Norwegian Seas (Nordic Seas). Surface (<100 m) concentrations of DOC ranged from 60 to 118 µM with elevated values in the East Greenland Current (EGC) which transports water from the Arctic Ocean to the North Atlantic. EGC surface waters also showed a pronounced fluorescence maximum between 30 and 120 m depth in all EGC sections indicating the abundance of Arctic river derived DOC in this current. Based on fluorescence we estimated that 20-50% of the annual river discharge to the Arctic Ocean was exported in the EGC. The fluorescence maximum was typically associated with salinity around 33 and temperatures below -1°C which are characteristic of surface and upper halocline water in the Arctic Ocean. The elevated fluorescence in this water mass suggests a strong Eurasian shelf component and also suggests that in situ fluorescence could be used to trace Eurasian shelf water in the central Arctic Ocean. DOC concentrations in the Nordic Sea basins (>1000 m) were relatively high (~50 µM DOC) compared with other ocean basins indicating active vertical transport of DOC in this region on decadal timescales. Based on existing vertical transport estimates and 15 µM of semilabile DOC we calculated an annual vertical net DOC export of 3.5 Tg C yr-1 in the Greenland Sea and about 36 Tg C yr-1 for the entire Arctic Mediterranean Sea (AMS) including the Greenland-Scotland Ridge overflow. It appears that physical processes play a determining role for the distribution of DOC in the AMS. |
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American Geophysical Union |
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Washington, DC |
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English |
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English |
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Nordic Seas |
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no |
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refbase @ user @ ms |
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5 |
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Author |
Mykhalichko, O.I.L.B. |
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Title |
Development of modified self-extinguishing epoxy amine polymers |
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Book Whole |
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2015 |
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Ph.D. thesis |
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Book of abstr. 4th International Caucasian Symposium on Polymers and Advanced Materials, Batumi. -2015. -P. 81 |
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Call Number |
nmv @ luydmyla31 @ |
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124 |
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Author |
Aberle, N; Witte, U |
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Title |
Deep-sea macrofauna exposed to a simulated sedimentation event in the abyssal NE Atlantic: in situ pulse-chase experiments using 13C-labelled phytodetritus |
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Journal Article |
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Year |
2003 |
Publication |
Marine Ecology Progress Series |
Abbreviated Journal |
Mar Ecol Prog Ser |
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Volume |
251 |
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Pages |
37-47 |
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Keywords |
Deep-sea; Pulse-chase experiment; δ13C; Benthic carbon remineralisation; Macrofauna; Atlantic Ocean, Porcupine Abyssal Plain |
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Abstract |
Tracer experiments with 13C-labelled diatoms Thalassiosira rotula (Bacillariophycea, 98% 13C-labelled) were conducted at the Porcupine Abyssal Plain (PAP) in the NE Atlantic (BENGAL Station; 48°50'N, 16°30'W, 4850 m depth) during May/June 2000. In situ enrichment experiments were carried out using de
ep-sea benthic chamber landers: within the chambers a spring bloom was simulated and the fate of this food-pulse within the abyssal macrobenthic community was followed. In focus was the role of different macrofauna taxa and their vertical distribution within the sediment column in consuming and reworking the freshly deposited material. T. rotula is one of the most abundant pelagic diatoms in the NE Atlantic and therefore 0.2 g of freeze dried T. rotula, equivalent to 1 g algal C m-2 yr-1, was injected into each incubation chamber. Three different incubation times of 2.5, 8 and 23 d were chosen in order to follow the uptake of 13C-labelled phytodetritus by macrofauna. After only 2.5 d, 77% of all macrofauna organisms showed tracer uptake. After 23 d the highest degree of enrichment was measured and 95% of the individuals had taken up 13C from the introduced algal material. In addition to that a downward transport of organic matter was observed, even though the mixing was not
very intense. The initial processing of carbon was dominated by polychaetes that made up a percentage of 52% of total macrofauna. In general macrofauna organisms that lived close to the sediment surface had higher access to the simulated food-pulse, confirming the hypothesis that individuals close to the sediment surface have the strongest impact on the decomposition of phytodetritus. In our study we observed only modest vertical entrainment of 13C tracers into the sediment. With regard to contradictory results from former 13C-enrichment experiments in bathyal regions, compared to results from our study site in the abyssal plain, we thus propose pronounced differences in feeding strategies between macrofauna communities from continental margins and abyssal plains. |
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Address |
Aberle, Witte: Max Planck Institute for Marine Microbiology, Celsiusstr. 1, 28359 Bremen, Germany; Aberle: Present address: Max Planck Institute for Limnology, August-Thienemann-Str. 2, 24306 Plön, Germany; Email: aberle@mpil-ploen.mpg.de |
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Publisher |
Inter-Research |
Place of Publication |
Oldendorf/Luhe |
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Language |
English |
Summary Language |
English |
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ISSN |
0171-8630 |
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NE Atlantic |
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Call Number |
refbase @ user @ 706 |
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4 |
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Author |
Lavrenyuk, H.; Mykhalichko, B. |
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Title |
Cu(II)-(polyamine) chelation as an efficient way of reducing combustibility of epoxy-amine composites modified by copper(II) inorganic salts |
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Journal Article |
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Year |
2020 |
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V " ". - , 2020. - . 61-64. |
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no |
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Call Number |
nmv @ luydmyla31 @ |
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70 |
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