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| Titel |
The 87Sr/86Sr aquatic isoscape of the Danube catchment from the source to the mouth as tool for studying fish migrations |
| VerfasserIn |
Andreas Zitek, Anastassiya Tchaikovsky, Johanna Irrgeher, Herwig Waidbacher, Thomas Prohaska |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250088633
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| Publikation (Nr.) |
 EGU/EGU2014-2764.pdf |
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| Zusammenfassung |
| Isoscapes - spatially distributed isotope patterns across landscapes - are increasingly
used as important basis for ecological studies. The natural variation of the isotopic
abundances in a studied area bears the potential to be used as natural tracer for studying
e.g. migrations of animals or prey-predator relations. The 87Sr/86Sr ratio is one
important tracer, since it is known to provide a direct relation of biological samples to
geologically distinct regions, as Sr isotopes are incorporated into living tissues as
a proxy for calcium and taken up from the environment without any significant
fractionation.
Although until now the focus has been mainly set on terrestrial systems, maps
for aquatic systems are increasingly being established. Here we present the first
87Sr/86Sr aquatic isoscape of the Danube catchment, the second largest river catchment
in Europe, from near its source starting at river km 2581 in Germany down to its
mouth to river km 107 in Romania. The total length of the river Danube is 2780 km
draining a catchment area 801 463 km2 (10 % of the European continent). The
major purpose of this study was to assess the potential of the 87Sr/86Sr isotope
ratio to be used as tool for studying fish migrations at different scales in the entire
Danube catchment. Within the Joint Danube Research 3 (JDS 3), the biggest scientific
multi-disciplinary river expedition of the World in 2013 aiming at the assessment of the
ecological status and degree of human alterations along the river Danube, water
samples were taken at 68 pre-defined sites along the course of the river Danube
including the major tributaries as a basis to create the so called ‘Isoscape of the Danube
catchment’.
The determination of 87Sr/86Sr isotope ratio in river water was performed by
multicollector-sector field-inductively coupled plasma-mass spectrometry (MC-SF-ICP-MS).
The JDS 3 data were combined with existing data from prior studies conducted
within the Austrian part of the Danube catchment. Finally, the dominating geological
formations in the catchment upstream of the sampling site were determined using
ArcGIS.
Analyses of water samples yielded several ‘Isozones’ along the course of the Danube,
indicating diverse geological conditions. Studying migration phenomena of fish using natural
isotopic marks in hard parts is especially possible between these ‘Isozones’. In geologically
similar regions with little differences in the 87Sr/86Sr isotope ratio, element distributions or
artificial marking methods (tagging, spiking) can be used complementarily. A significant
positive relationship between the 87Sr/86Sr ratio in river water and the proportion of siliceous
geological formations in the catchment was found. Moreover, the 87Sr/86Sr isotope ratio
along the Austrian part of the Danube and its tributaries proved to be stable between seasons.
The strong relation of the geology of a catchment to the 87Sr/86Sr isotope ratios in
river water provides the possibility to predict the 87Sr/86Sr ratios in river water
by the dominating geology in river catchments, for an estimation of the general
applicability of the 87Sr/86Sr ratio in European rivers to fish ecological questions. |
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