BIOMARKER INVESTIGATION ON THE CONTAMINANT EXPOSURE OF EUROPEAN EEL (ANGUILLA ANGUILLA) IN GERMAN RIVERS Sandra Stoffels1, Markus Brinkmann1, Marko Freese2, Jan-Dag Pohlmann2, Ulrike Kammann2, Reinhold Hanel2, Henner Hollert1 1Institute
for Environmental Research, Department of Ecosystem Analysis, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany Thünen Institute (TI) of Fisheries Ecology, 22767 Hamburg, Germany
Institute for Environmental Research
Contact:
[email protected],
[email protected]
AIM & SCOPE
MATERIALS & METHODS
The European Eel (Anguilla anguilla) is critically endangered (IUCN 2010)
Livers of eels (Abb. 1) from different German rivers (Elbe, Rhein, Schlei, Weser, Eider) were:
The panmicitic stock continuously declines since the early 1980s (approx. 80 %), reaching a new minimum in 2011
Removed and frozen in liquid nitrogen, then stored at -80°C
Apart from unsustainable harvest, migration obstacles and the swim-bladder parasite Anguillicoloides crassus, also an influence of contaminants is under discussion
homogenized and centrifuged (9.000 × g) The activity of 7-ethoxyresorufin-Odeethylase (EROD) in the resulting S9 fractions was determined according to Maria et al. (2005)
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In the Elbe River, a contamination gradient was observed that did not depend on maturation (Fig. 2 A)
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Fig. 4 – EROD activity in all investigated catchment areas depending on the maturation from yellow to silver eels (“Silvering Stage”).*
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During cessation of feeding (migratory stages, 4 & 5), EROD activity decreased (Fig. 4)
C - Stage 3
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There was also an influence of maturation, sex and the sampling season on EROD activity
EROD / pmol mg min
-1
EROD activities differed between the different rivers (Fig. 3) and along the investigated transect of the Elbe River (Fig. 2)
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RESULTS & DISCUSSION
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Fig. 3 – EROD activity in eels from different German catchment areas.*
2
EROD / pmol mg min
-1 -1
Fig. 1 – Life-cycle of the European Eel. Maturation from yellow to silver eels is divided in 6 “Silvering Stages” according to Durif et al. 2005.
B - Stage 2
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EROD / pmol mg min
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A - All stages
-1 -1 EROD / pmol mg min
EROD / pmol mg min
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To be able to describe the influence of contaminants on fitness and spawner quality, different biomarkers were studied
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In context of the European Data Collection Framework (DCF) a large number of eels were sampled for stock assessment
Fig. 2 – EROD activity in eel livers along the Elbe River: A – all investigated “Silvering Stages”, B – Stage 2 only, C – Stage 3 only. Bars represent mean values ± standard deviations, numbers within bars the number of investigated animals. Asterisks mark significant differences compared with Cuxhaven (One-way ANOVA, Dunn’s post-hoc test).
* Bars represent mean values ± standard deviations, numbers within bars the number of investigated animals. Groups with different letters are significantly different (Kruskal-Wallis ANOVA, Dunn’s post-hoc test). Maria, V.L., Correira, A.C., Santos, M.A. (2005) Anguilla anguilla L. liver EROD induction and genotoxic responses after retene exposure. Ecotoxicology & Environmental Safety 61: 230-238. Durif, C., Dufour, S., Elie, P. (2005) The silvering process of Anguilla anguilla: a new classification from the yellow resident to the silver migrating stage, Journal of Fish Biology 66: 1025-1043.
