Is the Aquatic Dikerogammarus Villosus a 'Killer Shrimp'
Is the aquatic Dikerogammarus villosus a ‘killer shrimp’ in the field?
– a case study on one of the most invasive species in Europe
Dr. Meike Koester1,2, Bastian Bayer1 & Dr. René Gergs3 1Institute for Environmental Sciences, University of Koblenz-Landau, Campus Landau, Germany 2Institute of Natural Sciences, University of Koblenz-Landau, Campus Koblenz, Germany 3Federal Environment Agency, Berlin, Germany Introduction
143 animal 58 invasive
2 Introduction
Bij de Vaate et al. (2002)
3 Introduction
1994/95 first record from the River Rhine
Colonised most major European rivers within 2 decades
www.aquatic-aliens.de 4 Introduction
Larger than native amphipods
High reproductive potential & growth rate
Colonises different substrates
Highly tolerant towards various environmental conditions
(e.g. T, O2, salinity)
Feeding behaviour
5 Introduction
River Rhine
species
of
number
Mean
Schöll, BfG-report Nr. 172 other gamarids Dikerogammarus villosus Gammarus roeselii Gammarus pulex/fossarum after Rey et al. 2005 6 Introduction
7 Hypothesis
D. villosus is also strongly predacious in the field
8 Stable Isotope Analyses (SIA)
12 13 Carbon C C 13C/12C 98,89 % 1,11 %
14 15 Nitrogen N N 15N/14N
99,64 % 0,36 %
δ15N: strong accumulation Predator 1 Trophic Level ca. 3.4 ‰ Secondary consumer N 13 15 δ C: less accumulated δ Primary consumer C-source of the food
Producer δ13C
9 Sampling areas of the River Rhine and its tributaries
B
Bulk analyses δ13C and δ15N SIBER-Analyses comparing amphipod species Genetic gut content analyses with group-specific C B rDNA primers (Koester Aet al. 2013)
A
C
10 A. Feeding river vs. Lake Constance
14 Feeding river Lake Constance n = 21 8 n = 21 12 1 × Ephemeroptera 1 × Ephemera sp.
5 × Caenis sp. 7
N 10
15 3 × Heptageniidae 1 × Heptageniidae δ 6 8 2 × Asellus aquaticus 3 × Gammarus sp. 6 5
-32 -31 -30 -29 -28 -27 -26 -25 -30 -25 -20 -15 δ13C Dikerogammarus villosus Caenis sp. Limnomysis benedeni Echinogammarus berelloni Chironominae Potamopyrgus antipodarum + Gammarus roeselii Dreissena polymorpha Simuliidae Asellus aquaticus Hydropsyche sp. Characea sp. Bithynia tentaculata Hirudinae Periphyton Seston
11 B. Upper Rhine vs. Lower Rhine
12 Upper Rhine 16 Lower Rhine n = 20 15 n = 20 10
14
N
15 8 13 δ 3 × Ephemera sp. 1 × Chelicorophium sp. 12 6 11
4 10 -28 -26 -24 -22 -20 -18 -32 -30 -28 -26 -24 δ13C
Dikerogammarus villosus Potamopyrgus antipodarum Echinogammarus ischnus Periphyton Corbicula fluminea Seston Jaera sarsi
12 C. Invasion front vs. Established
9 Invasion front Established 10 8 n = 32 from two sites n = 20 9 7 8
N 6 15
δ 7 5 1 × Ephemeroptera 1 × Jaera sarsi 6 1 × Ephemeroptera 4 5 3 -34 -32 -30 -28 -26 -32 -30 -28 -26 -24 -22 -20 δ13C Dikerogammarus villosus Diamesinae Echinogammarus ischnus + Gammarus fossarum Simuliidae Dreissena rostriformis × Gammarus pulex Orthocladiinae Jaera sarsi G. pulex/G. fossarum Rhyacophila sp. Potamopyrgus antipodarum Ancylus fluviatilis Periphyton Seston 13 Isotopic niche width D. villosus
5 A B C *
4
3
Area (‰²) Area 2
1
0
-
Feeding river Lake Constance Upper Rhine Lower Rhine Invasion front Estab lished 14 Conclusion
Hypothesis
D. villosus is also strongly predacious in the field ‘killer shrimp’? less predatory in the River Rhine system
supported by SIA and genetic analyses – apparently not more opportunistic at an invasion front
15 Thanks…
… for your attention … to Andreas Hirsch
… to Peter Rey, Uta Mürle and Johannes Ortlepp
… and numerous other people
Need more details?
16