Freshwater Pearl Mussel in Europe: Status and Conservation Issues

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1 Freshwater Pearl Mussel in Europe: Status and Conservation Issues Jürgen Geist Aquatic Systems Biology Unit

2 The Freshwater Pearl Mussel: Target Species for Conservation Indicator species Keystone species Umbrella species Flagship species Core problem: recruitment Geist (2010) Hydrobiologia

3 Distribution Geist (2010) Hydrobiologia

4 Diversity of Pearl Mussel Streams

5 Diversity of Pearl Mussel Streams

6 Environmental and Genetic Factors Status of host fish stocks? Habitat for juveniles / substratum? + Genetics? Fertility / Gravidity? + Environmental change? Geist (2010) Hydrobiologia

7 The First Step: Gravidity of Populations Normal levels of gravidity in most streams No decrease of gravidity with age High reproductive potential Induced release of glochidia

8 The Parasitic Phase on the Host Fish Salmo trutta Gill of S. trutta with encysted glochidia

9 Host Fish Densities in Functional and Non- Functional Pearl Mussel Populations Salmo trutta biomass [kg/ha] Salmo trutta Ind/ha juveniles no juveniles 0 juveniles no juveniles Geist et al. (2006) Aquatic Conserv.

10 Taeubert et al. (2010) Aquatic Conserv.

11 Temperature-Dependence of Metamorphosis U. crassus M. margaritifera Taeubert, Gum & Geist (2013) Limnologica Taeubert, El-Nobi & Geist (2014) Aquatic Conserv.

12 Stream Bed: The Core Problem for Juvenile Recruitment Pikku-Luiro, Finland Elez, France Zinnbach, Germany

13 Texture Functional populations: Well-sorted gravel Low percentage of fines Non-functional populations: Mixed texture High percentage of fines Geist & Auerswald (2007) Freshw. Biol.

14 Determining Functional Substrate Conditions Geist & Auerswald (2007) Freshw. Biol.

Changes in the Erosion Sedimentation Patterns

Endogenous factors Geomorphology / Structure

15 Changes in the Erosion Sedimentation Patterns Global / Climatic change Catchment area Landuse / vegetation Reduced water retention Lack of buffer strips Nutrient loads Endogenous factors Geomorphology / Structure (dead wood!) Stream regulation natural flow regime and dynamics

16 Comparisons of Different Stream Substratum Restoration Measures

Changes of Physicochemical Habitat Characteristics Euclidean

Engineering 16/32 8/16 SR SC Dissolved oxygen at 16/32 sites

17 Changes of Physicochemical Habitat Characteristics Euclidean distance to respective RF sites Sampling time point Pander, Mueller & Geist (2014) River Res. Appl. Mueller, Pander & Geist (2014) Ecolog. Engineering 16/32 8/16 SR SC Dissolved oxygen at 16/32 sites Dissolved oxygen interstitial zone [mg/l] Kruskal-Wallis-ANOVA: p < 0.001, pairwise Mann-Whitney-U-Test: p < 0.05

18 Artificial Culturing in Cages and Boxes Gum, Lange & Geist (2011) Aquatic Conserv.

19 Population Genetic Information Tuuloma Kemijoki Weser Danube Aulne Weser Elbe Danube Tuuloma Elbe 0.1 Kemijoki Margaritifera margaritifera Salmo trutta Aulne Geist & Kuehn (2008) Mol. Ecol.

20 Identification of Priority Populations Geist & Kuehn (2005) Mol. Ecol.

21 Landscape Genetics Technische Universität München Geist et al. (2009) Conserv. Genetics

22 Examples of Currently Applied Conservation Approaches and their Problems Approach Infestation and release of host fishes from hatcheries into natural populations Problem Does often not address the bottleneck Low persistence of allochthonous fishes Possible gene swamping, disease Release of early post-parasitic juveniles into wild populations Trial and error based Poor monitoring possibilities Population surveys / counts of mussels, Water quality control Only a monitoring tool No conservation action Gradivity monitoring of adult mussels Not a powerful indicator No conservation action

23 Successful Examples of Restoring Freshwater Mussel Populations Dr. Reinhard Altmüller and the Lutter Project Altmüller & Dettmer (2006)

24 Effective Conservation Management: A Stepwise Approach Step 1: Decisions on conservation objectives Step 2: Determination of status quo Step 3: Identification of bottlenecks and problems Step 4: Decisions on conservation action with stakeholders and sponsors Step 5: Conservation action Step 6: Evaluation and adaptive management Step 7: Publication of results

25 Conservation of Functionally Intact Populations (Kola peninsula)

26 Conservation of Functionally Intact Populations (North America)

27 Public Awareness and Communication Motto of the Freshwater Mollusk Conservation Society Meeting 2009 in Baltimore, USA

28 Conclusions Freshwater pearl mussel populations continue to be in trouble, despite of knowledge on the limiting factors for recruitment Prioritization of populations / areas of conservation based on ecological and genetic data is important Catchment conservation in functionally intact populations should have highest priority Combination of short-term remediation (culturing) with longterm objectives (catchment restoration) is essential Conservation needs to be more systematic and requires evaluation plus publication of positive and negative results

29 Merci beaucoup pour votre attention!

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