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Action Plan for a critically endangered Freshwater Pearl Mussel in Czechia - achievements of semi-natural breeding and population reinforcement in contrast with protracted restoration of its oligotrophic river ecosystems

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Abstract

Since 1980, due to an alarming decline of FPM population, missing reproduction and the deteriorating quality of entire unique oligotrophic river catchments, the activities to protect them are ongoing. Gradually, declarations of a first action plan for the FPM and its habitats and declaration of protected areas in most of FPM catchments with a detailed plan for the care of the entire ecosystem were being processed. Since 1990, successful semi-natural breeding of FPM and an invading of its host-fish brown trout progressed in order to population reinforcement in individual rivers.
achievements of semi-natural breeding and
population reinforcement in contrast with
protracted restoration
of its oligotrophic river ecosystems
Introduction
Even at the beginning of the 20th century, a strong population of freshwater pear mussel (FPM) amounting
millions of individuals lived in many Czech rivers. During the 20th century, this bivalve gradually lost up to 95%
of its original distribution area as well as many other organisms associated with this type of habitat due to a
number of anthropogenic interventions in river ecosystems. At present, its last population is limited to the border
area of Bohemia, where the last hundreds to thousands of individuals live in the catchment area of five rivers.
At the most of them the species stopped its spontaneous reproduction. Since 1980, due to an alarming decline
of FPM population, missing reproduction and the deteriorating quality of entire unique oligotrophic river
catchments, the activities to protect them are ongoing.
Despite the enormous efforts of
many people and organizations and
numerous successes of the Action
Plan, a future of the Czech FMPs is
still uncertain. In most rivers, among
other problems, the hyporheic
phase of FPM life does not work. It
works in Vltava river, but its problem
is lack of host fish. In other sites,
there are problems with juvenile‘s
food or with bottom colmatation by
fine fluvial sediments etc. Many
problems have already been
resolved, but many still remain.
A young individual (20 years, 6,5 cm) of
FPM after a hidden life period in the river
bed with well distinguishable annual
shoots; reserve Blanice the outcome of
first population rejuvenating round.
Long-term goal of the Action Plan: The restoration of
natural reproduction has not been reached yet
Catchment areas with FPM
sites have dramatically
changed during the last 50
years. The diagram shows
land use changes in
Zinnbach/Lužní area close
to the German border,
where the extend of
meadows significantly
decreased.
Juveniles as well as adult mussels have different
habitat quality demands and they are affected by
the whole drainage system. The habitat
restoration is a key for starting up the processes
of natural reproduction. In spite of existing
conservation strategy, several problems still
persist such as proprietary rights or a lack of
funding and human recources
Comprehensive habitat conservation more
strategies than putting into practice
Adults occur on the river bed and can reproduce only in a mosaic
landscape catchment in rivers with the water adequately warm in the
summer.
Juveniles live in deeper layers (hyporheos)
of the river bed and are sensitive to
eutrophication or bottom colmatation which
may cause lack of oxygen. Juveniles feed
on gentle detritus coming from spring areas
and water macrophytes.
Only indigenous young salmonids are
suitable hosts for glochidia.
Action Plan for a critically endangered Freshwater Pearl Mussel in Czechia
First assisted infection of brown trout
(Hruška 1992)
Massive extinction of 26 % individuals at
one site in Blanice river due to hotel
wastewater
Start of a successful long term
seminatural breeding process (8 years
old individuals in 1998)
Start of the project Active Conservation of FPM in the
Blanice river, selecting a suitable catchment area, detailed
monitoring of FPM population (Hruška 1982)
Active prevention of Spálenecký potok and
Sněžný potok catchment area against
square soil draining
Square soil draining of
Tetřívčí potok
catchment area
Declaration of Blanice
river basin
Conservation area
(>60 km2)
Invention of a small artificial river arm
for juveniles rearing implementing
special meadow management with
composted grass with Ca addition
Research findings of temperature
impact on FPM reproduction published
(Hruška 1992)
Introduction of in situ caging
method (Budensiek 1995)
Project MARGARITIFERA
action plan (NCA CR,
CUNC, Prachatice)
Project Complex management
of National Natural Monument
NNP Blanice 1996-1999 (State
Environmental Fund of the CR)
J. Hruška at Blanice river is rearing juvenile pearl mussels (up to 2004
had been released for over 50 thousands individuals in age of 5 years).
Review see in Simon et al. 2015
Declaration of New State Action Plan
for Freshwater Pearl Mussel in the
Czech Republic by Ministry of
Environment (Absolon & Hruška 2000)
Declaration of New Action
Plan for Freshwater Pearl
Mussel in the Czech
Republic by Ministry of
Environment (Švanyga et al.
2013)
The Milennial Flood kills over 50% of
FPM population in the Czech
Republic in 2002
Comprehensive outcomes
of the Action Plan
published (Hruška1998,
1999)
5 FPM conservation sites in the Czech Republic
became a part of NATURA 2000
Nature conservation authority representatives and
local conservationist at FPM site NATURA 2000
Zinnbach/Lužní potok on the German border
Long-lasting preparation of FPM catchment areas
restoration project as well as national conservation
strategies due to big personal changes.
The oldest reared individuals of
FPM getting into adult age
(Hruška,Volf 2003)
Declaration of 2 new FPM conservation areas
(river Arshunda, Norway; naturally reproducing populations with
young and old freshwater pearl mussels )
Securing of the residual FPM population in the Blanice
river due to river arm protection (Czech Union for Nature
Conservation ČSOP Volary, Hruška 1982)
The restoration of catchment areas
started: Construction of a natural
sand trap in Zlatýpotok river basin in
order to avoid fine sediment
transport to the FPM sites
The actual status of rejuvenated pearl mussel
populations in the Czech Republic published (Simon,
Vaníčková, Bílý et al. 2015)
2
1
6
Simon, O. P.1,2, Hruška, J.3, Horáčková, J.1, Dort, B.4, Douda, K.1,
Švanyga, J.5, Bílý, M.1, Švaříčková, J.6and other partners7
born
Semi-natural breeding
release
hidden hyporheos life phase
emerge at the sediment surface
Photo by Karel Horáček
1980
1985
1990
1995
2000
2005
2010
2015
0 0,05 0,1 0,15 0,2 0,25
Řada1
1980
1985
1990
1995
2000
2005
2010
2015
0 0,05 0,1 0,15 0,2 0,25
Řada1
2020
Increasing knowledge of hyporheic environments (Bílý et
al. 2021), limitation by pollution (see poster Barák et al.)
and new knowledges of host fish suitability at the
population level (see talk Vodáková et al.)
Crossborder INTERREG project CZ/AU Malschemuschel 2017-2020 (Ministry of
Environment) + INTERREG Strengthening of freshwater pearl mussel
populations in NATURA 2000 localities in the green belt of Bavaria-Czechia
2018-2020 (Nature ConservationAgency of the Czech Republic)
The second round of breeding young
FPMs reintroduced in 2021 to the
Vltava river in the Šumava NP by B.
Dort. Picture of 6yrs old juveniles
after a first big stormy flood in wild.
The Milennial drougthts demage two pearl mussel nature
reserves in Czech/German border near Aš (town)
Discharge m3.s -1
2021
For breeding juveniles,
mainly detritus from non-
freezing helocrenes is
used. These spring areas
(Tichá et al. 2012, 2020)
are strictly protected on
FPM sites.
Semi-natural breeding mussels rejuvenated
Czech populations however, natural
reproduction is still missing
About 50 000 individuals of FPM were reared up to 5 years using a special
Czech breeding method, which enables them to survive in the wild. The special
breeding experience allowed introduction of in situ caging method (Hruška
1999), using the youngest mussels for the habitat quality and local
management outcomes evaluation (Hruška 2000,Bílý aet al.2019) .
List of partners: Nature Conservation Agency of the Czech Republic: Jindřiška Jelínková, Jana Švaříčková, Lenka Tomášková, Alois Pavličko, Miloš Holub, Tomáš Bodnár,Kateřina Urbánková, Ivana Vaníčková, Kateřina Rambousková,Alena Peltanová,Ondřej Korábek, Václav Hlaváč, Jiří Pykal, Tereza Mináriková, Václav Říš, Ondřej Volf, Karel Absolon, et al.; Ministry of the Environment of
the Czech Republic: Jan Šíma, Jana Fuglíková, Dagmar Zíková, Olga Šuhájková, Jan Mengr, et al.; State Authority of South Bohemia Region: Petr Lhotka, Petra Doktorová, Kamil Zimmermann, Kateřina Jemelíková, et al.; State Authority of Karlovy Vary Region: Radoslav Brachtl, Martin Chochel, et al.; Šumava National Park and PLA: Eva Zelenková, Boris Hůlka, Josef Majer, et al.;
Military forests and estates: Květoslava Nováková, Eva Pláničková, et al.; T. G. M. Water Research Institute: Josef Rebec, Pavel Franče, Věra Kladivová, Kamila Tichá, Zuzana Hořická, Jiří Křivánek, Vojtěch Mrázek, Jana Vejmelková, Jitka Svobodová, Radka Čablová, et al., Czech University of Life Sciences Prague: Ondřej Simon, Jitka Horáčková, Karel Douda, Michal Bílý, Venda
Jahelková, Vojtěch Barák;Beleco: David Pithart, Jana Slezáková, et al.;ČSOP Volary: Jaroslav Hruška, et al.; NATUR management: Jaroslav Hruška since 1992 GAMMARUS: Bohumil Dort, Jana Dortová;PT PROLES: Karel Novotný;BIVALVIA: Ondřej Spisar, Robert Ouředník;Bund Naturschutz in Bayern: Michal Bláha, Erika Smrtová;freelancers: Jan Švanyga, Dětmar Jäger;volunteers:
Denisa Blažková, Mojmír Eliáš, Miroslav Böhm, Richard Faina, Jiří Maleček, and many others.
hyporheos 10 y
benthos
102y
nekton (endoparasite) 1 year
plankton 10-3 y
1 mm
7
Efforts to implement
new management
projects
1980
1985
1990
1995
2000
2005
2010
2015
0 0,05 0,1 0,15 0,2 0,25
Řada1
For conservation problems and successes in
FPM protected areas see talk Simon et al.
1+ FPM juvenile
Since 1990, successful semi-natural breeding of FPM and an invading
of its host-fish brown trout progressed in order to reinforce population in
individual rivers (for details, see talk Simon et al., Vodáková et al.).
Many rivers have undergone a number of more or less successful river
restorations and measures to protect the entire ecosystem and pearl
mussels as a flagship species over the last 40 years. The hope for
natural reproduction and rescue is still there.
References: Absolon, K., Hruška, J., 1999. Perlorodka říční (Margaritifera margaritifera Linnaeus, 1758) v České republice. [Freshwater Pearl Mussel (Margaritifera margaritifera Linnaeus, 1758) in the Czech Republic. (in Czech)], NCA CR, Prague, 1-27. Bílý, M., Simon, O., Barák, V., Jahelková, V., 2021. Occurrence depth of juvenile freshwater pearl mussels (Margaritifera margaritifera) in a river bed tested by experimental mesh tubes. Hydrobiologia, 848 (12-13), 3127-3139. Bílý, M., Němčíková, S., Simon, O. P., Douda, K., Barák, V., & Dort, B. (2018). Bioindication testing of stream environment suitability for young freshwater pearl mussels using in situ exposure methods. Journal of Visualized
Experiments, 2018(139) Buddensiek, V., 1995. The culture of juvenile freshwater pearl mussels Margaritifera margaritifera L. in cages: A contribution to conservation programmes and the knowledge of habitat requirements. - Biological Conservation 74, 33-40. Hruška, J., 1982. Návrh aktivních opatření k ochraně genofondu perlorodky říční na Blanici. - KSSPPOP České Budějovice, 5 pp. (unpublished, in Czech). Hruška, J., 1992. The freshwater pearl mussel in South Bohemia: Evaluation of the effect of temperature on reproduction, growth and age structure of the population. - Archiv für Hydrobiologie 126, 181-191. Hruška, J., 1998. Die Strategie des Tschech. Rettungsprogrammer mit besonderem
Augenmerk auf die Erneuerung der Nahrungsicherung der Flußperlmuschelpopulationen. In: Erhaltung und Wiederansiedlung der Flußperlmuschel, Kefermarkt, 5 pp. Hruška, J., 1999. Nahrungsansprüche der Flußperlmuschel und deren halbnatürliche Aufzucht in der Tschechischen Republik. In: Patzner, R. A., Glöer, P., Falkner, G. (eds), Ecology and taxonomy of freshwater Mollusca (Proceedings of the International Congress on Palaearctic Mollusca, Salzburg, February 1997. - Heldia 4, 69-79. Hruška, J., 2000. Experience of semi-natural breeding programme of freshwater pearl mussel in the Czech Republic. In: Die Flussperlmuschel in Europa: Bestandssituation und Schutzmassnahmen (Ergebnisse
des Kongresses vom 16.-18.10.2000 in Hof), 69-75. Hruška, J., Volf, O., 2003. 20 let výzkumu a aktivní ochrany perlorodky říční v ČR. I. část. [20 years of research and active protection of freshwater pearl mussel in the Czech Republic, part I. (in Czech)]. - Ochrana přírody 58(6), 168-171, and Ochrana přírody 58(7), 197-200. Švanyga, J., Simon, O., Mináriková, T., Spisar,O., Bílý, M., 2013. Záchranný program pro perlorodku říční v ČR. [Action plan for the endangered freshwater pearl mussel in the Czech Republic. (in Czech)] - NCA CR, 1-76. Simon, O. P., Vaníčková, I., Bílý, M., Douda, K., Patzenhauerová, H., Hruška, J., Peltanová, A., 2015. The status of freshwater pearl mussel in the Czech
Republic: several successfully rejuvenated populations but the absence of natural reproduction. - Limnologica Ecology and Management of Inland Waters 50, 11-20. Tichá, K., Simon, O. P., Douda, K., Kubíková, L., 2012. Detrital components in submontane organogenic springs in relation to their morphology, microhabitats and macroinvertebrates. - Polish Journal of Ecology 60, 163-175. Tichá, K., Simon, O. P., Houška, J., Peláková, L., & Douda, K. (2020). Helocrenic springs as sources of nutrient rich fine particulate organic matter in small foothill watershed. PLoS ONE, 15(4):
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