oSIST prEN 18161:2025
(Main)Water quality - Guidance standard on survey and monitoring freshwater mussel populations and their environment
Water quality - Guidance standard on survey and monitoring freshwater mussel populations and their environment
This document is intended to provide generic guidance applicable to a suite of mussel species in Europe. It will be based on best practice developed and used by experts in Europe and will describe approaches that individual countries have adopted for survey, data analysis and condition assessment. Its focus will be on the Family Unionidae, with only a brief reference to the small ‘pea clams’ in the Family Sphaeriidae. In contrast to the published CEN standard on freshwater pearl mussel (EN 16859:2017), which is restricted to specific types of running waters in certain geographical regions of Europe), this new standard will cover a much wider range of methods and recommendations applicable to a diversity of geographical regions and habitats including streams, lakes, ponds and reservoirs of different sizes.
Wasserbeschaffenheit - Anleitung für das Monitoring und Bewertung von Süßwassermuscheln
Dieses Dokument beschreibt die Informationen, die erforderlich sind, um die Bedingungen einer Unionidenpopulation über die Zeit zu beurteilen und den Informationsgrad, der für die Beurteilung erforderlich ist, ob ein Plan oder ein Projekt für deren Zukunftsaussichten abträglich sein könnte. Es enthält Anleitungen zu Verfahren für die Erhebung und das Monitoring von Unionidenpopulationen und die Umweltbedingungen, die für die Erhaltung von Populationen im guten Zustand wichtig sind. Das Dokument beruht auf der von Experten für Unionidenmuscheln in Europa entwickelten und angewendeten bewährten Vorgehensweise und beschreibt Herangehensweisen, die einzelne Länder zur Erhebung, Datenauswertung und Zustandsbeurteilung festgelegt haben.
Standardverfahren zur Wiederherstellung von Populationen fallen nicht in den Anwendungsbereich dieses Dokuments.
Qualité de l'eau - Norme guide pour l'étude et le suivi des populations de moules d'eau douce et de leur environnement
Le présent document fournit les informations nécessaires pour évaluer la situation au cours du temps d’une population d’unionidés, et le niveau d’information permettant d’évaluer si un plan de gestion ou un projet est susceptible de nuire à ses perspectives d’avenir. Il fournit des préconisations concernant les méthodes d’étude et de suivi des populations de moules unionidées et présente les caractéristiques environnementales importantes pour le maintien des populations dans des conditions favorables. Le présent document est basé sur les meilleures pratiques développées et utilisées par les experts des moules unionidées en Europe, et décrit les approches que les différents pays ont adoptées pour le recensement, l’analyse des données et l’évaluation de la situation.
Les méthodes normalisées de rétablissement des populations ne relèvent toutefois pas du domaine d’application du présent document.
Kakovost vode - Navodilo za monitoring populacije sladkovodnih školjk in njihovega okolja
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-marec-2025
Kakovost vode - Navodilo za monitoring populacije sladkovodnih školjk in
njihovega okolja
Water quality - Guidance standard on survey and monitoring freshwater mussel
populations and their environment
Wasserbeschaffenheit - Anleitung für das Monitoring und Bewertung von
Süßwassermuscheln
Ta slovenski standard je istoveten z: prEN 18161
ICS:
13.060.70 Preiskava bioloških lastnosti Examination of biological
vode properties of water
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2025
ICS 13.060.70
English Version
Water quality - Guidance standard on survey and
monitoring freshwater mussel populations and their
environment
Wasserbeschaffenheit - Anleitung für das Monitoring
und Bewertung von Süßwassermuscheln
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 230.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 18161:2025 E
worldwide for CEN national Members.
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Taxonomic summary of the species . 10
5 Survey and monitoring freshwater mussel populations . 11
5.1 General. 11
5.2 Monitoring methods for different attributes of freshwater mussel populations . 11
5.3 Distribution, abundance and population size of mussels . 12
5.4 Population structure: demography and recruitment . 15
5.5 Brooding levels . 16
5.6 Training and quality assurance for unionid mussel survey and assessment . 16
5.6.1 Survey training . 16
5.6.2 Training manuals . 17
5.6.3 Data entry and validation . 17
5.6.4 Licences . 17
6 Monitoring the environmental conditions needed to support freshwater mussel
populations . 18
6.1 Fish hosts . 18
6.1.1 General. 18
6.1.2 Host fish suitability . 18
6.1.3 Host fish availability . 18
6.1.4 Fisheries management . 18
6.1.5 Identification of problems . 19
6.2 Hydromorphology . 19
6.2.1 General. 19
6.2.2 Fluvial systems. 19
6.2.3 Standing water systems . 26
6.3 Water quality . 31
6.3.1 General. 31
6.3.2 Temperature. 31
6.3.3 pH, calcium, alkalinity . 32
6.3.4 Dissolved oxygen. 32
6.3.5 BOD /COD . 32
6.3.6 Electrical conductivity . 32
6.3.7 Nutrients . 32
6.3.8 Turbidity and suspended solids . 32
6.3.9 Contaminants . 33
6.4 Biotic features . 34
6.4.1 General. 34
6.4.2 Phytoplankton and phytobenthos . 34
6.4.3 Aquatic macrophytes . 34
6.4.4 Macroinvertebrates . 35
6.4.5 Riparian vegetation . 35
6.4.6 Predators and competitors . 36
6.4.7 Parasites and diseases . 37
6.4.8 Other aspects . 37
7 Monitoring environmental pressures . 37
8 Information needed to assess plans or projects on water bodies with freshwater mussels
............................................................................................................................................................................. 38
Annex A (informative) Geographical distribution of Margaritifera species in Europe . 41
Bibliography . 42
European foreword
This document (prEN 18161:2025) has been prepared by Technical Committee CEN/TC 230 “Water
analysis”, the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
Introduction
This document provides guidance on survey and monitoring populations of unionid mussels (i.e. Order:
Unionida, also referred to as naiads) and the environmental features on which they depend. There are 24
species of native unionid bivalves in Europe other than Margaritifera margaritifera, which is covered in
a CEN standard [1] to provide guidance on survey and monitoring. None of these unionid species can be
considered to be secure throughout their range based on IUCN threat assessments. A standard approach
to collecting the information required to undertake accurate threat assessments is not available.
Unionid species are distributed according to their natural habitat requirements, the distribution of their
host fish, and the historical means by which both mussels and hosts have been distributed, and the
biogeographical barriers to their spread. The European unionids fill a wide range of habitat types, and
survey, monitoring and condition assessment must be relevant to the individual requirements of each
species. Some species are generalists and occupy a wide range of habitats, while others are more
restricted by river/ lake/ canal bed substrate, water quality and water flow, in particular lentic or lotic
conditions.
Freshwater mussels are threatened by a range of pressures, as outlined in Lopes-Lima et al. [2]:
a) habitat loss, fragmentation, and degradation;
b) overexploitation;
c) pollution and eutrophication;
d) loss of fish hosts;
e) invasive species;
f) water abstraction and climate change;
g) other threats resulting in mussel declines (e.g. diseases),
where the habitat appears intact with healthy populations of fish, insects, gastropods, and other biota.
Further research is needed to detect new and emerging pressures, requiring consistent and comparable
mussel survey and data interpretation. This document aims to assist in the conservation of unionid
mussels through facilitating a consistent approach to understanding mussel populations across the
species and the bioregions in which they occur, including undertaking environmental impact assessment,
and restoring mussel populations. The applications of the standard also include the provision of site-level
data that will contribute to reporting under Article 17 of the European Habitats Directive (https://eur-
lex.europa.eu/legal-content/EN/TXT/).
NOTE Although freshwater mussels are invertebrates, their survey is conducted in a very different way from
standard surveys for other benthic macroinvertebrates. Surveys for mussels are concentrated on the restricted
habitat of the species of mussel being surveyed, and must also consider the habitat and water quality conditions
required to complete its full life cycle. For this reason it is not possible to use EN 16859 (‘Guidance standard on
monitoring freshwater pearl mussel (Margaritifera margaritifera) populations and their environment’) for other
mussel species. The freshwater pearl mussel is unique among other European mussel species in living in fast-
flowing oligo
...
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