SIST EN 16772:2016

SLOVENSKI STANDARD
oSIST prEN 16772:2014
01-oktober-2014
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FRQDKUHN
Water quality - Guidance on methods for sampling invertebrates in the hyporheic zone of
rivers
Wasserbeschaffenheit - Anleitung für die Probenahme von Invertebraten (Wirbellosen) in
der hyporheischen Zone von Flüssen
Qualité de l'eau - Lignes directrices relatives aux méthodes d'échantillonnage des
invertébrés dans la zone hyporhéique de rivières
Ta slovenski standard je istoveten z: prEN 16772
ICS:
13.060.10 Voda iz naravnih virov Water of natural resources
13.060.70 Preiskava bioloških lastnosti Examination of biological
vode properties of water
oSIST prEN 16772:2014 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 16772:2014

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oSIST prEN 16772:2014

EUROPEAN STANDARD
DRAFT
prEN 16772
NORME EUROPÉENNE

EUROPÄISCHE NORM

July 2014
ICS 13.060.70
English Version
Water quality - Guidance on methods for sampling invertebrates
in the hyporheic zone of rivers
Qualité de l'eau - Lignes directrices relatives aux méthodes Wasserbeschaffenheit - Anleitung für die Probenahme von
d'échantillonnage des invertébrés dans la zone Invertebraten (Wirbellosen) in der hyporheischen Zone von
hyporhéique de rivières Flüssen
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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey 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: Avenue Marnix 17, B-1000 Brussels
© 2014 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 16772:2014 E
worldwide for CEN national Members.

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Contents
Page
Foreword .3
Introduction .4
1 Scope .6
2 Terms and definitions .6
3 Survey objectives .8
4 Sampling strategy .9
5 Sampling methods . 10
5.1 General . 10
5.2 Karaman-Chappuis pit [15] . 10
5.3 Bou-Rouch pump [16] . 11
5.4 Vacuum pump [18] . 13
5.5 Standpipe trap [19] . 15
5.6 Williams corer [5] . 16
5.7 Colonization devices [21] . 17
5.8 Freeze coring [22] . 19
6 Sample processing . 20
Annex A (informative) Examples of sampling strategies for three different types of investigation . 21
A.1 Case Study 1 – Assessing regional biodiversity and species richness . 21
A.2 Case Study 2 – Assessing impacts on fish spawning sites . 21
A.3 Case Study 3: Assessing the impacts of pollution . 21
Bibliography . 22


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Foreword
This document (prEN 16772:2014) 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.

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Introduction
The term "hyporheic" is derived from two Greek words: hypo (under) and rheos (flow), and was first used by
Orghidan in 1959 [1] to delineate the area of saturated subsurface sediments beneath and lateral to the
wetted channel that contains a mix of surface water and groundwater. In the last 50 years, scientific
understanding of the hyporheic zone has improved [2] and the term has been modified and expanded by
hydrologists, hydrogeologists, chemists and biologists to reflect the importance of:
 the upwelling and downwelling of water into and out of the stream bed and the mixing ratio of surface
water and groundwater;
 the nature and rate of biogeochemical processes resulting from upwelling of interstitial water or
downwelling of surface water;
 the ecotonal nature of the hyporheic zone which provides important habitat for benthic taxa, specialist
hyporheic organisms and groundwater fauna, including both macroinvertebrates and meiofauna. The
latter include Microcrustacea, Rotifera and Nematoda as well early instars of many aquatic insects.
In this standard the hyporheic zone is defined as the spatio-temporally dynamic ecotone between the surficial
benthic sediments and the underlying aquifer. Within the hyporheic zone, water, solutes and biota are
exchanged with the stream above, the groundwater below and the saturated sediments lateral to the channel.
The term "hyporheic zone" is applied to the physical habitat while the term "hyporheos" coined by Williams
and Hynes in 1974 [4] is used to describe the faunal community inhabiting it.
Over the past few decades, the importance of the hyporheic zone has been increasingly recognized, with the
vertical dimension added to spatial concepts of lateral and longitudinal connectivity. Together with the
temporal dimension this has created a four-dimensional understanding of river ecosystems [4, 5, 6]. As the
hyporheic zone is an ecotone between surface water and groundwater, abiotic conditions may reflect a
transition between the two. Table 1 provides a general comparison of the physical characteristics of each
environment.
Table 1 — Physical characteristics of typical groundwater and hyporheic environments compared with
surface waters
Physical characteristic Groundwater Hyporheic
Light Constant darkness Constant darkness
Current velocity Much lower Lower
Annual and daily temperature range Much smaller Smaller
Substrate stability Much higher Higher

Approaches to river conservation and management recognize the need for a better understanding of the
interactions between surface water and groundwater when undertaking investigations in the field. As the
ecotone between the two, the hyporheic zone plays a vital part in ecosystem functioning in many rivers,
including a critical role in the flow of energy, cycling of nutrients and organic compounds, as well as pollution
attenuation. The hyporheic zone contributes to overall river biodiversity. It also provides a nursery for young
life-stages of some fish and invertebrates and a potential refuge for benthos during adverse environmental
conditions, such as flooding, low flows, chemical pollution, stream-bed drying or freezing. The hyporheic zone
may therefore enhance the recovery of the benthic community following disturbance.
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An increased interest in the hyporheic zone has resulted, in part, from international legislation, such as EC
directives: the Habitats Directive [9], the Water Framework Directive [10], the Groundwater Directive [11] and
the Nitrates Directive [12]. Although investigations into the hyporheic zone are not explicit within these
directives, they do require national regulatory authorities to adopt a more integrated approach to the
management of river catchments as a whole. Consequently, an understanding of the hyporheic zone,
including its functions and the potential threats to these, is vital in order to comply fully with the requirements
of these directives.
Investigations of the hyporheic zone may also be needed more generally for catchment management, river
restoration, site-based investigations or for research. Consequently, the purpose of any study should be
carefully considered when selecting the most appropriate method for sampling the hyporheos, especially if the
collection of water quality and associated sediment data is also required.

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1 Scope
This document provides guidance on methods for sampling invertebrates in the hyporheic zone of wadable
rivers. It describes each method, including details of the equipment involved and its use in the field. Guidance
is given on developing a sampling strategy and selecting an appropriate survey technique for the purpose of
investigation. Benthic macroinvertebrate sampling is covered elsewhere by other published standards (see
bibliography). Selected literature with references in support of this document is given in the bibliography.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
aquifer
underground layer of water-bearing permeable rock or unconsolidated sediments from which groundwater can
be extracted
2.2
benthic
relating to the surface sediments
2.3
benthos
faunal community inhabiting the surface sediments of rivers
2.4
biofilm
coating on a substrate composed of microorganisms, extra-cellular polysaccharides, other materials that
organisms produce, and particles trapped or precipitated within the matrix
2.5
biomass
total mass of living organisms per unit surface area or volume
2.6
catchment
basin
area from which precipitation and groundwater will collect and contribute to the flow of a specific river
2.7
diversity
taxonomic richness of a community and the distribution of individuals across taxa
2.8
downwelling
movement of water in a downward direction, typically from the surface stream to the hyporheic zone or
groundwater
2.9
ecotone
transition area between two adjacent ecosystems
2.10
exposed river sediments
particles, typically comprising cobbles, gravel, sand and silt, deposited by flowing water but exposed as water
levels fall
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2.11
groundwater
all water that is below the surface of the ground
2.12
hyporheic flow
flow of water through the hyporheic zone
2.13
hyporheic zone
spatio-temporally dynamic ecotone between the surficial benthic sediments and the underlying aquifer
2.14
hyporheos
faunal community inhabiting the hyporheic zone
2.15
interstitial
referring to the spaces between sediment particles
2.16
macroinvertebrate
invertebrate that is easily visible without magnification
[SOURCE: EN ISO 10870:2012, definition 2.8 – modified, "(> 0,5 mm)" was not adopted]
2.17
meiofauna
invertebrates that pass through a 500-µm or 1-mm sieve but are retained on a 45 µm- or 63- µm sieve
2.18
permeability
capacity of a rock or sediments to transmit water
2.19
pool
habitat feature characterized by distinctly deeper parts of the channel that are usually no longer than one to
three times the channel’s bankfull width, and where the hollowed river bed profiles are sustained by scouring
[SOURCE: EN 14614: 2004, definition 2.24]
2.20
porosity
proportion of a given volume of rock or sediments that is occupied by pores
2.21
reach
major sub-division of a river, defined by physical, hydrological, and chemical character that distinguishes it
from other parts of the river system upstream and downstream
[SOURCE: EN 14614: 2004, definition 2.25]
2.22
riffle
fast-flowing shallow water with distinctly broken or disturbed surface over gravel/pebble or cobble substrate
[SOURCE: EN 14614: 2004, definition 2.28]
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2.23
riparian zone
area of land adjoining a river channel (including the river bank) capable of directly influencing the condition of
the aquatic ecosystem (e.g. by shading and leaf litter input)
[SOURCE: EN 14614: 2004, definition 2.29 – modified, the NOTE was not adopted]
2.24
stream ordering
methods for classifying rivers and streams related to the complexity of the drainage basin, generally with
progressively higher order numbers usually assigned to streams with greater discharge lower down the
catchment.
[SOURCE: EN 14614: 2004, definition 2.37]
2.25
substrate
material making up the bed of a river
[SOURCE: EN 14614: 2004, definition 2.40]
2.26
upwelling
movement of water in an upward direction, typically from the groundwater or hyporheic zone to the surface
stream.
3 Survey objectives
The objectives of the survey should be clearly defined before selecting which method to use for sampling the
hyporheic zone, because the suitability of each method varies according to the purpose of study. Table 2
summarizes each sampling method according to its suitability for particular objectives. This includes
consideration of:
 attributes and variations in hyporheic fauna, sediments and the interstitial environment;
 whether the method can be applied instream and/or in the riparian zone;
 whether data collected are fully quantitative or semi-quantitative.
All methods can be used to describe diversity, taxon richness, abundance and biomass, recognizing their
known limitations.
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Table 2 — Overview of sampling methods described in this standard and their suitability for particular
surveys
Karaman- Bou- Vacuum Stand- Williams Coloniz- Freeze
Chappuis Rouch pump pipe trap corer ation coring
pit pump devices
Migration/dispersal No No No Yes No Yes No

Spatial No Yes Yes Yes Yes Yes Yes
heterogeneity
Temporal variability Yes Yes Yes Yes Yes Yes Yes
Interstitial sediment No No No Yes No Yes No
transport

Sediment No No No No No No Yes
characteristics
Used instream No Yes Yes Yes Yes Yes Yes
Used in riparian Yes Yes Yes Yes Yes Yes Yes
zone
Quantitative No No No No Yes Yes Yes
Semi-quantitative No Yes Yes Yes Yes No No

4 Sampling strategy
The design of a sampling strategy will vary according to the purpose of the investigation. Sampling site
location may be influenced by pre-existing monitoring networks or previous investigations. The following
should be considered:
 sampling method;
 number and location of sampling sites;
 number of replicates per site required to characterize site heterogeneity (e.g. upwelling and downwelling,
sediment characteristics);
 sampling frequency;
 sampling depth;
 seasonal variability;
 abiotic data requirements;
 spatial and temporal scale of investigation.
Scale is important when examining the hyporheic zone, as various processes occur at different spatial scales.
For example, at a stream-bed (patch) scale the size, shape, sorting and stability of sediments are the primary
determinants of porosity and permeability. These factors have a major influence on community composition
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over relatively short distances. At a catchment scale, connectivity between aquifers and the saturated
sediments lateral to the channel (e.g. beneath the riparian zone and out to the wider floodplain) is a key
consideration. Hyporheic flow paths occur at multiple scales, from the stream bed to the catchment.
Case studies are presented in Annex A, giving examples of suitable sampling strategies for three different
types of investigation.
5 Sampling methods
5.1 General
This standard describes only those techniques that are suitable for use in wadable rivers; other approaches
are available for sampling in deeper waters. Some techniques (e.g. freeze coring) require a recovery time
after the equipment has been installed, allowing organisms to recolonize the sample area. Some techniques
work better in fine-grained sediments while others can be used in coarser sediments. Surveyors should carry
out a preliminary investigation of the sediments before selecting an appropriate technique.
Each method is described in the following sections while Table 3 compares their ease of use, costs, recovery
time and the possibility of obtaining repeat samples. Further details on all of these methods can be found in
the PASCALIS sampling manual [13] and the Hyporheic Handbook [14].
Table 3 — Practical considerations when selecting sampling methods
Karaman- Bou- Vacuum Stand- Williams Coloniz- Freeze
Chappuis Rouch pump pipe trap corer ation coring
pit pump devices

Minimum number 1 1 1 1 1 1 2
a
of operators
Equipment cost 200 1.000 350 200 1.000 500 10.000
(in Euro, 2014)
Installation time ~15 min ~15 min ~15 min ~2 h ~15 min ~1 h ~30 min
Time to collect ~5 min ~10 min ~10 min ~10 min ~5 min ~10 min ~45 min
one sample
Portability High Medium High Medium High Medium Low
Typical recovery None None None 2 weeks None Variable 2 to 3
time after days
installation
Repeat sampling No No Yes Yes No Yes No
possible
a
Installation of equipment for some methods will require additional help, i.e. for the stand-pipe traps, colonization devices and freeze
coring.

5.2 Karaman-Chappuis pit [15]
5.2.1 Description and operation
This is a rapid, qualitative method for obtaining a hyporheic sample from exposed river sediments, particularly
in gravel and sand. A pit (~50 cm diameter) is excavated in exposed sediments to such a depth that its base is
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below the water level. Interstitial flow into the pit is maintained by extracting water, using a hand pump or
baler, which is then filtered to collect the invertebrates dislodged by the flow. In addition, small amounts of
sediment from the bottom of the pit should be collected and carefully examined to obtain gastropods and
bivalves. Pits should be dug on gravel bars or as close as possible to the river, while avoiding the risk of
contamination by river water and benthic invertebrates. The method cannot be used during high flows as
suitable sample sites will be inundated. Vegetated areas with compacted substrate should also be avoided.
This method is suitable for preliminary investigations or as a roaming technique, as it is cheap, quick and easy
to use. It is also safer than other methods as it does not require surveyors to enter the river. A disadvantage of
this method is that sampling is limited to the shallow portion of the hyporheic zone (~30 cm depth) and to
areas of exposed sediment. The need to remove sediment down to the water level further restricts sampling to
locations where this is near the surface.
5.2.2 Species sampled
A range of macroinvertebrates and meiofauna can be collected using this technique. Pits shall be excavated
and the sample taken quickly in order to capture all animals present.
5.2.3 Environmental variables
A full suite of water chemistry analysis can be undertaken provided that there is no ingress of surface water
into the excavated pit. Physical and chemical parameters (e.g. dissolved oxygen and water temperature)
should be measured immediately after pit excavation. It may be possible to make estimates of permeability by
timing infiltration into the excavated pit.
5.3 Bou-Rouch pump [16]
5.3.1 Description and operation
The principle of the method is to create a disturbance and maintain a flow around a pipe, sufficient to dislodge
hyporheic organisms for extraction by pumping. A hand-piston pump is fixed on top of a portable stainless
steel stand-pipe that is driven into the bed sediment at various depths (typically 20 cm to 60 cm but
occasionally up to 2 m) (see Figure 1). A standard volume should be collected for all samples; usually a
minimum of 5 l although samples up to 10 l may be extracted. Sampling efficiency can vary depending upon
the volume of water extracted and the nature of the sediments. The method can be used in submerged
conditions as well as in exposed river sediments such as gravel bars. Approximately 3 to 5 replicates should
be sampled at each site, with a gap of at least 1 m between them.
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Dimensions in millimetres

Key
1 Safety pin 9 Bolt
2 Lever 10 Screen
3 Upper piston valve 11 Tip
4 Liner 12 Hand piston pump
5 Body of the pump 13 Mobile pipe
6 lower piston 14 Hyporheic zone
7 Lower valve 15 Pipe with screen with 5-mm diameter holes
a
8 Cap for hammering Sampling depth
Figure 1 — The Bou-Rouch pump for sampling invertebrates in the hyporheic zone of rivers. [16]
An advantage of the Bou-Rouch pumping technique is that it causes relatively little disturbance to the river.
Samples can be taken immediately after the installation of equipment so it can be used rapidly and is suitable
for roaming surveys as the equipment is relatively portable. Pipes can also be left in situ for long periods if
desired. The main disadvantage is that the method is not strictly quantitative as the sampled volume of
hyporheic sediments cannot be measured and may vary depending upon the strength of force applied to the
hand-piston pump during operation. Also, the location from which organisms are drawn in is unknown; pore-
spaces and flow pathways are complex and often patchy in the hyporheic zone so some organisms may be
sucked in from the proximity of the stand-pipe while others from a greater distance.
5.3.2 Species sampled
Owing to its high extraction rate the pump samples swimming organisms and those linked to sediments. Note
that the sample passes through the pump itself which can damage the collected organisms. Both
macroinvertebrates and meiofauna are captured. However, smaller and more passive species may be
preferentially sampled.
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5.3.3 Environmental variables
Temperature, dissolved oxygen, conductivity and pH can all be measured within the pipe, before water is
extracted. Further chemical analyses can be performed, but water used to prime the pump shall be purged
first. A semi-quantitative measurement of dissolved/particulate organic matter and fine sediment can also be
made. Where sediments are completely saturated, a measure of permeability and porosity can be obtained by
quantifying the pumping rate, i.e. noting the time taken to pump a certain number of litres.
5.4 Vacuum pump [18]
5.4.1 Description and operation
The vacuum pump method uses a similar principle to the Bou-Rouch, except that it creates a vacuum inside a
closed bottle to extract and collect the sample (see Figure 2). Open-ended PVC pipes, with or without 5 mm
perforations, are driven into the bed sediment to various depths (typically 20 cm to 60 cm but occasionally up
to 1 m) using a stainless steel T-bar forming semi-permanent sampling wells. If used in coarse substrates the
addition of an outer metal tube can protect the PVC pipe from damage during insertion. Manual pumping
creates a vacuum which maintains an interstitial flow around the pipe that is sufficient to dislodge hyporheic
organisms for extraction. It is a self-priming system that does not damage the organisms because they do not
pass through the pump itself. A standard volume shall be collected for all samples, usually a minimum of 5 l
although samples up to 10 l may be extracted. If the pipe is submerged a seal should be made around the top
during pumping to prevent benthos from entering.
The method is most suitable for use instream, but it can also be used in exposed river sediments such as
gravel bars, as long as the sediments are saturated. Approximately 3 to 5 replicates should be sampled at
each site, with at least 1 m between them. Pipes can be left in situ for repeated surveys as long as bungs are
used to seal the top of the pipes between surveys to avoid contamination by benthos.
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Key
1 Membrane pump 6 Transparent vacuum jar
2 membrane 7 Mobile pipe
3 Air 8 Hyporheic zone
5 sample aspiration

Figure 2 — A vacuum pump for sampling invertebrates in the hyporheic zone of rivers. [13]
As with the Bou-Rouch pump, an advantage of vacuum pumping is that it causes minimal disturbance to the
river bed. The method is quick and easy to use making it particularly suitable for roaming surveys and
investigations into spatial dynamics (e.g. riffle-scale studies). As sampling wells can be left in situ indefinitely,
repeated sampling from the same location can be carried out providing temporal sequence data for long-term
studies. The main disadvantage is that the method is not strictly quantitative as the sampled volume of
hyporheic sediments cannot be measured. Also, the location from which organisms are drawn in is unknown;
pore spaces and flow pathways are complex and often patchy in the hyporheic zone so some organisms may
be sucked in from the proximity of the pipe while others from a greater distance.
5.4.2 Species sampled
The pump samples swimming organisms as well as those linked to sediment particles, including
macroinvertebrates and meiofauna. However, smaller and more passive species may be preferentially
sampled.
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5.4.3 Environmental variables
These can either be measured directly in water extracted from the pipe, or samples can be taken to the
laboratory for further chemical analysis. These measurements should not be taken from the first aliquot
extracted, to avoid contamination from water that may have been in the pipe for a long time. A semi-
quantitative measurement of dissolved/particulate organic matter and fine sediment can also be made. Where
sediments are completely saturated, a measure of permeability and porosity can be obtained by quantifying
the pumping rate, i.e. noting the time taken to pump a certain number of litres.
5.5 Standpipe trap [19]
5.5.1 Description and operation
Standpipe traps (perforated plastic tubes) are installed permanently within the river bed with a short internal
cylindrical bung for closing off the holes (see Figure 3). They are driven into the substrate at least 1 m apart,
at various depths (typically 20 cm to 60 cm but occasionally up to 1 m) and remain in situ for the duration of
the study. Once in place, the traps are opened (by removing the bung) and exposed to the hyporheic zone for
a define
...