SIST EN 17211:2019

SLOVENSKI STANDARD
01-november-2019
Kakovost vode - Navodilo za kartiranje morskih trav in makroalg v evlitoralni coni
Water quality - Guidance on mapping of seagrasses and macroalgae in the eulittoral
zone
Wasserbeschaffenheit - Anleitung zur Kartierung von Seegras und Makroalgen in der
Eulitoralzone
Qualité de l’eau - Lignes directrices pour la cartographie des herbiers et des
macroalgues dans la zone eulittorale
Ta slovenski standard je istoveten z: EN 17211:2019
ICS:
07.060 Geologija. Meteorologija. Geology. Meteorology.
Hidrologija Hydrology
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.

EN 17211
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2019
EUROPÄISCHE NORM
ICS 07.060; 13.060.70
English Version
Water quality - Guidance on mapping of seagrasses and
macroalgae in the eulittoral zone
Qualité de l'eau - Lignes directrices pour la Wasserbeschaffenheit - Anleitung zur Kartierung von
cartographie des herbiers et des macroalgues dans la Seegras und Makroalgen in der Eulitoralzone
zone eulittorale
This European Standard was approved by CEN on 6 January 2019.

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. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists 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, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 17211:2019 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 Principle . 7
5 Survey strategy . 7
5.1 Mapping plan . 7
5.2 Timing and frequency of sampling . 8
5.3 Pilot survey . 8
5.4 Baseline survey . 9
5.5 Temporal trend monitoring . 10
5.6 Specialized surveys . 10
6 Equipment . 10
6.1 General . 10
6.2 Field survey . 10
6.3 Equipment for species identification in the laboratory . 12
6.4 Equipment for direct biomass assays . 12
6.5 Aerial remote sensing surveys . 13
6.6 Visual aerial surveys . 13
7 Chemicals . 13
8 Survey procedures . 14
8.1 General principles . 14
8.2 Field mapping and sampling using quadrats . 14
8.2.1 Recording . 14
8.2.2 Quadrat numbers and positioning . 15
8.2.3 Determination of coverage within quadrats . 16
8.2.4 In situ species determination and biomass measurements . 17
8.2.5 Expression of result . 18
8.3 Taxa identification . 18
8.4 Biomass measurements . 19
8.4.1 General . 19
8.4.2 Determination of wet mass . 19
8.4.3 Determination of dry mass . 19
8.4.4 Determination of ash-free dry mass . 19
8.4.5 Expression of results . 20
8.5 Mapping of extent of seagrass (angiosperms) and macroalgae beds by ground
truthing . 20
8.6 Cover and proportion of intertidal seagrass beds . 20
8.7 Aerial and satellite remote sensing imagery . 20
8.8 Visual aerial surveys . 21
8.9 Data storage and reporting . 21
9 Quality assurance and quality control. 22
Annex A (informative) Aerial and satellite remote sensing options and resolution . 23
A.1 General . 23
Annex B (informative) Wind, weather and sea conditions . 25
Annex C (informative) Exposure characterization codes . 26
Annex D (informative) Substrate characterization codes . 27
Bibliography . 28

European foreword
This document (EN 17211:2019) has been prepared by Technical Committee CEN/TC 230 “Water
analysis”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by March 2020, and conflicting national standards shall
be withdrawn at the latest by March 2020.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: 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, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Introduction
Investigation of marine angiosperms (e.g. seagrasses) and macroalgae is an important part of marine
environmental monitoring, facilitating the assessment of general ecological quality and the monitoring
of ecological status. The requirement for using marine angiosperms and macroalgae in marine
monitoring is inherent in numerous European and national directives: e.g. Marine Strategy Framework
Directive (Directive 2008/56/EC), Water Framework Directive (WFD) (Directive 2000/60/EC), Urban
Waste Water Treatment Directive (91/271/EEC), Habitats Directive (92/43/EEC) and the OSPAR and
HELCOM conventions. Extensive green macroalgal beds are considered an indicator of eutrophication.
Seagrasses and some macroalgae species are important contributors to biodiversity, as well as IUCN
threatened species and they are investigated in very similar ways. They respond to environmental
changes - primarily availability of light, nutrients, temperature and are impacted by physical
disturbance. Monitoring of extent of area, biomass and species composition may therefore in many
cases be used to characterize the environment and the degree of impacts.
The characterization of environmental conditions based on marine angiosperms and macroalgae
requires the use of quantitative and qualitative mapping methods.
WARNING — Persons using this document should be familiar with normal fieldwork practice.
This document does not purport to address all of the safety problems, if any, associated with its
use. It is the responsibility of the user to establish appropriate safety and health practices
1 Scope
This document provides guidance for survey design, equipment specification, survey methods, sampling
and data handling of macroalgae and marine angiosperms such as Zostera in the intertidal soft bottom
environment. It does not include polyeuryhaline terrestrial angiosperms that are found in saltmarshes.
Ruppia is a genus of angiosperms that can be found in brackish water. This document can also be
applied to the study of Ruppia in these environments.
The document comprises:
— development of a mapping and sampling programme;
— requirements for mapping and sampling equipment;
— procedures for remote sensing data collection;
— procedures for direct mapping and sampling in the field;
— recommendations for taxon identification and biomass determination;
— data handling.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN ISO 7027-2, Water quality - Determination of turbidity - Part 2: Semi-quantitative methods for the
assessment of transparency of waters (ISO 7027-2)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
biomass
total mass of living material in an area (m )
[SOURCE: ISO 6107-3:1993, definition 12, modified – “a given body of water” has been replaced by “an
area (m )” to reflect the littoral location]
3.2
ground-truth
information that are confirmed in an actual field investigation which is done at a defined location
Note 1 to entry: Used to confirm the findings of, or to calibrate quantitative observations, from remote sensing.
3.3
eulittoral zone
intertidal zone
marine intertidal zone which is submersed and emerged, either periodically due to tides or
aperiodically due to irregularly occurring factors, as in the enclosed seas of the Baltic or the
Mediterranean
Note 1 to entry: Biologically, this zone is defined as the zone between the upper limit of barnacles and the upper
limit of laminarians. In the Baltic where there is no tide, the eulittoral zone is the zone of short-lived annual algae.
[SOURCE: EN ISO 19493:2007, 2.7]
3.4
littoral zone
shallow marginal zone of a body of water where light penetrates to the bottom
[SOURCE: ISO 6107-3:1993, definition 40]
4 Principle
Surveys of marine angiosperms and macroalgae are undertaken using ground surveys and/or remote
sensing methods. This document gives guidance on the survey design, geographic positioning on the
ground, field data collection and sample processing for biomass determination. It does not cover the use
of specialist remote sensing software or data handling approaches beyond that of their general
application.
5 Survey strategy
5.1 Mapping plan
The mapping and sampling plan shall be defined according to the aims of the survey and the required
precision of results and their intended use before the survey is initiated. Remote and direct sampling,
methods, location and number of sampling stations on the ground, and methods for data processing will
vary between different types of studies. During development of the programme, consideration should
be given to local tidal regimes and general environmental conditions. Knowledge from previous surveys
and from local information sources is important in locating beds and in planning safe and
representative survey locations and resources. For guidance on the design of sampling programme, see
EN ISO 5667-1 [4].
The survey plan can require work to take place over a defined substrate type. This should be defined by
the survey objectives. The use of existing habitat maps or sediments maps may be used to define this
area.
Eulittoral surveys should begin at a certain time before low tide and should end accordingly after low
tide. This time will depend on the local tidal flat morphology and the tidal conditions and can vary by
2 hours or more either side of low water. Particular caution has to be paid to tidal channels and the
rising tide.
The eulittoral survey may be a:
— full field survey, where all data are collected from work on the ground; e.g. where beds are large, a
survey may not be completed during one low tide and has to be done in several stages or by using
underwater survey techniques;
— combined field and remote sensing survey, where the field data are used to validate the remote
sensing results and to collect any biomass and supporting data;
— remote sensing survey. It is recommended that this approach is conducted by an experienced
surveyor or for pilot surveys (see 5.3) only as the results are not validated by ground- truth data.
Table 1 indicates the suitability in relation to scale of area of a number of different approaches.
However, methods are dependent on specific aims of the survey and restrictions in available survey
resources.
Table 1 — Decision matrix for the suitability of littoral/intertidal sampling methods for
macroalgae and angiosperms (H = high suitability, M = moderate suitability, L = low suitability,
N = not suitable)
Direct visual
Visual aerial Digital aerial
a a
field sampling/
Area
Aerial photo Satellite
a, b a
survey sensor
mapping only
km
< 0,01 H M M N N
0,01 to 1 H-M H-M H-M H N
1 to 100 M H H H M
> 100 L H H H H
a
Require ground validation.
b
Directly recorded by personnel in the field.
See Table A.1 for more information on aerial methods.
5.2 Timing and frequency of sampling
For baseline monitoring (see 5.4), sampling shall be carried out at least once in the year within the peak
vegetation period. This will vary with latitude, and thus should be based on local knowledge. At
important bird sites, consideration should be given to ensure minimum disturbance to birds. It should
be noted that the arrival of geese can lead to a reduction on bed extent (particularly seagrass) due to
grazing.
For trend monitoring (see 5.5), sampling shall be carried out at least once every two or three years. The
investigation shall include the peak vegetation period.
Aerial surveys and ground surveys shall be undertaken preferably synchronously, at least within a
restricted period of time between the two survey types. For aerial surveys where the field data are key
to validating the aerial imagery, e.g. when using multispectral imagery, aerial flights and ground
truthing surveys shall be no more than three weeks apart.
Aerial and ground surveys shall avoid quantitative surveys during the period of plant breakdown, as
highly variable results will be obtained.
5.3 Pilot survey
Initial visual surveys or predictive models may be used to locate areas of angiosperms and macroalgae
beds in order to focus a baseline mapping survey. This can also be achieved using existing aerial or
satellite images, etc. These surveys may not accurately quantify density, biomass or species
composition.
Such surveys assist the planning of the more detailed surveys and help focus remote sampling
programmes or data collection, ensuring they are cost effective. They may also be useful in confirming a
lack of significant plant cover in some locations.
Methods appropriate to this work include:
— analysis of recent remote sensing images. The value of this will depend on the age and optical
resolution of the images;
— optical surveys of the intertidal environment e.g. using telescopes from a high point or vessel
nearby. Typically, a survey done obliquely will foreshorten the view and provide an underestimate
of extent of cover.
5.4 Baseline survey
Baseline surveys are carried out to determine the distribution, extent and density of angiosperms and
macroalgae beds.
Repeat surveys in subsequent years may be necessary to establish temporal trends in extent or density
of plants. Detailed analyses shall be carried out on mapping the
— size, shape and position of beds;
— abundance which can be represented by density (as a percentage) of cover or shoot density or
biomass (g or kg/m ) as wet weight or dry weight of macroalgae or seagrass;
— species composition;
— other environmental parameters such as epiphyte cover or sediment type, etc.
The survey provides the basis for characterizing environmental conditions in the relevant areas in
accordance with set criteria or by comparison with angiosperms or macroalgae communities in other
representative areas. The requirements for scientific documentation and replicability are relatively
high.
The surveys shall be carried out using quantitative methods. The suitability of any remote sensing
methods should be considered (see Annex A). There shall be specified requirements for numbers of
stations, which is determined in accordance with the aims of the investigation (the geographical
resolution required) and the size and variation of density and extent of cover in the area to be mapped.
The principal aim should be to obtain an appropriate number of records that adequately reflect the
variation in density and cover for the algae and angiosperms within the waterbody. Care shall also be
taken not to oversample small beds as this could lead to destruction of the bed through trampling.
The detailed survey design shall be a regular (e.g. grid, transect along a depth contour), random or
random stratified approach. Randomly stratifying the survey design in the field will allow for more
effective use of resources and produce less variability in results where density or cover of beds is
complex.
Methods shall be chosen such that the data can be used as a basis for comparison with baseline surveys
in other areas. The design of the surveys shall be appropriate to match the level of accuracy and
precision required. Validation by ground-truthing is required when remote sensing options are chosen.
Remote sensing methods should be chosen that provide suitable representative information, for
example digital aerial sensors, aerial photography or satellites. Suitable new platforms for sensors may
emerge as technology develops in this area e.g. use of unmanned aerial vehicles.
See Annex A for more information on existing remote sensing options. The resolution of the aerial
images shall match the survey objectives.
5.5 Temporal trend monitoring
In areas where potential changes in environmental conditions are to be monitored, such as in impacted
areas or where there are activities that may cause environmental impacts, a baseline survey shall first
be carried out, and then follow-up monitoring surveys. Local knowledge may be used to add to the data
collected.
The survey data collected should allow production of a temporal description of natural variations of the
extent and abundance of the angiosperms and macroalgae beds communities and document any
gradual changes (trend monitoring). The survey shall be carried out to a specific survey design and
follow a carefully defined method.
The options for detailed survey design should follow those defined for baseline surveys.
5.6 Specialized surveys
Specialized surveys are recommended to assess the health of seagrass and macroalgal beds and any
associated impact of extensive macroalgal growth on infaunal communities. In these surveys, additional
measurements will need to be collected.
Surveys may include sediment particle size information and benthic infaunal community abundance
and species composition. For guidance on sampling soft sediment macrofauna, see EN ISO 16665 [5].
For seagrass health investigations, additional information on the extent of the protist disease causing
seagrass die-back should be considered as well as physical and environmental data. Environmental data
to consider collecting includes salinity, nutrient, turbidity, particle size, oxygen, and temperature data.
Hydromorphological data such as physical disturbance should also be considered.
6 Equipment
6.1 General
The lists in 6.2, 6.3 and 6.4 indicate the equipment that may be required for a field or aerial based
survey.
WARNING — Working shall be done with care. Risks associated with such work shall be managed and
all phases of the investigation should conform to current health and safety regulations. All personnel
shall be trained in safe working procedures. Appropriate protective equipment shall be available.
6.2 Field survey
At the beginning of a survey it should be checked that the equipment is in good condition, without
damage to the grids and that the weighing scales have been calibrated and are in good working
condition.
All equipment shall be operated in accordance with the relevant vendor’s instruction manual and shall
be maintained and cleaned in such a way that the equipment functions flawlessly. The equipment
should be serviced as required.
Equipment required will vary according to the type of survey methodology but may include:
6.2.1 Boat or light hovercraft, with safety equipment.
6.2.2 Global Positioning System (GPS) device or Differential Global Positioning System (DGPS)
for higher accuracy.
6.2.3 Secchi disc, according to EN ISO 7027-2.
6.2.4 Thermometer/salt content sensor.
6.2.5 Sampling frames.
2 2
6.2.6 Quadrats, between the size range of 0,25 m and 2 m .
The area of the quadrats is dependent on the complexity and homogeneity of the beds under
investigation. When surveying a new location, the recommended minimum quadrat sizes that could be
used are given in Table 2. Once this initial data are obtained alternative size quadrats may be used if it is
proven to meet the data requirements of the survey in those beds.
Table 2 — Recommended quadrat sizes for new surveys
Patchy or mixed species beds Continuous uniform beds
1 m (subdivided into a minimum
Seagrass 0,25 m quadrat
of four 0,5 m × 0,5 m squares) quadrat
2 2
Macroalgae
0,25 m subdivided quadrat 0,25 m subdivided quadrat

6.2.7 Corer/sampling tube (minimum size: 0,01 m ), for soft substrates and sub-bottom biomass.
6.2.8 Waterproof report form.
6.2.9 Specimen bag with markings.
6.2.10 Specimen storage bottles.
6.2.11 Waterproof digital camera, with at least 3 megapixel resolution.
6.2.12 Specimen ID labels, that allow each picture to be allocated to the relevant sampling frame;
colour comparison tables or compartments.
6.2.13 Analog compass.
NOTE Directions measured by compass in the field can be wildly inaccurate due to the effect of magnetic
deflection.
6.2.14 Blade or spatula, for biomass sampling.
6.2.15 Cooler, for storage of biomass samples.
6.2.16 Sampling record.
6.3 Equipment for species identification in the laboratory
The following equipment may be used for species identification in the laboratory:
6.3.1 Illuminated magnifier.
6.3.2 Stereo magnifier/binoculars, with a minimum of 40x magnification.
6.3.3 Cold light source.
6.3.4 Transmitted-light microscope, with a minimum of 40x magnification, a measurement
eyepiece and a lens micrometer.
6.3.5 Microphotographic equipment/microscope camera.
6.3.6 Dissecting set, for sorting botanical specimens and making microscope slides.
6.3.7 Suitable measuring equipment, for plant measurements such as measuring tape, ruler, and
measurement eyepiece.
6.3.8 Specimen storage bottles (wide-necked bottles made of clear glass or plastic).
6.3.9 Exhaust hood, for investigation of formaldehyde conserved samples.
6.3.10 Dispenser.
6.3.11 Sorting pans and dishes.
6.3.12 Specimen vials.
6.3.13 Microscope slides and cover glasses.
6.3.14 Stains, for pyrenoids and cell nuclei.
6.3.15 Sealing film.
6.3.16 Taxa identification record.
6.3.17 Identification keys and field guides.
6.4 Equipment for direct biomass assays
The following equipment may be used for biomass assays:
6.4.1 Scale with a measurement to the nearest 0,1 g;
6.4.2 Drying cabinet, whose operating temperature range is from +30 °C to +250 °C, equipped with a
fan, temperature selector, and temperature control display.
6.4.3 Muffle furnace, whose operating temperature range is from +200 °C to +1 000 °C, equipped
with a fan, temperature selector, and temperature control display.
6.4.4 Tweezers, needles and pipettes.
6.4.5 Sorting pans and dishes of various sizes.
6.4.6 Mesh bags or sieves for sample washing or draining.
6.4.7 Blotting paper.
6.4.8 Biomass recording sheet.
6.5 Aerial remote sensing surveys
The equipment used in aerial remote sensing shall meet the objectives of the survey in terms of
accuracy, precision and resolution. It will also need to be a practicable option for the survey area. Height
and access of aircraft or satellite path will be limited in some locations. See Annex A for remote sensing
options.
Since cloud cover can interfere with any type of aerial survey imagery, the amount of cloud cover
between the sensor and the ground should be considered in planning data capture. Resolution can be
affected by the devices used, but to obtain high accuracy data a high resolution is required which can be
met by 50 cm or less.
6.6 Visual aerial surveys
Printed map(s) of the survey area (scale depends on the altitude: 1:50 000 — 1:100 000) should be
used to ease visual orientation. Preferably made from satellite images and/or aerial photos.
7 Chemicals
Unless otherwise indicated, all chemical purity grades indicated here are the equivalents of the p. A.
grade for spectroscopic purposes. The following chemicals may be used:
7.1 37 % to 41 % aqueous formaldehyde solution, industrial (formalin, HCHO, fixing agent); the
standard dilution is 4 %. This solution is to be buffered with borax that is to be added until pH > 7 is
reached, for fixation;
7.2 Borax (sodium tetraborate, Na B O · 10 H O), industrial, for buffering.
2 4 7 2
7.3 Ethanol (C H OH) 70 % and 96 %, industrial, denatured, for preservation.
2 5
7.4 Mayers hematoxylin solution, for cell nucleus staining, as follows: Dissolve 50 g aluminium
ammonium sulphate (Alumn, (NH )Al(SO ) · 12 H O) in 1 000 ml demineralized water and add 1 g
4 4 2 2
certified hematoxylin (C H O ). Applying gentle heat and stirring may enhance the dissolution.
16 14 6
— When the hematoxylin is completely dissolved, add 0,2 g sodium iodate (NaIO ).
— After the sodium iodate is dissolved, add 50 g chloral hydrate (C H Cl O ) and 1 g anhydrous acetic
2 3 3 2
acid (C H O ) before bringing the mixture to boil and let cool to room temperature.
2 4 2
— Any precipitate should be removed by decanting or filtering the solution before use.
1 g/l certified hematoxylin;
— 0,2 g/l sodium iodate;
— 50 g/l aluminium ammonium sulphate ⋅ 12 H O;
— 50 g/l chloral hydrate;
— 1 g/l acetic acid.
7.5 Carmine acid, for cell nucleus staining, prepared as follows:
— Add 2 g carmine powder to a 100 ml 45 % aqueous acetic acid solution, heat under reflux at a slow
boil for one hour;
— filter after allowing to cool and store in a dark coloured bottle.
7.6 Iodine solution (Lugol's solution, 50 g/l), for starch detection, prepared as follows:
Weigh out 100 g of permanganate iodide in a 1 000 ml graduated flask and stir in the minimum amount
of distilled water necessary to obtain a clear solution. Add 50 g of resublimated iodine and stir until all
of the iodine has been dissolved in the solution. Fill the flask with distilled water to the 1 000 ml mark.
8 Survey procedures
8.1 General principles
All procedures shall be described, and all tasks and parts of the work shall be performed in a
standardized and reproducible way. The investigation shall be undertaken by qualified personnel with
relevant experience in this field.
A trip leader shall be designated for each sampling or mapping campaign that plans and coordinates the
activities and assumes responsibility for ensuring that all relevant work procedures are adhered to.
All equipment shall be checked prior to each campaign, and it is recommended to bring along spare
equipment for particularly lengthy sessions.
Prior to each survey action, certain target-area parameters shall be determined that characterize local
conditions as well as sampling related conditions. Aerial photographs of the target area and of specific
biological characteristics could be helpful.
The survey area shall be defined. The survey areas may be limited to suitable habitats for growth.
European Directives such as the Water Framework Directive or other survey objectives may define
location and scope of survey areas.
Local knowledge may be used to add to the data collected.
8.2 Field mapping and sampling using quadrats
8.2.1 Recording
The following information and accompanying parameters should be recorded
— name of the area being investigated;
— names of all investigators;
— type of positioning system used (projection, reference ellipsoid, or geodetic data such as WGS 84;
notation and the accuracy of this system);
— coordinates of the area being investigated;
— date, time (UTC);
— type and specifications of the sampling frame as overall and internal grid size;
— biomass areas investigated.
8.2.2 Quadrat numbers and positioning
8.2.2.1 General
The design of quadrats should be appropriate to the objectives of the survey and the likely variability of
the vegetation [10]. Where seagrasses and macroalgae beds grow together in one location, then the
differentiation of both groups by mean of aerial images may be difficult. The quadrat surveys may need
to be more resource intensive in these situations.
Where possible, quadrat number and size shall be determined before sampling. The number and size of
quadrats taken will depend on the precision required, without incurring excessive survey resource. To
determine the variance acceptable for the survey, a number of quadrats shall be chosen, and their
coefficient of variation compared. If it is not possible to obtain data from the survey location in advance,
representative data from a similar site may be used. Consideration should also be given to protecting
seagrasses, which can be damaged by surveyors. Oversampling should be avoided. Seagrasses should be
left in situ and sample sites may need to be changed to reduce the amount of walking across beds.
For regular survey designs, quadrats should be placed at predetermined points in a grid or along a
transect. For other survey designs, at the required location the quadrat should be randomly placed. This
shall be achieved by throwing the quadrat without previously observing the point in which it is to be
thrown. For sublittoral surveys, guidance given in EN ISO 19493 [7] may be applicable. The location of
the quadrat should be fixed using GPS.
Photographic images should be collected to allow quality checks of a proportion of the data on entry to
the database, see EN 14996 [2].
8.2.2.2 Regular design
To determine abundance in the intertidal environment, depth and salinity may have a reduced influence
on abundance. A transect approach, effectively forming a grid, throughout the intertidal environment is
an unbiased approach; as is a random, stratified approach with pre-determined points.
This regular approach can be resource intensive and may miss out key areas of interest. A more
appropriate method may be a random stratified design (see 8.2.2.4).
8.2.2.3 Random design
Quadrats are located randomly across the bed. The random nature ensures it is relatively unbiased, and
it provides a broad assessment, but it may be more resource intensive to obtain an acceptably low
coefficient of variability. There is still a risk of missing out key areas of interest.
8.2.2.4 Random stratified design
Quadrats are located randomly within predetermined areas of varying plant density in the survey area.
This patch approach is less resource intensive but will retain some bias. This approach can be more
precise than an absolute random approach as it ensures sampling occurs in representative areas. It
ensures key areas of interest are included and statistical differences between areas can be found.
8.2.2.5 Position fixing
Correct positions are important in establishing absolute boundaries of a bed or to contribute to
assessing relative positions for calculating extent. They are also important in accurately locating points
obtained by remote sensing for ground truthing. For either approach, knowledge of the accuracy of the
position is important. Positional accuracy should be maximized in accordance with the objectives and
survey design.
Positional accuracy on the ground is largely dependent on the equipment used, interference with “line
of sight” and atmospheric conditions. When using hand-held GPS devices consideration should be given
to the quality and type of device and its set up such as tracking intervals and operation. In each case the
following should be noted:
— geographic spatial location with clear reference to which geodetic datum was used;
— accuracy (with only results above a given accuracy used).
Set up should be standardized between operators for specific types of survey and the operator should
be trained in its proper use. Acceptable positional accuracy should be reached by the use of up to date
GPS techniques. Specialist knowledge is required to obtain and to georeference remotely sensed data.
When tracking the boundary of a bed, fixing or locating position for quadrat records, positional
accuracy will need to be defined and recorded. The acceptable positional accuracy on a device will be
less than the true accuracy. A minimum acceptable positional accuracy will depend on the survey
objectives but should be < 5 m.
The position of sampling stations shall be defined unambiguously, such that they can easily be relocated
by others. Positions shall be defined using geographic coordinates and in accordance with a reference
system (e.g. European Datum: ED-50, World geodetic System: WGS-84), and also in relation to the UTM-
system if appropriate.
When sampling near landmarks that can be relocated at low water, additional distance and bearing
information may be taken to improve site relocation and positional accuracy. This shall be done where
GPS devices are unable to provide an acceptable accuracy.
8.2.3 Determination of coverage within quadrats
In determining percentage coverage only, the plant components within the quadrat frame shall be
assessed. Multiple flora layers shall be assessed by the coverage determination of each taxon in the
topmost layer first. Then the frame should be lifted, and this topmost layer should be carefully pushed
aside. Then the frame shall be put back in its original position and the coverage for the next layer is
determined, likewise for each taxon. Finally, depending on the survey objectives, the sediment
composition should be described. This may be recorded as percentages of sediment category. Total
coverage, coverage of epiphytes and coverage of each taxon shall be determined. As this method
involves three-dimensional coverage measurements, the individual flora components may add up to
more than 100 %. Any drifting algae that are clearly not part of the investigation area should be
excluded. However, it can be recommended to measure the coverage and main components of these
algae. The percentage of bare ground should also be measured.
NOTE Some macroalgal species such as Chaetomorpha ligustica are devoid of rhizoids and can float freely or
be trapped by other plants.
Photographic documentation of the sampling location and the various vegetation layers may be
necessary depending on the matter being investigated and the specifications of the investigation. In
such cases, each of the various sampling locations (parallels) should be identified.
Inter-operator variability should be minimized by:
— the application of an approach that delivers highly repeatable results e.g. presence and absence at
specified point on a gridded quadrat, or
— via the comparison and agreements of more than one operator’s data at each location.
The second approach can still be open to variability as subsequent surveys may produce different
results with different operators and should only be used if the consistency and experience of operators
is high.
Judging percentage cover by eye can be subjective. Consistency is difficult to achieve especially for those
with limited experience of estimating cover. To minimize variability a standard approach should be
implemented. Image processing software may also be used to determine area of cover. There should be
validation of data obtained in this way.
EXAMPLE Gridded quadrat. The grid is 9 × 9 i.e. 100 squares, but 81 cross-hairs, see Figure 1. Below each of
the 81 cross-hairs field surveyors record a 0 or 1 depending on whether algae are absent or present respectively.
The number of cross hairs with algae present is divided by 81, and then multiplied by 100 to give a percentage.
Percent cover refers only to the visible surface percent cover.

Figure 1 — Gridded quadrat
8.2.4 In situ species determination and biomass measurements
For removal of samples for biomass measurements, the sample shall be extracted from within the area
of the quadrat. It may not be appropriate to remove seagrasses for biomass – as far as possible they
should be assessed in situ only. A blade is used to harvest the macroalgae present by removing the
macroalgae layer on the surface. Information may also be required on the macroalgae entrained (i.e.
well embedded to > 1,5 cm or more) within the sediment itself, in this case ensure the macroalgae
embedded within the sediment is all extracted separately (as below-ground biomass).
Biomass and species determination of fresh material should be carried out within 24 hours following
sample collection if possible. During this period, th
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