Water quality - Guidance on marine biological surveys of hard-substrate communities (ISO 19493:2007)

ISO 19493:2007 provides guidance for marine biological surveys of supralittoral, eulittoral and sublittoral hard substrate for environmental impact assessment and monitoring in coastal areas. It comprises development of the sampling programme, survey methods, species identification and storage of data and collected material.
ISO 19493:2007 specifies the minimum requirements for environmental monitoring.
The methods are limited to surveys and semi-quantitative and quantitative recording techniques that cause little destruction of the fauna and flora. In practice, this refers to direct recording in the field and photography. Sampling by scraping off organisms, use of a suction sampler, etc. are not covered in ISO 19493:2007.

Wasserbeschaffenheit - Anleitung für meeresbiologische Untersuchungen von Hartsubstratgemeinschaften (ISO 19493:2007)

Diese Internationale Norm enthält Anleitungen für marine biologische Untersuchungen auf supralitoralem, eulitoralem und sublitoralem Hartsubstrat zur Ermittlung von Umwelteinflüssen und zur Umweltüberwachung in Küstenbereichen.
Diese Internationale Norm beinhaltet:
   das Aufstellen eines Probenahmeprogramms;
   die Untersuchungsverfahren;
   die Bestimmung der Taxa und
   die Speicherung der Daten und die Lagerung des gesammelten Probenmaterials.
Diese Internationale Norm legt die Minimalanforderungen für Umweltüberwachungsaufgaben fest.
Die Verfahren erstrecken sich nur auf Untersuchungen und halbquantitative und quantitative Techniken, die die Flora und Fauna nur wenig beeinträchtigen. In der Praxis entspricht dies der direkten Erfassung vor Ort und der fotografischen Dokumentation. Probenahmen, bei denen Organismen abgekratzt oder durch Ansaugtechniken usw. gesammelt werden, sind in dieser Internationalen Norm nicht berücksichtigt. Solche Verfahren können allerdings ergänzend für kleine oder versteckt lebende Taxa eingesetzt werden.

Qualité de l'eau - Lignes directrices pour les études biologiques marines des peuplements du substrat dur (ISO 19493:2007)

L'ISO 19493:2007 fournit des lignes directrices pour conduire des études biologiques marines du substrat dur supralittoral, eulittoral et sublittoral afin d'évaluer et de surveiller l'impact environnemental dans les zones côtières. Elle couvre le développement du programme d'échantillonnage, les méthodes d'étude, l'identification des espèces, le stockage des données et la conservation du matériel collecté.
L'ISO 19493:2007 spécifie les exigences minimales relatives à la surveillance de l'environnement.
Les méthodes se limitent aux études et aux techniques d'enregistrement semi-quantitatives et quantitatives qui engendrent une destruction mineure de la faune et de la flore. Dans la pratique, elles s'appliquent à l'enregistrement direct sur le terrain et à la photographie. L'ISO 19493:2007 ne couvre ni les prélèvements d'organismes par raclage, ni l'utilisation d'un échantillonneur aspirant ou analogue.

Kakovost vode - Navodilo za biološki pregled morskega litorala/obrežnega pasu in sublitoralnega trdnega dna (ISO 19493:2007)

General Information

Status
Published
Publication Date
14-Jun-2007
Technical Committee
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
15-Jun-2007
Completion Date
15-Jun-2007

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SLOVENSKI STANDARD
SIST EN ISO 19493:2007
01-december-2007
Kakovost vode - Navodilo za biološki pregled morskega litorala/obrežnega pasu in
sublitoralnega trdnega dna (ISO 19493:2007)

Water quality - Guidance on marine biological surveys of hard-substrate communities

(ISO 19493:2007)
Wasserbeschaffenheit - Anleitung für meeresbiologische Untersuchungen von
Hartsubstratgemeinschaften (ISO 19493:2007)
Qualité de l'eau - Lignes directrices pour les études biologiques marines des
peuplements du substrat dur (ISO 19493:2007)
Ta slovenski standard je istoveten z: EN ISO 19493:2007
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
SIST EN ISO 19493:2007 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
EUROPEAN STANDARD
EN ISO 19493
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2007
ICS 13.060.10; 13.060.70
English Version
Water quality - Guidance on marine biological surveys of hard-
substrate communities (ISO 19493:2007)

Qualité de l'eau - Lignes directrices pour les études Wasserbeschaffenheit - Anleitung für meeresbiologische

biologiques marines des peuplements du substrat dur (ISO Untersuchungen von Hartboden-Lebensgemeinschaften

19493:2007) (ISO 19493:2007)
This European Standard was approved by CEN on 9 June 2007.

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 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 Management Centre has the same status as the

official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,

Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels

© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 19493:2007: E

worldwide for CEN national Members.
---------------------- Page: 2 ----------------------
EN ISO 19493:2007 (E)
Foreword

This document (EN ISO 19493:2007) has been prepared by Technical Committee CEN/TC 230

"Water analysis", the secretariat of which is held by DIN, in collaboration with Technical

Committee ISO/TC 147 "Water quality".

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 December 2007, and conflicting national

standards shall be withdrawn at the latest by December 2007.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of

the following countries are bound to implement this European Standard: Austria, Belgium,

Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece,

Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United

Kingdom.
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INTERNATIONAL ISO
STANDARD 19493
First edition
2007-06-15
Water quality — Guidance on marine
biological surveys of hard-substrate
communities
Qualité de l'eau — Lignes directrices pour les études biologiques
marines des peuplements du substrat dur
Reference number
ISO 19493:2007(E)
ISO 2007
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ISO 19493:2007(E)
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ii © ISO 2007 – All rights reserved
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ISO 19493:2007(E)
Contents Page

Foreword............................................................................................................................................................ iv

Introduction ........................................................................................................................................................ v

1 Scope ..................................................................................................................................................... 1

2 Terms and definitions........................................................................................................................... 1

3 Quality and safety................................................................................................................................. 3

4 Strategies and objectives for hard-substrate surveys...................................................................... 4

5 Sampling................................................................................................................................................ 8

6 Taxon identification and sample processing................................................................................... 11

Annex A (normative) Description of methods............................................................................................... 13

Annex B (informative) Field recording form .................................................................................................. 17

Annex C (informative) Biological definition of the supralittoral, eulittoral and sublittoral zones ........... 18

Annex D (informative) Basis for the choice of semi-quantitative surveys in a standard ......................... 19

Annex E (informative) Detailed method for calculating level of exposure ................................................. 20

Bibliography ..................................................................................................................................................... 21

© ISO 2007 – All rights reserved iii
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ISO 19493:2007(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies

(ISO member bodies). The work of preparing International Standards is normally carried out through ISO

technical committees. Each member body interested in a subject for which a technical committee has been

established has the right to be represented on that committee. International organizations, governmental and

non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the

International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 19493 was prepared by the European Committee for Standardization (CEN) Technical Committee

CEN/TC 230, Water analysis, in collaboration with Technical Committee ISO/TC 147, Water quality,

Subcommittee SC 5, Biological methods, in accordance with the Agreement on technical cooperation between

ISO and CEN (Vienna Agreement).
iv © ISO 2007 – All rights reserved
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ISO 19493:2007(E)
Introduction

Surveys of benthic marine algae and fauna on hard substrates represent an important part of marine

environmental surveys. The species composition, both in terms of the species present and their relative

abundances, is a result of the natural and anthropogenic environmental factors at the survey site. Natural

factors that influence species composition include wave exposure, depth, salinity, nutrient level, type of

substrate, slope, orientation, turbidity, current, temperature and grazing. Anthropogenic factors include

pollution (e.g. oil, contaminants, particles), physical disturbance, elevated nutrient levels and effects from

fisheries.

A number of different methods are being used to investigate flora and fauna on hard substrate according to

the survey aim and the type of biotope surveyed. To allow environmental authorities and others to make use

of this knowledge, it is essential that surveys are intercomparable in time and space, as well as between

operators, and that the data are of a high quality. This International Standard is based on a limited selection of

methods that allow precise documentation, that are replicable and which have been tested over many years.

In choosing methods for this standard, semi-quantitative and quantitative techniques have been emphasized,

such that species and quantities can be related to a known area of sea floor.

For the purposes of this International Standard, hard substrate is defined as bedrock, stable rocks and fixed

marine constructions (e.g. pipelines and quays). The main focus is on biological surveys based on species

that can be recorded in the field (i.e. that are visible to the naked eye).

The guidelines are applicable to seagrass communities and their epiflora and epifauna. They can also be used

for surveys of stable substrates comprising loose pebbles/boulders, stone blocks, coarse gravel and other

loose material as well as bedrock covered with loose sediment, but in general, such substrates require

specially adapted techniques. Additional methods are usually required for surveys in depths greater than

approximately 30 m.

For sediment sampling in marine areas, refer to ISO 5667-19. For surveys of sublittoral soft-bottom fauna, see

ISO 16665.
© ISO 2007 – All rights reserved v
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INTERNATIONAL STANDARD ISO 19493:2007(E)
Water quality — Guidance on marine biological surveys of hard-
substrate communities
1 Scope

This International Standard provides guidance for marine biological surveys of supralittoral, eulittoral and

sublittoral hard substrate for environmental impact assessment and monitoring in coastal areas.

This International Standard comprises
⎯ development of the sampling programme,
⎯ survey methods,
⎯ species identification, and
⎯ storage of data and collected material.

This International Standard specifies the minimum requirements for environmental monitoring.

The methods are limited to surveys and semi-quantitative and quantitative recording techniques that cause

little destruction of the fauna and flora. In practice, this refers to direct recording in the field and photography.

Sampling by scraping off organisms, use of a suction sampler, etc. are not covered in this International

Standard, but such techniques can be used as a supplement to obtain information on small-sized species or

those that live hidden.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
area of influence
area influenced or expected to be influenced, based on the available information
2.2
biotope

area of uniform environmental conditions (habitat) and its characteristic assemblage of plant and/or animal

species

EXAMPLE Laminaria hyperborea community (cuvie or tangleweed), knotted wrack community, blue mussel belt.

2.3
macroscopic organisms

algae and animals that are visible without magnification equipment (W 1 mm) and which can be recorded in

the field

NOTE Certain macroscopic organisms can require microscopic inspection for identification. For microscopy of

collected material, the lower size limit is set to 1 mm.
© ISO 2007 – All rights reserved 1
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ISO 19493:2007(E)
2.4
hard substrate

substrate consisting of bedrock, larger rocks/stones or fixed marine constructions such as wharfs, quays and

pipelines

NOTE For the purpose of this International Standard, hard substrate can also include other substrates that are not

likely to be moved or turned over during a reasonable time period so that perennial species communities are likely to

develop (e.g. pebbles and stones in sheltered environments).
2.5
hard substrate flora and fauna

attached algae and animals, together with relatively stationary animals living on or in close association with

hard substrate

EXAMPLE Attached: kelp, seaweeds, sponges, bryozoans, corals, mussels, barnacles, ascidians. Relatively

stationary: snails, sea-urchins, crabs.
2.6
supralittoral zone
zone above the eulittoral zone, which is reached by spray water

NOTE Its upper limit is normally determined by the upper limit of Verrucaria (black lichen belt), blue-green algae

(usually Calothrix scopulorum) or littorinid snails.
2.7
eulittoral 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 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.

2.8
sublittoral zone

zone below the eulittoral zone, which is submersed with the upper part at extreme low water levels

occasionally emerging

NOTE 1 In this International Standard, the lower limit is set by the deepest occurring algae.

NOTE 2 This is also referred to as the subtidal zone.

NOTE 3 Biologically, this zone is defined as the zone between the upper limit of laminarians and the lower limit of algal

vegetation (see Annex C).
2.9
level of exposure
level of wave and current exposure at a site
2.10
receiving water body

water body which receives an input of material, of either natural or anthropogenic origin

NOTE The term often appears in the context of contamination (for example effluent from municipal waste water

outlets or industrial processed water). Receiving water body surveys describe the state of contamination in a given area.

2.11
sampling station
precise location where recording is carried out and any samples collected

NOTE A sampling station is defined by its geographical position (OS National Grid Reference, latitude, longitude), its

depth (relative to chart datum and normalized to mean low water as given in tide tables) and any other information on

physical conditions (e.g. substrate type, slope and orientation).
2 © ISO 2007 – All rights reserved
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ISO 19493:2007(E)
2.12
reference station

one or more sampling stations chosen to represent environmental conditions in a given area, i.e. free from

direct anthropogenic influences
2.13
baseline survey

survey with emphasis on characterization and description of biotic and abiotic conditions in the survey area,

and which forms the basis for future monitoring and/or follow-up surveys
2.14
temporal trend monitoring

surveys of the hard substrate community in response to temporal changes in chemical and/or physical

conditions in the surrounding waters to document either pollution or natural variation over time

2.15
ROV
Remotely Operated Vehicle

remote-controlled underwater vehicle with video camera and often the possibility for mounting additional

equipment such as sonar, manipulator arm, etc.
3 Quality and safety
3.1 Health and safety requirements
3.1.1 General

All phases of hard substrate field work and sample processing should adhere strictly to national and

international health and safety regulations. The main points are listed below.
3.1.2 Laboratory safety facilities

A valid health and safety manual should be freely available in the institute or laboratory and the appropriate

first aid supplies and emergency facilities (such as an eyewash station and a shower) should be installed. The

laboratory and storage areas should further be equipped with point-ventilation outlets and preferably have a

monitor for chemical levels in the air.
3.1.3 Requirements for diving

For surveys that require diving, this should be carried out in accordance with the appropriate rules and

regulations. The diver and others participating in the diving work are required to follow the national or

international regulations implemented for the prevention of accidents and health risks. Diving and

communication equipment should fulfil the relevant requirements. A guide to planning and carrying out

scientific diving operations is given in Reference [2]. Persons participating in diving should have the necessary

certificates and official approval from the national authorities.

NOTE See also European Standards for Scientific Diving (European Scientific Diver and Advanced European Scientific

Diver) http://www.soc.soton.ac.uk/OTHERS/SDSC/ESD_AESD%20Standards.pdf.
3.1.4 Field safety

Work should not be undertaken alone. Risk assessments should be addressed for the specific locations where

a survey is being undertaken.
© ISO 2007 – All rights reserved 3
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ISO 19493:2007(E)

All personnel collecting and handling samples should be given training in the appropriate health and safety

procedures and, where in force, have attained certification status. Refresher training should be carried out

regularly. Staff should be trained in assessing risk to personnel or equipment and should follow any

documented procedures.
3.1.5 Handling of chemicals

Chemicals used for fixing or preserving samples should be stored and handled with proper precautions

according to health and safety regulations. Non-drip dispensers should be used for liquid chemicals.

Common chemicals used in hard substrate samples include the fixative formalin or substitutes, the

preservative ethanol and biological stains.

WARNING — Formalin is particularly hazardous to health, and prolonged or intense exposure can

cause long-term allergies. A number of less hazardous, but expensive, alternatives to formalin are

available and should be used where possible, especially when dealing with small sample volumes.

3.2 Quality assurance and quality control
3.2.1 General

Quality assurance and quality control measures should be incorporated during all stages of marine biological

surveys and sample processing programmes. These principles help to guarantee that all data produced are of

a specific quality and that all parts of the work are carried out in a standardized and intercomparable manner.

All procedures should therefore be clearly described and carried out openly, such that all of the laboratory’s

activities can be audited internally and externally at any time (see EN 14996).

NOTE The overall aim is to assure traceability and full documentation of field registration procedures, samples and

equipment from beginning to end.

National and/or international accreditation should be sought if appropriate; this is required for most

commercially operated laboratories. Guidance from relevant accreditation bodies should be sought in

developing specific in-house quality systems, work procedures and protocols. It is recommended that the

laboratories participate in intercomparative tests or learning schemes to develop expertise and maintain

appropriate skills. This ensures continued standardization and reproducibility of results.

3.2.2 Scientific requirements for personnel

The surveys should be carried out by appropriately qualified personnel (marine zoologists/marine botanists).

They should be able to document competence in their specialist field and regular structured training and

participate in ring-testing. For surveys spanning several years, priority should be given to continuity in

personnel carrying out the recordings.
4 Strategies and objectives for hard-substrate surveys
4.1 Sampling programme and plan

The sampling programme should be developed according to the individual aims of the survey, the required

precision of the results, local topographical and hydrographical conditions in the survey area, information

about local pollution sources, knowledge from previous surveys and any other conditions that can be of

importance for the survey. For guidance on the design of sampling programme, see ISO 5667-1. The

sampling programme should be determined before the survey is initiated, but appropriate adjustments may be

made in the field, particularly for a pilot survey (see 4.3.2).
4 © ISO 2007 – All rights reserved
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ISO 19493:2007(E)

Surveys in partly eulittoral and sublittoral zones require different equipment and techniques. Eulittoral zone

surveys are the easiest to carry out and require the least resources since surveys can normally be undertaken

at low tide. Surveys in the sublittoral zone usually involve SCUBA-diving or different ROV-techniques. This

International Standard describes a limited variety of different eulittoral and sublittoral survey methods. A

detailed description of the recording methods is given in Annex A.

NOTE Detailed guidance on sampling programmes and methods is also given in the Marine Monitoring Handbook

(http://www.jncc.gov.uk) and the Swedish EPA

(http://www.naturvardsverket.se/upload/02_tillstandet_i_miljon/Miljoovervakning/undersokn_typ/hav/vegbotos.pdf).

4.2 Positioning of sampling stations
4.2.1 General

Sampling stations should be positioned according to the particular aims of the individual survey, previous

surveys in the area and local topographical and hydrographical conditions. The hard-substrate community

structure depends on wave exposure, type of substrate, compass direction, bottom slope, water depth and

salinity. This shall be taken into account when locating the sampling and reference stations and when

comparing different areas and localities.

The sampling stations should preferably be placed in areas of hard rock or other stable substrate. Areas with

heterogeneous bottom conditions are difficult to record accurately and should be avoided. Particular attention

should be given to station positioning in areas exposed to fresh water seeps, desiccation, ice scouring or other

factors providing highly unstable conditions.

When surveys are made over time, the stratum (or strata) of the observations should be kept constant (fixed

site and depth) to minimize structural variation as the temporal variation is the only one of interest. Biotopes

that have little natural variation in species composition over time are best suited for temporal trend monitoring

[e.g. perennial communities like the knotted wrack community (Ascophyllum nodosum)].

For environmental descriptions and temporal trend monitoring, a pilot survey should be carried out before

sampling station positioning.
4.2.2 Strategies for locating sampling stations

Sampling stations can be located according to one or a combination of the following strategies.

⎯ Random sampling. In special circumstances, sampling stations may be positioned randomly or scattered.

For example, random sampling is used when no previous knowledge of the area is available as a guide to

appropriate stratification, or when an unbiased value for a whole area is desired.

⎯ Stratified random sampling. Based on a priori subdivision of the study area. The subdivisions may be

delineated according to depth, substrate type, wave exposure or other factors. This ensures that all the

main habitat types present on a site will be sampled and is the recommended strategy in most cases.

⎯ Systematic/grid sampling. Sample stations are arranged in a regular grid-like pattern. This arrangement

is appropriate for pilot surveys and for estimations of spatial pattern/extent, for instance, the zone of

influence around point source discharges. The survey area should be of topographic homogeneity.

⎯ Gradient sampling. Sampling stations are arranged along a known or anticipated gradient of interest.

This is applicable, for instance, to trace the influence of a known pollution source.

4.2.3 Fixed sampling points

To reduce random variability when temporal changes are to be monitored, fixed sampling points can provide

an effective approach.
© ISO 2007 – All rights reserved 5
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ISO 19493:2007(E)

NOTE Fixed sampling points provide a very precise measure of change and are useful for monitoring rare sessile

species that are only known from specific locations. There are, however, a number of significant disadvantages to using

permanent sampling points: they may be unrepresentative of the biotope/area as a whole and repeated monitoring may

damage the site. In addition, it may be time-consuming to relocate fixed sampling points.

4.2.4 Reference station

For surveys carried out in affected/contaminated areas or those believed to be affected/contaminated,

reference stations should be chosen outside the influenced area. The reference stations should, as far as

possible, be representative of conditions unaffected by effluent sources and allow assessment of natural,

temporal and spatial variation in the hard-substrate community. The reference stations should be comparable

with the ordinary stations in natural conditions (similar level of wave-exposure, salinity, depth, substrate, slope

and similar position in the inner, middle or outer coastal zone). The surveys at the various stations should be

carried out at the same time of the year and using the same methodology.

Statistical considerations and the required precision of results dictate the number of reference stations.

4.3 Types of surveys
4.3.1 General

In receiving water bodies where there are expected effects in the surface water only and in shallow areas, the

surveys should be carried out in the supralittoral and eulittoral zones (see Table 1). Examples of these are the

receiving water bodies of small domestic and industrial effluent as well as aquaculture activities. In these

cases, the effluent is either released directly or indirectly into the surface water.

In receiving water bodies with extensive sewage and waste-water effluents, other large-scale effluents, below

fish cages and in cases where new constructions can alter the current and sedimentation conditions, there are

additional requirements for sublittoral surveys (see Table 1).

Surveys in the eulittoral and sublittoral zones can be divided into three levels according to the objectives and

required precision of results.
4.3.2 Pilot survey

This is an initial assessment of substrate conditions and hard-substrate flora and fauna (biotopes and

characteristic species). The survey allows a coarse assessment of environmental conditions and may provide

the basis for development of a more comprehensive recording and sampling programme. The survey is not

suitable to record changes over time, with the exception of large-scale changes in dominant species. The

requirements for sampling methodology and repeatability are usually relatively simple.

The survey is carried out by visual inspection. In the sublittoral zone, diving, a submerged video camera or a

ROV may be used. There are no fixed requirements for positioning of sampling stations and the number of

stations to be sampled for a pilot survey, but the stations should, as far as possible, cover the area to be

described. Accurate sampling station positions, slope, tidal conditions and substrate type should be described.

The wave and current exposure at the site should also be categorized and noted (see Annex E).

When pilot surveys are used as a basis to design the size and calculate
...

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