Water quality - Guidance for the surveying of aquatic macrophytes in running waters

EN 14184 specifies a method for surveying aquatic macrophytes in running waters for the purpose of assessing ecological status, using these organisms as elements of biological quality. The information provided by this method includes the composition and abundance of the aquatic macrophyte flora. This European Standard is applicable to all kinds of surface running water bodies, like natural brooks, streams and rivers and their heavily modified equivalents, as well as to artificial water bodies like canals or run-of-river reservoirs. The general principles of the approach described in this European Standard may also be applied when monitoring water bodies in the fluvial corridor of a river, such as side channels and oxbows. It is recognized that for a complete assessment of ecological status, other elements of biological quality should also be assessed.

Wasserbeschaffenheit - Anleitung für die Untersuchung aquatischer Makrophyten in Fließgewässern

Diese Europäische Norm legt ein Verfahren zur Untersuchung aquatischer Makrophyten in Fließgewässern mit dem Ziel fest, den ökologischen Zustand von Gewässern mit Hilfe dieser Organismen abzuschätzen, indem diese als Qualitätselemente eingesetzt werden. Die nach diesem Verfahren erhaltenen Informationen berücksichtigen die Zusammensetzung und Häufigkeitsverteilung der aquatischen Makrophytenflora.
Diese Europäische Norm ist für alle Typen fließender Oberflächengewässer anwendbar wie natürliche Bäche, Flüsse und Ströme sowie ihre erheblich veränderten Äquivalente. Ebenso ist sie für künstliche Wasserkörper wie Kanäle und Talsperren anwendbar.
Die Grundsätze der in der Europäischen Norm beschriebenen Vorgehensweise können auch für die Überwachung von Gewässerbereichen im Umfeld eines Fließgewässers angewendet werden, z. B. in Seitenkanälen und Altwasserbereichen.
Bekanntlich sollten zur vollständigen Bewertung des ökologischen Zustands weitere Aspekte der biologischen Beschaffenheit abgeschätzt werden.

Qualité de l'eau - Guide pour l'étude des macrophytes aquatiques dans les cours d'eaux

La présente Norme européenne définit une méthode d’étude des macrophytes aquatiques dans les eaux courantes, dans le but d’évaluer leur état écologique, en utilisant ces organismes comme des éléments de qualité biologique. Les informations fournies par cette méthode comprennent la composition floristique et l’abondance des macrophytes aquatiques.
La présente Norme européenne est applicable à tous les types de masses d'eau courante de surface, notamment les ruisseaux naturels, les cours d'eau et les rivières et leurs équivalents fortement modifiés, ainsi que les masses d'eau artificielles telles que les canaux ou les retenues au fil de l'eau.
Les principes généraux de l’approche décrite dans la présente Norme européenne peuvent également être appliqués lors de la surveillance des habitats aquatiques dans le corridor fluvial d’une rivière, tels que les chenaux latéraux et les bras morts.
Il est reconnu que pour une évaluation complète de l’état écologique, il convient également d’évaluer d’autres éléments de qualité biologique.

Kakovost vode - Navodilo za pregledovanje vodnih makrofitov tekočih voda

Standard EN 14184 določa metodo za pregledovanje vodnih makrofitov tekočih voda za ocenjevanje ekološkega stanja, pri čemer se ti organizmi uporabijo kot elementi biološke kakovosti. Informacije, ki jih ponuja ta metoda, vključujejo sestavo in številčnost vodnih makrofitov. Ta evropski standard velja za vse vrste površinskih tekočih vodnih teles, kot so naravni potoki, tokovi in reke ter njihovi močno preoblikovani ekvivalenti, kot tudi za umetna vodna telesa, kot so kanali ali akumulacijska jezera. Splošna načela pristopa iz tega evropskega standarda se lahko uporabljajo tudi za spremljanje vodnih teles v fluvialnem koridorju reke, kot so stranski rokavi in mrtvice. Za popolno oceno ekološkega stanja je treba oceniti tudi druge elemente biološke kakovosti.

General Information

Status
Published
Public Enquiry End Date
30-Jun-2012
Publication Date
13-Apr-2014
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
31-Mar-2014
Due Date
05-Jun-2014
Completion Date
14-Apr-2014

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Wasserbeschaffenheit - Anleitung für die Untersuchung aquatischer Makrophyten in FließgewässernQualité de l'eau - Guide pour l'étude des macrophytes aquatiques dans les cours d'eauxWater quality - Guidance for the surveying of aquatic macrophytes in running waters13.060.70Preiskava bioloških lastnosti vodeExamination of biological properties of water13.060.10Voda iz naravnih virovWater of natural resourcesICS:Ta slovenski standard je istoveten z:EN 14184:2014SIST EN 14184:2014en,fr,de01-maj-2014SIST EN 14184:2014SLOVENSKI

STANDARDSIST EN 14184:20031DGRPHãþD
SIST EN 14184:2014
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 14184
March 2014 ICS 13.060.70 Supersedes EN 14184:2003English Version

Water quality - Guidance for the surveying of aquatic macrophytes in running waters

Qualité de l'eau - Guide pour l'étude des macrophytes aquatiques dans les cours d'eaux

Wasserbeschaffenheit - Anleitung für die Untersuchung aquatischer Makrophyten in Fließgewässern This European Standard was approved by CEN on 11 January 2014.

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, 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.

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 worldwide for CEN national Members. Ref. No. EN 14184:2014 ESIST EN 14184:2014

EN 14184:2014 (E) 2 Contents Foreword ..............................................................................................................................................................4 Introduction .........................................................................................................................................................5 1 Scope ......................................................................................................................................................6 2 Terms and definitions ...........................................................................................................................6 3 Principle ..................................................................................................................................................7 4 Equipment ..............................................................................................................................................8 4.1 General ....................................................................................................................................................8 4.2 Deeper waters (optional) .......................................................................................................................8 5 Survey planning .....................................................................................................................................8 5.1 General ....................................................................................................................................................8 5.2 Timing of initial and subsequent surveys ...........................................................................................9 5.3 Survey protocols....................................................................................................................................9 5.4 Selection of reference sites ............................................................................................................... 10 5.5 Selection of river reaches .................................................................................................................. 10 5.6 Selection of representative sites ....................................................................................................... 11 6 Survey procedure ............................................................................................................................... 12 6.1 Survey preparation ............................................................................................................................. 12 6.2 Survey technique ................................................................................................................................ 12 6.3 Field survey ......................................................................................................................................... 13 6.4 Recording and quantification scales for macrophytes................................................................... 14 6.5 Aquatic macrophyte identification .................................................................................................... 16 Annex A (informative)

Principles of interlaboratory comparison for macrophyte surveys in running waters – Occurrence and abundance of macrophyte species ........................................ 17 A.1 General ................................................................................................................................................. 17 A.2 General aspects of quality assurance in aquatic macrophyte survey .......................................... 17 A.3 Site selection ....................................................................................................................................... 17 A.3.1 General ................................................................................................................................................. 17 A.3.2 Site parameters ................................................................................................................................... 18 A.3.2.1 Flow ...................................................................................................................................................... 18 A.3.2.2 Depth .................................................................................................................................................... 18 A.3.2.3 Width .................................................................................................................................................... 18 A.3.2.4 Transparency ...................................................................................................................................... 19 A.3.3 Survey unit number, length and demarcation ................................................................................. 19 A.3.4 Aquatic vegetation characteristics suitable for IC .......................................................................... 19 A.4 Independence of participant’s results .............................................................................................. 19 A.5 Field protocol and time limit .............................................................................................................. 20 A.5.1 General aspects .................................................................................................................................. 20 A.5.2 Time limit for the field survey ............................................................................................................ 20 A.6 Data collection for the whole group of participants ........................................................................ 20 A.7 Reference values for the survey ....................................................................................................... 20 A.7.1 General ................................................................................................................................................. 20 A.7.2 Reference values for species number, taxonomic correctness and abundance of species ...... 20 SIST EN 14184:2014

EN 14184:2014 (E) 3 A.8 Description of results concerning species detection ...................................................................... 21 A.9 Description of results concerning species abundance ................................................................... 22 A.10 Reporting .............................................................................................................................................. 23 Bibliography ...................................................................................................................................................... 24

SIST EN 14184:2014

EN 14184:2014 (E) 4 Foreword This document (EN 14184:2014) has been prepared by Technical Committee CEN/TC 230 “Water analysis”, the secretariat of which is held by DIN. This document supersedes EN 14184:2003. 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 September 2014, and conflicting national standards shall be withdrawn at the latest by September 2014. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. This document contains the following technical changes to the previous edition: a) this document is applicable to all kinds of running surface waters (e. g. rivers, streams, artificial canals); b) requirements for survey planning and documentation were revised concerning the requirements of the Water Framework Directive (WFD); c) a further example for estimator scales widely used in Europe to assess aquatic macrophyte abundance was added in Table 1; d) informative Annex A “Principles of interlaboratory comparison for macrophyte surveys in running waters – Occurrence and abundance of macrophyte species” was added. 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, 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 the United Kingdom. SIST EN 14184:2014

EN 14184:2014 (E) 5 Introduction Macrophytes are an important component of aquatic ecosystems and can be used to facilitate the monitoring of ecological status. The requirement to use macrophytes in monitoring is inherent in numerous European directives (e. g. the Water Framework Directive (2000/60/EC), Urban Waste Water Treatment Directive (91/271/EEC), Nitrates Directive (91/676/EEC), etc.). In addition to their important ecological role, the use of macrophytes as indicators of ecological quality in running waters is based on the fact that certain species and species groups are indicators for specific running water types and are adversely affected by anthropogenic impact. In certain types of running water habitats the lack of macrophytes is not an effect of anthropogenic impact but a characteristic feature. For example, in geological formations like the flysch, or in the central part of deeper rivers macrophytes may be absent due to the habitat limitations imposed by geology and substrate, water depth, current flow velocity, turbidity, etc. A wide range of sampling and survey methodologies has been developed for specific applications including conservation, drainage impact, management, ecological habitat enhancement etc. The methodology of this guidance standard is recommended specifically for the surveying of macrophytes in running freshwaters, of natural, heavily modified and artificial character, and for the purpose of monitoring ecological status. It could be used as the basis for investigative monitoring of water quality or other applications, as well. According to the precise usage to which this European Standard is to be put, it is essential for specifiers and users to mutually agree on any necessary variations or optional procedural details prior to use. WARNING — Working in or around water is inherently dangerous. Persons using this European Standard should be familiar with usual field and laboratory practice. This European Standard 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 and to ensure compliance with any national regulatory conditions. SIST EN 14184:2014

EN 14184:2014 (E) 6 1 Scope This European Standard specifies a method for surveying aquatic macrophytes in running waters for the purpose of assessing ecological status, using these organisms as elements of biological quality. The information provided by this method includes the composition and abundance of the aquatic macrophyte flora. This European Standard is applicable to all kinds of surface running water bodies, like natural brooks, streams and rivers and their heavily modified equivalents, as well as to artificial water bodies like canals or run-of-river reservoirs. The general principles of the approach described in this European Standard may also be applied when monitoring water bodies in the fluvial corridor of a river, such as side channels and oxbows. It is recognized that for a complete assessment of ecological status, other elements of biological quality should also be assessed. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 aquatic macrophytes larger plants of fresh water which are easily seen with the naked eye, or which usually form colonies, including all aquatic vascular plants, bryophytes, stoneworts (Characeae) and macro-algal growths 2.2 bank permanent side of a river or island, which is above the normal water level and only submerged during periods of high river flow Note 1 to entry: In the context of this standard, bank species include macrophytes that overhang the channel or overgrow the water surface but are rooted in the bank. 2.3 channel course of a river or stream Note 1 to entry: In the context of this standard, this includes only the in-stream part, i. e. that which is under water most of the time although it may be exposed temporarily under conditions of dry-weather flow or for longer periods under certain natural (climatic, geological) conditions. 2.4 belt transect defined band across a river or stream at right angles to the bank Note 1 to entry: This may be virtual or physically delineated within which the aquatic vegetation is analysed (species composition, abundance, cover). 2.5 ecological status expression of the quality of the structure and functioning of aquatic ecosystems, expressed by comparing the prevailing conditions with reference conditions Note 1 to entry: As classified in accordance with Annex V of the EC Water Framework Directive (2000/60/EC). SIST EN 14184:2014

EN 14184:2014 (E) 7 2.6 helophyte plant usually rooted under water or in the wet part of the bank with emergent shoots, typically growing in marginal or marshy areas 2.7 hydrophyte aquatic plant that is usually rooted under water with floating or submerged leaves, or totally free floating at the water surface 2.8 reference site length of river representing the reference conditions for a given ecological type of river 2.9 reference conditions biological conditions reflecting a totally undisturbed state, lacking human impact, or a near-natural with only minor evidence of distortion Note 1 to entry: Biological reference conditions may be defined using field sites or, where necessary, using expert judgement or predictive modelling techniques. 2.10 representative site length of river reach representative of the ecological quality that characterizes that reach 2.11 river reach sub-division of a river, or surface water body with running water, defined by physical, hydrological and chemical characteristics that distinguishes it from other parts of the river upstream and downstream 2.12 survey stretch survey unit SU short length of river for which community composition and abundance of aquatic species is determined Note 1 to entry: Abundance can be assessed by quantitative or semiquantitative methods. This approach can be used for e. g. assessment of ecological status and/or for other purposes dealing with the description of the aquatic macropyhte vegetation. 3 Principle This European Standard describes the methodological approach for determining the ecological status of river reaches using aquatic macrophytes. The status of a river reach, or surface water body with running water, is assessed by surveying short river stretches (‘representative sites’) which are representative for the ecological conditions in this water body. Thereafter its deviation from the conditions recorded in reference sites is determined. Reference sites are located in river reaches of similar ecological type which are still in natural or near-natural conditions. If natural conditions in river reaches no longer exist, it is necessary to reconstruct these conditions upon whatever existing records, or by modelling or expert knowledge. A published approach can be applied to situations where near-natural conditions are absent [5]. The presence of aquatic macrophyte taxa in the channels of representative river lengths is recorded. Macrophyte abundance, measured in terms of the spatial extension of taxa or macrophyte beds (coverage or macrophyte biovolume, see Table 1), is assessed by different methods adapted to the scale and purpose of the study. SIST EN 14184:2014

EN 14184:2014 (E) 8 Numerical derivatives (‘metrics’) of the macrophyte composition and abundance in a surveyed river length can be used to identify the divergence from type-specific “natural” conditions. Methods for the sampling of macrophytes are given in EN ISO 10870. 4 Equipment 4.1 General 4.1.1 Maps, with scales compatible with the objectives of the survey. 4.1.2 Waterproof recording sheets, indelible pens/pencils and clipboard in a clear cover. 4.1.3 Plastic bags, small specimen tubes and waterproof labels. 4.1.4 Tape measure calibrated in metres, marking stakes and mallet. 4.1.5 Hand lens, magnification at least 10 x . 4.1.6 Identification keys and field guides. 4.1.7 Wading suit. 4.1.8 Polarizing sunglasses. 4.1.9 Camera with polarizing lens. 4.1.10 Global Positioning System (GPS)-instrument (for higher accuracy: differential GPS). 4.1.11 Rake with extendable handle and/or grapnel. 4.1.12 Underwater viewing aid/aqua-scope, bucket or box with clear Perspex base. 4.1.13 White plastic trays. 4.2 Deeper waters (optional) 4.2.1 Boat and necessary safety equipment. 4.2.2 Grapnel with depth markings in metres on the rope. 4.2.3 Underwater viewing aid/aqua-scope, viewing tube, bucket or box with clear Perspex base. 4.2.4 Wet-suit, diving equipment. 5 Survey planning 5.1 General At the beginning of a survey the geographic region (or ‘ecoregion’), the river order, the river type and the respective reference conditions characteristic for the river reach under investigation should be defined. SIST EN 14184:2014

EN 14184:2014 (E) 9 5.2 Timing of initial and subsequent surveys As far as possible, macrophyte surveys should be undertaken between late spring and early autumn, usually May to late September, but dependent on local climate and geographical region, when macrophyte growth will be at the optimum. NOTE 1 This may not necessarily be the optimum growing period for macroscopic algae. Surveying may need to be later in Northern Europe. Preferably, field survey should follow several days of lower flow where water clarity is maximised and water depths are reasonably low, thereby enhancing visibility and the possibility to detect submersed forms of macrophytes. Information regarding the timing of vegetation cutting is essential prior to surveying, where this is known to be usual management practice. NOTE 2 When water depths are enhanced and water clarity is reduced following periods of high flow, the observation of smaller species is difficult and the recording of abundance may be inaccurate. This will in turn reduce the reliability of the data. Macrophyte species grow and reach sexual maturity at different times over the summer period. Therefore, surveys at sites in the same river system should be undertaken in quite close chronological succession where comparative data are required. When trying to assess the optimum development period of the macrophyte vegetation for the first time in unknown rivers or areas it is beneficial to survey on two separate occasions (e. g. May/June and August/September) to cover possible different vegetation development occurring during the vegetation period. Once the optimum survey period for macrophyte assessment is known, practical experience all over Europe shows that a single survey per recording year is sufficient (running waters are not necessarily surveyed every year). Comparative surveys in subsequent years shall be performed at the same period of vegetation development as the original survey. This will ensure that changes resulting from different seasonal development patterns are minimised. But knowledge on inter-annual natural changes in species number and abundance and in the dominance pattern in survey sites should be known to avoid misinterpretation regarding aspects of water quality and ecological status. 5.3 Survey protocols There are many different survey protocols in use throughout Europe, therefore only general guidelines are given in this document. Macrophyte surveys can be undertaken at different levels of sophistication. In addition to the surveying of sites exhibiting reference conditions this can involve the surveying of the following. — Approach 1: short lengths of river which are representative for a river stretch of water body. This requires relatively little time and is recommended for the routine survey of aquatic macrophytes, e. g. within the process of assessing the ecological status under Water Framework Directive rules. When only the short reach of a representative site needs to be described, it still can be used for spatial and temporal monitoring. — Approach 2: longer river lengths in the process of defining the best location of representative sites; when defining representative sites a longer stretch of a river should be surveyed first using the second approach thereafter to prove “evenness” within this stretch of physical and biological variables. — Approach 3: complete river length surveys to produce inventories of whole rivers. To fulfil more specialized needs. For example, as part of the procedure to provide statistical data for the numerical differentiation of reference sites in different ecological river types. It is a labour-intensive approach not to be applied for routine surveys. It is used in special cases, e. g. single-river long-term monitoring and for SIST EN 14184:2014

EN 14184:2014 (E) 10 detailed background information for ecological classification or monitoring of longer river reaches composed of several water bodies which are failing to meet a good ecological status. The survey protocol may vary between these different approaches depending on the purpose of the survey, e. g. less intensive data collection during preliminary surveys designed to locate reference sites (high ecological status) or working at representative sites, which are indicative for the ecological status of certain river stretches or water bodies. 5.4 Selection of reference sites Ecological reference conditions for each type of river need to be established before the ecological status of representative sites can be assessed. This can be achieved either by the surveying of still existing reference sites or, where such suitable river reaches cannot be found, by modelling or expert opinion. Reference sites should be as close as possible to natural conditions with respect to their species composition and the abundance of each species, physical and chemical variables and hydromorphological features. Usually the location of reference sites can be selected from regional or national surveys with data on species composition, distribution, and diversity of the aquatic vegetation. Appropriate statistical methods can be used to differentiate numerically reference sites in different river reaches or water bodies following the natural continuum from the source to the mouth of a running water system. The length of river surveyed for the reference sites should be of sufficient length to adequately reflect the diversity of plant species characteristic of this river type. The length of the surveyed stretch shall be adapted to river size and character. In running waters with narrow width and low water depth the whole bottom can serve as macrophyte habitat. In such cases survey length of 50 m to 100 m are used most frequently. If necessary, longer stretches may be needed, especially if macrophytes occur in a scattered pattern, to detect all species characteristic for this stretch. It is recommended to locate more than one survey unit (of e. g. 50 m) within such longer river stretch. In larger and deeper streams and rivers macrophytes only develop near the banks, and both near-bank parts shall be surveyed, if physically possible (e. g. rock faces on one river side may prohibit access). Deep and large rivers require much longer survey stretches to detect the characteristic species composition. NOTE 1 In the Joint Danube Surveys of the International Commission for the Protection of the Danube River (ICPDR) an utmost minimum of 6 km (3 per river side) was found to be the shortest representative length for macrophyte survey in the navigable Danube course (single contiguous river kilometre surveys over the full length of the Danube served as background data for distinguishing this minimum length). NOTE 2 When determining the adequate length of stretch to be surveyed some sources recommend the use of cumulative species curves. Yet, these are based on ‘homogenous’ habitats. These are rather found in smaller running waters, but macrophyte pattern turns more scattered in larger streams and rivers. In such cases placing several shorter survey stretches in contiguous order within the survey stretch has shown adequate results to cover species diversity. NOTE 3 Regarding the assessment of reference conditions in absence of such river reaches in present anthropogenic landscapes a different approach is described by Birk et al.[5]. 5.5 Selection of river reaches Select the river reaches or water bodies to be surveyed. The selection should be dictated by factors including the objectives of the survey, degree of confidence required from the data, resources and expertise available etc. These decisions should be made before the initiation of fieldwork. Ensure that sufficient reaches of river are surveyed to enable the changes in the macrophyte assemblage due to anthropogenic factors to be distinguished from changes due to natural factors, such as differences in geology, slope or stream order, or changes in land use. EXAMPLE To monitor specifically the impact of a point discharge, the surveyed length should be as close upstream as practicable and yet in terms of geomorphological conditions as comparable as possible. The downstream location should be below the predicted effluent river-water mixing zone within the river or stream. The area of the mixing zone can be located by dye tracing or similar studies. Dye tracing should be undertaken under a range of flow conditions as these will influence the extent of the mixing zone in the receiving river reach. SIST EN 14184:2014

EN 14184:2014 (E) 11 To assist the process of site selection, gather relevant background information on the river(s) to be surveyed. Inspecting the area on foot, examination of detailed maps, aerial photographs and investigation of any other sources of relevant information such as water quality data sets is highly recommended. Identify potential point sources of pollution such as waste water treatment plants, fish farms, centres of high population density etc. Investigate land usage within the river catchment/sub-catchment to be surveyed. Establish where changes in catchment usage and potentially water quality in terms of nutrient loadings are likely to occur. Geomorphological criteria including solid and drift geology etc should be established. Locate any physical barriers such as reservoirs, weirs, navigation channels, ditches, drains and physical obstructions that may influence channel aquatic macrophyte communities. Detailed analysis of water quality databases can be important in this context. If not available, chemical survey should be undertaken in the same reaches at the time of macrophyte survey, but more intensive data sets are also of great value. It is recommended to map the collected background information in order to facilitate the ready identification of suitable survey sites. Report

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