A9. Unit-time invertebrate survey

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1. Objectives

Collecting invertebrate samples for a specific unit of time is a standard approach to sample collection which is applied widely. It is a semi-quantitative approach usually undertaken using a kick-sweep sampling technique.

2. Method summary

Standardized timed samples are generally collected using a 3-minute kick/sweep sampling. This technique is utilized within the ARMI citizen science monitoring. The Statutory Agencies apply a 3-minute kick-sample supplemented by a 1-minute hand search to assess ecological status for the WFD and within their wider river assessments. This is known as the RIVPACS monitoring protocol.

A summary of the approach is detailed below and available here:

The typical sampling method for streams and rivers involves a three-minute kick/sweep sample using a standard 1 mm mesh pond (hand) net. It is important to move around the site during this time to sample the different habitats in the stream, such as fast-moving riffles, shallow water, slow water, weeds and tree roots. This should ensure that the full complement of animals at the site is represented in the sample. Once the different habitats have been identified, divide the total sampling time (three minutes) proportionally according to the relative habitat areas. Place the pond net on the riverbed and disturb (with foot, kicking motion) the area just upstream of the net for the time allocated to that habitat type. The animals will then be carried downstream by the current into the net. For the weeds and tree roots, sweep the net through the area for the allocated time. It is also advisable to carry out an additional one-minute hand search of large stones by gently rubbing the stones in the water letting any animals be carried downstream into the net. Be careful as there may be glass, metal or other sharp objects on the riverbed. Fill your white tray with river water to a depth of a couple of centimeters and then lower the net into the water in the tray, carefully turn inside out, and shake gently, to release the contents for examination. If you have collected a large sample or lots of debris, it may be necessary to examine the contents by taking sub-samples. To do this you will need to empty the contents of the net into a bucket half filled with water. Remove a sample from that bucket using a kitchen sieve or similar, and empty the contents into your tray. When you have finished examining the sample, empty the contents into a second bucket or put it back into the river. Continue taking sub-samples until your first bucket is empty.

DOWNLOAD VIDEO: Underwater kick-sampling ® Tim Flood - Environment Agency

3. Advantages

  • Quick sample
  • Possible to do multiple sites in a day
  • Low cost material
  • Adaptable to a large range of protocols
  • Provide both temporal and spatial changes data

4. Disadvantages

  • Doesn’t provide quantitative data on the macroinvertebrates
  • Can lead to observer bias because the observer chose different sampling locations
  • Disturb the waterbed

5. Recommendations for methods application

  • Do a training course with a professional before, to carry out the sampling the right way regarding the river habitats
  • Avoid low flow and flood period and sample at the same period over years (usually spring (March-May) and autumn (September-November)
  • When applied to a river restoration scheme it is important to follow BACI (Before, After, Control, Impact) (Underwood, 1994)
  • Existing data on your site is possible, please contact your Environment Agency to avoid replicating the same method over the same site and lead to bias
  • Check and clean your material after each sampling site to avoid carrying invasive species and bias data with animals from previous samples

6. Cost

Material is around £100. Working time remains the main cost.

7. Protocol and data analysis

A lot of indices involving the Kick sampling method exists and data analysis rely on the protocol used. * Collecting freshwater macroinvertebrate sample

River Invertebrate Classification Tool (RICT) has been made by the Environment Agency to contextualize WHPT (Whalley, Hawkes, Paisley & Trigg) scores by using a RIVPACS (River Invertebrate Prediction And Classification System (Wright (1997)) model to predict site specific reference values and provide a WFD compliant probabilistic classification WFD 2014.

7.1 Whalley, Hawkes, Paisley & Trigg Average Score Per Taxon (ASPT):

Each family of macroinvertebrates has a pollution tolerant score. The sample is analysed by totalling the scores of each identified family to give the old “Biological Monitoring Working Party” (BMWP) score. This score is divided by the number of taxa to get the ASPT. Abundance is also recorded. ASPT is independent from sample size and less influenced than the BWMP method.

Source : https://oart.org.uk/our-work/projects/water-quality/biological-monitoring/

7.2 Whalley, Hawkes, Paisley and Trigg Number of taxa contributing to the assessment (WHPT NTAXA):

This is simply the number of families contributing to the assessment. It is involved in the ASPT calculation as:


Where AB : value for each taxonaccording to its abundance NTAXA is the number of taxa contributing to the assessment

Source and all details to calculate these indices are available here.

Ecological Quality Ratios (EQRs) are derived from both of the metrics by RICT, based on observed data and site-specific predicted reference values derived from physical and chemical parameters. It represents the O/E ratio or observed (O) to expected (E). EQR are calculated on the basis of the WHPT ASPT and the WHPT NTAXA. Data should be collected according to standard RIVPACS procedures defined in the EU-STAR (2004). The kick sampling method is always used for these two metrics.

7.3 Water Framework Directive Acid Water Indicator Community (WFD -AWIC)

The goal of the Acid Water Indicator Community (AWIC) is to generate Ecological Quality Ratio according to the requirements of the Water Framework Directive including two factors: 1) the water chemistry, because a large part of an invertebrate community’s response to anthropogenic acidification is mediated by the toxic effects of labile Aluminium (lAl) and Dissolved Organic Carbon and 2) geographical location, because the method has been developed in Scotland and Wales and can produce undesirable results if not adapted to other locations. First, sites must pass chemical screening criteria of pH <7 & Ca <4 mg/l, before any application of the indices otherwise it is out of the primary environmental gradient used to build the method and could lead to erroneous results.

Source and all details to calculate these indices are available at:

7.4 Lotic-Invertebrate Index for Flow Evaluation (LIFE)

This index was created by (Extence, Balbi and Chadd, 1999) to assess the potential impact of flow related stresses on lotic macroinvertebrate communities. In this article, for a long data period (16-28 years), they showed that temporal variation of this index occurs for individual sites in correlation with recent and preceding flow conditions. The need for this index is increased as periods of low flows and/or slow flows appear to be repeated and more frequent events. The sampling protocol technique is the one used in Murray-Bligh (1999) to provide presence, absence and abundance of the taxa. A flow-score is dedicated to each taxa to calculate the LIFE.

Source and all details available at:

7.5 Proportion of Sediment-sensitive Invertebrates index (PSI)

The pressure specific index has been created and tested by (Glendell et al., 2014) to act as a tool to measure sedimentation through its impact on macro-invertebrates. Studies have been done to include ecologically relevant taxa considering their sediment-sensitive characteristics. Results have proven that the PSI Index is closely related to % fine bed cover and both are useful data by allowing a more accurate comprehension of ecological and physical processes compared to the use of other indices alone (LIFE, EPT). The goal is to provide a simple tool to understand the quantitative link between sedimentation, and ecological responses and variability between rivers, based on the nature of their waterbed sediments.

7.6 Drought Effect of Habitat Loss on Invertebrates (DEHLI)

The DEHLI index has been recently tested to better understand the underlying processes of drought on the invertebrate’s community. Evidence shows a greater sensitivity of this index for drought assessment compared to the LIFE Index. The usual 3min kick sampling method has been used and weight is assigned to each taxa depending on their association with key stages of channel drying. Effects of drought can be persistent months or years after the flow recovery. By using existing data on south east England to calibrate a statistical model simulating the effect of a multi-year’s drought on macrofauna community, it is possible to monitor shifts in the benthic community. It could open perspective to drive restoration projects (according to the BACI principles) - in order to allow a better resilience of these community facing cumulative effects of human activities and climate change. This work mainly relies on statistical analysis derived from conventional sampling.

Source and all details available here

All indices described above can be used to help assess the background conditions of a restoration scheme prior to implementation. Although none of these indices give a measure of habitat quality, they are all influenced by habitat and may show a response to a river restoration scheme.

Ecological quality Indices can be calculated on the basis of WHPT ASPT and WHPT NTAXA to get the river score. These indices are used for WFD classification. Depending upon the sampling design it is possible to perform a number of different statistical techniques upon the data including times series, trend analysis, modified ANOVA, biotic indices or multivariate and linear model analysis. There are many complete sources that can help such as (Monk et al., 2006; Zuur et al., 2009; Crawley, 2013; Rosenberg et al., 2015; Hervé, 2016)

8. References

Sampling and methods

  • Murray-Bligh, JAD (1999) Procedure for collecting and analysing macro-invertebrate samples. Quality Management Systems for Environmental Monitoring: Biological Techniques BT001. Version 2.0. Bristol, Environment Agency.
  • Murray-Bligh, JAD (1999) Procedure for quality assurance for RIVPACS compatible macro-invertebrate samples analyzed to the taxonomic level needed for the BMWP- score system. Quality Management Systems for Environmental Monitoring: Biological Techniques, BT003. Version 1.0. Bristol: Environment Agency.
  • Clarke, R. T. et al. (2002) Investigation of the relationship between the LIFE index and RIVPACS. Putting LIFE into RIVPACS.
  • Extence, C. A., Balbi, D. M. and Chadd, R. P. (1999) ‘River flow indexing using British benthic macroinvertebrates: a framework for setting hydroecological objectives’, Regulated Rivers: Research & Management, 15(6), pp. 545–574. doi: 10.1002/(sici)1099-1646(199911/12)15:6<545::aid-rrr561>3.0.co;2-w.
  • Glendell, M. et al. (2014) ‘Testing the pressure-specific invertebrate index (PSI) as a tool for determining ecologically relevant targets for reducing sedimentation in streams’, Freshwater Biology, 59(2), pp. 353–367. doi: 10.1111/fwb.12269.
  • Monk, W. A. et al. (2006) ‘Flow variability and macroinvertebrate community response within riverine systems’, River Research and Applications, 22(5), pp. 595–615. doi: 10.1002/rra.933.
  • Rosenberg, D. M. et al. (2015) Protocols for measuring biodiversity : Benthic Macroinvertebrates in Fresh Waters.
  • Underwood, A.J. 1994. ‘On beyond Baci: Sampling designs that might reliably detect environmental disturbances.’ Ecological Applications 4:3-15.
  • WFD-UKTAG (2014) UKTAG River Assessment Method Benthic Invertebrate Fauna Invertebrates ( Anthropogenic Acidification ): WFD Acid Water Indictor Community.

Data analysis

  • Crawley, M. J. (2013) The R book, Wiley. Edited by John Wiley & Sons Ltd. Chichester, West Sussex. doi: 10.1017/CBO9781107415324.004.
  • Hervé, M. (2016) Aide-mémoire de statistique appliquée la biologie.
  • Monk, W. A. et al. (2006) ‘Flow variability and macroinvertebrate community response within riverine systems’, River Research and Applications, 22(5), pp. 595–615. doi: 10.1002/rra.933.
  • Rosenberg, D. . M. . et al. (2015) Protocols for measuring biodiversity : Benthic Macroinvertebrates in Fresh Waters.
  • Zuur, A. F. et al. (2009) Mixed effects models and extensions in ecology with R, Springer Science & Business Media. doi: 10.1017/CBO9781107415324.004.


RIVPACS database

Macroinvertebrates of the river Thames catchments UK: Data comprise species level descriptions of macroinvertebrate communities and habitat descriptions from wadeable rivers of the Thames catchment, in the United Kingdom (UK), sampled over three seasons in the years 2009 - 2010. https://catalogue.ceh.ac.uk/documents/5700501d-feb4-445d-aa08-81a158e54bac