School of Science and Technology

COURSEWORK ASSESSMENT SPECIFICATION

MODULE CODE : BIOL22451MODULE TITLE : Freshwater EcosystemsMODULE LEADER : Dr Rachel StubbingtonTUTOR(S) : Dr Rachel Stubbington

TITLE : Biomonitoring poster presentation

LEARNING OUTCOMES ASSESSED :This exercise will allow you to achieve the following module learning outcomes:

K1. Describe the biological communities present in aquatic ecosystemsK2. Evaluate biomonitoring programmes as means of improving ecosystem health. S1. Conduct a biomonitoring survey, including use of keys to identify organisms and

calculation of biotic indices.S2. Work safely in the field and laboratory to collect accurate data, both independently

and as part of a team.S3. Analyse, evaluate, interpret and present data S4. Communicate effectively in written, graphical and oral formats.

CONTRIBUTION TO ELEMENT : Only piece of coursework, 50 % of module mark

DATE SET : Monday 16th February 2015

DEADLINE : 23.59 Monday 23rd March 2015

SUBMISSION : Upload a pdf file to the Dropbox on module page by 23.59 METHOD on Mon 23rd March, and present your ‘poster’

(as a pdf file on a computer screen), 11-2 Tues 24th March in CELS102.

FEEDBACK DATE : Within 3 weeks of the presentation day

FEEDBACK : A completed marking matrix with feedback and feed-forward

© NTU Copyright 2015

METHOD comments will be returned by RS by email. Additional verbal feedback is available on request

NOTE : The usual University penalties apply for late submission and plagiarism. Consult your student handbook for further details.

© NTU Copyright 2015

I. INTRODUCTION

Biomonitoring uses freshwater organisms to evaluate ecosystem health. Regulatory bodies including the Environment Agency routinely use biotic groups such as macroinvertebrates and diatoms to monitor the health of rivers and lakes in this country. In this study, you will be using macroinvertebrates to investigate the health of a local river ecosystem, Gilt Brook near Newthorpe, Nottinghamshire.

Five practical sessions relate to this biomonitoring survey. All are practical classes and if you miss any (without good reason), your module coursework % will be reduced by 10%:

1. Planning the biomonitoring survey – dry lab (this session)

Monday - (16/02/15) 14:00  17:00   180   (Clif) Erasmus Darwin 290 IT Room Adam Bates

2. Conducting the biomonitoring survey – a field trip(preceded by a talk by Martin from the Environment Agency – please do attend this)

Friday - (20/02/15) 11:00  12:00   60   (Clif) Erasmus Darwin 171 Adam Bates, Rachel StubbingtonFriday - (20/02/15) 12:00  17:00   300   Adam Bates, Rachel Stubbington

3. Identifying and counting the invertebrates – lab session(preceded by a related seminar – you’ll struggle in the lab if you don’t attend this)

Monday - (02/03/15) 11:00  13:00   120   (Clif) Ada Byron King 107Monday - (02/03/15) 14:00  18:00   240   (Clif) Erasmus Darwin 147 Physiology/Pharmacology

4. Analysing your data – computer lab session

Tuesday - (10/03/15) 10:00  13:00   180   (Clif) Mary Ann Evans 117 IT Room Adam Bates

5. Individually presenting a scientific poster – assessed presentation.

Tuesday - (24/03/15) 11:00  14:00   180   (Clif) Centre for Effective Learning in Science 102 IT Room

Going back a week, there is also an optional drop-in session in advance of poster presentation day

Thursday - (19/03/15) 10:00  12:00   120   (Clif) Centre for Effective Learning in Science 102 IT Room

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II. DETAIL ON THE FIVE PRACTICALS1. Planning a biomonitoring surveyYou’ve been given a real world problem to investigate by Martin Winter, an Environment Agency ecologist who will join us in practical 2. The problem will relate to the effects of effluent from Newthorpe sewage treatment works (STW), NW of Nottingham, on Gilt Brook (Fig. 2 on page 5). Your task is to design a survey to determine whether the effluent is having an impact on invertebrate communities in Gilt Brook. You will work in 4 groups of 4.

Each group has some decisions to make before the site visit – and you must be able to justify each decision you make. All of the suggested options (below) are appropriate, so you need to choose between 2+ valid options with no approach necessarily being “best”.

Decision 1: WHERE are you going to take samples?

This decision has partly been taken for you – you’re going to visit two sites, one upstream and one downstream of the STW (in the general area shown in Fig. 1). You do, however, have some say in the precise sampling locations, which will be decided on site. When you get to the site, what factors will help you to identify the most appropriate sampling sites? In other words, if there is instream habitat diversity, which habitats are you going to target? Martin describes both sites as “cobbley with gentle riffles”.

Figure 1. Gilt Brook near Newthorpe, indicating the channel and adjacent land use.

You also need to decide how many samples you are going to take. Bear in mind that your group will have one 4 hour lab to process the samples and that we need to avoid unnecessary damage to the site.

PTO – you have three more decisions to make yet…

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Decision 2: HOW are you going to take samples?

Choose 1 sampling method from: 1-min kick sampling 30-sec Surber sampling Bou-Rouch hyporheic sampling (only one group can use this method)Do some internet searching to find out the pros and cons of each of these methods. Also see ‘Link to kick sampling info’ in: BIOL22451 > Content > Assessment information > Coursework.

You also need to decide who (of the people in your group) is going to take the sample(s).

Decision 3: HOW are you going to characterize the environment? (Water samples can only be analysed in the field, not in the lab).

Are you going to record: Water quality - conductivity, pH, temperature, dissolved oxygen? Substrate? (estimated % of boulders, cobbles, pebbles, gravel, sand, silt and clay) Vegetation? (Types - riparian, marginal, instream, and % cover of each) The extent of channel modification / management?Anything else? How will you measure each factor? (Probes can be provided for each water quality variable.)

Do you need to make a field sheet on which to record your data? If so, you can start designing this sheet in this session.

Decision 4: HOW are you going to analyse your data?

You can make this decision as an individual, not a group, but your chosen analytical ap-proach may mean you need to revisit your decided sampling strategy.

Everyone needs to give a general description of the taxa present, and to calculate some basic community metrics: abundance, richness, diversity and dominance (Appendix 3). In addition, you need to choose 1 (no more!) analytical approach from: BMWP and ASPT scores (see Appendix 1) LIFE scores (see Appendix 2 and also Extence et al. 1999 in: BIOL22451 learning room

> Content > Assessment information > Coursework > For the data analysis session.) Modified BMWP scores (i.e. the ‘WHPT’ index - see Paisley et al. 2013 in: BIOL22451

learning room > Content > Assessment information > Coursework > For the data ana-lysis session. Info on abundance categories is on the 4th page in The data section, and taxon scores are in Appendix A at the end of the paper)

Multivariate analysis (see Appendix 4)

You should also do significance testing to establish differences between upstream (US) and downstream (DS) sites. (Note that you can only do this if your group has 3+ samples from US and 3+ from DS). Note: you must submit a list of equipment you require in the field during this session.

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2. Conducting the biomonitoring survey

We (Rachel, Martin and Jackie) will accompany you to Gilt Brook, where your group will carry out the survey – i.e. collect the invertebrate samples and environmental data – as planned.

Photos of the whole site / your particular study sites may well prove useful.

Regardless of what you decided would be best practice, it would be good for everyone to have a go at sampling. But – we must be careful to minimize the ecological damage we do, by working sensibly, minimizing instream movements, and spreading the groups over a reasonably long stretch.

Place each collected sample into a separate re-sealable A4 plastic bag. Label the bag using a permanent marker, noting: the date; sampling method; the river name; a descriptive site name e.g. “100 m upstream effluent”); and, the name of the person who took the sample. Seal the bag carefully, excluding air. Place it in a 2nd bag, as they sometimes leak

You must ensure your samples are preserved before you go home

Figure 2. Location map of Gilt Brook near Newthorpe, NW of Nottingham. US = upstream site; DS = downstream site.

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3. Identifying and counting the invertebrates

Continue working as a group; each member of the group can identify and count invertebrates from a different sample if appropriate.

1. Get your bags of samples. Decide which of your group is processing which sample(s).2. Each individual should empty their sample into a 500 µm mesh or alternatively a 1 mm

mesh sieve. Put a finer mesh sieve under this sieve, to prevent fine sediment being washed down the sink.

3. One of the main sinks has a length of hose attached to the cold tap. Using this length of hose, wash the sample until the water runs clear.

4. Place a small handful of the clean sample into a white tray and add water to the tray, so that it is about one third full.

5. Return to your work station. Using tweezers (recommended) or a spoon as you prefer, remove the invertebrates from the tray. You’ll definitely need to identify each taxon present, so pick out representatives of

each taxon Depending on the analytical approaches you have chosen, you’ll probably also need

to know the abundance of each taxon, so pick every individual out the sample – if any are very abundant (>100), you can sub-sample from gridded trays. At the very least, you should qualitatively estimate abundance, from ‘very rare’ to ‘very abundant’ – make sure you are using these terms consistently with other members of your group.

Some samples can be large – if you don’t think you have time to process each sample in full, you can instead spend a fixed amount of time (1 hour, 2 hours, 30 mins) on a sample. Ensure that the same amount of time is spent on each sample being processed by members of your group.

7. Use keys to identify each taxon. Most taxa will be identified to Family level, but Species level may be possible (e.g. Gammaridae), whilst others (e.g. Oligochaeta) will be left higher taxonomic level.

8. Write down each taxon found and its actual or estimated abundance. 9. Share your taxa lists with the other members of your group.

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4. Analyzing the data

IMPORTANT: You must bring an Excel spreadsheet of biotic data to this session, either on a USB or saved to an internet location. This spreadsheet should be laid out as in Fig 3 – taxa in column 1; sample names in row 1; and no empty cells in the working area. Ensure that no row and no column adds up to zero.

Fig. 3. How your invertebrate data should look in Excel.

We’ll be working in a computer room, and laptops with specialist software will also be available. Appendices 1-4 indicate how to do most analyses: BMWP, LIFE, community metrics, multivariate analysis; info on the modified BMWP (WHPT) is available on NOW. Written guidance is not provided for Analysis of Variance (ANOVA) as you’ve recently done this on other modules, but help can be provided on request during the session.Important: at the point that you leave the data analysis lab, you must work

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independently from the other members of your group to produce an individual poster. 5. Your poster – the assessed work

You will present an individual scientific ‘poster’ detailing your investigation. Details of how to prepare the poster and the required content are below in Section III. On the day, you will be asked to arrive by 11.00 to display your poster on a computer screen in CELS 102.

Between 11-2 you are required to look at other posters, and ask the authors questions to complete a question sheet which will be provided on the day. You are free to leave for a short (up to 15 mins) comfort break but everyone must be present at the end of the session (i.e. don’t just sneak off after you’ve presented).

We (Rachel & Adam) will ask each of you to come to the front as your poster is shown on the big screen. We will ask you questions about your poster, for approximately 5-6 minutes.

III. Assessment RequirementsIn preparing your poster, the particular sections of Content you should include are: Title – write your own. It should make readers interested in your study. Authorship – just you (although you can mention the other members of your group in

the acknowledgements). Also put your address: NTU, School of Science & Technology… Introduction – about 150 words. You need to: give general background e.g. to the idea

of invertebrates as biomonitors; introduce the study conducted (mention organic pollu-tion) and the study site (Gilt Brook); state the aim(s) of your study.

Methods – about 150 words, including field methods, lab methods and data analysis conducted. Use figures (e.g. photos) if they are useful, add interest, and/or reduce the amount of text you need to write. Justify key choices made e.g. sampling method.

Results – About 300 words. Describe (but do not explain) your results, including biotic and environmental data. Regardless of your chosen analyses, you should start this sec-tion with a brief description of the community present. Text needs to be supported by multiple figures, which will depend on your analytical approach but should include graphs that effectively compare upstream and downstream sites. State p values for sig-nificant / non-significant results.

Discussion – about 200 words. Explain what your results indicate about the impacts of the Newthorpe STW effluent on the invertebrate community / individual taxa. You may make recommendations for Environment Agency actions e.g. for restoration, further fieldwork, or no further action required. Back up points with a few carefully selected ref-erences.

Acknowledgements – short, and in a smaller font than the rest of the poster. References – a minimal amount, and in the same font size as acknowledgements. Use

a numbering system and concise referencing style, as used on the example poster provided on NOW (in BIOL22451 Content, ‘Assessment’ unit, ‘Poster…’ subunit).

This poster needs to be a step up from posters you’ve done in previous years. Plenty of examples of posters can be found in SST buildings (two outside my office, for example) and there are also a couple on NOW (in BIOL22451, as stated above, and in BIOL29001 Content).

As detailed in the marking matrix below, you will be marked on content and design of the poster, as well as your responses to questions.

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Prepare your poster as a single PowerPoint file. To ensure it will be the right size, manually change the Page setup to A2 before you start:

All text on your poster must be easily readable from a distance of 60 cm. As a guide, have a look at the font sizes used on the pptx version of the example poster in the BIOL22451 Content.

Once the slide is ready, save your pptx file as a pdf and then check the formatting (i.e. check it looks OK). Also check that text can be easily read when the full width of the poster is displayed on a computer screen (screen size of the computers in CELS102). We appreciate that we’ll need to scroll down to see the bottom half of the poster.

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MARKING MATRIXUse this marking matrix to see what we expect you to do to achieve each grade between a fail and an exceptional first. Also read the information earlier in Section III.Learning outcome

What is assessed? (%)

Exceptional 1st (96-100)

1st

(70-95) 2:1(60-70)

2:2(50-60)

3rd (40-50)

Marginal fail(35-39)

Fail(0-34)

K1. K2. S2. S4. Content: Introduction (5%)

Methods (5%)

Introduction is exceptional: concise, comprehensive and interesting.

All methods used are described; clear, comprehensive and entirely relevant. Methods selected are well-justified

Intro. is excellent: concise, detailed and with no real omissions.

All methods are clearly described, with no real omissions

Intro is very good: well-written, appropriate detail and with no major omissions.

All methods are well-described but there is a lack of clarity in places / a few omissions

Intro is good: outlines relevant info but with some omissions and/or lack of clarity

Methods are quite well described but are unclear in places / there are some omissions

Intro is adequate: gives some rele-vant info but with major omissions & /or a lack of clarity

Methods are described but descriptions are unclear and or incomplete

Intro is inadequate: fails to outline enough info to understand the study correctly.

Description of methods is inadequate, very unclear & / or with major omissions

Intro is completely inadequate, meaning that the study cannot be understood.

Description of methods is totally inadequate: miss-ed, incorrect &/or incomprehensible

S1. S3. Content:Results (25 %)

Useful description of community. Choice of analyses is entirely appropriate; analyses are conducted flawlessly. Figures are professionally presented, effectively highlight important results, and are supported by descriptive text which includes an indication of result significance. Figure captions are clear and concise.

Useful description of community. Choice of analyses is appropriate and analyses are conducted correctly. Figure presentation is attractive; figures clearly show important results. Figures are described (but not explained) and the significance of results is given. Captions are clear / well-written.

Description of community quite useful. Choice of analyses is acceptable and analyses are conducted with few errors. Figure presentation is clear; significance of results may be given. Captions are clear. All figures are described appropriately.

Description of community given. Choice of analyses is acceptable but some errors in analyses conduct-ed. Presentation of figures is adequate but with some lack of clarity. Significance of results is not considered. Captions provided but lack clarity. Figures may be described; may also be interpreted

Description of community is poor. Choice of analyses is not well-justified. Analyses may be inaccurate. Figures are not presented clearly and may not be described. Figure titles are unclear. Significance of results is not considered.

Description of community is inadequate. Analyses appear poorly understood. Significant errors in analyses conducted. Figures and their titles are inappropriate and or unclear, and are not described adequately.

Description of community is very limited. Analyses are not understood / not correct. Figures and their titles are inappropriate and are not described.

K1. K2. S3. S4. Content: Discussion and referencing

A clear and concise explanation of key findings, indicating exceptional under-

A clear & concise explanation of key results. Excellent understanding of

A clear explanation of the key results, indicating very good understand-

Results are explained but a lack of clarity indicates limited

Results are explained but explanations are unclear, indicating

Explanation of results is confused or unclear. Recommendations

Explanation of results is missed or is confused. No useful

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(15%) standing of the work done. Appropriate recommendations made. Arguments supported by key references. No errors in referencing style.

the work done. Appropriate recom-mendations made. Points supported by well-chosen references, mainly cited correctly.

ing of work done. Appropriate recom-mendations may be made. Points supported by valid references, minor errors in citation.

understanding. Some recommend-ations may be made. References, if used, are mainly websites / some errors in citation.

limited understand-ing. Recommendations may be misguided. References, if used are poor quality / errors in citation.

are not appropriate. References, if used, are not appropriate and are cited poorly

recommendations made. No appropriate references used.

S4. Questions (20 %)

Answers clearly show broad knowledge of, and interest in, the topic beyond the scope of the poster

Questions are answered well, showing a broad and detailed understanding of all information presented

Most questions are answered well, showing an appropriate level of understanding of the information presented

Many answers indicate that the information presented is understood, but there are some gaps in knowledge

Answers show fundamental gaps in understanding of the topic, although basic facts are grasped

Answers show no real evidence of understanding beyond the word level

No attempt made to answer questions

S3. Layout / Design (30%)

The material is presented to a standard expected of a research conference poster. PowerPoint used with exceptional skill and judgement. Title is informative and generates interest.

PowerPoint used to excellent effect to create a poster which effectively conveys information using an attractive balance of text and figures. Title is informative

PowerPoint used to very good effect to create an attractive poster which effectively conveys information using both text and figures. Title effectively describes study.

Competent use of PowerPoint to create a poster. Choice of e.g. colours and/or font sizes reduces clarity but information is still conveyed. Title relates to study but is imprecise.

Poster is not well designed e.g. in terms of font size, colour scheme, and/or amount of text. This design does partly prevent information being conveyed. Title is rather vague or unclear.

Poor poster design, e.g. in terms of font size, colour scheme and/or amount of text, means little information is conveyed. Title does not effectively describe study.

The poster is so poorly designed that the audience are unable to glean information from it.

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General grading descriptors – Second year (NQF Level 5)These descriptions indicate how you will be assessed at the element level (i.e. all coursework/all exams) and at the module levelClass Scale General Characteristics

FIRST

(Excellent)

Exceptional 1st Exceptional breadth and depth of knowledge and understanding of the area of study; evidence of extensive and appropriate selection and critical evaluation/synthesis/analysis and of reading/research beyond the prescribed range, in both breadth and depth, to advance work/direct arguments; exceptional demonstration of relevant skills; excellent communication; performance deemed to be beyond expectation.

High 1st Outstanding/excellent knowledge and understanding of the area of study as the student is typically able to go beyond what has been taught (particularly for a mid/high 1st); evidence of extensive and appropriate selection and critical evaluation/synthesis/analysis of reading/research beyond the prescribed range, to advance work/direct arguments; excellent demonstration of relevant skills; excellent communication; performance deemed beyond expectation of the level.

Mid 1stLow 1st

UPPER SECOND

(Very good)

High 2.1 Very good knowledge and understanding of the area of study as the student is typically able to relate facts/concepts together with some ability to apply to known/taught contexts; evidence of appropriate selection and evaluation of reading/research, some beyond the pre-scribed range, may rely on set sources to advance work/direct arguments; demonstrates autonomy in approach to learning; very good demonstration of relevant skills; strong communication skills.

Mid 2.1Low 2.1

LOWER SECOND

(Good)

High 2.2 Good knowledge and understanding of the area of study balanced towards the descriptive rather than analytical; evidence of appropriate selection and evaluation of reading/research but generally reliant on set sources to advance work/direct arguments; good demonstration of relevant skills, though may be limited in range; communication shows clarity but structure may not always be coherent.

Mid 2.2Low 2.2

THIRD

(Sufficient)

High 3rd Knowledge and understanding is sufficient to deal with terminology, basic facts and concepts but fails to make meaningful synthesis; some ability to select and evaluate reading/research however work may be more generally descriptive; strong reliance on available support set sources to advance work; arguments may be weak or poorly constructed; adequate demonstration of relevant skills over a limited range; communication/presentation is generally competent but with some weaknesses.

Mid 3rd Low 3rd

FAIL

(Insufficient)

Marginal Fail Insufficient knowledge and understanding of the area of study; some ability to select and evaluate reading/research however work is more generally descriptive; fails to address some aspects of the brief; a limited use of sources to advance work; arguments may be weak/poor or weakly/poorly constructed; demonstration of relevant skills over a reduced range; communication shows limited clarity, poor presentation, structure may not be coherent.

Mid Fail Highly insufficient knowledge or understanding of the area of study; understanding is typically at the word level with facts being reproduced in a disjointed or decontextualized manner; fails to address the outcomes addressed by the brief; typically ignores important sources in de-velopment of work and data/evidence inappropriately used; weak technical and practical competence hampers ability to demonstrate/com-municate achievement of outcomes.

Low Fail

ZERO Zero Work of no merit OR absent, work not submitted, penalty in some misconduct cases.

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III. Feedback OpportunitiesFormative (Whilst you’re working on the coursework)You are welcome to approach Rachel for guidance whilst working on this report but, in line with University policy, we’re not able to comment on drafts of your work.

Summative (After you’ve submitted the coursework)You will receive specific feedback regarding your coursework submission together with your awarded grade when it is returned to you. The feedback provided with your coursework is for developmental purposes so that you can improve you work in future assessments.

IV. ModerationThe Moderation ProcessAll assessments are subject to a two-stage moderation process. Firstly, any details related to the assessment (e.g., clarity of information and the assessment criteria) are considered by an independent person (usually a member of the module team). Secondly, the grades awarded are considered by the module team to check for consistency and fairness across the cohort for the piece of work submitted.

V. Evidence for your Skills PortfolioThis piece of assessment allows you to obtain the following skills; the information in brackets indicates the evidence that you could put in your Skills Portfolio:

Accurate recording of lab data by use of a lab book/ record/ journal/ (extended) lab file

Information retrieval/literature searching & awareness of plagiarism Data analysis and interpretation (including replicates, variables, appropriate use of

statistics IT skills (word processing, spreadsheets, databases, graphics & presentation

packages)

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APPENDICES

Appendix 1. The Biological Monitoring Working Party (BMWP) index

The BMWP index was developed by British ecologists in the ‘Biological Monitoring Working Party’ and was published by Armitage et al. (1983). Scores are assigned to macroinvertebrate families based on their tolerance of pollution, in particular organic pollution. Each identified taxon is scored between 1 and 10, where 1 indicates tolerance of organic pollution and 10 means a taxon is restricted to unpolluted waters (Fig. 4 on page 15 – a more comprehensive list will be available in the lab). Taxon scores are summed to produce a BMWP sample score. The ASPT (average score per taxon) is also calculated, by dividing the BMWP by the number of taxa present. The ASPT can be a better indicator of water quality if few taxa are present for reasons other than organic pollution. Various papers have recommended revisions to BMWP scores, as our understanding of the ecological requirements of individual taxa has improved. You are encouraged to investigate and, if appropriate, use these updates to inform your results and discussion sections. Despite these recommendations, this method is still routinely used by the Environment Agency.

Appendix 2. The Lotic-invertebrate Index for Flow Evaluation (LIFE) indexThe LIFE index, which was developed by Environment Agency ecologists and colleagues and was published by Extence, Balbi and Chadd (1999), assigns scores to macroinvertebrate families based on their flow regimes preferences (e.g. fast or slow flowing waters). It can be calculated based either or family or species level data – family scores are shown in Fig. 4 (some taxa, which cannot accurately be classified based on their flow regime preferences, do not score). The method:1. Give each scoring taxon a score, as indicated in Fig. 4, where: 1 = taxon associated

with rapid flows; 2 = moderate / fast flows; 3 = slow / sluggish flows; 4 = taxon associated with flowing / standing water; 5 = standing water; and 6 = taxon is drought resistant / associated with sites that dry.

2. Place each taxon in a second category relating to its abundance: category 1 = 1-9 individuals in sample; 2 = 10-99 individuals; 3 = 100-999; 4 = 1000-9999; 5 = 10,000+. (NOTE: you have taken 1 min rather than the usual 3 min kick sample, so multiply your abundances by 3 to do this analysis.)

3. You now have two scores for each taxon: a flow preference score and an abundance score. Use Table 1 to calculate the flow score (fs) for each taxon

Table 1. Flow scores (fs) for different abundance categories of taxa (1-5) associated with each flow group (1-6)

Abundance category1 2 3 4/5

Flow

gro

up

1 - rapid 9 10 11 122 8 9 10 113 7 7 7 74 6 5 4 35 5 4 3 26 - drought

4 3 2 1

4. The LIFE score for the sample = ∑ (fs) / n. In plain English (I hope), this means that to

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get the sample LIFE score, you sum the individual taxon LIFE scores from Table 1 and divide the total by the number of taxa present in the sample.

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Figure 4. BMWP and LIFE scores for invertebrate families found in British waters. Oligochaeta are not shown - they score 1 for both indices.

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Appendix 3. Community metrics: abundance, richness, diversity and dominance

These are all fundamental metrics used to describe and characterize an invertebrate community.

Abundance can be calculated for the sample as a whole, but will only be accurate if you have taken quantitative samples (e.g. Surber but not kick samples). Abundance can also usefully be determined for individual taxa (e.g. mayflies) or groups of taxa (e.g. EPT): overall abundance may be the same upstream and downstream of a pollution input but this may disguise reductions in the downstream abundance of sensitive taxa if the abundance of pollution-tolerant taxa concurrently increases.

Abundance can be simply calculated using Excel or a calculator.

Taxon richness is a measure of the number of taxa (not necessarily species) present at a site. Remember that considering richness without also considering the composition of the community can be misleading: richness may stay the same even if the types of taxa change considerable upstream to downstream.

Richness can be simply calculated using Excel or a calculator.

Diversity is a measure of two things: taxon richness and also evenness – how equal the community is numerically (is it dominated by one taxon, or do many species have similar abundance?). Simpson’s index is a popular diversity index, and describes the probability that a second individual drawn from a population should be the same species as the first. Magurran (2004) describes Simpson’s index as a meaningful and robust measure of community diversity.

Simpson’s diversity index can be calculated using the programme ‘Species Diversity and Richness’, which will be available in the data analysis session. Higher values indicate higher diversity (check that this makes sense looking at your data – a number of Simpson’s variations exist).

Dominance is, in part, the opposite of dominance: a community with low diversity is very likely to have a high dominance score. However, it’s simpler to calculate diversity because it only considers the numerical importance of the most abundant taxon (not taxon richness). The most common measure of dominance is the Berger-Parker dominance index, in which:

d = Nmax / N

where Nmax is the number of individuals of the most abundant taxon and N is the total number of invertebrates (all taxa) in the sample. (For example, if you sample contains 80 invertebrates and 40 of those are one taxon of mayfly, d = 0.5.)

The Berger-Parker dominance index can simply be calculated using Excel or a calculator

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Appendix 4. Multivariate analysis

This is conceptually the most difficult of the analytical approaches, but it’s manageable if you remember that all it does is show you how similar samples (communities) are to one another. Multivariate means multiple ‘variables’ (i.e. taxa) are analysed at once. The type of analysis that you will do is called correspondence analysis (CA). CA will produce a graph called an ‘ordination’ (because it’s based on arranging, or ordering, samples along axes).

CA can be used to examine spatial variation in invertebrate community composition – in other words, to determine if upstream communities overlap with or are distinct from downstream communities. In Fig. 2a, there is considerable overlap between communities at upstream sites (filled circles) and downstream sites (open circles), whilst in the scenario shown in Fig 2b, upstream and downstream sites have very different communities.

CA is an exploratory analytical method and the ordinations tell you nothing about the taxa responsible for the observed differences. You therefore need to support your CA with reference to the community / taxa present. At least ‘eyeball the data’ to spot taxa that occur at very different abundances upstream and downstream, or do a one-way ANOVA to find out which taxa are significantly more / less abundant upstream / downstream.

Figure 2. Example correspondence analysis ordinations, with filled circles representing upstream sites and open circles representing downstream sites.

CA output includes the % of variation in the dataset explained by each axis (Fig. 2). These values are never high e.g. Stubbington et al. (2009) show an ordination in which 18 % of the variation in the community data is explained by axis 1, whilst 13 % is explained by axis 2 – this is not bad.

A B

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References

Armitage, P.O., Moss, D., Wright, J.F. and Furse, M.T. 1983. The performance of a new biological water quality score system based on macroinvertebrates over a wide range of unpolluted running-water sites. Water Research 17:333-47.

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 and Management 15: 545–574.Magurran, A. E. 2004 Measuring Ecological Diversity. Blackwell Publishing, Oxford. 256pp.

Stubbington R., Greenwood A.M., Wood P.J., Armitage P.D., Gunn J. and Robertson A.L. 2009. The response of perennial and temporary headwater stream invertebrate communities to hydrological extremes. Hydrobiologia 630: 299-312.

Other recommended reading / useful resources

http://www.pisces-conservation.com/sdrhelp/index.html?life.htm – website for the organisation that developed various pieces of software do to the types of analyses you’ll be doing – there is info about e.g. LIFE and BMWP scores.

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