School of Science and Technology
COURSEWORK ASSESSMENT SPECIFICATION
MODULE CODE
:
MODULE TITLE :
MODULE LEADER :
TUTOR(S)
:
BIOL22451
Freshwater Ecosystems
Dr Rachel Stubbington
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 ecosystems
K2.
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
METHOD
:
Upload a pdf file to the Dropbox on module page by 23.59
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
METHOD
:
A completed marking matrix with feedback and feed-forward
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
2
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
Monday - (16/02/15)
14:00
– dry lab (this session)
17:00
180
(Clif) Erasmus Darwin 290 IT Room
Adam
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
Friday - (20/02/15)
12:00
17:00
300
(Clif) Erasmus Darwin 171
Adam Bates, Ra
Adam Bates, Ra
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 107
Monday - (02/03/15)
14:00
18:00
240
(Clif) Erasmus Darwin 147 Physiology/Pharmacology
4. Analysing your data
Tuesday - (10/03/15)
– computer lab session
10:00
13:00
180
5. Individually presenting a scientific poster
Tuesday - (24/03/15)
11:00
14:00
180
(Clif) Mary Ann Evans 117 IT Room
Adam
– assessed presentation.
(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
II. DETAIL ON THE FIVE PRACTICALS
3
1. Planning a biomonitoring survey
You’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…
Decision 2: HOW are you going to take samples?
4
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
approach 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
analysis 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.
2. Conducting the biomonitoring survey
5
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.
3. Identifying and counting the invertebrates
6
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.
4. Analyzing the data
7
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
independently from the other members of your group to produce an individual poster.
5. Your poster – the assessed work
8
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 Requirements
In 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
pollution) 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
section 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
significant / 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
references.
 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.
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:
9
1
2
3
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.
10
MARKING MATRIX
Use 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
K1.
S4.
K2.
S1. S3.
S2.
1st
(70-95)
2:1
(60-70)
2:2
(50-60)
3rd
(40-50)
Marginal fail
(35-39)
Fail
(0-34)
Introduction
is
exceptional: concise,
comprehensive and
interesting.
Intro. is excellent:
concise,
detailed
and with no real
omissions.
Intro is very good:
well-written,
appropriate detail
and with no major
omissions.
Intro
is
good:
outlines
relevant
info but with some
omissions
and/or
lack of clarity
Intro is adequate:
gives some relevant info but with
major omissions &
/or a lack of clarity
Intro
is
inadequate: fails to
outline enough info
to understand the
study correctly.
Intro is completely
inadequate,
meaning that the
study cannot be
understood.
Methods (5%)
All methods used are
described;
clear,
comprehensive and
entirely
relevant.
Methods selected are
well-justified
All methods are
clearly described,
with
no
real
omissions
All methods are
well-described but
there is a lack of
clarity in places / a
few omissions
Methods are quite
well described but
are
unclear
in
places / there are
some omissions
Methods
described
descriptions
unclear
and
incomplete
are
but
are
or
Description
of
methods
is
inadequate,
very
unclear & / or with
major omissions
Description
of
methods is totally
inadequate: missed, incorrect &/or
incomprehensible
Content:
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 conducted. 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
welljustified. 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.
What
is
assessed? (%)
Exceptional
(96-100)
Content:
Introduction
(5%)
Results (25 %)
1st
11
K1.
S4.
K2.
S3.
Content:
Discussion and
referencing
(15%)
A clear and concise
explanation of key
findings,
indicating
exceptional
understanding of the work
done.
Appropriate
recommendations
made.
Arguments
supported by key
references. No errors
in referencing style.
A clear & concise
explanation of key
results.
Excellent
understanding
of
the work done.
Appropriate recommendations made.
Points
supported
by
well-chosen
references, mainly
cited correctly.
A clear explanation
of the key results,
indicating
very
good understanding of work done.
Appropriate recommendations
may
be made. Points
supported by valid
references, minor
errors in citation.
Results
are
explained but a
lack
of
clarity
indicates
limited
understanding.
Some recommendations
may
be
made. References,
if used, are mainly
websites / some
errors in citation.
Results
are
explained
but
explanations
are
unclear, indicating
limited understanding.
Recommendations
may be misguided.
References, if used
are poor quality /
errors in citation.
Explanation
of
results is confused
or
unclear.
Recommendations
are
not
appropriate.
References,
if
used,
are
not
appropriate
and
are cited poorly
Explanation
of
results is missed or
is confused. No
useful
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.
General grading descriptors – Second year (NQF Level 5)
12
These descriptions indicate how you will be assessed at the element level (i.e. all coursework/all exams) and at the module level
Class
Scale
General Characteristics
FIRST
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.
(Excellent)
Mid 1st
Low 1st
UPPER SECOND
(Very good)
High 2.1
Mid 2.1
Low 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
prescribed 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.
LOWER SECOND
High 2.2
(Good)
Low 2.2
THIRD
High 3rd
(Sufficient)
Low 3rd
FAIL
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
Low 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 development of work and data/evidence inappropriately used; weak technical and practical competence hampers ability to
demonstrate/communicate achievement of outcomes.
Zero
Work of no merit OR absent, work not submitted, penalty in some misconduct cases.
Mid 2.2
Mid 3rd
(Insufficient)
ZERO
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.
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.
13
III. Feedback Opportunities
Formative (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. Moderation
The Moderation Process
All 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 Portfolio
This 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)
APPENDICES
14
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) index
The 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
Flow group
Table 1. Flow scores (fs) for different abundance categories of taxa (1-5) associated with
each flow group (1-6)
Abundance category
1
2
3
4/5
1 - rapid
9
10
11
12
2
8
9
10
11
3
7
7
7
7
4
6
5
4
3
5
5
4
3
2
6 - drought 4
3
2
1
4. The LIFE score for the sample = ∑ (fs) / n. In plain English (I hope), this means that to
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.
Appendix 3. Community metrics: abundance, richness, diversity and dominance
16
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.
A
B
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.
References
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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.