Environmental Monitoring &
Technology
Certificate 4 - Trainee Learner Resource
Environmental Fieldwork
Study Module 7 – Biological assessment
cffet.net/env
Environmental Fieldwork
Study Module 7
Assessment details
Purpose
This subject covers the ability to site and set up basic ‘ground level’ meteorological
equipment and collect and record reliable data. It also includes the ability to assess data
quality, interpret significant data features and use the data to ensure the validity of air and
noise monitoring measurements.
Instructions
◗
Read the theory section to understand the topic.
◗
Complete the Student Declaration below prior to starting.
◗
Attempt to answer the questions and perform any associated tasks.
◗
Email, phone, book appointment or otherwise ask your teacher for help if required.
◗
When completed, submit task by email using rules found on last page.
Student declaration
I have read, agree to comply with and declare that;
◗
I know how to get assistance from my assessor if needed…
☐
◗
I have read and understood the SAG for this subject/unit…
☐
◗
I know the due date for this assessment task…
☐
◗
I understand how to complete this assessment task…
☐
◗
I understand how this assessment task is weighted…
☐
◗
I declare that this work, when submitted, is my own…
☐
Details
Student name
Type your name here
Assessor
Marker’s use only
Class code
EF
Assessment name
SM7
Due Date
Total Marks Available
50 (by assignment)
Marks Gained
Marker’s use only
Final Mark (%)
Marker’s use only
Marker’s Initials
Marker’s use only
Date Marked
Click here to enter a date.
Weighting
This assessment contributes 5% to the overall mark for this subject
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 1
Environmental Fieldwork
Study Module 7
Introduction
The use of biological organisms, whether they be micro (cannot be seen with the naked eye)
or macro (visible to the naked eye), as indicators of environmental quality is now a wellregarded science in most developed countries and there are many Australian government
departments that deal with this type of monitoring including the Environmental Protection
Agencies (of each State) and various fishing, agricultural and primary industry government
bodies.
While environmental technicians will predominantly be involved in collecting water samples
with sterile equipment for coliforms (the most common indicator of human faecal
contamination), there are many other forms of biological sampling that can be encountered
and this section deals with the major categories associated with surface and potable waters.
In short, the three types of biological sampling we shall discuss are;
◗
Microbiological
◗
Macro-invertebrate
◗
Vertebrate
Types of aquatic biological organisms
A typical aquatic ecosystem such as a river or lake will have a significantly complex food web
which will range from the top predators, in the form of fish or yabbies, down to detritus
cycling microorganisms such as bacteria and fungi, such as those depicted in Figure 7.1
below;
Figure 7.1 – Simple aquatic food chain. [source]
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 2
Environmental Fieldwork
Study Module 7
Vertebrates
Vertebrates are animals with ‘backbones’ of the subphylum Vertebrata. Vertebrates include
about 64000 species of the phylum Chordata. Vertebrates include the jawless fish, bony fish,
sharks and rays, amphibians, reptiles, mammals, and birds, but we are only interested in
fish, sharks, rays and amphibians. Vertebrates make up about 4% of all described animal
species with the rest are invertebrates.
Note that it is unusual for environmental technicians to undertake vertebrate sampling.
Usually this work is performed by biologists or other specialists due to ethical concerns for
animal welfare, but also problems associated with species identification.
Having said that, some work at government levels is performed and you may end up as part
of a team that performs these tasks. Two main types of assessment are performed;
◗
Biological indices (lethal or non-lethal), or,
◗
Chemical or microbiological analysis.
Fish index work involves collecting samples of the fish populations at each water body and
using the data derived from these samples to develop metrics of biological integrity.
Biological integrity is defined by the USEPA as;
“a measure of the ability of the biotic components of an ecosystem to maintain a level of
diversity and functional organization that is comparable to natural systems unimpacted by
human disturbance”
Figure 7.2 – Examples of freshwater fish
Analysing fish tissue for contaminants can produce an indicator of characteristics for both
response and diagnostic indicators. As a response indicator, tissue contaminant levels can
be used to infer effects on fish populations in and around lakes. When response indicators
identify lake degradation, the fish tissue contaminants indicator can also be used to detect
contaminants such as a number of organo-chlorinated pesticides, PCB congeners, and heavy
metals, including mercury. There is no one specific index used anywhere in the world (that I
could find anyway), so these would be developed by government agencies or universities.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 3
Environmental Fieldwork
Study Module 7
Invertebrates
An aquatic macroinvertebrate is a water bug that we can see with our naked eye. Many of
these macroinvertebrates make their homes in rocks, leaves and sediment in stream beds.
Some of these insects and non-insects spend their entire lives in water, like scuds, clams,
mussels and snails. However, usually just the larva and nymph stages (the immature stages
of insects' lives) are spent in water. Then the larva or nymph will spend it's adult life out of
the water.
Figure 7.3 – Examples of macroinvertebrate species
They are indicators of water quality. Different types of macroinvertebrates tolerate different
stream conditions and levels of pollution. Depending on the types of macroinvertebrates
found in a stream, predictions about water quality can be made. For example, caddisflies,
mayflies, and stoneflies cannot live in polluted water. If these bugs are found in a stream,
the water quality there is probably good. However, that doesn't mean that if these bugs are
not found in a stream the water quality is bad. Other factors like temperature and flow also
come into play.
Natural influences that cause macroinvertebrate populations to change:
◗
Seasons
◗
Dissolved Oxygen
◗
Substrate (habitat)
Human influences that cause macroinvertebrate populations to change:
◗
Nutrient enrichment
◗
pH
◗
Removal of riparian vegetation
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 4
Environmental Fieldwork
Study Module 7
Microorganisms
Microorganisms are the smallest living organisms on Earth but at the same time they are the
most abundant ones as they have occupied the entire biosphere. They are also the most
diverse and in their majority unknown to scientists. They can be found in every macro or
micro environment. Microbial ecology and particular the water microbial ecology studies
the relationships among microorganisms and the way they influence water environments,
by using principles and methods from microbiology, chemistry, physics and ecology.
Important types of aquatic microorganisms
Cyanobacteria
Cyanobacteria are found in most aquatic habitants and can range from 1μm in diameter to
several 100 μm. Most of them are O2 producing photosynthetic bacteria which utilize the
CO2 available in water and they are responsible for N2 fixation. The ecology of cyanobacteria
is of concern as they often tend to increase in population (blooms) in eutrophic
environments with a tremendous impact on water quality and aquatic life due to their
ability to be toxic.
Bacteria
The bacteria are a ubiquitous class which colonizes any habitant of the planet having the
grater active biomass than any other group of organisms. They are also the most
metabolically diverse group that obtain energy from oxidizing organic carbon, parasitism,
chemoautotrophy and photoautotrophy. In aquatic environments they play a crucial role in
most biogeochemical fluxes as in nitrogen cycle, carbon cycle, oxygen and sulfur.
Plankton
The term ‘‘plankton’’ refers to those microscopic aquatic forms having little or no resistance
to currents and living free-floating and suspended in natural waters and can range in both
size and complexity from single celled organisms (such as some algae) to complex
multicellular microscopic animals. This section will cover phytoplankton, which are aquatic
photosynthesisers and zooplankton which are planktonic animal.
Phytoplankton have long have been used as indicators of water quality for three reasons;
◗
They respond quickly to changes in their environment
◗
They are an excellent indirect indicator of nutrient loading in eutrophication studies
◗
Some species are noxious or poisonous in large quantities (i.e. red tides, blue-green
algae)
Because water of rivers and streams usually is well mixed vertically, subsurface sampling,
i.e., the upper meter or a composite of two or more strata, often is adequate for collection
of a representative sample.
As with all sampling, there are many factors to consider. In reality, most of these factors will
be excluded or dealt with statistically due to cost, time, convenience and safety
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 5
Environmental Fieldwork
Study Module 7
considerations. Unlike chemical sampling or even sampling for colloidal bacteria, algae and
zooplankton can be affected by several parameters including;
◗
Temporal changes (seasonal and daily)
◗
Temperature changes (thermoclines)
◗
Salinity gradients (isohalines)
◗
Flow and turbulence (mixing and settling effects)
◗
Surface effects (such as algal films)
Generally speaking, there are three sample collection techniques, all of which have pros and
cons and as such you will be told which technique to use. They include;
◗
Sample bottles (same as for chemical sampling)
◗
Sample ‘thieves’
◗
Filter nets for concentration
Be aware that most preservatives distort and disrupt certain cells. For a sample that will be
preserved make sure you fill the container completely. The most suitable phytoplankton
preservative is Lugol’s solution, which can be used to preserve most species of interest.
To preserve samples with Lugol’s solution add 0.3 mL Lugol’s solution to 100 mL sample and
store in the dark. For long-term storage add 0.7 mL Lugol’s solution per 100 mL sample and
buffered formaldehyde to a minimum of 2.5% final concentration after 1 h. Any other
preservative will be used in accordance with the laboratories instructions. To retain colour
in preserved plankton, store samples in the dark or add 1 mL saturated copper sulfate
(CuSO4) solution/L.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 6
Environmental Fieldwork
Study Module 7
Microbiological sampling using AS2031-2012
Note: This subject does not cover any microbiological techniques other than sampling. Any
specific tasks associated with microbiological analysis (such as aseptic (sterile) techniques
will be dealt with by other units of study.
The sampling and subsequent analysis of microbiological properties is covered in Australia
by the AS 2031-2012 Water Quality – Sampling for microbiological analysis which is based
on the international standard ISO 19458:2006. This section outlines the general approach as
determined by the standard methods.
Sampling requirements
As with all sampling, the sample site must provide samples which are representative of the
statistical population characteristics and must account for vertical, horizontal and temporal
variations. Specific problems that can be present for the microbiological sampling of surface
waters include (but are not limited to);
◗
False positive or negative results from the inclusion of surface ‘films’ during sample
collection,
◗
Different points of collection as a result of confluence or ‘dead ends’ or mixing.
These variations must be accounted for or at least acknowledged prior to sampling
otherwise there is a risk of poor quality data being generated.
Sample containers
The choice of sample container is governed by the physiochemical properties of the water
and the purpose of the sampling.
Sterilisation and asepsis
At a minimum, all samples containers used for microbiological sampling must be sterile
inside and out. There are many techniques to achieve the required level of asepsis including
autoclaving, UV and gamma radiation as well as a suite of specific materials that can be
used. Your laboratory will provide the required equipment prior to the sampling event.
Sample volume
The volume of sample collected can vary between 100 mL and 500 L depending upon the
species being analysed (i.e. E Coli versus Cryptosporidium).
Disinfectant removal
Microbes are killed by disinfectants, so to sample a water body that has disinfectants
present will lead to a false negative response and as such it is important to remove the
disinfecting agents.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 7
Environmental Fieldwork
Study Module 7
The most common disinfectant is chlorine which is removed by adding a chemical called
sodium or potassium thiosulphate and ensuring the sample when full is neutral as this
chemical can decompose at lower pH values. Note that other disinfectants can be removed
using other techniques such as chelation or precipitation.
Sample collection
The standard breaks down the filling procedure based on the type of sample being
collected;
Potable water from a tap
This monitors the drinking water quality at the point of consumption and provides
information about potential sources of contamination between the source of the water
(either a treatment plant of some sort or bore water) and the consumer.
Specific procedures are outlined in the Standard but generally involve flushing for a period
of time or a specific amount for water.
◗ Flushing is followed by sterilisation to ensure no external contamination occurs which
would lead to a false positive value
◗ Avoiding contact between the sample vessel and any other object.
◗ Leaving a headspace for sample shaking before sample preparation and laboratory
analysis.
Other specific circumstances, such as dealing with storage tanks, are dealt with in the
Standard.
Water from springs and wells
This type of monitoring is done to determine general water quality, and the specific reason
depends on the use of the water. The only real difference is with the equipment used permanent equipment versus portable equipment.
◗ If permanent equipment is being used, it cannot not be sterilised so longer pumping
times are used.
◗ For portable equipment, it must be disinfected prior to use and also use extended
pumping times to ensure a representative sample.
Water from swimming pools
Swimming pools are monitored for public safety reasons by determining the effectiveness of
chlorine dose rates. The purpose of the bacteriological sampling is to ensure disinfection is
to Standard.
Because swimming pools use chlorine as the primary disinfectant, this needs to be
incorporated into any microbiological sampling event. This is performed by the addition of
Sodium thiosulfate which neutralises the residual chlorine and ensures that any
bacteriological entities are not destroyed prior to analysis.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 8
Environmental Fieldwork
Study Module 7
The sample bottle is introduced horizontally to avoid any losses of the thiosulfate. It is then
turned to the vertical position to ensure filling is complete, and then returned to the surface
to ensure the sampled water doesn’t rinse out the thiosulfate.
Surface waters
This is the most common form of sampling that environmental field technicians will
perform. Bathing waters (lakes, rivers, seaside) are usually classified by statistical analysis
from historical series of measurements, usually conducted over a season or more. The
general procedures are below;
◗ The sampling points should be strictly defined and be representative of the water quality
at the site.
◗ Take subsurface samples (−20 cm to −30 cm) in a 1 m to 1.5 m deep water column.
◗ Introduce the bottle upside down in the water to the sampling depth. Subsequently, fill
the bottle by turning it sidewards and upwards to avoid contaminations.
◗ Where a current exists, hold the bottle upstream.
◗ At some beaches, a water column of 1 m is not achieved and the sample needs to be
taken at a shallower depth.
◗ Pay special attention paid to re-suspension effects. One of the major sources of variation
in beach water quality is the re-suspension of bacteria adsorbed on clay or organic silt.
Faulty sampling can have the same effect (e.g. filling too close to the bottom, agitating
the sediment, own ship movement).
◗ Seasonal patterns and vertical stratification of lake and sea water and mixing of river
water should be considered when selecting the exact sampling sites.
◗ Many devices are available to take subsurface or deep samples offshore, but
oceanographic bottles used for chemistry (Go-Flow, Nansen or Van Doorn bottles) are
not sterilisable and are not appropriate, and sterile vacuum systems are recommended.
◗ From a water craft adrift, take samples from the lee side, not to windward. Any possible
contamination from ropes carrying sterile instruments should be minimized, using, for
example, stainless steel wire or a chain at the bottom of the line.
Waste waters
Use disposable gloves or sterilizable poles or forceps for subsurface sampling, to minimize
the infection risk for the sampling personnel. Remove dirt from the bottle outer surfaces
and/or put them in clean bags and transport them separately from drinking water samples.
Procedures are as for sea’s lakes and rivers.
Transportation considerations
Transportation od the samples is the same as for all water samples. They should be stored
after sampling as soon as possible, and kept at around 4°C by use of artificial ice blocks
(preferred) or ice cubes ensuring that no contamination from ice cubes occurs. If long
transportation times are expected (maximum is usually 8 hrs), it may be required to monitor
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 9
Environmental Fieldwork
Study Module 7
the temperature during the storage and transportation time, and all documentation should
be completed.
Quality assurance and control
Special bottles are prepared that travel with the sample collection vessels that allow for the
quantification of contamination by ambient sources. These bottles are sort of ‘blank’
controls and are prepared and analysed by the laboratory.
Other more specific tests can be performed on samples for the presence of preservatives,
inactivation agents and residual toxicity.
All TAFE students can acquire a free copy of Australian Standard AS2031-2012: Water
quality-Sampling for microbiological analysis (ISO 19458:2006, MOD) from the Libraries
online database.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 10
Environmental Fieldwork
Study Module 7
Macro-invertebrate sampling
Macroinvertebrate sampling has been used for over 20 years by many countries as a
potential source of information about water quality.
The general idea behind the theory is that if we know how stable populations of aquatic
organisms behave, we can monitor data collected over several years and any observed
changes in their statistical distributions could indicate that there has been a change in the
quality of the water.
In practice, it takes a high level of skill to perform the sampling, and an even higher level of
skill in interpreting the data, which leads to the following generalisation;
A poorly run rapid biological assessment provides more questions than answers and can be
a complete waste of time and resources. So if you are going to start one of these
programmes, you need to make sure that you have a good team and access to all the
required resources to get the job done properly.
Sources of information
There is now a plethora of information sources that deal with this kind of biological
monitoring. Listed below are the key resources that should enable you to get a good
grounding in the practice.
◗ The Australian Rivers Assessment System (AUSRIVAS)
◗ NRHP Signal Index Stream Invertebrate Grade Number Average Level (SIGNAL)
◗ US EPA Rapid Bio-assessment Protocols
◗ Australian Museum Streamwatch
◗ NSW DEC Waterwatch program
Macroinvertebrate sampling
An invertebrate aquatic animal that can be seen with the naked eye is called a macroinvertebrate. These organisms play a vital role in ecosystem and can be used to monitor the
health of aquatic systems under certain circumstances. Complexities arise due to several
complicating factors;
◗
Life cycle stages of the organisms
◗
Individual organism sensitivity to pollution
◗
Different habitat requirements of species
◗
Seasonal effects on populations
As a result of these complicating factors, a large and comprehensive data set is required to
make sense of the data, which as a minimum should be 2 years covering all seasons, so it is
not a fast process to determine the health of an ecosystem at first.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 11
Environmental Fieldwork
Study Module 7
Once the data has been collected, and sense can come from the data, the assessments do
become rapid, as results can be seen on the day when referenced against the whole
historical picture.
Figure 7.4 - Examples of macro-invertebrates found in freshwater aquatic systems
This technique has been used extensively in Europe, the USA and Australia and the literature
on methods and analysis is comprehensive. Macro-invertebrate analysis is often constrained
to benthic (sediment) systems, but in this section we shall explore the whole ecosystem
including pelagic (free water) and benthic organisms. The approach that we shall base our
discussion on will be the AUSRIVAS system, but note that there are many more.
The AUSRIVAS program
To quote the website [source];
“AUSRIVAS (Australian River Assessment System) is a rapid prediction system used
to assess the biological health of Australian rivers. AUSRIVAS was developed under
the National River Health Program (NRHP) by the Federal Government in 1994, in
response to growing concern in Australia for maintaining ecological values.”
Invertebrate sampling and analysis forms only one part of the AUSRIVAS program, with
physio-chemical assessment making up the other (which is effectively what the other six
sections of these notes are about).
Note: AUSRIVAS is a huge and complex program, we are only using the sampling
methodology and are not interested in the overall river health program.
The following information comes directly from the NSW AUSRIVAS Sampling & processing
manual which is available from http://ausrivas.ewater.com.au/.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 12
Environmental Fieldwork
Study Module 7
Introduction
Site based information
Sampling time
The samples collected for developing the NSW AUSRIVAS models were collected in either
autumn or spring and hence cover only six months of the year. The models will only give
reliable results if sampling is undertaken within these two seasons. The autumn sampling
season runs from March 15 to June 15 and the spring sampling season from September 15
to December 15.
Defining a site
The width of a river is used to define the section of that river that constitutes a site for the
purposes of AUSRIVAS sampling in NSW. The site is defined by measuring;
◗ The modal width of the stream
◗ The reach length is determined on the modal width
AUSRIVAS is very particular about these definitions for their mathematical models.
Selecting sampling sites
Site selection is determined on sampling purpose;
◗ General ecological monitoring
◗ Point source effects
The site selection will need to incorporate the habitat and the representativeness required
based on the purpose.
Habitats to be sampled
For the purposes of AUSRIVAS a habitat is an instream environment within a sampling site
that supports a distinct macroinvertebrate fauna. In NSW AUSRIVAS models were developed
for Riffle and Edge habitats, which are defined as;
The riffle habitat is an area of broken water with rapid current that has some cobble or
boulder substratum.
The edge habitat is an area along the creek bank with little or no flow
Other areas within these are referred to as ‘sub-habitats’ which is defined as the various
types of in-stream structure present in a habitat.
For example, one sub-habitat type may be all areas of overhanging bank in the edge habitat
of a reach, whether overhanging banks are patchily distributed or form a continuous
segment of the edge.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 13
Environmental Fieldwork
Study Module 7
Data collection
Site location and access information
Data collection is the key to the AUSRIVAS success and there is a very strict code of practice
for the collection of data, which includes;
◗ Site codes
◗ Collection dates
◗ Location names
◗ Sampling team
◗ Sample location
◗ Map details
◗ Site details, including the distance from source, slope, geographic position, mean annual
rainfall
◗ Access details, including access route and land owner details
Site attributes
This section aims to provide a general description of the environment within and
immediately surrounding the site, and includes the following information;
◗ Definition of the site boundaries
◗ Topography
◗ Water level
◗ Shading of the river
◗ Percentage of micro and macrophytes
◗ Stream width
◗ Water quality
◗ Birds eye view
◗ landuse
Attributes of edges and riffles
More information about the riffle and edge habitats is required, including;
◗ Collector or sorter ID
◗ Whether the bugs were picked on site or off site
◗ Descriptions of the natural substrate
◗ Water depth
◗ Detritus cover
◗ Bank overhang
◗ Trailing bamk vegetation
◗ Macrophytes
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 14
Environmental Fieldwork
Study Module 7
◗ Other comments regarding this type of information
Visual assessment of disturbance
This assessment is aimed at summarising evidence available at the site of alteration caused
by human activities to different components of the stream ecosystem. Some evidence is
objective, easy to identify and valid for all stream types.
Other evidence, however, may be specific to the type of river in question and harder to
identify. The operator is required to use her/his knowledge of streams in the nearby area
and decide how much this site has changed as a result of human activities.
Macroinvertebrate sampling
Equipment required
◗ All macroinvertebrate sampling must be done with a kick net of 0.25 mm mesh size.
◗ The preferred net frame is one with a pentagonal shaped opening with a base of 35 cm
or greater.
◗ The net should be long enough to not cause backwash (60 cm or more)
◗ the net handle should be long enough (1.2 m) to reach animals and sub-habitats that are
not immediately near the operator.
◗ Nets should be rinsed well prior to each sampling occasion to ensure no animals
collected from another habitat or site remain stuck to the net.
Riffle sampling
All available combinations of flow (fast, moderate, and slow flowing), depth (shallow to
deep), and substratum (boulder, cobble, pebble, etc) should be considered potentially
different sub-habitats and each sub-habitat should be represented in a sample.
It may be necessary to stop and rinse the net a couple of times during sampling to remove
fine particles that can block the flow of water through the net which can cause backwash
and loss of captured macroinvertebrates. The general AUSRIVAS method is outlined below;
◗ Locate the downstream end of the riffle zone within the site and begin sampling there.
◗ Disturb the substratum with your feet while holding the net downstream with its mouth
facing upstream.
◗ Vigorously move the substratum about by digging your feet well into the cobbles and
boulders.
◗ If necessary, turn and rub the boulders and cobbles by hand to dislodge organisms.
◗ Continue this process until you have sampled a total of 10 metres of riffle habitat.
◗ Depending on the extent and structure of the riffle habitats being sampled this may be a
continuous 10 metres or consist of a number of discrete segments totalling 10 metres.
◗ In rivers where there is little variation in riffle type or where only 10 metres of riffle is
available, you may have to sample a continuous 10 metres of riffle.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 15
Environmental Fieldwork
Study Module 7
However, in most rivers, to ensure the inclusion of all riffle sub-habitat types available in
that reach, it will be necessary to sample a number of discrete segments, 1 to 2 metres in
length.
Edge sampling
As for riffles, a total length of 10 metres is sampled in edge habitats. Once again, these 10
metres need not be continuous and can be composed of a number of discrete segments, 1
to 2 metres in length, that ensure the inclusion of all edge sub-habitat types available in the
reach.
Samples in edge habitats are collected by using two types of sweeping motions with the net.
The first type, sequential, short sweeping movements at right angles to the bank, dislodges
benthic animals and suspends them in the water column. This movement includes scraping
of hard surfaces such at submerged logs, bedrock or boulders as well as the upper parts of
soft surfaces such as clay banks and the in-stream parts of sandy beaches, etc.
The second type of movements, when the net is swept through the cloud of suspended
material, collects macroinvertebrates in the net.
◗ This procedure (combining both types of net sweeping) should be repeated in each of
the discrete segments sampled in the edge habitat.
◗ Attempts should also be made to collect surface dwelling insects and record of their
presence on the field data sheet.
◗ It is also worthwhile writing the name of the surface dweller on a label and placing it in
the jar containing the live picked macroinvertebrate sample for the edge habitat.
◗ When sampling the edge habitat, try to sample all sub-habitats present in the reach.
◗ Sweep the net in amongst tree roots, trailing bank vegetation, under overhanging banks
and along logs if present.
◗ Do not, however, work into log crevices or use your hands or any means other than the
net to extract animals.
◗ Macrophytes can be included in the edge habitat and should be sampled if abundant,
however, small patches of macrophytes should not be deliberately sought for while
sampling.
As mentioned for the riffle it is recommended to thoroughly rinse the sample in a clear
water area once sampling is completed. This will assist in the sorting process by
Identification and processing
In NSW a live-pick sorting procedure is used. Samples should be sorted as soon as possible
after collection.
◗ Edge and riffle samples must be processed separately.
◗ Sorting should be conducted close to the site and during daylight hours.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 16
Environmental Fieldwork
Study Module 7
If this is not possible and the sample must be transported a considerable distance from the
site the contents of the net should be transferred into a labelled container or bag and kept
cool and moist with a little water.
The aim of the live-sorting procedure is to pick as many macroinvertebrate taxa from the
sample as possible. An ability to recognise macroinvertebrate families will be of great help
in this process. Standardisation of picking effort and performance during the live picking
procedure is achieved by meeting set criteria as detailed below.
Macroinvertebrate samples need to be identified to family level with the exception of
Oligochaeta (to class), Polychaeta (to class), Ostracoda (to subclass), Nematoda (to phylum),
Nemertea (to phylum), Acarina (to order) and Chironomidae (to subfamily).
Data interpretation
Data interpretation using the AUSRIVAS method is performed by the use of their proprietory
statictical software (the AUSRIVAS model).
The model can be accessed by anyone who registers, for a fee, on their site;
http://ausrivas.ewater.com.au/index.php/get-the-predictive-modelling-software
This will yield whatever magical numbers it yields and the rest is up to you!
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 17
Environmental Fieldwork
Study Module 7
The SIGNAL Index
Another commonly used technique is called the Stream Invertebrate Grade Number
Average Level, or SIGNAL Index which was developed by the National Healthy Rivers
Program.
This system is the one followed by our teaching section as it is more user friendly and free!
Like the AUSRIVAS and other international methodologies, the SIGNAL index uses a
combination of physical, chemical and biological water quality data. A SIGNAL score gives an
indication of water quality in the river from which the sample was collected. Rivers with
high SIGNAL scores are likely to have low levels of salinity, turbidity and nutrients such as
nitrogen and phosphorus. They are also likely to be high in dissolved oxygen. When
considered together with macroinvertebrate richness (the number of types of
macroinvertebrates), SIGNAL can provide indications of the types of pollution and other
physical and chemical factors that are affecting the macroinvertebrate community.
The exact methodologies used in the SIGNAL Index derivation are as described by the
AUSRIVAS and Streamwatch or Waterwatch techniques.
Calculating a SIGNAL score
Note that Veriosn 2.4 was the current version of the SIGNAL Index scoring system at the
time of writing.
Once all the specimens are identified to either the family or the order-class-phylum level,
the SIGNAL 2 score can be calculated. Each type of macroinvertebrate has a ‘grade number’
between 1 and 10.
A low grade number means that the macroinvertebrate is tolerant of a range of
environmental conditions, including common forms of water pollution.
A high number means that the macroinvertebrate is sensitive to most forms of pollution.
The higher the number, the greater the average sensitivity.
Generally, grades for the family and order-class-phylum levels of identification should not
be mixed in the same calculation. However, in family-level studies, a few groups that are
more difficult to take to family level are often left at order-class-phylum level, for example
mites (Acarina) and segmented worms (Oligochaeta). In these cases the order-class-phylum
grades can be used in the family-level calculation. However, this must be done consistently
if valid comparisons are to be made between SIGNAL 2 scores for different samples.
SIGNAL 2 scores can be calculated with or without abundance weighting. If no weighting is
used, the SIGNAL score is the average of the grade numbers for those macroinvertebrate
types collected.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 18
Environmental Fieldwork
Study Module 7
If abundance weighting is used, a weight factor is derived for each type of
macroinvertebrate.
Various weighting schemes are possible. The one used in this manual has been employed for
several years in the New South Wales Streamwatch ‘Water Bug Survey’.
The calculations proceed by the following steps outlined below;
Step 1
A list of the macroinvertebrate types found in the sample is made at either the family or the
order-class-phylum level, depending on how far the identification is taken.
Step 2
The relevant grade number is entered alongside each type of macroinvertebrate in the list.
If a type has been recorded that has no grade number assigned, it should be deleted from
the list. This will happen only rarely.
Step 3
The number of specimens of each macroinvertebrate type that were collected (abundance)
is entered alongside the grade number.
Step 4
The weight table is used to determine the weight factor for each type of macroinvertebrate,
according to the number of specimens collected. The weight factors are tabulated next to
the abundance values.
Step 5
The grade number for each macroinvertebrate type is multiplied by the corresponding
weight factor and the results are tabulated.
Step 6
The weight factors for all macroinvertebrate types are added.
Step 7
The products of grade numbers and weight factors are added.
Step 8
The second of these totals is divided by the first to produce the abundance-weighted
SIGNAL 2 score.
An example of a datasheet used collect and calculate the data is seen in the figure below;
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 19
Environmental Fieldwork
Study Module 7
Figure 7.5 – Example of the macroinvertebrate field sheet used to calculate the score for
macroinvertebrates by our teaching section.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 20
Environmental Fieldwork
Study Module 7
Plotting the results
In order to interpret the SIGNAL 2 score, the next step is to plot both the score and the
number of types of macroinvertebrates recorded on a graph with two axes (a biplot). The
figure below is an example of a bi-plot for the order-class-phylum (OCP) version.
The vertical axis (SIGNAL 2 (OCP) score) ranges from 1 to 10, since these are the minimum
and maximum possible scores respectively. However, it most cases, scores will lie between 3
and 7. The maximum possible number of orders-classes-phyla varies among regions of
Australia, but it is very rare to collect more than 20.
This plot can also be used for family values as opposed to order/class/phylum values.
Unfortunatley, the bi-plot means little by itself, so we require more information to actually
interpret the data collected. This is achieved by the use of quadrant diagrams. The basic
quadrant diagram is shown below for the order-class-phylum version of SIGNAL 2). The area
of the biplot is divided into four quadrants. The appropriate boundaries between the four
quadrants will differ between geographic regions of Australia because of natural variation in
macroinvertebrate assemblages. They will also vary according to sampling effort and the
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 21
Environmental Fieldwork
Study Module 7
types of habitats sampled. For this reason, numbers on the axes corresponding to the
quadrant boundaries are not shown.
Figure 7.5 – Example of a quadrant plot for data analysis.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 22
Environmental Fieldwork
Study Module 7
Data interpretation
Quadrant 1 (at the top right)
This quadrant represents high values of both SIGNAL 2 and the number of
macroinvertebrate types.
The presence of large number of types suggests that the diversity of physical habitats is high
and that stress factors like toxic chemicals and harsh physical conditions are not present.
The high SIGNAL 2 scores suggests that turbidity, salinity and nutrient concentrations are
low. Streams in undisturbed native forest will often fall in this quadrant.
Quadrant 2 (at the bottom right)
This quadrant represents lower SIGNAL 2 scores and a high diversity of macroinvertebrate
types.
Sites falling in this quadrant are likely to have higher levels or turbidity, salinity or nutrients
than those in quadrant 1, as suggested by the lower SIGNAL 2 score.
These levels may be high either naturally, because of local geology and soil types, or as a
result of human activities. The high number of macroinvertebrate types suggests that
physical conditions are still benign and toxic chemicals are not present in large amounts.
Many agricultural streams without severe impacts fall into this quadrant.
Quadrant 3 (at the top left)
This quadrant represents high values of SIGNAL 2 but few macroinvertebrate types.
Sites with toxic pollution, such as those with below old mine sites where acidic drainage can
result in low pH and high concentrations of trace metals, usually fall either in this quadrant
or in quadrant 4. This occurs because the tolerances of some macroinvertebrate types differ
according to the type of pollution.
Harsh physical conditions can also result in sites falling in quadrant 3. A very simple habitat
structure, such as occurs on mobile sand beds or bare muddy beds, can result in few
macroinvertebrate types being able to colonise and survive, even if water quality is suitable
for them.
Poor sampling technique or inadequate sampling effort can also result in a site falling in
quadrant 3, because few macroinvertebrates are collected even though many are present.
Quadrant 4 (at the bottom left)
This quadrant represents low values of both the SIGNAL 2 score and the number of
invertebrate types.
Most sites falling into this quadrant will be suffering from one or more forms of human
impact.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 23
Environmental Fieldwork
Study Module 7
Setting the boundaries
It is necessary to set the boundaries on the quadrant diagram individually, in order to suit
each study region and the local sampling methods.
The figure below shows a simplified example of how this can be done. The coloured dots in
the bi-plot represent three macroinvertebrate samples. The image is keyed out as follows;
◗ Blue dots - a forest area with very little human disturbance.
◗ Pale and dark green dots - agricultural areas where high levels of stream turbidity,
nitrogen, phosphorus and salinity are common.
◗ Yellow dots - downstream of a disused metal mine.
◗ Brown dots - immediately downstream of a large dam
◗ Red dots - a small stream below the discharge point of a sewage treatment plant.
The boundaries were set so that the samples from undisturbed sites fall in quadrant 1.
Figure 7.6 – A completed quadrant plot for the SIGNAL data.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 24
Environmental Fieldwork
Study Module 7
Interpreting the results
With large numbers of samples, there will often be some overlap between sites with and
without human disturbance. In these cases, setting the boundaries so that all samples for
undisturbed sites are in quadrant 1 may result in too many disturbed samples being in this
quadrant. On the other hand, setting the boundaries of quadrant 1 to exclude all samples
from disturbed sites may result in many samples from undisturbed sites being in quadrants
2, 3 and 4. In these cases, a compromise must be found between the two extremes.
In many regions, there may be no sites without human disturbance. A considerable amount
of judgment is needed in such cases. If some sites are considered to be in good condition
and well managed, the boundaries could be set so that such sites are in quadrant 1. If even
the best sites available are considered to be degraded and poorly managed, the boundaries
should be set so that these sites are somewhat outside quadrant 1.
It is always important to remember that SIGNAL 2 scores and biplots are a simple, rapid
assessment and not a comprehensive assessment of a stream or even of its
macroinvertebrates. The biplot provides an indication of things that may be affecting the
macroinvertebrates at the site, such as water and habitat quality.
Difference between AUSRIVAS and the SIGNAL system
The Australian River Assessment System (AusRivAS) is a set of computer models that
compare a macroinvertebrate family list from a sampling site (test site) with a data base
from a large number of reference sites throughout Australia.
The AusRivAS models can also calculate a reference SIGNAL score for comparison with the
actual score at a test site. However, there is some debate in the scientific community about
how a reference score for SIGNAL should be calculated.
AusRivAS outputs involving SIGNAL should be interpreted with caution until this is resolved.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 25
Environmental Fieldwork
Study Module 7
Assessment Task
The assessment task for this module will be performed practically in the field (either during
prac week or in the workplace).
The practical assessment will involve the following tasks;
◗ Collecting sterile surface water microbiological samples for the assessment and
enumeration of Escherichia coli as per the Australian Standard. (you are only assessed
on the sampling, the rest is for ‘fun’)
◗ Performing sampling of aquatic macroinvertebrates (using simple equipment)
◗ Field identification of aquatic macro-invertebrates (using simple charts)
◗ Calculation of a SIGNAL Index suing the appropriate method.
◗ Assessing the score of you site to the historical data for your site.
◗ Comparing all sites to each other and determining the boundaries of the site based on
given information about each site.
Details of this assessment will be given during practical week.
Chemical, Forensic, Food & Environmental Technology [cffet.net]
Version 1.0 30/05/2016
Page | 26