3.4.2. Biological WQAssessment

- 3.4.2. -BIOLOGICAL WATER QUALITY

ASSESSMENT

3.4.2. BIOLOGICAL WATER QUALITY ASSESSMENT

Diederik RousseauUNESCO-IHE Institute for Water Education

Online Module Water Quality Assessment

CONTENTS

1. Why biological monitoring?

2. Biological assessment systems

3. Bio-alarm systems

The quality of the aquatic environment can be defined by:

1. A set of concentrations, speciations, and physical partitions of inorganic and organic substances

BUT ALSO

2. The composition and state of aquatic biota found in a water body

Revised definition of water quality

1. Biological effects occur sometimes at concentrations lower than the analytical detection limit

Example: Scientists have pointed to endocrine disruptors (ED) as the cause of adeclining alligator population in Lake Apopka, Florida. The alligators in this areahave diminished reproductive organs that prevent successful reproduction.These problems were connected to a large pesticide spill several years earlier,and the alligators were found to have EDs in their bodies and eggs. These EDscan occur at ppb levels or even lower and are therefore hard to detect reliably.

Why biological monitoring?

2. Effects of single pollutants can be different from effects of mixtures of pollutants:

synergisticThe joint action of two factors, which producer a greater effect than that of the two agents working alone. (e.g. 1 + 1 = 3)

antagonisticThis is the consequence of one chemical (or group of chemicals) counteracting the effects of another chemical (e.g. 2 + 2 = 3)


3. Toxic effects on organisms influenced by characteristics of receiving water

Example: certain types of organic material in water can form complexes with heavy metals and thus reduce the bioavailability and hence toxicity of heavy metals


4. Biological indicators can show problems otherwise missed or underestimated (e.g. chemical sampling = momentaneous).

"Chemical measurements are like taking snapshots of the ecosystem, whereas biological measurements are like making a videotape" ... (David M. Rosenberg)


5. Biological assessment uses information gathered directly from the aquatic organisms and the biological community of which they are a part.


6. The biota that biological integrity is concerned with, is shaped by all environmental factors to which it is exposed over time, whether chemical, physical, or biological.

Definition of biological integrity: functionally defined as the condition of the aquatic community that inhabits unimpaired water bodies of a specified habitat as measured by community structure and function.

This means that organisms need more than only clean water! Also flow velocity, sediment composition, presence/absence of aquatic vegetation etc. are important, see figure on next slide.


geological factors

pH

ecological factors

reproduction

physiographical factors biocenotic factors

foodgeographical factors

chemical watercomposition

predator-prey

relations

current velocity

canalisationslope

nutrient status

oxygen

vegetation sediment

geographical position altitude

climate irradiation

temperature precipitation

topographical area of distribution

distribution history

spatial size of biotope

toxicants

substrate, morfology

Occurence of stream organisms

Determining factors in the occurrence of benthic organisms in running water: abiotic factors; biotic factors; water quality criteria; anthropogenic determinants (De Pauw & Hawkes, 1993).

biological vs physical-chemical monitoringCOMPLEMENTARY

Biological Physical-chemical

Effects Causes

?


Definition of bio-indicators

Some species are known to have particular requirements with regard to nutrients or levels of dissolved oxygen. Once defined, the presence of species indicates that the given parameter is within the tolerance limits of that species.

= indicator species

Bio-indicator organisms

0

20

40

60

80

100

120

10 15 20 25 30 35

mg N/L

abun

danc

especies A species B

Species A has a growth optimum around 16 mg N/L whereas species B has an optimum around 28 mg N/L. It can also be seen that the specific intervals in which species A and B can survive are not overlapping, so they are typical for that range of conditions. This means that instead of monitoring nitrogen concentrations, you can also monitor which species is prevailing and from that gain some knowledge on the range of nitrogen concentrations in the water.

Bio-indicator organisms

CONTENTS




Most systems are structural and taxonomic in approachand based on presence or absence of

bio-indicators belonging to various organism groups

periphyton

zooplankton

phytoplankton macroinvertebrates necton

macrophytes

Biological assessment systems

Biological communitiesas indicators of waterquality

Schematic representation of the changes in water quality and the populations of organisms in a river below a discharge of an organic effluent (from Hynes, 1960).

A. Physical changesB. Chemical changesC. Changes in microorganismsD. Changes in macroinvertebrates


One major problem:Imagine you have sampled macroinvertebrates (snails, beetles, wurms, insects, …) in a river. After processing the samples and identification, you will probably end up with a list of 10 – 30 different taxa, each of which can have abundances between 1 – 10000!

How to interpret this complex biological data?


Translation of complex biological information by means of

Indices

Running waters Saprobic indicesBiotic indicesDiversity indices

Stagnant waters Trophic indicesDiversity indices


Objective: - aims to provide a water quality classification by means of a system of aquatic organisms

Principle: - every species has a specific dependency of decomposingorganic substances and thus the oxygen content: this tolerance is expressed in a saprobic indicator value

Advantages: - quick classification of the investigated community (saprobic index) can be made on a universal scale

- saprobic index can be obtained for several biotic groups Problems: - identification of organisms at species level required

- saprobic index calculation requires assessment of abundance

- the saprobic system implies more knowledge than actually exists: pollution tolerances are highly subjective and based on ecological observations and rarely confirmed by experimental studies

Saprobic indices

Σ s x hS =----------

Σ h

S = saprobic index (for interpretation see frame above)s = indicator value of each species (can be found in literature)h = frequency of each species found (qualitative, not quantitative estimation)

1 = species found only by chance 3 = species occurring frequently 5 = species occurring in abundance

Saprobic index Significance

1.0 - 1.5 Oligosaprobic 1.5 - 2.5 β-mesosaprobic2.5 - 3.5 α-mesosaprobic3.5 - 4.0 Polysaprobic

Example of a saprobic index (Pantle & Buck 1955)

Example of list with saprobic values for diatoms.

Taken from Streble & Krauter (2006)

Saprobic indices

Example: monitoring of Diptera larvae (flies) à S=?

Family s Abundance

Chironomidae 3 – 4 +++

Stratiomys 3 ++

Eristalomyia 4 ++

Atherix 1 – 2 ++ = rare abundance++ = medium abundance+++ = very high abundance

Example for saprobic indices

Example: monitoring of Diptera larvae (flies) à S=?

S = (3.5 x 5) + (3 x 3) + (4 x 3) + (1.5 x 1) = 3.33(5 + 3 + 3 + 1)

S = 3.33 = α-mesosaprobic= strongly polluted water

Example for saprobic indices

Objective: - Assess biological water quality of running waters in most cases based on macroinvertebrates

- Can measure various types of environmental stress, organic pollution, acid waters, etc.

Principle: - combines features of diversity approach and saprobic approach

- macroinvertebrate groups disappear as pollutionincreases

- number of taxonomic groups is reduced as organicpollution increases

Advantages: - requirement of qualitative sampling only - identification is mostly at family or genus level- no need to count abundances per species

Problems: - how to determine representative reference communities to which investigated stations can be compared

- an optimal biological assessment can only be achieved through regional adaptations

Biotic indices

Disappearance of macroinvertebrates subsequent to pollution

Stoneflies PlecopteraMayflies EphemeropteraCaddisflies TrichopteraScuds AmphipodaAquatic sowbugs IsopodaMidges DipteraBristle worms Oligochaeta

Most sensitive

Least sensitive

Example of biotic index = Belgian Biotic Index (see next slides)

Biotic indices

Biotic indices

nDe grotere(met het bloteoogzichtbare; >500μm) ongewerveldeorganismendie in de waterkolomleven.

Wat zijn macro-invertebraten?

Larven van Chironomidae (dans-of vedermuggen)

Larven van Plecoptera (steenvliegen)

...

Larven van Odonata (libellen)

Crustacea (schaaldieren)

Molusca (weekdieren)Hirudinea (bloedzuigers)

Coleoptera (kevers)

Belgian Biotic Index (BBI): based on macroinvertebrates (>500 µm)

Advantages

- easy to collect and identify- generation time not too short- motility feable - numerous groups with different sensitivity to pollution

Disadvantages

- dependent on substrate- difficult to compare between

regions

Macroinvertebrates visible with the naked eye (>500 µm )

leeches snails

gammaridsmidgesbeetles

stoneflies

Belgian Biotic Index vervangen door BMWP

HandnetKicknet

Active sampling – qualitative (no good ideas of densities)

The general idea is to disturb the sediment with the feet or hands and catch the invertebrates in a downstream positioned net with an appropriate mesh size (usually 300-400 μm). Various habitats should be sampled.

flow direction

Belgian Biotic Index

Shipek grab

Active sampling – quantitative (densities known)

A known surface area of sediment is sampled by means of a grab. Therefore after counting one can calculate the density (organisms per m2). Applied when densities need to be known and/or when the water is too deep for net sampling.


Bag sampler

Passive sampling – artificial substrates - qualitative

Nets or cages filled with rocks, bricks or similar substrates are put in the water for several weeks. Macroinvertebrates will find shelter between the rocks and will thus colonize the artificial substrate. Typically also used for deeper water where net sampling is not possible.


Belgian Biotic Index (BBI): sieving, sorting out

n Sieving on 3 to 4 sieves (20 tot 0,5 mm mesh size) to remove sediments

n Sorting out and preserving in denaturated alcohol

Elements of biological assessment methodsBelgian Biotic Index

Identification of macro-invertebrates up to required level (species, genus, family)using appropriate identification keys


For online version, see for instance: http://people.virginia.edu/~sos-iwla/Stream-Study/Key/MacroKeyIntro.HTML

Belgian Biotic Index (BBI): index calculation

Tolerance class Number of taxa Indicator groups Class frequency 0-1 2-5 6-10 11-15 ≥ 16 1. Plecoptera ≥ 2 - 7 8 9 10 Heptageniidae 1 5 6 7 8 9 2. Trichoptera (with case) ≥ 2 - 6 7 8 9 1 5 5 6 7 8 3. Ancylidae > 2 - 5 6 7 8 Ephemeroptera 1-2 3 4 5 6 7 (excl. Heptageniidae) 4. Aphelocheirus ≥ 1 3 4 5 6 7 Odonata Gammaridae Mollusca (excl. Sphaeriidae) 5. Asellidae ≥ 1 2 3 4 5 - Hirudinea Sphaeriidae Hemiptera (excl. Aphelocheirus) 6. Tubificidae ≥ 1 1 2 3 - - Chironomus thummi-plumosus 7. Syrphidae-Eristalinae ≥ 1 0 1 1 - -

Increasing diversity

Incr

easi

ng s

ensi

tivity

for p

ollu

tion

Elements of biological assessment methodsBelgian Biotic Index

Belgian Biotic Index (BBI): example of index calculation

• 5 taxa

• Most sensitive taxon = Ephemeroptera• Only one species of Ephemeroptera

è BBI = 4 (previous table: intersection of 2nd column, 6th row)

Gammaridae Chironomidae t. Hirudinea Ephemeroptera Coleoptera


BMWP score (Biological Monitoring Working Party)(see for instance http://www.cies.staffs.ac.uk/origbmwp.htm)

Trent Biotic Index

Chandler Biotic Index

!They all follow similar principles!

Other wellknown biotic indices based on macroinvertebrates

CONTENTS




Bio-alarm or biological early warning systems make use of living organisms to signal a change in water quality.

Often used for drinking water intakes, effluent monitoring etc.

Bio-alarm or early warning systems

Conduct system= intake of river

water

Arena basin with gold-ides

Registration system+ alarm

Bioalarm at Lobith (Germany) along the river Rhine

Bio-alarm systems with fish

Arena basin of Juhnke and Besch (1971) in which the loss of rheotaxis offish which normally swim against the current is registered by meansof pressure sensitive strings (2).


Indeed, certain fish species always tend to swim against the current. However, when this current contains for instance toxic substances, these fish will change their behaviour and swim the other way to escape from the toxic pulse. By doing this inside the arena basin, fish touch a system of wires, thereby giving a signal to the computer system.


Example of alarm reporting on the Rhine river nearLobith in 1990 (from Balk, 1992).

Num

ber o

f tim

es th

at th

e w

ires

wer

e to

uche

d by

the

fish

(x10

)


Scheme of bioalarm based on the movement of the valves ofmussels (Jenner,1989). Valves are closed when water quality is bad.

Bio-alarm systems with mussels

Mussel will close its valves in case of sudden “pollution” à alarm signal


Results from the “mussel monitor” on 15 April 2000 as a reaction to a toluene pulse in the river Meuse. Mussels 4, 5, 6 & 7 all closed at the same instance. Mussels 2 and 3 were dead (no reaction).


Daphnia (water fleas) in earlywarning systems(“changing movements”)

48

E.g. IR detection

Sensitive for e.g. organo-phosphorus pesticides(malathion, parathion,..)See e.g. Ren et al. (2007) - Env.Monit.Assessm. 134, 373-383

Algae monitor

Chlorella VulgarisSensitive for herbicides

Measurement by fluorescense

Prerequisites and application problems

- Sensitivity test organism: sufficiently large- Criterium selected: quantifiable - Detection: sufficiently fast - Alarm threshold: assessment - False alarms: minimal- Operation: simple - Test organisms: cheap, easy to handle- Alarm system: reliable, little maintenance

reasonable cost price

Bio-alarm systems

De Pauw, N. and Hawkes, H. A.: 1993, Biological Monitoring of River Water Quality , in: Walley, W. J. and Judd, S. (eds.), River Water Quality Monitoring and Control, Aston Univ. Press, U. K., pp. 87–111.

Hynes, H. B. N. 1960. The biology of polluted waters. Liverpool, Univ. Press.

Pantle, R., Buck, H. (1955). Die biologische uberwachung der Gewasser und die Darstellung der Ergebnisse. Gas. u Wasser-fach 96, 604 pp.

Streble and Krauter (2006). Das Leben in Wassertropfen – Mikroflora und Mikrofauna des Süzzwassers. Franckh-Kosmos Verlags-GmbH & Co. KG, Stuttgart, Germany. ISBN 978-3-440-10807-9

Useful references

Documents

3.4.2. Biological WQAssessment