- 3.4.2. BIOLOGICAL WATER QUALITY ASSESSMENT

3.4.2. BIOLOGICAL WATER QUALITY ASSESSMENT Diederik Rousseau UNESCO-IHE Institute for Water Education

Online Module Water Quality Assessment

CONTENTS 1. Why biological monitoring? 2. Biological assessment systems 3. Bio-alarm systems

Revised definition of water quality 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

Why biological monitoring? 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 a declining alligator population in Lake Apopka, Florida. The alligators in this area have 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 EDs can 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: synergistic The joint action of two factors, which producer a greater effect than that of the two agents working alone. (e.g. 1 + 1 = 3) antagonistic This is the consequence of one chemical (or group of chemicals) counteracting the effects of another chemical (e.g. 2 + 2 = 3)

Why biological monitoring?

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

Why biological monitoring?

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)

Why biological monitoring?

5.

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

Why biological monitoring? 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.

ecological factors biocenotic factors

physiographical factors geological factors chemical watercomposition

nutrient status

reproduction

geographical factors climate irradiation temperature precipitation vegetation sediment oxygen

geographical position altitude slope

canalisation

current velocity

substrate, morfology

food

spatial size of biotope

pH

toxicants

predatorprey relations

Occurence of stream organisms

topographical area of distribution distribution history

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

Why biological monitoring?

biological vs physical-chemical monitoring COMPLEMENTARY

Biological

Effects

?

Physical-chemical

Causes

Bio-indicator organisms

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 120

species A

species B

abundance

100 80 60 40 20 0 10

15

20

25

30

35

mg N/L

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.

CONTENTS 1. Why biological monitoring? 2. Biological assessment systems 3. Bio-alarm systems

Biological assessment systems Most systems are structural and taxonomic in approach and based on presence or absence of bio-indicators belonging to various organism groups

zooplankton

phytoplankton

periphyton

macrophytes

macroinvertebrates

necton

Biological assessment systems Biological communities as indicators of water quality

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 changes B. Chemical changes C. Changes in microorganisms D. Changes in macroinvertebrates

Biological assessment systems 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?

Biological assessment systems Translation of complex biological information by means of

Indices Running waters

Saprobic indices Biotic indices Diversity indices

Stagnant waters

Trophic indices Diversity indices

Saprobic indices Objective: Principle:

Advantages:

Problems:

- aims to provide a water quality classification by means of a system of aquatic organisms - every species has a specific dependency of decomposing organic substances and thus the oxygen content: this tolerance is expressed in a saprobic indicator value - quick classification of the investigated community (saprobic index) can be made on a universal scale - saprobic index can be obtained for several biotic groups - 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

Example of a saprobic index (Pantle & Buck 1955)

S sxh S =---------S h

Saprobic index 1.0 - 1.5 1.5 - 2.5 2.5 - 3.5 3.5 - 4.0

Significance Oligosaprobic b-mesosaprobic a-mesosaprobic Polysaprobic

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 indices Example of list with saprobic values for diatoms. Taken from Streble & Krauter (2006)

Example for 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

= a-mesosaprobic = strongly polluted water

Biotic indices Objective:

Principle:

Advantages:

Problems:

- 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. - combines features of diversity approach and saprobic approach - macroinvertebrate groups disappear as pollution increases - number of taxonomic groups is reduced as organic pollution increases - requirement of qualitative sampling only - identification is mostly at family or genus level - no need to count abundances per species - 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

Most sensitive

Least sensitive

Stoneflies Mayflies Caddisflies Scuds Aquatic sowbugs Midges Bristle worms

Plecoptera Ephemeroptera Trichoptera Amphipoda Isopoda Diptera Oligochaeta

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

Biotic indices

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

Advantages

Macroinvertebrates visible Wat zijn macro-invertebraten? with the naked eye (>500 µm ) nDe grotere(met het bloteoogzichtbare; >500

μm) ongewerveldeorganismendie in de waterkolomleven.

Larven van Plecoptera stoneflies (steenvliegen)

Hirudinea (bloedzuigers) leeches

Larven van Odonata (libellen)

Molusca (weekdieren)

snails

Crustacea (schaaldieren)

Coleoptera (kevers)

beetles

Larven van Chironomidae (dans-midges of vedermuggen)

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

... gammarids

Disadvantages - dependent on substrate - difficult to compare between regions

Belgian Biotic Index 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

Handnet

Kicknet

Belgian Biotic Index Active sampling – quantitative (densities known)

Shipek grab

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.

Belgian Biotic Index 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.

Bag sampler

Belgian Biotic Index Elements of biological assessment methods 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

Belgian Biotic Index Identification of macroinvertebrates 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 Elements of biological assessment methods Belgian Biotic Index (BBI): index calculation

Increasing diversity Increasing sensitivity for pollution

Tolerance class Indicator groups

Number of taxa Class frequency

0-1

2-5

6-10

11-15

³ 16

1. Plecoptera Heptageniidae

³2 1

5

7 6

8 7

9 8

10 9

2. Trichoptera (with case)

³2 1

5

6 5

7 6

8 7

9 8

3. Ancylidae Ephemeroptera (excl. Heptageniidae)

>2 1-2

3

5 4

6 5

7 6

8 7

4. Aphelocheirus Odonata Gammaridae Mollusca (excl. Sphaeriidae)

³1

3

4

5

6

7

5. Asellidae Hirudinea Sphaeriidae Hemiptera (excl. Aphelocheirus)

³1

2

3

4

5

-

6. Tubificidae Chironomus thummi-plumosus

³1

1

2

3

-

-

7. Syrphidae-Eristalinae

³1

0

1

1

-

-

Belgian Biotic Index Belgian Biotic Index (BBI): example of index calculation

Gammaridae

Chironomidae t.

Hirudinea

•

5 taxa

•

Most sensitive taxon = Ephemeroptera

•

Only one species of Ephemeroptera

Ephemeroptera Coleoptera

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

Other wellknown biotic indices based on macroinvertebrates 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!

CONTENTS 1. Why biological monitoring? 2. Biological assessment systems 3. Bio-alarm systems

Bio-alarm or early warning systems 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 systems with fish Bioalarm at Lobith (Germany) along the river Rhine

Conduct system = intake of river water

Arena basin with gold-ides

Registration system + alarm

Bio-alarm systems with fish

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

Bio-alarm systems with fish

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.

Number of times that the wires were touched by the fish (x10)

Bio-alarm systems with fish

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

Bio-alarm systems with mussels

Scheme of bioalarm based on the movement of the valves of mussels (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

Bio-alarm systems with mussels

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 early warning systems (“changing movements”)

E.g. IR detection

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

48

Algae monitor

Sensitive for herbicides Measurement by fluorescense

Chlorella Vulgaris

Bio-alarm systems Prerequisites and application problems - Sensitivity test organism: - Criterium selected: - Detection: - Alarm threshold: - False alarms: - Operation: - Test organisms: - Alarm system:

sufficiently large quantifiable sufficiently fast assessment minimal simple cheap, easy to handle reliable, little maintenance reasonable cost price

Useful references

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