Τομέας Ζωολογίας, Τμήμα Βιολογίας, Σχολή Θετικών Επιστημών Α.Π.Θ.

Periphyton (aufwuchs) as an indicator of water quality

Dr G.Dussart
Canterbury Christ Church University College,
Canterbury,
Kent CT1 1QU

Introduction

  • planktonic algae indicate water quality (eg. Christie & Smol, 1993)
  • periphyton exists on solid surfaces under water (aufwuchs – Russell Hunter, 1970)
  • long history of use as indicators
    • Kolkwitz and Marsson 1908 (Kolkwitz, 1950)
    • Butcher (1932, 1947)
    • Ruth Patrick (1954)
    • Douglas (1958)
    • Palmer (1969)
    • Fjerdingstad (1965)
    • Sladecek (1978) (figure adjacent)
  • then quiet period, though used by professional ecologists (eg Dussart 1982,1984, 1981)
  • resurgence when global warming recognised physico-chemistry used to predict the distributions of the biota eg. regression relationships current biotic information models past aquatic environments(Battarbee et al., 1988)

What is the periphyton ? (peri = on top of…………phyton = plant).

epipelic silt and sediment habitats usually in depositional areas with slow current. Algae may form a thin mat that loosely adheres to the surface of the epipelon suck material from the mud-water interface using an eye-dropper bulb and a disposable pasteur pipette or gently lift algal mat from the surface of the sediment using a knife.
episammic sand habitats. as above
epilithic rock or other hard surface habitats including dams, bridge abutments, boat ramps, etc. scrape or hand-pick material from epilithon in riffles, pools, and runs.
epidendric woody habitats. scrape or hand-pick material from submerged logs, tree roots, drifts, etc.
epiphytic usually associated with aquatic mosses, macrophytes, and filamentous algae. scrape, wring out, hand-pick, or collect the entire substratum.
epizooic animal habitats including turtle shells, snail shells, and other macroinvertebrates. scrape, hand-pick, or collect the entire substratum

In the river, it is best to focus on the whole community (aufwuchs) on submerged surfaces, including

diatoms Tabellaria
desmids Pediastrum
dinoflagellates Xiphophoridium
filamentous green algae

left Tribonema

 

right Oedogonium

 …………
flagellate protista

left Euglena

right Chlamydomonas
filamentous bacteria Sphaerotilus
fungi Tetracladium
blue-green algae Oscillatoria
protoctistans Chaos (Amoeba)
microfauna eg. rotifers Brachnionis
Why use the aufwuchs?
  • present all year and in most localities
  • present even when macroinvertebrates are difficult to find
  • taxonomy easy to family level
  • sampling is not expensive and easy assessment can be done in the field with a portable microscope
  • taxa respond quickly
  • community response times are commensurate with needs of monitoring (cf chemistry)

Methods

Sampling

  • method depends on purpose
  • is there an impact ? – qualitative
  • how strong is the impact ? – quantitative or semi quantitative
Auchwuss are in clumped distributions. Therefore, either

  • normalise quantitative data for statistical analysis OR
  • estimate abundance on a scale of 1-6 (Dussart, 1982) (saves time)
 Gomphonema
From a representative substratum, standard sample is removed from its surface.

Sample preparation

  • semi-quantitative by a mask of standard sampling area
  • samples looked at at x400….
    • live, or
    • preserved in Lugol’s iodine

For diatoms,

  • dissolve protoplasm with potassium dichromate (K2CrO4)and 30% hydrogen peroxide (H2O2) to leave frustules
  • dry on a glass slide and mounted in Naphrax
  • observe under oil immersion

but not usually justified because

  • modern diatom taxonomy to species level requires electron microscopy and molecular genetics
  • family and genus level is adequate for most monitoring purposes
  • dissolving other components such as desmids removes important information

 

Qualitative approaches

Valency issues (Kolkwitz and Marsson, 1908)

  • taxa are given a value
  • mathematically manipulated eg. average score per taxon

Palmer (1969) 80 most tolerant algae valencies value to each. Top nine (1= most polluted) are….

  1. Euglena viridis (95)…green single celled flagellate
  2. Nizschia palaea (60) …diatom
  3. Oscillatoria limosa (42) …blue green algae
  4. Scenedesmus quadricauda (41) …green one-celled
  5. Oscillatoria tenuis (40) …blue green algae
  6. Stigeocloneum tenue (34) ..green filamentous
  7. Synedra ulna (33) …diatom
  8. Ankistrodesmus falcatus (32) …green one-celled
  9. Pandorina morum (30) …green multicellular flagellate

Quantitative approaches

  • direct analyses by diatometer
    • floating artificial substrata (glass slides or plastic bottle) observe directly under a microscope at x400.
    • strip-off and homogenise before counting.
  • indirect analyses
    • chlorophyll; preserve or analyse quickly as chlorophyll degrades to phaeophytin

Data handling

Archibald (1972) compared a range of diversity indices

  • Simpson – Margalef – Brillouin
  • Menhinick
  • Cairns & Dickson
  • simple index may not be appropriate. Dussart (1982) used subjective measures of diversity, contamination and productivity on scales of 1-10 to describe water quality status of rivers
  • Battarbee et al. (1988) and Dussart (1984) used multivariate techniques to study auchwuss.
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