Introduction to Freshwater Algae - Freshwater Algae: Identification, Enumeration and Use as Bioindicators - page 33

Table 1.11 Range of Body Structure and Form in Chrysophytes.

General Structure Colony Status Examples

Flagellate cells (monads)
Simple cell wall Single cells: Chromulina, Ochromonas

Colonies Uroglena

Surrounded by envelope (lorica) Colony Dinobryon (Fig. 4.2)

cells covered in silica scales Single cells Mallomonas

Colony Synura (Fig. 4.37)

Non-flagellate unicells
Motile by pseudopod Golden amoebae Chrysamoeba

Non-motile Cells surrounded by a jelly Chrysocapsa

Cells surrounded by solid cell wall Stichogloea

Colonies with distinctive
morphology

Simple branched filaments Sphaeridiothrix

Phaeothamnion

Two-dimensional cell plates Phaeoplaca

1.9.4 Chrysophytes as bioindicators

species (with silica scales) require specialised light
microscopy (Cumming etal ., 1992) or scanning elec-
tron microscopy - neither of which may be available
for quality assessment.
Although chrysophytes have traditionally been
held to indicate oligotrophic conditions, the situa-
tion is more complex. Studies by Kristiansen (2005)
have shown that the presence of a few species such
as Uroglena and Dinobryon may indicate oligotro-
phy, but greater chrysophyte species diversity at
lower overall biomass is more indicative of eutrophic
conditions. The value of individual chrysophyte
species as ecological indicators varies considerably
(Kristiansen, 2005). Synura petersenii , with a broad
ecological range, is of limited use - but other narrow-
range species (Table 1.12) can be used particularly in
relation to pH and salinity.

Their diverse ecological preferences (Table 1.12)
make chrysophyte species potentially useful as envi-
ronmental indicator organisms - both in terms of con-
temporary water assessment and sediment analysis.

Contemporary water quality

Although potentially very useful, chrysophytes are
rarely used in monitoring projects. The main rea-
son for this is that the best ecologically studied

Table 1.12 Chrysophyte Species as Bioindicators.

Strongly acid, often
humic conditions

Dinobryon pediforme, Synura
sphagnicola, Mallomonas
paludosa, Mallomonas
hindonii, Mallomonas canina

Sediment analysis

Weakly buffered,
slightly acid
clear water lakes

Mallomonas hamata, Synura
echinulata, Dinobryon
bavaricum var. vanhoeffenii
Alkaline conditions Mallomonas punctifera, Synura
uvella

The main application of chrysophytes as environ-
mental bioindicators is in paleoecology. Their major
advantage for this (as with diatoms) is the presence
of non-degradable silica cell wall material, so that
they remain undamaged in the lake sediments. The
use of these algae in paleoecology depends on

Alkaline/saline
conditions

Mallomonas tonsurata,
Mallomonas tolerans