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TitleEasy identification of freshwater algae
Tags
LanguageEnglish
File Size4.5 MB
Total Pages212
Table of Contents
                            Introduction
Cyanophyta
Chrysophyta
Bacillariophyta
Cryptophyta
Dinophyta
Euglenophyta
Chlorophyta
GLOSSARY
References
Index
                        
Document Text Contents
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Easy identificationEasy identification
of the most common

FREFRE SSHH WWAATETE RR
ALALGG AEAE

A guide for the identification of microscopic
algae in South African freshwaters

May 2006

Sanet Janse van Vuuren
Jonathan Taylor
Carin van Ginkel
Annelise Gerber

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Michael
Typewritten Text
North-West University and the Department of Water Affairs have made this digital version of "Easy identification of the most common freshwater algae" available as a public service.

Michael
Typewritten Text
You may copy and distribute the complete version of this digital copy, but you may not resell it.

Michael
Typewritten Text
Suggested citation:

Michael
Typewritten Text
Janse van Vuuren S, Taylor J, Gerber A, van Ginkel C (2006) Easy identification of the most common freshwater algae. A guide for the identification of microscopic algae in South African freshwaters. ISBN 0-621-35471-6.

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Peridinium Ehrenberg

Origin: From Greek peridineo, "to whirl around".

Characteristics: Peridinium is a medium to large sized dinoflagellate. The
cells are more or less round to oval-shaped, and slightly flattened when seen
from the side (convex dorsal surface and a concave ventral surface). Most
cells are without horns, although a few species may possess dorsal flanges
and distinctive horns. Grooves on the cell surface are quite noticeable, and
the cingulum groove (encircling the cell) is deep and nearly at the cell
median. Most representatives are photosynthetic with numerous
yellowish-brown chloroplasts. Flagella are implanted in the cingulum and
sulcus grooves. The cells are enclosed in a number of thick, angular thecal
plates. The thecal plates are generally smooth or reticulated and sometimes
small groups of spines may be present. Often the apical view shows a
terminal pore. Species are differentiated by shape and size of the cell, and
by the number, shape and arrangement of the thecal plates.

Dimensions: 10-100 µm long, 15-90 µm wide.

Ecology: Peridinium is a free-swimming, widespread and common
dinoflagellate which may be abundant in the plankton of ponds, lakes and
rivers. Most species are found in fresh or brackish waters, and cannot
tolerate high salinity levels. The genus is nearly cosmopolitan in hard waters
rich in calcium, but can also be found in waters of low pH and low nutrients.

Notes: Most researchers agree that Peridinium should be separated into two
genera. The first group would include large cells (as much as 65 µm in
diameter) with three intercalary plates. The second group would have
significantly smaller cells less than half that size, with only two intercalary
plates. For the proper identification of Peridinium species, it is essential to be
able to observe the number and arrangement of the thecal plates on the
surface. Similarly shaped but unarmoured (naked) cells are likely to belong
to the genus Gymnodinium Stein. Resting cysts may be produced.

Problems: Some species may form large, conspicuous blooms. It can be
responsible for taste and odour problems.

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a

d

b

e

c

f

Caption: Cells of Peridinium may be fairly large or medium-sized,
depending on the species. When cells are dead and the inner contents
released, the prominent thecal plates are clearly visible (photos e and f).
Living cells are usually yellow-brown in colour. The position of the cin-
gulum groove is clearly visible.

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