Images on this page correspond to the numbered plates in the Detailed Identification Key (What Scum is that?).

Warning - Due to the quality required of each image to make it a useful identification tool, there may be a long download time for this page of the website, but the wait will be worth it!

These images and text have been adapted from the DLWC publication "What Scum is That? Algal Blooms and other Prolific Plant Growth" (Simon Mitrovic,1995). Unless otherwise stated, all images are copyrighted to DLWC ? 2002. Copies of this booklet may be obtained from DLWC . (Acknowledgements of photographers)



Anabaena, Azolla , Chlaydomonas, Chara, Cladophora, Diatom, Enteromorpha, Euglena, Hydrodictyon, Microcystis, Nitella, Nymphoides, Pediastrum, Potomogeton tricarinatius, Riccia, Ricciacarpus, Spirodela , Spirogyra.



PLATE 1 Azolla - free floating fern up to 1cm wide, 3cm long. Plants red or green.Common in waters with slow movement, high nutrients.


PLATE 2 Azolla species growing with Ludwigia peploides. Mat forming.

Duckweed - Spirodela

PLATE 3 Spirodela - duckweed (small leaves) with some Potamogeton tricarinatius (large leaf). Spirodela can cover large areas of the surface, matlike, plants may have small roots if lifted out of water. Grows in still waters.





Chara and Nitella

PLATE 4 (right) Chara (muskgrass), often dark grey-green with orange or green pinpoint fruits (left) Nitella often greener in colour, grows in more aid conditions


PLATE 5 Riccia - a liverwort. Open network of branched thallus up to 5cm diameter. Found in areas of slow moving wter, often swamps and creeks.


PLATE 6 Ricciocarpus - found on water surface. Free floating thallus. usually green on top and purple underneath.




PLATE 7 Hydrodictyon - alga forms a green/yellow mass, like a hair net

Filamentous alga in channel

PLATE 8 Filamentous green alga in channel near Griffith, NSW. Dominated by Hydrodictyon and Cladophora

Filamentous alga - Cladophora

PLATE 9 Cladophora - filamentous alga, grows in clumps, can form large mats green or brown in colour. Filaments look and feel like coarse hair.

Filamentous alga - Enteromorpha

PLATE 10 Enteromorpha - filamentous green alga, green to yellowish-brown. Often indicative of high nitrogen levels.

Filamentous alga - Spirogyra

PLATE 11 Spirogyra - filamentous green alga that feels like soapy hair. Usually bright green, grows in slow flowing or static water.




Blue-green bloom - Anabaena

PLATE 13 Anabaena - blue-green alga bloom on Namoi river. Lighter colour due to Euglena presence in the mixed bloom..

Darling River - Anabaena circinalis

PLATE 14 Anabaena circinalis bloom, Darling river . Strong green colour with scum formed. note blue colour due to phycocyanin pigment.

Anabaena circinalis - bloom

PLATE 15 Anabaena circinalis in Darling river . Growing with water plant, Ludwigia peploides. Strong blue-green colour due to algal cells breaking down and releasing pigments.

Microcystis bloom

PLATE 16 Microcystis species in Chaffey Dam, NSW. the scum is a thick green, paintlike cover.

Algal bloom -Microcystis and Anabaena

PLATE 17 Microcystis and Anabaena bloom in Carcoar Dam, NSW.




EUGLENOIDS (flagellates)

Green alga scum - Chlamydomonas

PLATE 18 Chlamydomonas - Scum of this microscopic alga. Green/khaki in colour. These scums look similar to blue-green alga species and identification is by microscopic examination.

Euglena bloom

PLATE 19 Green Euglena bloom in a farm dam. Scum often has skin like surface with folds. Scums common where there is lots of organic material in the water.

Red Euglena bloom

PLATE 20 Red Euglena bloom in creek near Boomi, NSW. Euglena species have the ability to swim freely to the surface and form scums when there is little water movement.



BLUE-GREEN ALGA (colonies)


Diatom bloom

PLATE 21 Diatom bloom. Found in both fresh and saline water. These blooms may colour the water brown.

Microcystis bloom

PLATE 22 Microcystis growing in a pond. The algae forms as colonies on the surface of the water. These colonies may form scums as they get bigger and algae numbers increase.

Pediastrum scum

PLATE 23 Pediastrum scum on a farm dam near Windsor, NSW. Algae form a scum that is made up of many small, rectangluar green specks less than 3mm long.



Healthy water plant mix

PLATE 24 A healthy mix of the aquatic plants Nymphoides (large roundleaf), Ludwigia and the small floating duckweeds. (Toonumbar Reservoir)

Urban creek

PLATE 25 A healthy urban creek. Albury, NSW.


Acknowledgements of Photographs - The above plates are attributed to these photographers -

•  Simon Mitrovic - 2, 7-9,18, 21-23 : Geoff Sainty - 1,3,11,19,20: Surrey Jacobs - 4-6 :

•  Bruce Cooper - 13 : Peter Bek - 14-17, 24: Janet Buchan - Plate 25


Beijing photograph attributed to Wayne Carmichael ( Wright State University ), Mark Schneeugurt ( Wichita State University ) and Cyanosite (

Photographs 1,2 and 3 attributed to Roger Burks ( University of California at Riverside ), Mark Schneeugurt ( Wichita State University ) and Cyanosite (

Photo 4 attributed to Mark Schneeugurt ( Wichita State University ) and Cyanosite (

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MRACC Chairman

? 2002. NSW Murray Regional Algal Coordinating Committee, MRACC. Unless otherwise specified, maps and images are copyrighted to Department of Land and Water Conservation, NSW.