Australian Shovelers in danger – swimming and feeding in a noxious algal bloom

Australian Shovelers in danger – swimming and feeding in a noxious algal bloom
Species: Australian Shoveler   Spatula rhynchotis
Author: Bob Humphries and Sally Robinson
Wednesday, May 22, 2019
Added to IBC: 25 May 2019 - 07:58
Your rating: None
Average: 4.3 (4 votes)
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Altitude (m): 
17 meters


These beautiful Australasian Shoveler ducks (Spatula rhynchotis) are at risk of becoming ill or even dying because their lake has been overwhelmed with a heavy bloom of the toxic blue-green alga (or cyanobacterium), Microcystis aeruginosa.  Many types of cyanobacteria are toxic, and grow out of control when waterways are over-enriched with nutrients (eutrophic), particularly phosphorus and to a lesser extent nitrogen.  Contaminated stormwater carries much of the nutrient pollution that enters the lake – some of the nutrients are dissolved in the water, but much of it is bound in leaf litter.

Submitted by Greg Baker on
Greg Baker's picture

I don't believe the algae is dangerous to waterfowl.  They seem to be happily feeding on it as they do in the UK.  Last year a bloom of algae at my local lake attracted large numbers of Northern Shovelers to feed; usually only small numbers loaf there.

Submitted by Bob Humphries a... on
Bob Humphries and Sally Robinson's picture

Hi Greg - Microcystis aeruginosa has many different strains.  Unfortunately at least one that we have here is very toxic - I found a dead Little Black Cormorant in the algal scum on the lake's edge yesterday, and waterbird deaths in Perth's lakes have been atributed to Microcytis in the past, as well as to botulism.


Bob Humphries and Sally Robinson, IBC1586303. Accessible at

Extended version
Bob Humphries and Sally Robinson, IBC1586303. Video of Australian Shoveler Spatula rhynchotis at Como, Australia. Accessible at

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