Our very own homegrown Algal Bloom
Earlier this week our friend Ian Gibbins sent me a copy of a presentation he gave recently.
Here's what Ian wrote to me about that event:
So I'm now going to do a very lazy thing and, with Ian's permission, copy the entire transcript of the event :
South Australian harmful algal bloom – 2025
Since the middle of March 2025, South Australian coasts have been afflicted by a toxic algal bloom of unprecedented size and duration. The effects of the bloom on marine life have been devastating, with untold thousands of dead creatures, from tiny worms to large sharks, washing up on the beaches from Encounter Bay and Kangaroo Island to shores on both sides of Gulf St Vincent. Underwater surveys indicate that mortalities seen on the beaches are only a small fraction of what is happening off-shore.
The dominant organism in the bloom is a dinoflagellate, Karenia mikimotoi. It is highly cytotoxic, although the precise mechanism of its primary toxic action is still not fully understood. Other species of dinoflagellates detected in the bloom include Karenia papilionacea which produces brevetoxin, which has well-described neurotoxic and non-neural actions, and Karlodinium species which produce a range of karlotoxins, which are well understood cytotoxins.
As the bloom has progressed, various citizen science groups, independent researchers, university researchers and government departments have been working to monitor and understand the genesis, progression and effects of the toxic algal bloom. As a result of my background in zoology, comparative anatomy and physiology, and both cellular and systems neuroscience, it turns out that I am one of the few people around who has significant background knowledge of how the various algal toxins affect different cell types and organ systems is a wide range of marine creatures. Consequently, I have contributed directly to several citizen science projects and have spoken about the toxins at public forums.
Other than the fact that they existed, I knew almost nothing about dinoflagellates before this bloom event. I experienced some of their toxic effects after windsurfing in Encounter Bay on the weekend of the bloom’s first significant appearance along that coast. Since then, I have learned a huge amount from independent scientists, Janine Baker, Faith and Peri Coleman, amongst many other experts who have been willing to share their time and knowledge.
The following extended article is based on a talk about the microalgal toxins I gave on 31st July 2025 at Flinders University as part of a forum on the bloom. I have not gone far into the general biology of the bloom organisms and the nature of the bloom itself, since neither of those things are my expertise. You can read more about those areas in the links below.
Unless specified otherwise, all illustrations and photographs are by Ian Gibbins. Most technical terms are hyperlinked to the relevant pages in Wikipedia or other on-line resources. The scientific literature underpinning this article is large and diverse: key papers are cited via footnotes. Where possible, the selected publications are open access.
Click on the headings or images in the topic list below to go the relevant section.
For key information on the bloom, the organisms in it, its effects, and how it is being monitored, visit these sites:
The Great Southern Reef Foundation
https://greatsouthernreef.com/2025-algal-bloom-june-update
The Government of South Australia Algal Bloom portal
https://www.algalbloom.sa.gov.au
The SA Marine Mortality Events 2025 community on iNaturalist
https://www.inaturalist.org/projects/sa-marine-mortality-events-2025
A comprehensive up-to-date resource is Harmful Australian Marine Microalgae by Gustaaf M Hallegraeff (CSIRO Publishing, 2024):
https://www.publish.csiro.au/book/8143
For an excellent overview of plankton in general, with a strong Australian focus, see Plankton: A Guide to their Ecology and Monitoring for Water Quality, 2nd Edition, edited by Iain M Suthers, David Rissik & Anthony J Richardson (CSIRO Publishing, 2019): https://www.publish.csiro.au/book/7808
For the most comprehensive overview of the biology, evolution and development of marine invertebrates affected by the bloom (as well as all other types of invertebrates!) see Invertebrates, 4th Edition, by Richard C Brusca, Gonzalo Giribet & Wendy Moore (Sinauer / Oxford, 2023). https://www.oup.com.au/books/higher-education/science/9780197554418-invertebrates
Introduction to toxins in the South Australian bloom
The effect of cytotoxins on gill function
Why are so many dead juvenile leatherjackets washed up?
What might be causing the skin flushing in sharks and rays?
Effects of the toxins on humans
Effects of the toxins on other creatures
If you find an error or something that needs a more clear explanation, please send me a message via the form below. Thank you.
This was a terrible thing to happen to the coast of South Australia which has a wonderful range of underwater flora and fauna. We wonder what has prevented it from spreading to Victoria as there's been no mention of it down here. (DJK)
ReplyDeleteI think we need expert opinion to answer that question David.
ReplyDeletept