Citizen scientists needed to document SA’s harmful algal bloom

In the February newsletter I wrote a piece on how we’ve noticed swings is sea surface temperatures locally in the South East of SA over the last couple of years (see article here). As we hit send on that newsletter I was not prepared for what was about to unfold along the South Australian coastline and most likely into Victoria. Since then there has been huge mortalities of sea life over a wide range of taxa. From fish and sharks, to octopus and cuttlefish, crabs, sea snails, cockles, sponges and the iconic leafy and weedy seadragons.

These deaths have been caused by a harmful algal bloom, predominantly a dinoflagellate species named Karenia mikimotoi. Other species have now also been detected in samples, and all are growing due to high sea temperatures, low wind and low swell. It shows the effects of climate change are well and truly happening, with blooms occurring in other countries in recent years.

While I’ve been trying to wrap my head around this event, a recent article in the Great Southern Reef Foundation newsletter, written by Janine Barker, has explained it perfectly. Janine is a marine ecologist and educator with 35 years of experience in South Australian marine research.

You can read the article here, on the Grout Southern Reef Foundation website. It also includes a video showing the devastating impact from the dive hotspot of Edithburgh jetty, on the Yorke Peninsula, which was a well-known sponge garden supporting a wide range of species.

We don’t know the full impact of the event yet, as most of the evidence can only be seen from what has washed onto beaches. To help analyse its impact, Janine and other marine experts in SA have set up a citizen science project on iNaturalist. If you’ve seen any of the effects, please document them with any photos through the project SA Marine Mortality Events 2025. Once the algal bloom has dispersed and divers can get back into the water, we may start to see some information about the full extent. I’ll try to pass this information on as I come across it.

A couple of other things to remember if you’re in the effected area:

• I you see find dead seals, dolphins, penguins or sea birds, please ring National Parks and Wildlife for carcasses to be collected for pathology and toxicology.

• For any pelagic sharks such as great whites, bronze whaler, gummy shark, whiskey shark and others that wash up, or signs of unusual behaviour or distress, please call PIRSA Fish Watch to be collected for necropsy.

So, if you’re out and about and happen to see any deceased sea creatures that may have been affected by the toxic algal bloom, please record your sightings in the iNaturalist app, in the SA Marine Mortality Events 2025 project here.