september 2026

Monthly Reef Update

As spring returns across the Great Southern Reef, this issue reflects on the changes seen across southern waters and what they may mean for the months ahead. With summer approaching, we look back at recent losses and lessons while considering how research, protection and public awareness can help prepare for another testing season.

Citizen scientists in South Australia document world’s worst known seadragon losses

A new Dragon Search South Australia report has documented the loss of almost 1,700 seadragons during the state’s prolonged harmful algal bloom, alongside hundreds of pipefish and seahorses.

Led by marine ecologist and citizen science project manager Janine Baker, the report draws on records from 253 citizen scientists between January 2025 and May 2026. They recorded approximately 1,524 dead weedy seadragons and 159 leafy seadragons, with deaths spanning 13 species in the broader Syngnathidae family - seadragon, pipefishes, seahorses and pipehorses.

What the records may have missed

The recorded deaths capture only part of the large-scale loss. Thousands of seagrass-dwelling pipefishes appeared in beach wrack mounds without individual counts, and many cryptic, benthic-dwelling pipefishes may have died in situ on the sea floor, and never reached shore.

With many seadragon deaths having occurred before and during the spring and summer breeding season, alongside HAB-induced habitat damage that is continuing long after the active in-water phase of Karenia, the report warns of likely long-term consequences.  

What remains unknown

The full scale of population decline remains unknown as there have been no systematic university-or government-led research surveys of Syngnathidae fishes across SA, either past or present. Previous Statewide Syngnathidae distribution data comes from divers and snorkellers, beachcombers, independent research surveys, museums, fisher observations and trawl bycatch – most dating from 1980s to 2000s, collated and mapped in previous public Dragon Search SA reports. The Dragon Search SA project page on iNaturalist also contains spatially-protected observation data from the 2020s, for some key nearshore locations in the gulfs region of SA. The current broadscale loss of seadragons in the gulfs region, Investigator Strait and the southern Fleurieu / Encounter Bay coast has prompted initiatives for systematic surveys of remaining seadragon populations, especially weedy seadragons in seagrass habitats, and populations of both seadragon species in high-current offshore environments that are largely inaccessible to citizen science divers. Pipefish and seahorse distribution and abundance data are also required, and previous documentation again comes from citizen science community project efforts, and museum data.

What monitoring is showing

The current community observations across South Australia provide evidence of the bloom’s impact on the Great Southern Reef. Since spring 2025, citizen science divers in 7 areas of SA have been documenting records of live seadragons (including previously identified individuals) in nearshore areas monitored by Dragon Search SA during the past 15 years. There is no doubt that numbers are lower than pre-bloom in those inshore habitats, but offshore numbers remain undocumented.

Broader-scale spatial assessment, and continued and expanded monitoring of surviving populations and key habitats, will help assess the magnitude of the losses, and guide population and habitat recovery efforts.

Minister Refers Giant Cuttlefish to Scientific Committee

Last month, the Great Southern Reef Foundation wrote to the Federal Environment Minister Murray Watt seeking an urgent EPBC Act assessment of the Upper Spencer Gulf giant Australian cuttlefish population.

Soon afterwards, the South Australian Government released its official 2026 survey report. SARDI recorded no cuttlefish along its standard survey transects in June or July. DEW also recorded very few animals during surveys conducted across the breeding season.

How the 2026 estimate was calculated

Using a method comparable with the standard SARDI survey, the July DEW results produced an estimated population of 113 cuttlefish. When DEW expanded its search to include cuttlefish hidden beneath rocks, then scaled those observations across the survey area, the resulting population estimate was 1,811.

PIRSA described this as a 97 per cent decline from the 2025 estimate of 63,734 and the lowest estimate on record. The report identified the harmful algal bloom as the most likely explanation for the decline.

Minister Watt has since responded directly to the Foundation and the scientists who supported our letter. He confirmed that he had asked the Threatened Species Scientific Committee to urgently consider listing the giant Australian cuttlefish subpopulation under the EPBC Act and to undertake an assessment if appropriate.

What happens next?

The Minister advised that the Committee was due to consider the matter at its meeting beginning 1 September. His department has also contacted the South Australian Department for Environment and Water.

This does not yet amount to a threatened species listing or confirmation of a formal assessment. However, it is a welcome response and an important step towards stronger national recognition and protection for this genetically distinct population.

We thank Minister Watt for acting quickly as new evidence became available. The Foundation will continue following the process and advocating for the fastest available pathway to assessment.

Marine heatwaves are lasting longer around Australia

Marine heatwaves around Australia are lasting longer, occurring more often and exposing coastal ecosystems to increasing heat. A new study has mapped these changes across 60 marine bioregions using more than four decades of sea surface temperature data.

Along the Great Southern Reef, the pattern differs between regions. Some areas have been shaped by exceptional events, others by persistent lower-intensity heat, while North Spencer Gulf recorded Australia’s fastest increases in marine heatwave intensity.

read the full feature

Tanitjari: A Warning from Sea Country

When H5 bird flu reached Bial-bial on the Limestone Coast, the deaths of Tanitjari carried a warning far beyond disease. Professor Irene Watson reflects on the relationship between Meintangk Bunganditj Peoples, Greater Crested Terns and ngamath, and what their threatened loss would mean for Country, culture and future generations.

Read Irene's Reflection

Kelp Forests Explained for Young Minds

A new open-access article in Frontiers for Young Minds explains why kelp forests matter, the marine life and communities they support, and the growing pressures they face.

Illustration by Tori Gorham

Lead author Dr Chanelle Webster admits she did not initially feel equipped to write for children. Feedback on the first version was blunt: it was “boring”. That response pushed her to rethink the article, get creative and communicate the science in a way young readers could follow. Graphic illustrator Tori Gorham worked with Chanelle to turn the concepts into colourful visual stories.

read the young minds article

The article brings together collaborators from GSRF and the Great Southern Reef Research Partnership. It also reflects a growing national focus on ocean literacy, identified as a key enabler in work informing Australia’s National Marine Science Strategy for 2026–36. It shows why scientists need to communicate beyond academic audiences and help young people understand the marine environments around them.

Public submissions are open on the Australian Government’s proposal to prepare six new management plans covering 44 Commonwealth marine parks, closing at 4 pm AEST on 30 September.

Commonwealth Marine Parks Review Now Open

For the Great Southern Reef, the review offers an opportunity to strengthen representative and connected protection across Australia’s temperate reef system. A strong outcome should protect a range of habitats, fund repeated monitoring and public reporting, coordinate management where ecological connections cross park boundaries, and support direct, paid participation by Traditional Owners.

have your say

Thank You Nev

This week marks the retirement of Associate Professor Neville Barrett from IMAS after more than three decades studying and documenting Australia’s temperate marine ecosystems.

A member of the Great Southern Reef Research Partnership, Nev has made an immense contribution to reef monitoring, marine park science and our understanding of the Great Southern Reef. We thank Nev for his leadership, generosity and lasting contribution to the Great Southern Reef, and wish him all the best for this next chapter.

Video: Nev shares the remarkable ecology of Tasmania’s Bathurst Channel, one of the marine environments he has studied throughout his career.

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