Weedy seadragon

Australia’s Great Southern Reef (GSR) is a series of temperate, rocky reefs and undulating kelp forests spanning about 5,000 miles (8,000 kilometers) along the border of New South Wales and Queensland.

The weedy sea dragon (Phyllopteryx taeniolatus), calls GSR home. It is a creature from a fantasy novel, with orange and red coloring and yellow and purple accents. It has algae-like appendages and is dotted with dots and spots unique to each one.

And earlier this year, the weedy sea dragon was the subject of a massive wash-up that killed 200 people ashore. Citizen scientists worked alongside marine experts to figure out why it happened and how to stop it from happening again.

Dangerous storm

They may not look like it, but weed sea dragons are fish. They are related to seahorses and share some common traits. Both use the tube-like snout to suck up small shrimp and zooplankton, and the male churns the eggs. However, unlike seahorses, sea dragons do not have a pouch.

Instead, the male fuses the fertilized eggs to the underside of his tail, protecting them until they hatch about two months later. The tail also differs from that of a seahorse in that it is non-prehensile, so it cannot grab onto things. This could make them more vulnerable to storm surges.

Professor David Booth, a marine ecologist at the University of Technology Sydney, has been working with the species since 2001. A normal year “might see a dozen” strandings, but this April alone saw more than 150 weedy sea dragons washed ashore from the Central Coast in NSW Wales, down to the Illawarra.

A hazardous weather event brought wind, record precipitationfloods and storm surges along Australia’s east coast from February to April in 2022. While much of the focus has been on the loss of life and property, as the weather calmed down and people resumed normal activities, another effect of the devastating storms came to light — the death of nearly 200 weedy sea dragons.

Reports first started coming in from divers, but after Booth put out a plea for information and photos from the public, social media spread the word and concern. Emails started pouring in from people finding dead sea dragons.

Citizen science

While the weedy sea dragon is not currently threatened with extinction, according to IUCN Red List, there is evidence that their numbers are declining. There are several places in Tasmania where populations have become locally extinct. Population numbers in the areas affected by the recent washout are difficult to confirm, but Booth estimates there are “probably several thousand” sea dragons.

“With the wash, if we lost 200 or more sea dragons […] that’s 10 percent. That’s pretty important,” says Booth.

Sending citizen scientists clear images and details of where they found a stranded sea dragon was invaluable, and Booth says: “We realize that people walking on the beach are an incredible source of data.”

Many of these people have walked the same stretch of beach for years and are attuned to what is normal for the area and for each season.

“There is a woman called Margaret ‘Betty’ Ratcliffe who has been walking on the same beach at Narrabeen for 30 or 40 years and has found seven near her. So, she was able to say, “never, ever has there been anything like this before.” You might say, ‘that’s not scientific,’ but it’s good enough for me,” says Booth.

There are other citizen science-based projects currently collecting data on wild sea dragon populations. The project Seadragon Search allows “anyone who visits the beach or swims in the sea” the ability to provide information and images of sea dragons they see while diving. This has enabled an extensive library of information on sea dragons and their unique markings.

And while investigations into the cause of the mass washout are ongoing, Booth says it was “almost certainly caused by the terrible breaking of the East Coast lows.”

Their main food source, the mysid shrimp, was drastically reduced in numbers as the storm grew and strong currents pushed them up the coast. Images from the April washup and those taken of the bodies recently collected by Professor Booth and his team will be uploaded to the Seadragon Search site. They will see if they can match any of these previously identified sea dragons to determine which locations were most affected.

But scientists aren’t the only ones benefiting from citizen science data. In a world where climate and environmental change can feel overwhelming, something as simple as a walk on the beach can help those creatures that live there.

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