Unprecedented salp event at Tasmanian beaches excites biologists
By Eliza Kloser
Topic:Marine Biology
16m ago16 minutes agoWed 11 Dec 2024 at 6:27pm
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In short:
An unprecedented number of small jelly-like creatures called "salps" are blooming around south-eastern Tasmania this year.
An abundance of phytoplankton caused by agricultural and aquacultural processes has attracted salps, which feed on nutrients in the water.
They reproduce like crazy and don't leave many nutrients for other animals to eat — and while they don't sting, they can kill other animals if they consume toxins.
It's the most wonderful time of the year, but it's not the festive season that has Tasmanian scientists giddy.
A "phenomenal" number of jelly-like creatures called "salps" have been spotted at beaches and bays all over south-eastern Tasmania over the last few weeks.
Dr Lisa-Ann Gershwin has been studying jellyfish for 32 years and says she has "never seen anything like this before".
She said it was like Christmas coming early.
"They make me giddy with delight," she said.
"'T'is the season to be jelly."
Woman smiling for photos
Dr Lisa-Ann Gerschwin says she has never seen a salp-event like this in her 32 years studying jellyfish. (ABC News: Ebony ten Broeke)
So what are they and why are there so many?
The little creatures are found all over the world and while they look like jellyfish, salps are actually a species of zooplankton.
"They're more closely related to us than they are to normal jellyfish," Dr Gershwin said.
"They've got all of our organs — well, most of our organs: they don't have eyes.
"But they've got a brain, they've got a heart, they've got lungs, a stomach, a back end, they have muscles."
A hand holding a small jelly-like sea creatures.
The salps love to feed on nutrients in the water, which are currently in abundance. (IMAS: Katherine Baker)
Salps feed on nutrients in the water called phytoplankton, which are at a "tipping point" of abundance at the moment due to agriculture and aquaculture runoff.
"[The phytoplankton] comes from rain washing nutrients off the land, everything from rotting trees to bird poo on the sidewalk, it all washes down," Dr Gershwin said.
"They naturally bloom every time there's a burst of nutrients, but not usually this much," she said.
Hands holding small jelly-like sea creatures.
Salps have most of the same organs as humans, including a brain, heart, lungs, stomach and muscles. (IMAS: Louise Creely)
Salps reproduce at massive speed, doubling every 12 hours.
"Salps can grow up to 10 per cent of their body length per hour," Dr Gershwin said.
"Let's say that it's born at midnight. By noon, it's a parent, and by midnight, it's a grandparent."
a chain of bioluminescent underwater organisms
Swimming with salps could be fun, but they are known to attract jellyfish that sting. (Supplied: Lisa-ann Gershwin)
Do they impact other animals?
Yes, salps eat a lot of nutrients in the water, meaning not much is left for other animals.
"They literally wipe out the phytoplankton wherever they occur, so everything else starves," Dr Gershwin said.
"So we generally see a suppression in the local productivity of other marine life."
A shoreline at the beach, awash with small jelly-like sea creatures.
Mass killings of animals such as dolphins have occurred as a result of toxic salps being eaten. (IMAS: Abigail Smith)
But Dr Gershwin said salps could become a "toxic bullet" for other animals that eat them.
When there are toxins present in the water, they eat and store them in their bodies.
"Storm Bay has quite a legacy of heavy metal pollution like mercury and zinc," she said.
"We've seen many dolphin strandings, where the dolphin's guts are full of salps, and we've seen massive fish kills."
Bioluminescent organism lit up by a torch
Salp visits are annual but quick, due to their short life spans. (Supplied: Lisa-ann Gershwin)
Can you swim in them?
Yes, they don't sting and actually make the water clearer because they filter out a lot of the murky elements.
"You get the benefit of the clear water and the benefit of snorkelling in bubble tea. Who could ask for anything more?" Dr Gershwin said.
But beachgoers should be wary, because stinging jellyfish are known to flourish around salps.
How long will they stick around?
They have a short life span — from a few days to a few weeks — so the salps won't be around for long.
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Posted16m ago16 minutes agoWed 11 Dec 2024 at 6:27pm
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