February 21, 2022

Watch where you walk: Threatened species has home under world’s highest tides | CBC News

On the shores of Nova Scotia’s Minas Basin lies a threatened species of mollusc that is only visible when 160 billion tonnes of water pull back to reveal the ocean floor. 

The Atlantic Mud-piddock, sometimes called the “fallen angel wing” because of the shell’s wing-like appearance, lives year-round in the soft red mudstone found around the basin. 

But their survival has been threatened by climate change and people walking on their habitats — especially during the summer months — and so experts are trying to draw more attention to the species in the hopes of mitigating those threats.

The Mud-piddocks reside in what is called an intertidal zone, meaning they are visible when the tide is low, but are hidden when the record 15-metre tides come back in.  

Mud-piddocks only start habitats in oxygenated water with red mudstone, which makes up less than 184 hectares of Nova Scotia’s coastline.

If you haven’t heard of this small mollusc, you’re not the only one.

This photo shows the habitat of the Atlantic Mud-piddock. (Department of Fisheries and Oceans)

Anita Benedict, an interpreter at Burntcoat Head Park in Noel, N.S., said people are genuinely interested in learning about the Mud-piddock and do their best to avoid the areas they indicate as habitat.

Burntcoat and Five Islands provincial parks have the most Mud-piddock out of anywhere else in the basin, and Benedict said awareness is important for their survival.

She said even though the tides go out, that doesn’t make Burntcoat a beach — it’s the ocean floor.

“It’s a pretty amazing ecosystem that you are having an opportunity to walk among,” said Benedict.

There is a sign on the stairs near the ocean floor to remind visitors of the habitat before making the trek down.

Spawning begins in mid-summer, and as small larvae, new Mud-piddocks spend most of their time free swimming and eating phytoplankton in shallow waters. At this stage they can be consumed by anything that eats plankton.

The Atlantic Mud-piddock’s habitat pictured here shows the holes in the red mudstone that indicate they are there. A Mud-piddock has two tube-like filters, one to take in food and the other to remove waste. (Submitted by Department of Fisheries and Oceans)

Thirty-five days later they head to the ocean floor, where they grow a small muscle which is referred to as a “foot” to search for red mudstone. After making contact, the process of burrowing begins.

As they grow, they continue to burrow. This results in the burrow forming a cone-like shape, which gives them protection against predators and traps them inside as they grow to be about three to five centimetres in length. 

They eat by filtering water for plankton and other organic particles through a tube-like muscle called a siphon that stretches up to the opening of their burrow. This part of the body remains out of the shell and cannot be fully retracted.

They spend their entire lives inside these small, isolated holes for approximately 11 years. 

When they die, their burrows can become home to other sea creatures.

If the Mud-piddock were to completely disappear from the shores, biologists are not sure what repercussions could be. 

Paige Crowell, lead recovery biologist for Atlantic Mud-piddocks with the Department of Fisheries and Oceans, said the species population appears to be stable, but they still aren’t sure what the exact population is.

Watch where you walk

The main risk to the Mud-piddock is destruction of their habitat.

This can happen anytime sediment from sand, rocks, or mudstone covers up their burrow holes. 

Anything from increased storms from climate change or people accidentally stepping on the habitat could result in the Mud-piddock suffocating.   

Crowell said the best thing visitors can do to help the Atlantic Mud-piddock while walking the red mud flats at low tide in the Minas Basin is to watch where you’re walking.

“If people could watch out for small holes in the sea floor that kind of cluster together, this is a sign that Mud-piddock are clustered there,” she said.

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