Atlantic Mud-piddock

Barnea truncata

SARA Status

No Status
NS
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

SARA Status

  • No Status NS
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX

COSEWIC Status

Not at Risk
NR
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

COSEWIC Status

  • Not at Risk NR
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX

Description

The Atlantic Mud-piddock (Barnea truncata) is an intertidal bivalve mollusc. Sometimes referred to as “fallen angel wing” because of its delicate ridged shell, the Atlantic Mud-piddock is greyish-white in colour and approximately 3-5 cm long. There is no noticeable difference between males and females.

Habitat

The Atlantic Mud-piddock is found in the intertidal zone, meaning it is above water at low tide and under water at high tide. In Canada, the species burrows into only one type of surface called red mudstone, which is somewhat firm and offers protection. Individuals become entrapped in their burrows as they grow, where they remain for their lifetime. When they die, the resulting burrow can provide habitat for other marine species.

The Atlantic Mud-piddock is found along the eastern and western continental margins of the Atlantic Ocean, from Florida to Nova Scotia and from South Africa to Senegal. In Canada, the only population is found in the Minas Basin, Bay of Fundy, approximately 475 km from the next nearest population in Maine. Red mudstone in the Minas Basin is extremely limited, totalling less than 1.84 km². The Bay of Fundy’s high tides and large temperature fluctuations provide highly oxygenated waters with lots of suspended particles for the molluscs to feed on.

Atlantic Mud-piddock live separately from one another in their burrows, releasing their eggs and sperm into the surrounding water. Fertilized eggs grow into larvae. After 35 days of growth, the larvae settle and begin burrowing when they contact red mudstone. The population size is unknown, but thought to be stable.

Threats

The main threat to the Atlantic Mud-piddock is changes to the ocean bottom, particularly increases in sediment, such as sand, over their limited habitat. Increases in sediment can smother the animals and make their limited habitat unusable. These changes may occur as a result of natural processes, such as tidal erosion, ice scouring and major storm events. There is concern that increased storm activity and sea-level rise due to climate change may negatively impact the species. In addition, dredging, large scale tidal turbine operations, and oil spills may pose potential threats. Recreational activities, such as running, mountain biking, and using ATVs may harm Atlantic Mud-piddock or destroy their habitat.

Further Information

In Canada, the Atlantic Mud-piddock has been assessed as threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) due to its limited distribution.

The Atlantic Mud-piddock is not a harvested species. There are no commercial, recreational, nor food, social and ceremonial (FSC) fisheries for the Bay of Fundy population.

The residence of an endangered, threatened or extirpated species is protected from damage and destruction under the Species at Risk Act. The residence of the Atlantic Mud-piddock is described briefly below:

The Atlantic Mud-piddock’s burrow is its residence. Once a Mud-piddock larva settles on its preferred red mudstone substrate, it invests energy in creating a burrow that is essential to its survival. The Mud-piddock grows and matures in its burrow. It feeds and releases spawn from within its burrows where it remains for the duration of its adult life stage.

Visit the Species at Risk (SARA) Public Registry.

Atlantic Mud-piddock

Atlantic Mud-piddock. Illustration by Jeff Domm.

Illustration by Jeff Domm

Scientific name: Barnea truncata
SARA Status: Threatened
COSEWIC Status: Threatened
Region: Atlantic Canada
Taxonomy: Molluscs

Mud-piddock Survey Location, 2017-2018

Distribution of Atlantic Mud-piddock in Canada based on field surveys in 2017/2018. The Atlantic Mud-piddock population in Canada is limited to the Minas Basin, which is located in Nova Scotia at the northeast end of the Bay of Fundy. The map indicates the 13 discrete sites in the Minas Basin where the species is found. The Minas Basin is a very dynamic area where natural processes such as ice scour and movement of sand over short timeframes can cause the extirpation of small sub-populations, and can even expose new habitat allowing for settlement at new sites.

Did you know?

After a brief (35 days) planktonic stage, floating in the water, the Atlantic mud-piddock larva settles and moves along the ocean bottom using its “foot” until it finds red mudstone and begins burrowing. It becomes trapped as it grows inside its burrow and depends on the surrounding water to provide food to eat, oxygen to breathe, and a place to carry out life functions such as reproduction. Water quality is therefore very important for its survival. The body of the Atlantic Mud-piddock cannot be completely withdrawn into its shell, which is why burrowing is crucial for further protection.

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