Scientific Name: Barnea truncata
Taxonomy Group: Molluscs
COSEWIC Range: Nova Scotia, Atlantic Ocean
COSEWIC Assessment Date and Status Change: May 2021
COSEWIC Status: Threatened
COSEWIC Status Criteria: D2
COSEWIC Reason for Designation: In Canada, this intertidal marine bivalve species is restricted to small sections of Minas Basin in Nova Scotia. Here, the species is entirely dependent on the red-mudstone facies geological formation where it bores into the mudstone and remains as an immobile adult. Changes in sediment deposition can bury habitat, and smother and kill individuals. The main threat to the species is increased frequency and intensity of severe storms due to climate change, which can abruptly shift and redeposit sediments. Additional threats include human activities that change water current, erosion and sediment deposition patterns, pollution run-off from agricultural or urban sources, and climate-change induced sea-level rise.
COSEWIC History of Status Designation: Designated Threatened in November 2009. Status re-examined and confirmed in May 2021.
SARA Status: Schedule 1, Threatened
Date of Listing (yyyy-mm-dd): 2017-04-13
Please note that this information is provided for general information purposes only. For the most up to date and accurate list of species listed under the Species at Risk Act, please see the Justice Laws Website.
Image of Atlantic Mud-piddock
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.
Distribution and Population
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.
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.
The Atlantic Mud-piddock is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.
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 as: 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.
Provincial and Territorial Protection
PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.
10 record(s) found.
- COSEWIC Status Reports (1 record(s) found.)
- Response Statements (2 record(s) found.)
- Orders (2 record(s) found.)
- COSEWIC Annual Reports (2 record(s) found.)
- Permits and Related Agreements (1 record(s) found.)
- Consultation Documents (1 record(s) found.)
- Residence Description (1 record(s) found.)
COSEWIC Status Reports
Response Statement - Atlantic Mud-piddock (2010-12-02)This intertidal marine bivalve species is restricted to a single population in the Minas Basin, Nova Scotia. Although this species is adapted to boring into hard clay and soft rock, in Canada it is entirely dependent on a single geological formation, the red-mudstone facies within the basin. The total available habitat for this species is < 0.6 km2. This species settles on and bores into the mudstone, and once settled, is immobile. Any changes in deposition of sediments can smother individuals or cover entire areas of habitat. Disturbances that change the sediment depositional regime are considered the main threat. Most serious is the increased frequency and severity of storms, due to climate change, which have the potential to rapidly bury habitat and smother individuals. It is expected that erosion from rising sea levels (storm surges) and increased rainfall (floods), would also contribute to habitat loss by sediment deposition. Proposed development in the basin could also alter or add to sediment deposition. The Canadian population is clearly disjunct from the nearest population, 350 km south, in Maine, and rescue is very unlikely.
Response Statement - Atlantic Mud-piddock (2022-01-10)In Canada, this intertidal marine bivalve species is restricted to small sections of Minas Basin in Nova Scotia. Here, the species is entirely dependent on the red-mudstone facies geological formation where it bores into the mudstone and remains as an immobile adult. Changes in sediment deposition can bury habitat, and smother and kill individuals. The main threat to the species is increased frequency and intensity of severe storms due to climate change, which can abruptly shift and redeposit sediments. Additional threats include human activities that change water current, erosion and sediment deposition patterns, pollution run-off from agricultural or urban sources, and climate-change induced sea-level rise.
COSEWIC Annual Reports
COSEWIC Annual Report - 2010 (2010-09-03)Under Canada’s Species At Risk Act (SARA), the foremost function of COSEWIC is to “assess the status of each wildlife species considered by COSEWIC to be at risk and, as part of the assessment, identify existing and potential threats to the species”. During the past year, COSEWIC held two Wildlife Species Assessment Meetings and reviewed the status of 79 wildlife species (species, subspecies, populations). During the meeting of November 2009, COSEWIC assessed or reviewed the classification of the status of 28 wildlife species. COSEWIC assessed or reviewed the classification of an additional 51 wildlife species (species, subspecies and populations) during their April 2010 meeting. For species already found on Schedule 1 of SARA, the classification of 32 species was reviewed by COSEWIC and the status of the wildlife species was confirmed to be in the same category (extirpated - no longer found in the wild in Canada but occurring elsewhere, endangered, threatened or of special concern). The wildlife species assessment results for the 2009-2010 reporting period include the following: Extirpated: 6 Endangered: 39 Threatened: 16 Special Concern: 17 Data Deficient: 1 This report transmits to the Minister the status of 46 species newly classified as extirpated, endangered, threatened or of special concern, fulfilling COSEWIC’s obligations under SARA Section 24 and 25. A full detailed summary of the assessment for each species and the reason for the designation can be found in Appendix I of the attached report. Since its inception, COSEWIC has assessed 602 wildlife species in various risk categories, including 262 Endangered, 151 Threatened, 166 Special Concern and 23 Extirpated. In addition, 13 wildlife species have been assessed as Extinct. Also, to date, 46 wildlife species have been identified by COSEWIC as Data Deficient and 166 wildlife species were assessed as Not at Risk. This year has been a particularly productive year for COSEWIC’s Aboriginal Traditional Knowledge (ATK) Subcommittee. In April 2010 COSEWIC approved the Aboriginal Traditional Knowledge Process and Protocol Guidelines, providing clear and agreed principles for the gathering of Aboriginal Traditional Knowledge to carry out COSEWIC functions as required under Section 15(2) of SARA (See Appendix III of the attached report). We are grateful for the rich and enthusiastic contribution made by community elders and experts in helping the ATK Subcommittee prepare the ATK protocols.
COSEWIC Annual Report 2020 to 2021 (2021-10-12)Over the past year COSEWIC assessed a total of 66 wildlife species, of which 4 were assigned a status of Not at Risk. Of these 66, COSEWIC re-examined the status of 41 wildlife species; of these, 80% were reassessed at the same or lower level of risk. To date and with the submission of this report, COSEWIC’s assessments now include 826 wildlife species in various risk categories including 369 Endangered, 196 Threatened, 239 Special Concern, and 22 Extirpated (i.e. no longer found in the wild in Canada). In addition, 19 wildlife species have been assessed as Extinct, 62 wildlife species have been designated as Data Deficient, and 202 have been assessed as Not at Risk.