COSEWIC Assessments

COSEWIC Assessment Summary – Atlantic Mud–piddock Barnea truncata

Assessment Summary – November 2009

Common name
Atlantic Mud–piddock

Scientific name
Barnea truncata


Reason for designation
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.

Atlantic Ocean

Status history
Designated Threatened in November 2009.


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Contact Person(s)

COSEWIC Secretariat
c/o Canadian Wildlife Service
Environment Canada
Ottawa, ON
K1A 0H3
Tel: 819-938-4125
Fax: 819-938-3984
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Related Species


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