Information à l'appui d'une évaluation du potentiel de rétablissement du ptychobranche réniforme (Ptychobranchus fasciolaris)

Abstract

Kidneyshell (Ptychobranchus fasciolaris, Rafinesque 1820) was first assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 2003 as Endangered. The status was re-assessed and confirmed in 2013, owing to large declines in the historical range and declines in abundance at extant localities related to invasive dreissenid mussels and habitat degradation from agricultural land use practices. The species was listed under the Species at Risk Act (SARA) in 2005. The Recovery Potential Assessment provides background information and scientific advice needed to fulfill various requirements of the Species at Risk Act (SARA). This research document provides the current state of knowledge on the species including its biology, distribution, population trends, habitat requirements, and threats. Kidneyshell is a medium-sized, relatively long-lived, bradytictic species thought to use several darter species (Etheostoma spp., Percina spp.) as hosts. Historically, it was known from 10 localities in Canada, but is currently confirmed in two, the Ausable and Sydenham rivers. Kidneyshell occupies small- to medium-sized rivers and occasionally shallow lake environments with wave action over sand and gravel substrates. Many threats related to habitat loss and modification, and impacts from invasive dreissenid mussels are thought to be responsible for the extirpation of this species from much of its historical range. Persistent threats related to agricultural and urban sources of pollution, aquatic invasive species, and impacts from climate change are likely negatively impacting Kidneyshell currently; however, the impacts appear to be low at the population level. Important knowledge gaps remain surrounding the historical and current abundance and distribution in Ontario, many aspects of its reproductive biology including timing of spawning and glochidial release, habitat preferences by life stage, mussel host interactions, physiological tolerances to environmental conditions, and the magnitude of impact and spatial extent of threats.