Nore pearl mussel

The Nore pearl mussel (Margaritifera durrovensis) is a critically endangered species of freshwater pearl mussel, an aquatic bivalve mollusc in the family Margaritiferidae.

Nore pearl mussel
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Order: Unionida
Family: Margaritiferidae
Genus: Margaritifera
Species:
M. durrovensis
Binomial name
Margaritifera durrovensis
(Phillips, 1928)

The species is endemic to Ireland and was first identified by R.A. Phillips in 1926, who later declared it a new species in Volume 18 of the Proceedings of the Malacological Society. This designation was controversial, and the taxonomic status of the Nore pearl mussel remains inconclusive. It is often described as a rare ecophenotype of M. margaritifera. The European Union's Habitats Directive on the conservation of natural habitats and wild fauna placed Margaritifera durrovensis on Annex II and Annex V as a separate taxon.[2]

Distribution

The species is native to the Three Sisters - the rivers Barrow, Suir and Nore, the latter of which being the mussel's namesake. However, specimens have not been found outside of the River Nore since 1993. Unlike M. margaritifera, which can tolerate acidic conditions, the Nore pearl mussel requires highly calcareous waters, and generally inhabits sections of the River Nore which have CaCO3 concentrations of over 330 mg/L. The Nore pearl mussel also has a significantly shorter lifespan than M. margaritifera, typically living for 60 to 80 years.

Threats and conservation

Studies conducted on Nore pearl mussel distribution revealed that the population of the species had declined by approximately 75% between 1991 and 2009. The primary pressure identified was agricultural intensification leading to elevated levels of phosphorus, nitrate and suspended solids across the mussel's native range. A captive breeding program was set up in 2005 by the National Parks and Wildlife Service, whereby juvenile mussels complete their first growing season in captivity before being re-introduced to the River Nore.[3]

References
  1. "Ireland Red List No.2 - Non-Marine Molluscs" (PDF). Byrne et al. 2009. National Biodiversity Data Centre. Retrieved 2020-03-10.
  2. Geist, Juergen; Moorkens, Evelyn; Killeen, Ian; Feind, Sarah; Stoeckle, Bernhard C.; Connor, Áine O.; Kuehn, Ralph (2018). "Genetic structure of Irish freshwater pearl mussels (Margaritifera margaritifera and Margaritifera durrovensis): Validity of subspecies, roles of host fish, and conservation implications". Aquatic Conservation. 28 (4): 769–1022. doi:10.1002/aqc.2913. S2CID 90028332. Retrieved 2020-03-10.
  3. "Freshwater Pearl Mussel, Nore Sub-Basin Management Plan" (PDF). DEHLG. Water Framework Directive Ireland. Retrieved 2020-03-10.
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