Friday, 14 June 2013

Publication on freshwater pearl mussel

How many people can spend a day in the sunshine, dipping in and out of streams and rivers in a beautiful landscape, and call it work? That's exactly what we did in a survey of freshwater pearl mussels in Co Cork. The results of the survey were published in the Royal Irish Academy's Biology and Environment.

The freshwater pearl mussel, Margaritifera margaritifera (L.), is listed on Annex II and Annex V of the EU Habitats Directive 92/43/EEC. Ireland has designated 19 Special Areas of Conservation (SACs) for the freshwater pearl mussel that include 75% of the national population (see Moorkens 2010). 27 individual populations are protected within the 19 SACs. The species has been identified as being of the highest national conservation priority in Ireland.
Freshwater pearl mussels are highly dependent on water quality, which in turn
is highly dependent on land use practises in the river catchment.

The abstract of our 1998 paper was as follows:
A census of the population of freshwater pearl mussel Margaritifera margaritifera in a 1.6-km stretch of lowland river in south-west Ireland was taken as part of an environmental impact study for a proposed flood relief scheme. Ninety-four cross-sections (2-3m wide) were taken and various habitat parameters were recorded. The total population was estimated to be 14,194 and four juveniles were recorded. High mussel densities were associated with shaded channels and low channel depths.

Gittings, T., O’Keeffe, D., Gallagher, F., Finn, J.A. and O’Mahony, T. 1998. Longitudinal variation in abundance of a freshwater pearl mussel Margaritifera margaritifera population in relation to riverine habitats. Biology and Environment, 98B, No. 3, 171-178.

Note that Evelyn Moorkens has published a significant paper that will likely guide conservation priorities for the freshwater pearl mussel in Ireland. In an admirable effort to produce evidence-based guidance, she used a multi-criteria objective methodology to prioritise conservation efforts for catchments with pearl mussels. Her work concluded that "prioritisation of the largest populations in the closest to sustainable conditions is of key importance, and that appropriate catchment management measures need to be urgently implemented as there can be a long time delay in the recovery of suitable habitat conditions". 

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