Margaritifera margaritifera is declining throughout its range and is extinct or seriously threatened in many parts of Europe. The main cause of this decline is deteriorating river water quality although a variety of other factors are also implicated. Habitats Directive monitoring programmes have been initiated on 18 rivers to date. Monitoring involves distribution mapping, permanent transects and assessing population demographics. Stretches of river are assigned to one of four abundance categories (abundant, common to frequent, rare or absent). Permanent transects are established and counted; the number of mussels visible on the substrate surface in each constituent one by one metre quadrat being counted. In order to assess the population demographics and recruitment rates, all visible mussels in a series of 0.5 by 0.5 metre quadrats are counted before being carefully measured. The substratum is then searched for additional adult and juvenile mussels (i.e. shell length <30 mm).
Length frequency distribution for typical Freshwater Pearl Mussel population
The River Nore is the only known location for the freshwater mussel species, Margaritifera durrovensis, the Nore pearl mussel. The River Nore main channel is currently suffering from siltation and elevated nutrient levels. As a result, the Margaritifera durrovensis population has declined at an alarming rate in recent years. Expert National and International advice has indicated that the extant adult population will not survive in situ. A project to captively breed the species was initiated in late 2004 and the mussels moved to the fish farm May 2005. The two main objectives of this project are: (1) to provide necessary scientific advice and monitor the captive breeding programme for Margaritifera durrovensis, which will initially be funded by the NRA as part of its M7/M8 planning condition fulfilment; (2) to assess rivers within the Nore catchment as potential translocation sites for the natural population of Margaritifera durrovensis, as well as any mussels bred in captivity.
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Freshwater Pearl Mussel (Photo: Eugene Ross) |
Freshwater Pearl Mussels in captivity (Photo: Evelyn Moorkens) |
A draft Species Action Plan is in prep. for both species of Margaritifera. It is intended to release these for public consultation towards the end of 2007. An assessment of the conservation status of Margaritifera in Ireland is also nearing completion. NPWS have also funded and overseen research into the potential impacts of forestry operations on water quality and Margaritifera in a number of catchments.
Adapting the methods outlined in Reynolds, J.D (2006) Manual for monitoring Irish lake stocks of white-clawed crayfish,
[766KB], Austropotamobius pallipes (Lereboullet), baseline monitoring will be initiated 25 lakes in 2007.
White-Clawed Crayfish (Photo: NPWS)
There are eight species of the tiny whorl snails in Ireland, and three are protected under Annex II of the Habitat’s Directive, Vertigo geyeri, V. angustior and V. moulinsiana.
These species are all dependant on stable and specific ground water conditions, and as they only live for just over a year, they are vulnerable to the effects of negative changes in wetness conditions and have been lost from many sites both in Ireland and across the EU.
The Republic of Ireland has 14 SACs for Vertigo geyeri, 12 for V. angustior, and 7 for V. moulinsiana, a few of which overlap, and with one SAC hosting all three species.
A monitoring programme is underway to assess the condition of the populations of the three Vertigo species within their SACs, and at a range of representative sites outside SACs throughout their range in the country.
The monitoring assesses the amount and the quality of habitat present for each of the species at the sites being studied, and surveys also sample repeated transects in more detail to identify more subtle changes in the micro-habitats of these very small species.
The results of the survey work will be maintained in a database that will allow useful comparison during repeat visits, aid the conservation of the sites by providing management recommendations, and assess the condition of the sites for six year EU reporting.
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Vertigo moulinsiana (Photo: Derek Rands) |
Transect for V. geyeri at Lough Talt, Co. Sligo. (Photo: Evelyn Moorkens) |
The hoverflies (Syrphidae) occur in a very wide range of habitats. Some are very specialist in their needs, while others have wide ecological niches. Detailed surveys of their occurrence within a study farm are being used to provide information on how farm management affects populations, and how habitat management can contribute to biodiversity of this group and other invertebrates.
An All-Ireland water beetle red list will be published in web format shortly. The water beetle red list project is also producing a list of sites of conservation importance, species accounts for red-listed species, a monitoring methodology for water beetles and a set of conservation priorities for water beetles. nbsp;
NPWS is also providing two thirds funding to the National Biodiversity Data Centre to produce a full Atlas of Water Beetles in Ireland. Further information on the atlas project can be found at the water beetles of Ireland website.
[574KB], has been produced.
Members of Research Branch can be contacted by e-mailing: natureconservation@environ.ie
