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The Slender Amber Snail (Oxyloma sarsii (Esmark, 1886)) (Pulmonata: Succineidae) in Ireland; results of a habitat and distribution survey on the River Shannon, and recommended Red List status update.

Authors:
  • National Parks and Wildlife Service
  • Botanical, Environmental and Conservation Consultants

Abstract and Figures

The Slender Amber Snail Oxyloma sarsii was only recently recorded in Ireland and consequently it was assessed as Data Deficient in the Red List of Irish non-marine molluscs. The results of a survey in 2012 on and near the River Shannon for this poorly-known species are presented here. As part of the targeted survey, eight sites were visited and sixteen spot samples taken. The species was re-found at its four known sites, and also discovered at three new sites which extend its range to the south to Portumna and Lough Derg and into a third county (Tipperary). Due to the necessity for dissection to confirm identification, numbers of confirmed individuals from study sites were low, but nonetheless, the species appears to be relatively common and widespread along the middle reaches of the Shannon. One of the most common habitat types for this species was found to be ‘reed and large sedge swamp’, and more specifically, Glyceria maxima swamp. Recommendations on its Red List status are made. Keywords: Oxyloma sarsii, River Shannon, wetland mollusc
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This article should be cited as:
Long, M.P., Nelson, B., Anderson, R. and Brophy, J.T. (2015) The Slender Amber Snail
(Oxyloma sarsii (Esmark, 1886)) (Pulmonata: Succineidae) in Ireland; results of a habitat and
distribution survey on the River Shannon, and recommended Red List status update. Irish
Naturalists’ Journal 34(2): 95-100.
Date of publication: 9 October 2015
THE IRISH NATURALISTS’ JOURNAL
National Museums Northern Ireland, Cultra, Holywood, Co. Down BT18 0EU
UK Company No. NI 027133 Charity Ref. XO 887/91
www.irishnaturalistsjournal.org
94 Irish Naturalists’ Journal Vol. 34 Part 2 Irish Naturalists’ Journal Vol. 34 Part 2 95
various herbivores.
e gradual decline (Fig. 7) of the Keeragh Beg
colony may be due to predation factors. As birds
gradually shifted to the large island, the dwindling
Keeragh Beg colony faced more challenging nest
protection issues with fewer adults and a sizeable
gull colony on site, including some 57 AON
of Greater Black-backed Gull (Larus marinus
Linnaeus, 1758) on the island.
For the purposes of monitoring and
assessment, it is recommended that the numbers
of cormorant for the Saltee and Keeragh islands
should be considered together as there is much
interchange between them (MacDonald 1987), a
fact supported by the pattern of shifting numbers
presented in this paper. In the past 7 years where
all sites have been covered, the trend has been
remarkably stable (Fig. 6). While Great Saltee
numbers rose rapidly after recolonisation, this
mirrored a sharp drop on Little Saltee. is trend
reversed when Little Saltee numbers more than
doubled in 2013, a year in which numbers fell
to an 8 year low on Great Saltee. Recent data on
the Keeragh Islands compare favourably with the
initial period of monitoring of 1970-1991, the
rst period recorded a peak of 236 AON, while
in 2008 to 2014, the peak was 242 in 2009.
Cormorants showed a tolerance to breeding
ground habitat alterations on the Keeragh Islands,
when in the winter of 2013/2014 the islands
were over washed. ese storms attened an
area of Tree Mallow (Lavatera arborea Linnaeus,
1753) where no nests were located but mobile
juveniles sheltered. ese storms also washed
away repeatedly used nests, some of which were
approximately three feet tall.
acKNowLeDgemeNTs
We would like to thank the owners – Henry
Gratten Bellew (Little Saltee), the O’Neill family
(Great Saltee) and the Herrling family (Keeragh
Islands) for allowing us to carry out eld work
on their islands. We would like to thank Jim
Hurley for historical information on the Keeragh
Islands (1987-1991). We would also like to thank
Wesley Atkinson, Lorcan Scott, Jimi Conroy,
Irene O’Brien, Ben McCabe, Ann Fitzpatrick,
Alyn Walsh and Damian Clarke for assistance
with eldwork on Great Saltee and the Keeragh
Islands. For assistance with eld work on Little
Saltee and the Keeragh Islands, we would like to
thank Maurice Cassidy, Brian and Linda West,
Penny Cabot, Liam Cabot, Tim Cabot, Redmond
Cabot, Michael Greer-Walker, Fiona Guinness,
Frank Jeal, Jimmy Mercer, Rod Young, Mary
Crichton, Karl Partridge, Veronika Oblak, Linda
Scott, Johnny Tolkin, Karl Partridge, Richard and
Wendy Nairn, Killian Mullarney, Rod Young,
Peter Craven, Charles Keane, Colin Walker,
Patrick Bellew, Werner Khulbrant, Lorraine and
Hillis Fegan, Kevin Shipman, Ciaran O’Keee,
Jim Hurley and Richard Webb.
ReFeReNces
Anonymous (1977) Annual Report and
Conservation Review 1976. Irish Wildbird
Conservancy, Dublin.
Cabot, D. (1999) Ireland: A natural history.
HarperCollins, London.
Coulson, J.C. and Brazendale, M.G. (1968)
Movements of cormorants ringed in the
British Isles, and evidence of colony specic
dispersal. British Birds 61: 1-21.
Gurney, J.H. (1893) Irish rock birds. Transactions
of the Norfolk and Norwich Naturalists
Society. 5 (1889/1890 to 1893/1894).
Fletcher & Son, Norwich.
Hurley, J. (1989) Keeragh Update 4. Privately
Published Report.
Kennedy, P.G., Ruttledge, R.F., Scroope, C.F.
and Humphreys, G.R. (1954) Birds of Ireland.
Oliver and Boyd, London.
Lloyd, C., Tasker, Mark L. and Partridge, K.
(1991) e status of seabirds in Britain and
Ireland. T. & A.D. Poyser, London.
MacDonald, R.A. (1987) e breeding
population and distribution of the cormorant
in Ireland. Irish Birds 3: 405-416.
Mitchell, I.P., Newton, S.F., Ratclie, N. and
Dunn, T.E. (2004) Seabird populations of
Britain and Ireland – Results of the Seabird
2000 Census (1998-2002). T & AD Poyser,
London.
Pollard, R.S. (1931) Bird-life on the Great Saltee
Island, Co. Wexford, 1930. Irish. Naturalists
Journal 3: 150-151.
Roche, R. and Merne, O.J. (1977) Saltees - islands
of birds and legends. O’Brien Press, Dublin.
Snow, D.W. and Perrins, C. (1998) e Birds of
the Western Palearctic. Concise Edition. Oxford
University Press.
Ussher, R.J. and Warren, R. (1900) Birds in
Ireland. Gurney and Jackson, London.
Walsh, P.M., Halley, D.J., Harris, M.P., del Nevo,
A., Sim, I.M.W. and Tasker, M.L. (1995)
Seabird monitoring handbook for Britain and
Ireland: a compilation of methods for survey and
monitoring of breeding seabirds. Peterborough,
JNCC/RSPB/ITE/Seabird Group.
West, B., Cabot, D. and Greer-Walker, M. (1975).
e food of the cormorant Phalacrocorax
carbo at some breeding colonies in Ireland.
Proceedings of the Royal Irish Academy 75B:
285-304.
MuRRay, t. & cabot, d.
e Slender Amber Snail
Oxyloma sarsii (Esmark, 1886)
(Pulmonata: Succineidae) in Ireland;
results of a habitat and distribution
survey on the River Shannon, and
recommended Red List status update
*maRia P. LoNg1, bRiaN NeLsoN2, Roy aNDeRsoN3 aND JohN T. bRoPhy4
1Newtownshandrum, Charleville, Co. Cork.
2National Parks and Wildlife Service, Department of the Environment,
Heritage and Local Government, Ely Place, Dublin 2
31 Belvoir View Park, Newtownbreda, Belfast BT8 7BL
4BEC (Botanical, Environmental and Conservation) Consultants Ltd, 43 Herbert Lane,
Dublin 2, D02 TE86
*Corresponding author – longma@tcd.ie
e Slender Amber Snail Oxyloma sarsii was only recently recorded in Ireland and consequently
it was assessed as Data Decient in the Red List of Irish non-marine molluscs. e results of a
survey in 2012 on and near the River Shannon for this poorly-known species are presented here. As
part of the targeted survey, eight sites were visited and sixteen spot samples taken. e species was
re-found at its four known sites, and also discovered at three new sites which extend its range to
the south to Portumna and Lough Derg and into a third county (Tipperary). Due to the necessity
for dissection to conrm identication, numbers of conrmed individuals from study sites were
low, but nonetheless, the species appears to be relatively common and widespread along the middle
reaches of the Shannon. One of the most common habitat types for this species was found to be
‘reed and large sedge swamp’, and more specically, Glyceria maxima swamp. Recommendations
on its Red List status are made.
Keywords: Oxyloma sarsii, River Shannon, wetland mollusc
iNTRoDucTioN
e Slender Amber Snail Oxyloma sarsii (Esmark,
1886) (Fig. 1) is a poorly-known species of
wetland habitats in Ireland. It is very similar in
appearance to the more common and widespread
Pfeier’s Amber Snail O. elegans (Risso, 1826),
and the two species can only be reliably
dierentiated by dissection. Oxyloma sarsii was
rst conrmed from Ireland in 2004, when
it was found on the western bank of the River
Shannon near Banagher Bridge in Co. Galway
(Holyoak and Holyoak 2005). Further work by
Holyoak (2006) resulted in the nding of the
species at six points in three other locations, all
in Co. Oaly. Holyoak (2006) considered the
species to be a native but likely to have been
overlooked by malacologists in Ireland due to its
external similarity to O. elegans. is species is
also uncommon in Great Britain, being largely
Figure 1. Juvenile Oxyloma sarsii, Banagher, Co. Galway.
Photo: Roy Anderson.
96 Irish Naturalists’ Journal Vol. 34 Part 2 Irish Naturalists’ Journal Vol. 34 Part 2 97
limited to a few locations in eastern England
(Kerney 1999), and is generally uncommon
in central and northern Europe (Holyoak and
Holyoak 2005).
Oxyloma sarsii was found on exposed mud
and vegetation within the ood zone at Banagher
Bridge (Holyoak and Holyoak 2005), and
was associated with Glyceria maxima (Hartm.)
Holmb., or bare mud at the other Irish sites
(Holyoak 2006). Kerney and Cameron (1979)
note the species’ habitat as “richly vegetated fens
and marshes, characteristically on Glyceria and
oating waterplants”. In Ireland, areas supporting
such habitats are relatively commonly found
along the River Shannon and some other major
waterbodies including the canals, and smaller,
more isolated examples may be found elsewhere.
In the Red List of Irish Mollusca (Byrne et al.
2009), O. sarsii was categorized as Data Decient
because of its recent discovery in Ireland and
consequent lack of information on its status. In
order to rectify this, National Parks and Wildlife
Service (NPWS) commissioned a survey for this
species and the results of this inform this paper.
meThoDs
Holyoak and Holyoak (2005) and Holyoak
(2006) mention seven positive records for
Oxyloma sarsii, from four distinct locations
(Table 1). All four of these sites with previous
records, plus an additional four, all on or near
the River Shannon between Shannonbridge and
Portumna, were visited and sixteen spot samples
taken in appropriate habitat for the species across
these nine sites (Fig. 2). e additional sites were
chosen by examining aerial photographs and
from habitat information available from previous
NPWS site surveys. Sites were chosen to be
representative of areas with potentially suitable
habitat, and to give good geographic spread, but
clearly not all areas of potentially suitable habitat
along the River Shannon between Shannonbridge
and Portumna were visited or mapped. Details of
all the sites and samples are given in Table 1.
Autumn is generally a good time of year to
survey for molluscs. Breeding will have taken
place during the summer in many species, and
weather conditions are generally suitable as it is
usually not very dry at this time of year, nor is it
very cold (Cook 2001). e survey work for O.
sarsii therefore took place on 5 and 6 November
2012.
Oxyloma sarsii is a large species (10-20 mm),
as is the similar O. elegans, and so individuals can
readily be searched for and seen in the eld. Spot
Figure 2. Map of sites surveyed for Oxyloma sarsii along the River Shannon between Shannonbridge and Portumna.
Site No. Site name, County,
Vice-County
Grid
Reference
Note on vegetation Fossitt
habitat
Holyoak
sample
also?
No.
samples
2012
No. of
Oxyloma1
1 Grand Canal at
Shannon Harbour, Co.
Oaly, H18
N025187 Tall vegetation
dominated by
Glyceria on canal
bank
FS1, FW4 Yes 3 i- 1 (3, 48)
ii- 2 (0, 19)
iii- 0 (0, 2)
2 R. Shannon at
Banagher Bridge, Co
Galway, H15
N001158 River bank
vegetation
dominated by
Phalaris
FS1 Yes 2 i- 0 (0, 1)
ii- 2 (0, 22)
3 Gortachallow, Co.
Oaly, H18
M967153 Vegetated ditch
near side channel of
main river, Glyceria-
dominated
FS1, FW4 Yes 3 i- 0 (0, 0)
ii- 1 (4, 34)
iii- 0 (0,21)
4a R. Shannon at Victoria
Lock, Co. Oaly, H18
M946129 Bank of main river,
with Glyceria and
Phalaris
FS1 Yes 1 i- 3 (0, 47)
4b Canal at Victoria Lock,
Co. Oaly, H18
M950131 Vegetated section
of ditch near small
canal. Dominant
species Glyceria
maxima.
FS1 Yes 1 i- 1 (2, 61)
5 R. Shannon at
Ballymacegan, Co.
Oaly, H18
M905104 River bank
vegetation,
dominated by
Glyceria.
FS1 No 1 i- 2 (1,113)
6 R. Shannon at
Portland Park, Co.
Tipperary, H10
M882063 Reedbed on
riverbank, main
species Glyceria and
Phragmites.
FS1 No 2 i- 2 (0, 40)
ii- 0 (1, 4)
72R. Shannon at
Lehinch,
Co. Tipperary, H10
M870041 River bank
vegetation, main
species Glyceria.
FS1 No 1 i- 2 (0, 5)
Negative Sites
8 Grand Canal, Ferbane,
Co. Oaly, H18
M987226 Canal bank
vegetation
FW3 No 1 i- 0 (0, 3)
9 Near Shannonbridge,
Co. Oaly, H18
M989226 Ditch with mixed
wetland vegetation,
including Glyceria
maxima
FW4, GS4 No 2 i- 0 (0, 0)
ii- 0 (0, 4)
Table 1. List of sites surveyed for Oxyloma sarsii, with grid reference and brief description of the habitat. The records
from this study were all collected by Maria Long and John Brophy, and determinations requiring dissection were by Roy
Anderson. 1Results from each spot sample shown separately for each site. Numbers of conrmed O. sarsii given rst,
then numbers of O. elegans and unconrmed succineids, respectively, given in brackets. Dissection was used to conrm
identications in all cases for these two species. Dead specimens/empty shells not included in counts here. 2Extra site
discovered nearby, not part of targeted survey
samples were taken in areas of suitable habitat,
the locations of which were recorded using a
hand-held GPS. At each site, areas containing
potentially suitable habitat for O. sarsii were
mapped. At each sampling location, initial searches
for the Oxyloma morphotype were undertaken
on areas of bare mud under vegetation. A sample
point was then chosen based on the presence of
potentially suitable vegetation or the presence of
Oxyloma sp. individuals. Vegetation (covering
approx. 1 m2) was beaten over a white tray (c.50 x
50 cm). Molluscs collected on the tray were either
identied in the eld and recorded, or retained
for microscopic examination. is was done
once at each of the sixteen sampling points. All
succineids encountered in either the eld search
or in the beating samples were retained and a sub-
set were identied by dissection.
Digital photographs were taken at each
sampling spot, and details of the vegetation were
recorded. is comprised a species list (vascular
plants and bryophytes), with percentage cover
for each species, for a 5 x 5 m area around each
spot sample (see Long and Brophy 2013 for the
loNg, M.P. et.al.sleNdeR aMbeR sNail Red list status uPdate
96 Irish Naturalists’ Journal Vol. 34 Part 2 Irish Naturalists’ Journal Vol. 34 Part 2 97
limited to a few locations in eastern England
(Kerney 1999), and is generally uncommon
in central and northern Europe (Holyoak and
Holyoak 2005).
Oxyloma sarsii was found on exposed mud
and vegetation within the ood zone at Banagher
Bridge (Holyoak and Holyoak 2005), and
was associated with Glyceria maxima (Hartm.)
Holmb., or bare mud at the other Irish sites
(Holyoak 2006). Kerney and Cameron (1979)
note the species’ habitat as “richly vegetated fens
and marshes, characteristically on Glyceria and
oating waterplants”. In Ireland, areas supporting
such habitats are relatively commonly found
along the River Shannon and some other major
waterbodies including the canals, and smaller,
more isolated examples may be found elsewhere.
In the Red List of Irish Mollusca (Byrne et al.
2009), O. sarsii was categorized as Data Decient
because of its recent discovery in Ireland and
consequent lack of information on its status. In
order to rectify this, National Parks and Wildlife
Service (NPWS) commissioned a survey for this
species and the results of this inform this paper.
meThoDs
Holyoak and Holyoak (2005) and Holyoak
(2006) mention seven positive records for
Oxyloma sarsii, from four distinct locations
(Table 1). All four of these sites with previous
records, plus an additional four, all on or near
the River Shannon between Shannonbridge and
Portumna, were visited and sixteen spot samples
taken in appropriate habitat for the species across
these nine sites (Fig. 2). e additional sites were
chosen by examining aerial photographs and
from habitat information available from previous
NPWS site surveys. Sites were chosen to be
representative of areas with potentially suitable
habitat, and to give good geographic spread, but
clearly not all areas of potentially suitable habitat
along the River Shannon between Shannonbridge
and Portumna were visited or mapped. Details of
all the sites and samples are given in Table 1.
Autumn is generally a good time of year to
survey for molluscs. Breeding will have taken
place during the summer in many species, and
weather conditions are generally suitable as it is
usually not very dry at this time of year, nor is it
very cold (Cook 2001). e survey work for O.
sarsii therefore took place on 5 and 6 November
2012.
Oxyloma sarsii is a large species (10-20 mm),
as is the similar O. elegans, and so individuals can
readily be searched for and seen in the eld. Spot
Figure 2. Map of sites surveyed for Oxyloma sarsii along the River Shannon between Shannonbridge and Portumna.
Site No. Site name, County,
Vice-County
Grid
Reference
Note on vegetation Fossitt
habitat
Holyoak
sample
also?
No.
samples
2012
No. of
Oxyloma1
1 Grand Canal at
Shannon Harbour, Co.
Oaly, H18
N025187 Tall vegetation
dominated by
Glyceria on canal
bank
FS1, FW4 Yes 3 i- 1 (3, 48)
ii- 2 (0, 19)
iii- 0 (0, 2)
2 R. Shannon at
Banagher Bridge, Co
Galway, H15
N001158 River bank
vegetation
dominated by
Phalaris
FS1 Yes 2 i- 0 (0, 1)
ii- 2 (0, 22)
3 Gortachallow, Co.
Oaly, H18
M967153 Vegetated ditch
near side channel of
main river, Glyceria-
dominated
FS1, FW4 Yes 3 i- 0 (0, 0)
ii- 1 (4, 34)
iii- 0 (0,21)
4a R. Shannon at Victoria
Lock, Co. Oaly, H18
M946129 Bank of main river,
with Glyceria and
Phalaris
FS1 Yes 1 i- 3 (0, 47)
4b Canal at Victoria Lock,
Co. Oaly, H18
M950131 Vegetated section
of ditch near small
canal. Dominant
species Glyceria
maxima.
FS1 Yes 1 i- 1 (2, 61)
5 R. Shannon at
Ballymacegan, Co.
Oaly, H18
M905104 River bank
vegetation,
dominated by
Glyceria.
FS1 No 1 i- 2 (1,113)
6 R. Shannon at
Portland Park, Co.
Tipperary, H10
M882063 Reedbed on
riverbank, main
species Glyceria and
Phragmites.
FS1 No 2 i- 2 (0, 40)
ii- 0 (1, 4)
72R. Shannon at
Lehinch,
Co. Tipperary, H10
M870041 River bank
vegetation, main
species Glyceria.
FS1 No 1 i- 2 (0, 5)
Negative Sites
8 Grand Canal, Ferbane,
Co. Oaly, H18
M987226 Canal bank
vegetation
FW3 No 1 i- 0 (0, 3)
9 Near Shannonbridge,
Co. Oaly, H18
M989226 Ditch with mixed
wetland vegetation,
including Glyceria
maxima
FW4, GS4 No 2 i- 0 (0, 0)
ii- 0 (0, 4)
Table 1. List of sites surveyed for Oxyloma sarsii, with grid reference and brief description of the habitat. The records
from this study were all collected by Maria Long and John Brophy, and determinations requiring dissection were by Roy
Anderson. 1Results from each spot sample shown separately for each site. Numbers of conrmed O. sarsii given rst,
then numbers of O. elegans and unconrmed succineids, respectively, given in brackets. Dissection was used to conrm
identications in all cases for these two species. Dead specimens/empty shells not included in counts here. 2Extra site
discovered nearby, not part of targeted survey
samples were taken in areas of suitable habitat,
the locations of which were recorded using a
hand-held GPS. At each site, areas containing
potentially suitable habitat for O. sarsii were
mapped. At each sampling location, initial searches
for the Oxyloma morphotype were undertaken
on areas of bare mud under vegetation. A sample
point was then chosen based on the presence of
potentially suitable vegetation or the presence of
Oxyloma sp. individuals. Vegetation (covering
approx. 1 m2) was beaten over a white tray (c.50 x
50 cm). Molluscs collected on the tray were either
identied in the eld and recorded, or retained
for microscopic examination. is was done
once at each of the sixteen sampling points. All
succineids encountered in either the eld search
or in the beating samples were retained and a sub-
set were identied by dissection.
Digital photographs were taken at each
sampling spot, and details of the vegetation were
recorded. is comprised a species list (vascular
plants and bryophytes), with percentage cover
for each species, for a 5 x 5 m area around each
spot sample (see Long and Brophy 2013 for the
loNg, M.P. et.al.sleNdeR aMbeR sNail Red list status uPdate
98 Irish Naturalists’ Journal Vol. 34 Part 2 Irish Naturalists’ Journal Vol. 34 Part 2 99
full vegetation data). e habitat was classied
according to Fossitt (2000) and the National
Vegetation Classication (NVC) (Rodwell 1995).
e eld-collected mollusc specimens
were sorted and counted and, apart from any
Succineidae, identied by ML. Resources used
include Cameron (2003) and Kerney and
Cameron (1979) for terrestrial and wetland
species, and Macan (1977) for aquatic species.
Nomenclature follows Anderson (2005). All
specimens were assigned as either adult (a),
juvenile (j) or dead (d). ‘Dead’ signies specimens
which were clearly long-dead. In the case of the
succineids, the largest specimens from each spot
sample point, and hence those most likely to
be adults and most easily identied, were sent
to RA for identication by dissection. All the
species records of molluscs and plants have been
forwarded to NPWS and will be incorporated in
the all-Ireland non-marine Mollusca database and
have been provided to the National Biodiversity
Data Centre. Voucher specimens of O. sarsii from
a selection of positive samples have been lodged
with the National Museum of Ireland – Natural
History (NMINH:2014.6.1-4, seven individuals
from four sites).
ResuLTs
During this survey sixteen spot samples were
taken across eight sites between Shannonbridge
and Portumna, and Oxyloma sarsii was found in
eight of these (from across six of the sites). To
that we can also add one extra site – a positive
sample collected at Lehinch, Co. Tipperary
during a survey for Vertigo moulinsiana (Dupuy,
1849) in the same year. is was an opportunistic
nd, and not part of the targeted O. sarsii survey.
Details are presented in Table 1.
e most common habitats at the sample sites
were reed and large sedge swamp (FS1), drainage
ditch (FW4) and canal (FW3) (Fossitt 2000). e
main NVC vegetation classications recorded
were Glyceria maxima swamp (S5) (Fig. 3) and
Phalaris arundinacea L., tall-herb fen (S28). No
areas were classied as being of EU Habitats
Directive Annex I quality. Full details of all plant
species and other ecological data collected at each
sample point can be found in Long and Brophy
(2013).
A total of twelve habitat areas were mapped
at the nine sites visited. e total area of
potentially suitable mapped habitat was 1.88 ha,
with the average size of mapped patches being
0.21 ha. ese areas mostly consist of strips of
potentially suitable vegetation and habitat along
water features such as rivers, canals and drainage
ditches. Ideal habitat conditions appear to consist
of a muddy substrate, with relatively tall-growing
vegetation, usually found in areas with standing
water. Drains and banks of large rivers and canals
can all satisfy these habitat requirements. Glyceria
maxima was the most commonly recorded
dominant plant in both the current study, and
by Holyoak and Holyoak (2005) and Holyoak
(2006), though Phragmites australis (Cav.) Trin.
ex Steud., and Phalaris arundinacea were often
important vegetation components also. e
species requires moist conditions generally – it
has a high tolerance for inundation, but a low to
moderate tolerance for drying out (Falkner et al.
2001).
A total of 22 molluscan species were recorded
from the sixteen spot samples (768 specimens
identied in total, full details in Long and
Brophy 2013). e samples were dominated by
species of the Family Succineidae (total of 464
individual shells), either the genus Oxyloma or
Succinea (with Succinea putris Linnaeus, 1758,
being the most likely species for this latter
genus). e next most numerous species, found
in only two samples, both from Portland Park,
was the rare Vertigo moulinsiana (229 individuals,
of which 27 were adult). Other species of note
included two other Red Listed species, Aplexa
hypnorum (Linnaeus, 1758) (VU) and Vertigo
antivertigo (Draparnaud, 1801) (VU) (Byrne et
al. 2009). Aplexa hypnorum was found along the
Grand Canal at Shannon Harbour (7 adults) and
at the site near Shannonbridge (2 adults). Vertigo
antivertigo (1 adult) was found along the canal
at Victoria Lock. One juvenile of Bithynia leachii
(Sheppard, 1823) was recorded from the banks of
the Grand Canal near Ferbane. is species is of
interest as it is probably an introduced species in
Ireland (rst record 1908) and has been recorded
only relatively recently from the Shannon lakes
(Roy Anderson, unpublished data). Planorbarius
corneus (Linnaeus, 1758) is also an introduced
species, though it is relatively widespread in the
country now. It has only recently spread widely
throughout the Shannon system (Roy Anderson,
unpublished data), and was found at the Grand
Canal, Shannon Harbour (1 adult) during this
survey.
DiscussioN
is survey revealed that Oxyloma sarsii is
widespread and relatively common on the section
of the Shannon between Lough Ree and Lough
Derg. is species was originally recorded from
four locations, all within an approximately 12 km
stretch of river and canal habitat near Banagher.
e current survey re-conrmed its presence at
all of these locations, and added a further three,
which extend the range of the species south to
Portumna, more than doubling the stretch of
river bank from which it is known. e species
is also present on the Grand Canal, but its extent
here is still unclear.
As noted above, O. sarsii was also recorded
at one site that was surveyed for Vertigo
moulinsiana, which is listed under Annex II of
the Habitats Directive (92/43/EEC). is co-
occurrence with V. moulinsiana and the two other
Red Listed species is of interest and highlights
the importance of the River Shannon for its
molluscan populations. e importance of the
Shannon and its associated riverbank habitats
for a range of plant and animal species, as well as
vegetation communities, is widely recognised (e.g.
Heery 2003, Maher 2013). Also reinforcing this
view was the discovery of the rare thirteen-spot
ladybird at three of the study sites – Gortachallow,
Ballymacegan and Lehinch – during this survey
(Anderson, Long and Brophy 2013).
e extent of the habitat for O. sarsii at the
surveyed sites was limited and small in area, but
reedbed and wetland vegetation along riverbanks
often occur in narrow, linear bands. Additionally,
only a small proportion of the potentially
suitable habitat was sampled and mapped. Based
on the fact that suitable habitat (reedbed or
drainage ditch, with Glyceria maxima, Phragmites
australis or Phalaris arundinacea abundant) is
present along much of the river bank between
Shannonbridge and Portumna there is no reason
to assume that the species is not present almost
continuously along this middle section of the
Shannon. Consequently there is little reason to
consider the habitat of the species as threatened.
e main threat to the species is direct habitat loss
or fragmentation through riverside development
(e.g. marinas). However, from the current study,
it can be seen that the species is present in sites
that have been heavily modied, so it appears
to be able to cope with some level of physical
disturbance.
Based on the results of this survey, and the
records from Holyoak and Holyoak (2005)
and Holyoak (2006), a Red List category of
Vulnerable (IUCN 2012) is proposed for O.
sarsii. is is based on criterion D2: “Population
with a very restricted area of occupancy (typically
less than 20 km2) or number of locations
(typically ve or fewer) such that it is prone to
the eects of human activities or stochastic events
within a very short time period in an uncertain
future, and is thus capable of becoming Critically
Endangered or even Extinct in a very short
time period.” Should further surveys extend the
known range for this species, this category may
be revised, but based on current information, the
species should be treated as Vulnerable based on
its extremely limited known geographical range
in this country.
As noted above, suitable habitat for O. sarsii
can be found in the wider River Shannon system,
along the Grand and Royal canals, and perhaps in
other waterbodies. In order to further investigate
the distribution of this rare species in Ireland,
targeted spot surveys need to be carried out and
mature individuals collected. e main limiting
factor to furthering our knowledge of this species
is that identication can be conrmed only
Figure 3. Glyceria maxima-dominated Oxyloma sarsii habitat on the banks of the River Shannon at Victoria Lock, Co. Oaly.
Photo: John Brophy.
loNg, M.P. et.al.sleNdeR aMbeR sNail Red list status uPdate
98 Irish Naturalists’ Journal Vol. 34 Part 2 Irish Naturalists’ Journal Vol. 34 Part 2 99
full vegetation data). e habitat was classied
according to Fossitt (2000) and the National
Vegetation Classication (NVC) (Rodwell 1995).
e eld-collected mollusc specimens
were sorted and counted and, apart from any
Succineidae, identied by ML. Resources used
include Cameron (2003) and Kerney and
Cameron (1979) for terrestrial and wetland
species, and Macan (1977) for aquatic species.
Nomenclature follows Anderson (2005). All
specimens were assigned as either adult (a),
juvenile (j) or dead (d). ‘Dead’ signies specimens
which were clearly long-dead. In the case of the
succineids, the largest specimens from each spot
sample point, and hence those most likely to
be adults and most easily identied, were sent
to RA for identication by dissection. All the
species records of molluscs and plants have been
forwarded to NPWS and will be incorporated in
the all-Ireland non-marine Mollusca database and
have been provided to the National Biodiversity
Data Centre. Voucher specimens of O. sarsii from
a selection of positive samples have been lodged
with the National Museum of Ireland – Natural
History (NMINH:2014.6.1-4, seven individuals
from four sites).
ResuLTs
During this survey sixteen spot samples were
taken across eight sites between Shannonbridge
and Portumna, and Oxyloma sarsii was found in
eight of these (from across six of the sites). To
that we can also add one extra site – a positive
sample collected at Lehinch, Co. Tipperary
during a survey for Vertigo moulinsiana (Dupuy,
1849) in the same year. is was an opportunistic
nd, and not part of the targeted O. sarsii survey.
Details are presented in Table 1.
e most common habitats at the sample sites
were reed and large sedge swamp (FS1), drainage
ditch (FW4) and canal (FW3) (Fossitt 2000). e
main NVC vegetation classications recorded
were Glyceria maxima swamp (S5) (Fig. 3) and
Phalaris arundinacea L., tall-herb fen (S28). No
areas were classied as being of EU Habitats
Directive Annex I quality. Full details of all plant
species and other ecological data collected at each
sample point can be found in Long and Brophy
(2013).
A total of twelve habitat areas were mapped
at the nine sites visited. e total area of
potentially suitable mapped habitat was 1.88 ha,
with the average size of mapped patches being
0.21 ha. ese areas mostly consist of strips of
potentially suitable vegetation and habitat along
water features such as rivers, canals and drainage
ditches. Ideal habitat conditions appear to consist
of a muddy substrate, with relatively tall-growing
vegetation, usually found in areas with standing
water. Drains and banks of large rivers and canals
can all satisfy these habitat requirements. Glyceria
maxima was the most commonly recorded
dominant plant in both the current study, and
by Holyoak and Holyoak (2005) and Holyoak
(2006), though Phragmites australis (Cav.) Trin.
ex Steud., and Phalaris arundinacea were often
important vegetation components also. e
species requires moist conditions generally – it
has a high tolerance for inundation, but a low to
moderate tolerance for drying out (Falkner et al.
2001).
A total of 22 molluscan species were recorded
from the sixteen spot samples (768 specimens
identied in total, full details in Long and
Brophy 2013). e samples were dominated by
species of the Family Succineidae (total of 464
individual shells), either the genus Oxyloma or
Succinea (with Succinea putris Linnaeus, 1758,
being the most likely species for this latter
genus). e next most numerous species, found
in only two samples, both from Portland Park,
was the rare Vertigo moulinsiana (229 individuals,
of which 27 were adult). Other species of note
included two other Red Listed species, Aplexa
hypnorum (Linnaeus, 1758) (VU) and Vertigo
antivertigo (Draparnaud, 1801) (VU) (Byrne et
al. 2009). Aplexa hypnorum was found along the
Grand Canal at Shannon Harbour (7 adults) and
at the site near Shannonbridge (2 adults). Vertigo
antivertigo (1 adult) was found along the canal
at Victoria Lock. One juvenile of Bithynia leachii
(Sheppard, 1823) was recorded from the banks of
the Grand Canal near Ferbane. is species is of
interest as it is probably an introduced species in
Ireland (rst record 1908) and has been recorded
only relatively recently from the Shannon lakes
(Roy Anderson, unpublished data). Planorbarius
corneus (Linnaeus, 1758) is also an introduced
species, though it is relatively widespread in the
country now. It has only recently spread widely
throughout the Shannon system (Roy Anderson,
unpublished data), and was found at the Grand
Canal, Shannon Harbour (1 adult) during this
survey.
DiscussioN
is survey revealed that Oxyloma sarsii is
widespread and relatively common on the section
of the Shannon between Lough Ree and Lough
Derg. is species was originally recorded from
four locations, all within an approximately 12 km
stretch of river and canal habitat near Banagher.
e current survey re-conrmed its presence at
all of these locations, and added a further three,
which extend the range of the species south to
Portumna, more than doubling the stretch of
river bank from which it is known. e species
is also present on the Grand Canal, but its extent
here is still unclear.
As noted above, O. sarsii was also recorded
at one site that was surveyed for Vertigo
moulinsiana, which is listed under Annex II of
the Habitats Directive (92/43/EEC). is co-
occurrence with V. moulinsiana and the two other
Red Listed species is of interest and highlights
the importance of the River Shannon for its
molluscan populations. e importance of the
Shannon and its associated riverbank habitats
for a range of plant and animal species, as well as
vegetation communities, is widely recognised (e.g.
Heery 2003, Maher 2013). Also reinforcing this
view was the discovery of the rare thirteen-spot
ladybird at three of the study sites – Gortachallow,
Ballymacegan and Lehinch – during this survey
(Anderson, Long and Brophy 2013).
e extent of the habitat for O. sarsii at the
surveyed sites was limited and small in area, but
reedbed and wetland vegetation along riverbanks
often occur in narrow, linear bands. Additionally,
only a small proportion of the potentially
suitable habitat was sampled and mapped. Based
on the fact that suitable habitat (reedbed or
drainage ditch, with Glyceria maxima, Phragmites
australis or Phalaris arundinacea abundant) is
present along much of the river bank between
Shannonbridge and Portumna there is no reason
to assume that the species is not present almost
continuously along this middle section of the
Shannon. Consequently there is little reason to
consider the habitat of the species as threatened.
e main threat to the species is direct habitat loss
or fragmentation through riverside development
(e.g. marinas). However, from the current study,
it can be seen that the species is present in sites
that have been heavily modied, so it appears
to be able to cope with some level of physical
disturbance.
Based on the results of this survey, and the
records from Holyoak and Holyoak (2005)
and Holyoak (2006), a Red List category of
Vulnerable (IUCN 2012) is proposed for O.
sarsii. is is based on criterion D2: “Population
with a very restricted area of occupancy (typically
less than 20 km2) or number of locations
(typically ve or fewer) such that it is prone to
the eects of human activities or stochastic events
within a very short time period in an uncertain
future, and is thus capable of becoming Critically
Endangered or even Extinct in a very short
time period.” Should further surveys extend the
known range for this species, this category may
be revised, but based on current information, the
species should be treated as Vulnerable based on
its extremely limited known geographical range
in this country.
As noted above, suitable habitat for O. sarsii
can be found in the wider River Shannon system,
along the Grand and Royal canals, and perhaps in
other waterbodies. In order to further investigate
the distribution of this rare species in Ireland,
targeted spot surveys need to be carried out and
mature individuals collected. e main limiting
factor to furthering our knowledge of this species
is that identication can be conrmed only
Figure 3. Glyceria maxima-dominated Oxyloma sarsii habitat on the banks of the River Shannon at Victoria Lock, Co. Oaly.
Photo: John Brophy.
loNg, M.P. et.al.sleNdeR aMbeR sNail Red list status uPdate
100 Irish Naturalists’ Journal Vol. 34 Part 2 Irish Naturalists’ Journal Vol. 34 Part 2 101
by dissection of mature adults. Surveyors and
naturalists keen on searching for this species
are recommended to bear this in mind before
collecting specimens. Training in dissection and
subsequent identication is needed for freshwater
ecologists to help advance work in this area.
ReFeReNces
Anderson, R. (2005) An annotated list of the
non-marine Mollusca of Britain and Ireland.
Journal of Conchology 38: 607-637.
Anderson, R.A., Long, M.P. and Brophy
J.T. (2013) Observations on the status of
Hippodamia tredecimpunctata (Linnaeus)
(Coccinellidae) in Ireland, with three new
records. e Coleopterist 22: 75.
Byrne, A., Moorkens, E.A., Anderson, R.,
Killeen, I.J. and Regan, E.C. (2009) Ireland
Red List No. 2 – non-marine molluscs. National
Parks and Wildlife Service, Dublin, Ireland.
Cameron, R.A.D. (2003) Keys for the identication
of land snails in the British Isles. Field Studies
Council, Shropshire, UK.
Cook, A. (2001) Behavioural ecology: On doing
the right thing, in the right place, at the right
time. In Barker, G.M. (ed.) e biology of
terrestrial molluscs. CABI Publishing, United
Kingdom.
Falkner, G., Obrdlik, P., Castella, E. and
Speight, M.C.D. (2001) Shelled Gastropoda of
western Europe. Friedrich-Held-Gesellschaft,
Munchen.
Fossitt, J.A. (2000) A guide to habitats in Ireland.
e Heritage Council, Kilkenny, Ireland.
Heery, S. (2003) Callows and Floodplains.
In Otte, M.L. (ed.) Wetlands of Ireland -
Distribution, Ecology, Uses and Economic Value.
University College Dublin Press, Dublin.
Holyoak, G.A. (2006) Additional records
of Oxyloma sarsii (Esmark) (Gastropoda:
Succineidae) in Ireland. Irish Naturalists
Journal 28: 223.
Holyoak, G.A. and Holyoak, D.T. (2005)
Oxyloma sarsii (Esmark) (Gastropoda:
Succineidae) living in Ireland. Irish Naturalists
Journal 28: 68.
IUCN (2012) IUCN Red List Categories and
Criteria: Version 3.1. Second edition. Gland,
Switzerland and Cambridge, UK.
Kerney, M.P. (1999) Atlas of the land and
freshwater molluscs of Britain and Ireland.
Harley Books, Colchester.
Kerney, M.P. and Cameron, R.A.D. (1979)
A eld guide to the land snails of Britain and
north-west Europe. Collins, St. James’s Place,
London.
Long, M.P. and Brophy, J.T. (2013) Survey,
habitat and population assessments of Vertigo
geyeri, Vertigo moulinsiana, Oxyloma sarsi
and Omphiscola glabra at selected sites. Report
to National Parks and Wildlife Service,
Department of the Arts, Heritage and the
Gaeltacht, Ireland.
Macan, T.T. (1977) A key to the British fresh-
and brackish-water gastropods. Freshwater
Biological Association, Scientic Publication
No. 14.
Maher, C. (2013) e River Shannon Callows,
Ireland: An examination of how ooding patterns
and farming practices aect plant communities
and dipteran assemblages on unregulated
oodplain meadows. Unpublished PhD thesis.
National University of Ireland, Galway.
Rodwell, J.S. (ed.) (1995) British plant
communities Volume 4: Aquatic communities,
swamps and tall-herb fens. Cambridge
Community Press, Cambridge.
loNg, M.P. et.al.
Phreodrilidae in Irish peatlands:
Invasion from down-under or
ancient relict?
RüDigeR m. schmeLz1, RacheL wisDom2 aND *Thomas boLgeR2
1Departamento de Biología Animal, Biología Vegetal y Ecología, Facultad de Ciencias,
Universidad de A Coruña, Campus da Zapateira s/n. 15008 A Coruña, Spain
2School of Biology and Environmental Science, University College Dublin, Beleld, Dublin 4
*Corresponding author – tom.bolger@ucd.ie
Oligochaeta of the Family Phreodrilidae are recorded at three peatland sites in Co. Mayo. ese
are only the second records for this family from Europe and pose the question as to the origin of this
group in this part of the world.
Keywords: Phreodrilidae, biogeography, peatland, Oligochaeta
iNTRoDucTioN
Peatlands occupy 16.2 % of the land surface of
the island of Ireland, i.e. 1.34 million hectares,
and in the Republic of Ireland, they cover 17.2
% of the total land surface (Hammond 1979,
Taylor 1983). ey are an important part of the
Irish landscape and are the habitats for a wide
range of plants and animals. However, human
activity has modied to some degree much of
these ecosystems in Ireland and therefore peatland
conservation is a high priority.
e history and nature of peatland can be
elucidated by studying the invertebrates that
occur in them. Because of the extreme conditions
in a peatland environment the invertebrates are
very environmentally sensitive and are therefore
useful as bioindicators (Spitzer and Danks 2006).
ey are extremely diverse and small in size,
which has resulted in a paucity of studies of their
ecology (Reynolds 1990), especially in Ireland.
A component of the BOGLAND: Sustainable
Management of Peatlands in Ireland project
(Renou-Wilson et al. 2011) was designed to study
invertebrate taxa occurring in various types of peat.
One of the groups targeted was Enchytraeidae
which are ubiquitous in terrestrial habitats but
are also found in freshwater and marine habitats
(Healy and Bolger 1984); however, they make
up as much as 70 % of the faunal biomass in
Sphagnum peatlands (Springett 1970).
meThoDs
A variety of sites were sampled during May
2006. e sampling focused on non-impacted
and impacted areas of eleven core sites chosen
as representatives of the four dierent peatland
types, i.e. raised bog, fen, Atlantic blanket bog
and mountain blanket bog, and distributed in
counties Wicklow, Oaly, Roscommon and
Mayo. Five soil cores (6cm diameter, 5 cm
deep) were collected at each site in May 2006
and the animals were extracted using modied
Baermann funnels (O’Connor 1955). Extraction
took approximately 1-2 hours. Once the worms
were extracted they were stored in specimen
tubes containing distilled water and refrigerated
at 2-5 ºC. Identication was done on live
specimens.
ResuLTs aND DiscussioN
A strange inhabitant of Irish boglands was
discovered at three sites in Co. Mayo, an intact
and an impacted area of the Atlantic blanket
bog at Owenirragh (54°16’N 9°37’W) and an
impacted area at Bellacorick ush (53°11’N
6°50’W). is was a microdrile oligochaete
worm of the family Phreodrilidae. Microdrile
oligochaetes are the smaller relatives of the
‘megadrile’ earthworms, and their lifestyle is
mostly aquatic. ere are about 2 500 species of
microdrile worldwide distributed among a dozen
families. Phreodrilidae is one the smaller families
with about 50 species described. It has a marked
southern distribution with most species known
from southern Australia, Tasmania, New Zealand
and the sub-Antarctic islands. So the nd of
phreodrilids in Ireland is somewhat surprising,
although a single specimen of phreodrilid had
been found previously in Ireland (Gunn et al.
2003). e specimens occurred at 3 of the 12
sites sampled, and more than 100 specimens
were collected, which suggests a stable population
rather than an accidental ‘visitor’. Specimens
were minute, not longer than 3-4 mm when alive
(1-2 mm after xation), and they belong to a
hitherto unknown species of the genus Insulodrilus
(a formal description is in preparation). e
ResearchGate has not been able to resolve any citations for this publication.
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