Southwest Ireland Research Articles

Heteroscyphus fissistipus (Hook.f. & Taylor) Schiffn. established in south-west Ireland, new to the Northern Hemisphere

Heteroscyphus fissistipus (Hook.f. & Taylor) Schiffn. is reported from Garinish Island in south-west Ireland, new to the Northern Hemisphere. Material collected in 1999 is described and illustrated. Male and female plants are present in pure and mixed patches, and evidence for sporophyte production was observed. H. fissistipus has probably reached Ireland from introduced horticultural sources of antipodean origin.

Large deep-water coral banks in the Porcupine Basin, southwest of Ireland

The Porcupine Basin, southwest of Ireland, was one of the earliest sites from where the deep-water corals Lophelia sp. and Madrepora sp. were recovered. These deep-water corals have since been found all along the Atlantic margins of Europe, in water depths ranging from 50 to more than 2000 m. Recent geophysical studies have demonstrated the mound-building potential of deep-water corals. Available data indicate that three major provinces of coral bank occurrences can be identified in the Porcupine Basin: (1) high-relief surface mounds which have a dimension of 1 by 5 km and a height up to 200 m (‘Hovland’ mounds), flanked to the north by (2) a swarm of buried mounds, somewhat smaller (up to 90 m), and with more irregular shapes than those recognised in area 1 (‘Magellan’ mounds), and (3) outcropping or buried, conical mounds (single or in elongated clusters, up to 150 m high) occurring on the southeastern slope of the basin (‘Belgica’ mounds). As far as can be inferred from shallow cores, the surface lithology predominantly consists of an upper layer rich in foraminiferal sand and terrigenous silty clay with intercalations of biogenic rubble. The banks host a remarkable number of colonies of living and dead Lophelia pertusa and Madrepora oculata. The living and dead assemblages are underlain by a significant layer of coral debris in a muddy matrix. Deep-water coral debris together with a living association of the same species covers the surface of the ‘Belgica’ and ‘Hovland’ mounds, which may suggest that these corals have played a significant role in the development of the mound structures. The capacity for mound formation by scleractinian corals in the aphotic zone has been known for some time. Examples are found at different locations along the shelves and the continental margins of the North Atlantic. The role of the corals in these deep-water build-ups is still a point of debate. Though the genesis and initial control of mound settings in this basin might be related to hydrocarbon seeps, it appears that the major development of the Porcupine coral banks in recent geological times has most likely been controlled by oceanic circulation and dynamics in water masses and nutrient supply.

A multi‐technique study of the glacial stratigraphy of Co. Clare and Co. Kerry, southwest Ireland

AbstractA multi‐technique approach has been adopted in a study of the lithostratigraphy of glacial deposits in southwestern Ireland, including clast lithological analysis, fine sand geochemistry, low frequency mass specific susceptibility and fine sand calcium carbonate (equivalent) content. A revised lithostratigraphical scheme is suggested for the Quaternary glacial deposits of the region, together with a simple strategy that may be adopted for stratigraphical studies in other regions of southern Ireland. It appears that geochemical determinations via inductively coupled plasma–atomic absorption spectrometry are particularly useful in characterising and discriminating between till units within local stratigraphical studies and may be used to inform the applicability of other utilitarian techniques for use on a regional scale. Copyright © 2002 John Wiley & Sons, Ltd.

Effects of resource matrix, gut region analysed and sample size on diet statistics in co-existing species of flatfish

The diet breadth and diet overlap of two co-existing species of flatfish, plaice (Pleuronectes platessa) and dab (Limanda limanda) inhabiting a shallow bay in south-west Ireland are compared. They were shown to vary with the resource matrix, the gut region and the sample size. Diet breadth was calculated using Levin's index and diet overlap calculated using Horn's index. Values of diet breadth were considerably less for numerical abundance data when compared to percentage occurrence data. Similarly, diet overlap values were less for numerically derived data. In dab, diet breadths were significantly lower for stomach-only contents than for intestine-only or whole gut contents. In plaice, there were no significant differences in diet breadths between gut regions. Significantly lower diet overlaps for stomach-only data were also found. Reducing the size of sample to N=30 and N=10 resulted in increases in the calculated value of diet breadth, by as much as 0·13 and 0·34 respectively, these increases were frequently significant. The same reductions in sample size for diet overlap decreased overlap values by 0·02 and 0·13 respectively, significant only when sample reduced to N=10.

Movements and activity of male and female dogfish in a tidal sea lough: alternative behavioural strategies and apparent sexual segregation

Movements and habitat selection of male and female dogfish, Scyliorhinus canicula, in a tidal sea lough in south-west Ireland were determined over two temporal scales. Continuous acoustic tracking of four individuals (two males, two females) for 6 days was used to monitor fine-scale changes in behaviour patterns and extent of home ranges. Mark-recapture by number-tagging dogfish captured at sampling stations during August-September in consecutive years was used to reveal long-term philopatric behaviour. Transmitter-tagged male dogfish showed very similar behavioural patterns of low activity during the day in deep water (12–24 m depth) followed by more rapid movements into shallow areas (<4 m) at dusk to feed, before returning to the core space in deep water at dawn. Home ranges occupied by males overlapped almost entirely and were centred in an area where tidal currents form gyres and large crab prey are found. Female S. canicula exhibited a different behavioural strategy. They refuged in caves in shallow water (0.5–1.5 m) during the day and during the 6-day tracking period were nocturnally active two or three times, primarily in deep water. Activity areas of females did not overlap with those of males. Acoustic telemetry, netting, underwater surveys and tag returns revealed males and females were apparently segregated by sex in the lough. Mark-recapture data showed males and females were recaptured from the locations where they were originally caught between 359 and 371 days earlier suggesting at least seasonal segregation in consecutive years. Because female dogfish store sperm enabling temporal separation of the energetically demanding act of copulation with the process of egg-laying, we suggest that this apparent spatial segregation by sex could be driven by the need for females to conserve energy by limiting multiple matings during a time when mating coincides with a peak in egg production and laying.

Our Common Humanity

MOUNTAINS AND THE HILLS never meet, but the people do. I heard this Irish proverb for the first time last month on a boat tour of the magnificent Kenmare River in southwest Ireland. The skipper, Captain Raymond, greeted us in Celtic with this charming saying—and though I'm sure it lost something in translation, I turned to it for comfort after the Sept. 11 terrorist attacks and their aftermath (see page 57). We are all still reeling with sadness from the tragic loss of life. Nearly everyone with whom I've spoken is exhausted— physically and emotionally—and terrified of the unknown and what lies ahead for this nation and the world. But the people—most people— did meet. They came from many walks of life to help rescue the injured, search for survivors, provide food and shelter, donate money, and offer solace to the bereaved. They gave unstintingly of their time and energy and in some cases ...

Prehistoric burial and ritual, in southwest Ireland

Archaeological monitoring of the construction of the N21 road improvements, Co. Kerry, Ireland, in 1999 uncovered four sub-circular features in the townland of Rockfield (FIGURE 1).The central feature revealed itself to be small pit containing a cremation burial. The bones in this shallow pit had been subjected to intense heat, though the boulder clay beneath was unburnt. Radiocarbon (calibrated σ2) dating showed that this cremation dated from 1440–1140 BC, the date being firmly placed in the Irish Bronze Age. The total weight of the cremation was 29 g. The general size of the bone fragments recovered was very small with 72.4% being less than 5 mm in size. This severely limited the osteological analysis. At least some of the fragments, particularly some of the long bone pieces appeared to be human. On the basis of size, the cremation represents at least one adult. The uniform chalky white appearance of the bones recovered indicated that the individual was very well cremated and was probably processed by crushing or pounding of the bones after cremation.

The economic impact of forestry in the Ballyvourney area of County Cork, Ireland

Little is known about the impact of forestry on local development in Ireland. This paper describes one of the first attempts to evaluate the economic activity and employment generated by forestry and to relate it to local development. The study determined the economic activity generated from plantation management and timber production from four forests owned by Coillte Teoranta (the State Forestry Board which is a commercial state-owned company established in 1988 to manage public forests) located in south-west Ireland. The technique used was input–output analysis with the data on the direct economic activities being sourced from Coillte's management information system and from surveys. The indirect economic activities were estimated using an existing input–output model of the region. The data on the direct employment generated were derived from the data collected on the economic activity with additional data being obtained from surveys. To link these data to the concept of local development, the location of the economic activity and employment was related to the centre of the study area. In this way it was possible to determine what areas and communities benefited from the operation of forestry within the study area and consequently to show the benefits that the community local to the forest were gaining from those forests.

Diet of Dippers Cinclus cinclus during an early winter spate and the possible implications for Dipper populations subjected to climate change

The prey composition of the diet of Dippers Cinclus cinclus was shown to differ between baseflow and spate conditions. In southwest Ireland, faecal pellets were collected during a heavy spate in early winter 1991 and during a period of baseflow conditions three weeks later. The diet composition differed significantly between the two periods. During baseflow conditions diet was dominated by trichopteran larvae, especially Limnephilidae, whereas during the spate period diet was composed primarily of ephemeropteran nymphs, particularly Baetidae, and dipteran larvae of the family Simuliidae. Diet during the spate period also contained greater proportions of prey taxa of terrestrial origin. Enhanced hydrological cycles with greater precipitation, predicted under current climate change models, may have an effect on the diet of Dippers and this is discussed.

Impacts of biodeposits from suspended mussel (Mytilus edulis L.) culture on the surrounding surficial sediments

The effects of increased sedimentation on the macrobenthic community, physical structure, and biogeochemistry of the surficial sediment around two farms in southwest Ireland were examined in conjunction with current characteristics. Both farms had been in production for over eight years, were of reasonably large size (>100 MT) and located in low-energy environments. At one site, the benthic community was subjected to bulk sedimentation and organic enrichment and reduced macrobenthic infaunal diversity and elevated levels of organic carbon were recorded close to the farm. In general, effects were restricted to a radius of 40 m around the farm. Conversely, at the second site, there were no observed effects of mussel biodeposits on the benthos and a diverse macrobenthic community persisted. We propose that variations in the dispersion of biodeposits caused by local current patterns had a significant influence on the impact observed, and that this could also account for differences reported in other studies.

Hazel leaf breakdown in two low-order streams differing in the functional efficiency of their detritivore assemblages

Using a reciprocal exchange experimental design, the processing rate of hazel leaf packs was measured in two low-order streams in south-west Ireland that differed in their macroinvertebrate assemblages and in their susceptibility to acid pulses during spates. One stream had a deciduous riparian zone and the other flowed through a conifer plantation. The influence of the detritivore assemblage relative to the initial microbial conditioning was assessed. Hazel leaf packs and plastic 'habitat-only' packs were initially conditioned in each stream and were then either transferred to the other stream or replaced in the stream of conditioning. The rate of macroinvertebrate colonisation and hazel leaf pack breakdown were subsequently measured in all four treatments. There was no significant difference between streams in leaf mass loss during the conditioning period. During the subsequent exposure period, there was a significant difference between streams in hazel leaf breakdown rate, regardless of the stream in which the leaf pack was conditioned. Within each stream, detritivores (shredders and deposit feeders) did not differentially colonise packs conditioned in the different streams, indicating that there was no consequential difference in initial conditioning between streams. However, there were significant differences between the streams in their colonising detritivore assemblages, both in the abundance of individual taxa and in the relative dominance of different functional feeding groups. From this study it would appear that the impact of detritivore activity in the leaf packs outweighs any potential differences in microbial processing between the two streams and also exceeds the effect of differential conditioning on the attractiveness of the detritus. Factors influencing the structure of the detritivore assemblages are thus of primary importance in the decomposition of leaf litter in these systems.

Actinosporean infections in oligochaetes in a river system in southwest Ireland with descriptions of three new forms.

Sediment samples were collected in April, June and August 1998 from a river in southwest Ireland. A total of 1,836 oligochaete specimens were collected from these sediments, and examined for actinosporean infections. Actinosporean-infected oligochaetes have been determined, symptoms and course of infection have been considered and the spores released from them have been described. Spore characteristics for each actinosporean were defined and the prevalence of infection in each oligochaete species was also determined. The overall prevalence of infection with actinosporeans within the oligochaete sample was approximately 2%. Seven types were distinguished, belonging to echinactinomyxon, aurantiactinomyxon and neoactinomyxum forms, from Tubifex ignotus, Lumbriculus variegatus and Limnodrilus hoffmeisteri, and compared with actinosporean types previously reported in the literature. Three of these forms have not been previously described, while the other 4 are morphologically and morphometrically similar to known forms. These actinosporeans may be stages in myxozoan life cycles.

Holocene alluvial-fan development in the Macgillycuddyʼs Reeks, southwest Ireland

Holocene alluvial landforms in the Macgillycuddy9s Reeks, southwest Ireland, were investigated to determine the controls and timing of postglacial geomorphic activity. Detailed geomorphologic analysis of three alluvial-fan and debris cones within high-level cirque basins demonstrates evidence of episodic phases of late Holocene surface aggradation and incision. Radiocarbon dates from peat horizons above and below inorganic units show that phases of aggradation cluster into two distinct periods, the first after 230–790 calibrated (cal.) yr A.D. and the second from 1510 cal. yr A.D. to the present. An additional phase of fan aggradation at one site is dated after 1040–1280 cal. yr A.D. All three phases coincide with episodes of enhanced late Holocene valley-floor alluviation and debris-flow activity from upland Britain. Alluvial fans and debris cones have developed primarily as a result of the resedimentation of late Midlandian (Wisconsin) drift and talus slopes, and mobilization of materials involved flooding, transitional-flow, and debris-flow processes. Pollen analysis of peat horizons interbedded with alluvial-fan and debris-cone sediments indicates that land-use changes were an important factor in lowering the threshold for local slope erosion. Phases of aggradation also coincide with well-documented episodes of climate change, and, hence, fan development is probably a function of both anthropogenic and climatic forcing. A sequence of events may have involved initial slope destabilization due to overgrazing and removal of vegetation that was followed by debris mobilization and fan aggradation during intense rainstorms associated with climate change.

Life-history patterns and spatial and temporal overlap in an assemblage of lotic Plecoptera in the Araglin Catchment Study Area, Ireland

Irish streams have fewer macroinvertebrate species than those of continental Europe, and thus offer useful natural models for the study of community patterns and processes. Plecoptera distribution and spatial overlap amongst species were examined across 15 sites in the River Araglin Catchment Study Area in south west Ireland over a three-year period; the larval life histories and temporal overlap of nine species were examined in detail at two of the sites over twelve months. Chloroperla tripunctata took two years to complete larval growth, whilst all of the other species -Siphonoperla torrentium, Isoperla grammatica, Leuctra fusca, L. inermis, L. hippopus, Protonemura meyeri, Amphinemura sulcicollis and Brachyptera risi - were univoltine. Three additional species occur in the Araglin catchment but not at either of the two intensively-studied sites - Nemurella pictetii, Nemoura cambrica (in smallest streams) and Perla bipunctata (in the main river). Apparent temporal segregation between closely related Plecoptera has been reported by others, and two cases were examined in detail in this study. The overlap of observed seasonal growth patterns in three Leuctra species was lower than most simulated overlaps based on alternative model permutations of their respective seasonal distributions; under the rather conservative model used, provenance of the low overlap by chance (p <0.05) could not be rejected. Temporal segregation of larval growth amongst two Chloroperlidae species was also compelling visually but this arose from their differing voltinism, rather than the absolute timing of their specific larval growth periods. An inverse correlation between temporal and spatial overlap of the detritivorous species might be expected if species with contemporaneous growth patterns were competing for similar resources. At the spatial scale of typical benthic samples and at the catchment scale examined here, however, no such relationship was found.

Using fire scars and growth release in subfossil Scots pine to reconstruct prehistoric fires

Fire scars indicating low- to moderate-intensity fires on peat deposits have been sampled from subfossil Scots pine ( Pinus sylvestris L.) at sites in England, Wales and south-west Ireland. Analysis of ring-width responses to one fire event in 2800 BC illustrates its rejuvenating effect on Pinus sylvestris woodland, supporting a growing body of modern and palaeoecological data that illustrates the regenerative role played by fire in persistence of Pinus sylvestris woodland. Both the scale and timing of these fires suggest that infrequent low- to moderate-intensity fires are sufficient to stimulate Pinus sylvestris growth. This effect is shown by average increases in ring-width following the fire of between 0.62 and 1.16 mm in non-scarred trees and between 0.92 and 2.74 mm in fire-scarred individuals. Growth release in non-scarred trees may prove to be a more reliable method of detecting fire than using the relatively rare fire scars alone. Radii at time of scarring varied between 1.85 and 11.2 cm, much smaller than is predicted to survive from modern studies.

Movements of Dippers Cinclus cinclus in southwest Ireland

Totals of 1,833 nestling and 478 full grown Dippers Cinclus cinclus were ringed in southwest Ireland between 1989 and 1998. Three of these birds were reported by the public and we recaptured 373 individuals. Of these, 151 (40%) had moved from the ringing site on recapture or when found dead. Juvenile dispersal began in June. Birds ringed as nestlings moved the greatest distances (mean 6.7km) while those ringed as adults moved least. There was strong fidelity to breeding sites by adults of both sexes. Females (mean 7.47km) moved greater distances than males (mean 4.69km). Females ringed as nestlings accounted for 63.6% of movements over 5km, while only 31.2% of males ringed as nestlings travelled more than this distance. Females were more likely to cross watersheds than males. A greater proportion of birds travelled more than 5km than reported in other studies.

The impact of clearfelling operations on physico-chemical parameters of aquatic ecosystems in southwest Ireland

(2000). The impact of clearfelling operations on physico-chemical parameters of aquatic ecosystems in southwest Ireland. SIL Proceedings, 1922-2010: Vol. 27, No. 2, pp. 1108-1115.

Conifer forest location and fish populations in southwest Ireland

Conifer forest location and fish populations in southwest Ireland

Epilithic boulder communities of Lough Hyne, Ireland: the influences of water movement and sediment

The Marine Nature Reserve of Lough Hyne (south-west Ireland) encompasses an extremely wide range of marine conditions within a small area. A total of 378 boulders were collected from a range of depths at five sites subjected to very different degrees of water movement and sedimentation. Encrusting biota were identified and the communities compared between sites and upper and lower surfaces. In all, 114 taxa were identified. Alpha diversity was generally found to be higher for lower surfaces at sites with intermediate flow/disturbance. Sites with high water flow had much greater space occupation, predominantly cheilostomatid bryozoans. Multivariate analyses divided the samples into six groupings. Similarity percentage analysis (SIMPER) was used to indicate particular species characteristic of each group. Equations for the species-area curves generated tended to indicate communities at equilibrium except at sites subjected to stresses such as high sediment load or high disturbance. For high disturbance sites it was apparent that number of species cm−2 was significantly negatively correlated with surface area of rock implying non-random distribution.

A link between predator density and arm loss in the starfish Marthasterias glacialis and Asterias rubens

Arm loss in two species of starfish Marthasterias glacialis and Asterias rubens (Echinodermata: Asteroidea) was recorded at eight sites in Lough Hyne, south-west Ireland. There was a significant positive correlation between the density of predators (Luidia ciliaris (Echinodermata: Asteroidea) and Cancer pagurus (Crustacea: Brachyura)) and arm loss in both species of starfish. The results suggest that predators may be responsible for a significant proportion of observed arm loss in these two species of starfish in Lough Hyne.