Biology & Environment Proceedings of the Royal Irish Academy

Online ISSN: 2009-003X
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1. INTRODUCTIONSymbioses between cyanobacteria and marine organisms are abundant and widespreadamong marine plants and animals. Generally, they are most likely to be found inoligotrophic areas in which either fixation or dissolved organic carbon (DOC) releasebenefit the host organism, although a few occur in nutrient rich areas such as mudflats.Research on these symbioses is in its infancy, and generally there is very little knownabout the nature of many of these symbioses. Furthermore, from microscopicobservations, it appears that there are many more symbiotic relationships yet to bediscovered.In the marine environment, symbioses are known to occur between cyanobacteriaand sponges, Ascidians (sea squirts), and Echuroid worms in the benthos, and diatoms,dinoflagellates and a protozoan among the plankton. These symbioses can often besignificant in terms of the biogeochemistry of coastal and open ocean areas. Forexample, the heterocystous cyanobacterium,
 
Article
Species of Alcyonidium occur commonly on rocky shores and in the shallow sublittoral. Five of them, A. diaphanum, A. gelatinosum, A. hirsutum, A. mytili and A. polyoum , are described, including new taxonomic information. A. gelatinosum has been the subject of extensive nomenclatural confusion, its name until recently having been incorrectly applied to two other species (A. diaphanum and A. polyoum). Three species, A. gelatinosum, A. mytili and A. polyoum, have been consistently misidentified. However, A. mytili is oviparous, whereas A. gelatinosum and A. polyoum are larviparous. A. gelatinosum and A. polyoum can be distinguished by, for example, gut shape, tentacle number and number of embryos per brood chamber, but breeding season is the main distinguishing characteristic, as A. gelatinosum is a winter breeder (like A. hirsutum ) and A. polyoum reproduces in summer (or in autumn in some places outside Ireland). New data on settlement seasons are presented and the variation found between localities is discussed. A key to species is included. Irish distributions are given, corrected from the literature where possible, and based on a recent survey by the authors. A. gelatinosum and A. hirsutum are by far the most widespread and abundant species.
 
Article
Clara Bog is an oceanic raised bog of international ecological importance located in central Ireland. The occurrence of soak systems (areas of mesotrophic/minerotrophic vegetation within acid bog) adds greatly to the scientific interest of Clara Bog. Recent research into the vegetation history of a soak system on Clara Bog known as Lough Roe indicates that major vegetation changes have occurred within the soak over the past century. Vegetation communities were classified and mapped on three different occasions over the last thirty years, most recently in 2003. The results show that the characteristic fen type vegetation has changed considerably with increased representation of ombrotrophic species and a decline in open water communities. Indications are that these changes are occurring as a result of human activity over the past century. It is expected that the soak system will be totally dominated by ombrotrophic bog communities within the next 50 years. This paper describes research investigating the possible restoration of poor fen vegetation within the Lough Roe soak system. Results of hydro-chemical sampling and vegetation monitoring indicate that it is possible to recreate more alkaline conditions suitable for poor fen vegetation to develop by removal of Sphagnum-dominated floating scragh vegetation from the soak. The possible application of the research is discussed with reference to potential future restoration and conservation of the site
 
* /Water soluble, exchangeable, carbonate bound,  
* /Acid volatile sulphide (AVS) concentrations in substrates of the inflow cells of treatment wetlands 1 (W1) and 2 (W2) at 4.58 years after flooding. Concentrations are given as means/standard deviations (n /3) for depths of 0 Á /10cm (10) and /15cm (15).  
Article
Substrates from four and a half year old constructed wetlands built to treat wastewater from an active metal mine were analysed for elevated metal and sulphur concentrations by chemical sequential extractions and x-ray diffraction analyses. Amounts of Fe, Pb, Zn and S were quantified in substrates from the first cells of multi-celled (in-series) treatment wetland systems at three different depths. The analyses showed that the majority of metals removed from the wastewater were retained in residual immobile forms in the upper 0-5 cm of the waterlogged anaerobic substrates. Although substantial concentrations of metals and sulphur were retained in the substrates, the amounts were generally not sufficient to allow accurate mineralogical identification by x-ray diffraction. Classification of the sediments using x-ray techniques was further confounded by the highly organic nature of the wetland substrates. These results suggest that chemical analyses of wetland substrates may still provide a clearer interpretation of metal accumulation over time, especially in wastewaters characterised by relatively low metal concentrations flowing through organically rich substrates. While x-ray diffraction can provide useful interpretation of sediment crystallography and mineralogy, there are limitations in using this technology to characterise young wetland substrates.
 
Article
peer-reviewed Samples of Mytilus edulis, together with samples of sediment and Fucus vesiculosus, were taken monthly from each of five shores on the south coast of the Shannon Estuary from March 1992 to December 1993 inclusive. Samples were digested individually and the levels of iron, zinc, manganese, cobalt, chromium and copper were determined using atomic absorption spectrophotometry. Levels of metals were lower than previously published values from Irish east coast estuaries, including Dublin, except for a few high levels in M. edulis, which did not persist in the tissues and were probably lost through excretion, spawning or detoxification. Of the metals analysed iron showed the highest levels. This was attributed in part to the background levels of iron in sediment. On some occasions high metal levels in sediment did not lead to higher levels either in F. vesiculosus or in M. edulis, suggesting that metals in M. edulis may come from other sources, including anthropogenic inputs, in the estuary. On an international scale the levels in M. edulis of the six metals studied were relatively low in the Shannon Estuary. The longer-term monthly sampling regime followed in this study is important since it shows that occasional high levels, which may be detected by once-off studies, are not always maintained. FORBAIRT
 
Article
peer-reviewed Metal levels (iron, zinc, manganese, cobalt, chromium, copper and nickel) were determined in Cerastoderma edule, Mytilus edulis, Monodonta lineata, Patella vulgata, Nucella lapillus, Littorina obtusata and L. littorea at two sites close to the mouth of the Shannon Estuary (Ireland) in November 1993 and May 1994, using standard atomic absorption spectrophotometer techniques. Samples of seaweeds were included at one shore for comparative purposes only. The best all-round indicators for all the metals studied were C. edule, M. edulis and N. lapillus. Metal levels in the seaweeds were much lower than in the molluscs. No species was a universal indicator of the metals studied when site and season were taken into consideration. High levels of metals accumulated from water and:or sediment were observed in a number of cases. Levels of Zn in N. lapillus were significantly different to those in all other species and C. edule had high levels of Ni. These levels were dependent on site and season. A detrended correspondence ordination showed that the two species of bivalve mollusc and P. vulgata formed one cluster and that the remaining gastropod species formed a second cluster. This study shows that species-specific bioaccumulation occurs and is seasonally specific in certain species. This needs to be taken into account when choosing a bioaccumulator model and when comparing data from different studies. FORBAIRT
 
Article
North Atlantic right whales (Eubalaena glacialis) once occurred seasonally in Irish waters but in recent decades their presence has declined. This study reviews the existing literature to develop an understanding of the past distribution of North Atlantic right whales, their abundance, temporal occurrence, interspecies associations and apparent use of Irish waters. Ancillary information supporting these core aims was investigated to provide a context for the historical misidentification of North Atlantic right whales and the development of Irish whaling to evaluate the presence of this species in Irish waters. Records of the species within the Irish Exclusive Economic Zone (EEZ), between 1300—1987 were validated based on the available data to three confidence levels: definite, probable and possible right whales. Seventeen records comprising at least 42 individual whales exist (including probable Basque whaling effort from the fourteenth century to the sixteenth century). Of the records available, 52% were considered ‘definitely’ right whales with eight comprising 22 individuals from two early twentieth century and two mid-seventeenth century commercial whaling stations operating in the northwest of Ireland. Six ‘probable’ right whale records involving 15 individuals were identified, including two sightings from the late twentieth century while two ‘possible’ records of five individuals were also noted. The previous importance of Ireland's north western coastline as a potential early summer feeding area in the Northeast Atlantic for migrating right whales, along with the apparent extirpation of the species in the region are also discussed.
 
Article
Ireland has good coverage of late Quaternary pollen sites but they are concentrated in the west and north. This paper presents the first full late-glacial and Holocene record from eastern Leinster. It charts vegetation development over the last 15,000 years in the Glendalough Valley. Late-glacial vegetation development shows close correlation to western sites and sampling resolution is sufficient to register short but significant deviations in the pollen record. Anthropogenic impact on the landscape is not evident until the late Neolithic (c. 5,400 cal BP), which contrasts with earlier activity in the west and north which was followed by a lull. This geographical difference in anthropogenic activity may have been influenced by an east-west precipitation gradient. Once established, anthropogenic activity continued to have an increasing influence on the landscape. The establishment of an early Christian monastic site followed by iron smelting in the thirteenth and eighteenth centuries and then lead mining in the nineteenth century had significant impacts on the vegetation. This work provides useful context for the contemporary vegetation communities in the Glendalough valley which currently forms the core of the Wicklow Mountains National Park.
 
Article
The zebra mussel (Dreissena polymorpha, Pallas 1771) invaded Lough Sheelin in the midlands of Ireland in 2001, providing a novel potential food resource for the resident fish species. This paper assesses fish predation on the mussel after the recent colonisation of the lake (with supplementary data from Lough Arrow). In addition, implications for the resident fish community are considered. Roach (Rutilus rutilus L.), and roach—bream hybrids (R. rutilus × Abramis brama L.) were found to consume zebra mussels in all sampling seasons. For other fish species (European perch [Perca fluviatilis L.], northern pike [Esox lucius L.] and the brown trout [Salmo trutta L.]) the occurrence of zebra mussels in the diet was low, in addition to being seasonal, and possibly consumed as incidental by-catch in some cases. The incorporation of mussels into the diet represents the most important change to the feeding habits of cyprinids. Adult roach populations have not increased despite feeding on zebra mussels and appear to be the most negatively impacted fish taxa since the establishment of the mussel in the lake. Brown trout and perch may be advantaged in the long-term, most likely due to reductions in chlorophyll a, habitat changes and altered food resources. The extent of fish predation on zebra mussels does not appear to be sufficient to suppress the mussel population in the lake.
 
Article
As the Noble false widow spider Steatoda nobilis (Thorell 1875) continues to expand its range across Europe, Asia and the Americas, its potential as an invasive species has not yet been fully assessed. Latrodectinae spiders are remarkably adaptable and possess fast-acting neurotoxic venom that can cause neuromuscular paralysis in vertebrates and occasionally feed on small reptiles. We describe here a predation event by a mature female Steatoda nobilis on a juvenile Zootoca vivipara lizard in suburban Dublin. This is the first report of Steatoda nobilis preying on a vertebrate, and the first report of a ter­restrial vertebrate organism falling prey to an arachnid in Ireland. Zootoca vivipara is a protected species in both the Republic of Ireland and Northern Ireland and may increasingly fall prey to Steatoda nobilis as urbanisation encroaches on lizard habitat. Therefore, Steatoda nobilis should be closely monitored outside of its original native range to assess its status as an invasive species.
 
Article
Coregonus pollan Thompson, 1835 is an Irish endemic whitefish with five known lake populations. Lough Derg has the most downstream population of three lakes in the Shannon catchment. We report on the occurrence of recently hatched larvae from a river section captured above Lough Derg during March 2011. This is the first indication of a downstream movement of larval pollan to a lake, which could have important implications for conservation of this red-listed teleost. This finding is consistent with earlier reports of adult pollan, in spawning condition, captured in fyke nets upstream of Lough Derg. There are also accounts of pollan spawning in the river section below Lough Derg during the 1960s, when they were once common.
 
Article
Understanding past and present genetic diversity within endangered species is crucial for the identification of evolutionary significant units (ESUs) and subsequent conservational decisions. Direct access to genetic diversity of extinct populations can only be gained from (sub) fossils or specimens housed in natural history collections. With probably less than 50 extant specimens, the Javan rhinoceros, Rhinoceros sondaicus, is a critically endangered species. It is rare even in museum collections, thus each newly discovered specimen is of conservation importance. Although the Indian (Rhinoceros unicornis) and Javan rhinoceros differ in size, skinfolds and skin texture, the two have been confused on several occasions in the recorded history of both species. Examples can be found in textbooks, zoological gardens and museums. As for the latter, identification of mounted specimens can be compromised by among other factors poor preservation of the skin. An example of such an ambiguous specimen is the Dublin Zoo rhinoceros (f 1865) housed in the Zoological Museum at Trinity College Dublin. Ever since it was mounted, it has borne a name plate that claims it represents a specimen of R. unicornis, but this is not necessarily supported by a number of morphological characters. With this study, we determine the identity of this one-and-a-half century old specimen by DNA sequencing a fragment of mitochondrial Cytochrome B.
 
Article
The analysis of decadal change in regional floras has received fresh impetus in recent years with studies often detecting anthropogenic effects and biotic homogenisation. Here we analyse the changing flora of the island of Ireland (i.e. both the Republic and Northern Ireland) using data derived from the New Atlas of the British Flora (Preston et al. 2002b) to compare changing plant status from the previous national plant atlas of Perring and Walters (1962). We compare the number of 10km × 10km grid squares occupied by individual plant species and enter these into a regression analysis. The null hypothesis assumes that all the species will be located on the line of best fit hence the resulting residuals are used as an Index of Change. This Index was entered into correlation analysis with independent environmental indicators to interpret the potential causes of any change. Despite some potential sampling bias in the data the findings point to several factors being implicated in change with eutrophication being a major correlate of change of native species. Declines in archaeophytes was particularly pronounced for those species confined to single habitats. These and other findings are discussed in relation to land use change and agricultural intensification over the period of the survey.
 
Article
Mysis salemaai forms an important part of the food web, linking the trophic networks of the pelagic and benthic zones. This study examined the current distribution of M. salemaai in Ireland and the species was recorded from eight lakes. This included some previously known one-off records overlooked in distribution reviews and a new record from Lough Derravaragh. Together with its well-documented occurrence in Northern Ireland, this makes ten lakes where the species is known on the island of Ireland. On account of its deep-water habit, M. salemaai has been under-recorded in Ireland, and its distribution may extend to other Irish lakes. There were significant differences in body size in the studied lakes and adults ranged from 11.5 ±0.01mm in Lough Allen to 15.6 ±0.01mm in Lough Corrib. The abundance varied significantly and ranged from 0.3 ±0.1m 3 and 0.5 ± 0.3m 3 in Lough Ree and Lough Derg (respectively) through 1.8 ±0.5m 3 in Lough Allen to 12.8 ±4.7m 3 in Lough Corrib. Despite its relatively wide distribution in Ireland, the abundance in most lakes appears low and its status may be under threat from eutrophication, climate change and the introduction of alien species.
 
Article
The hen harrier in Ireland has suffered a loss in numbers and distribution, primarily through habitat loss, and persecution. Further declines are possible if current issues (involving public opinion, forestry, wind farming and loss of traditional farming practices) are not addressed. Without public support or goodwill towards this, one of Ireland's rarest and most vulnerable birds of prey, it will be difficult to conserve both the population and its habitats. Education and awareness programmes regarding the hen harrier and upland wildlife in general should continue to be supported. Within Special Protection Areas, Appropriate Assessments of the potential impacts of further afforestation and wind-farming on hen harriers (and other species) appears necessary. Proactive steps can be taken with regard to forest biodiversity and structure with hen harriers in mind. Support should continue for those managing the upland landscape in ways that benefit the hen harrier and other wildlife.
 
Top-cited authors
Douglas Evans
  • European Topic Centre on Biological Diversity (retired)
Marinus Otte
  • North Dakota State University
Thomas Bolger
  • University College Dublin
John A Finn
  • TEAGASC - The Agriculture and Food Development Authority
Andrew Ferguson
  • Queen's University Belfast