Is There a Threat of Malaria in Britain and Ireland as a Result of Global Warming?

 Anopheles stephensi. Source: CDC

This blog post is based on my article called Climate Change Bites, originally published on Yahoo. That was in turn based on an essay I wrote as part of my degree studies. The essay won a Highly Commended award at the Undergraduate Awards in 2012. The information here is still valid, and there is, in my opinion, still a significant risk of widespread indigenous malaria occurring in the British Isles if temperatures continue to rise; this situation will be exacerbated by a stalling economy, which constitues a contributing factor not mentioned in the original essay, or in the article based upon it, which is reproduced below.

Malaria is one of the biggest health problems facing developing nations at present. It can cause severe fevers and is often fatal if untreated. But what is perhaps less well known is that malaria was once a problem native to Western Europe, including Britain and Ireland. Could it ever return to these countries? Given the suitability of a large percentage of land cover for mosquito breeding, and the possibility of global temperatures rising by at 2.5°C this century, it seems likely that malaria will once again become indigenous in Britain and Ireland within our children’s lifetime.

Let’s look at the reasons why malaria might become a problem in these countries. First of all, Britain and Ireland are particularly wet places, with a lot of standing water, such as lakes, wetlands, and fields impeded by slow-draining soils. This water cover provides ample habitat for indigenous Anopheles mosquitoes, the species that carry malaria. Anopheles mosquitoes behave as generalist aquatic breeders and will reproduce in almost any wet environment if undisturbed.

So the habitat,and the mosquito species that carry malaria are already present. But what about malaria itself? Malaria does occur in Britain and Ireland, but it is not yet indigenous. It is brought in by people returning from countries where malaria is a daily fact of life. But the infection is usually treated, and in those cases where it is not, malaria hits a brick wall. Why? The only reason that the species of Plasmodium responsible for this blood-borne disease do not multiply in these countries at present is because ambient temperatures are currently too low. The bottom line: it is too cold here for malaria to get a foot-hold. But that could change if temperatures rise. And that is precisely what climatologists are predicting.

What if that happens, and temperatures hit the required level for Plasmodium to reproduce? Well, another three prerequisites must be satisfied for malaria to become native: (1) people return from abroad carrying the disease and it goes untreated, (2) the specific mosquito hosts then bite the infected person/s, and (3) the parasite develops within the mosquito. Once all of these prerequisites have occurred, the infection may spread and malaria will soon have become indigenous.

But there may be some hope, even if that does happen. Because of the localised nature of the human-mosquito-Plasmodium relationship, the first outbreak of indigenous malaria is likely to be small and limited to a particular area, which will probably be marshy or coastal. If infections go unchecked, however, it is likely that the outbreak will spread; a worst-case scenario would involve an outbreak in an area with a high population density, such as London, Dublin, or Cork.

The mosquito species that carry malaria are already present in Britain and Ireland, as are the parasites responsible. It is only a matter of time before the climate in these countries changes sufficiently to allow malarial Plasmodium species to multiply and become indigenous. Whether it will then become epidemic is largely a matter for public health infrastructures to decide.

The Biodiversity and Conservation of Pollardstown Fen

Tufted Duck. Source: Wikimedia Commons

The Biodiversity and Conservation of Pollardstown Fen, County Kildare 

The protection of fen habitats and species in Ireland can be said to have begun in the late 1960s, when An Foras Forbartha conducted the first major national survey of peatlands, which concluded in 1974. This was the government‟s first organised response to losses of large tracts of peatland through increased development and turf cutting. The main objective of the survey was to identify which raised and blanket bogs required the most immediate conservation action. Dúchas took on the second survey which lasted from the early 1980s into the early 1990s, aiming to identify which sites had scientific importance. The sites identified by this survey were designated Areas of Scientific Interest (ASIs) but these had no legal basis. A further survey then resurveyed these ASIs and assessed them for redesignation as Natural Heritage Areas (NHAs). These were better protected than the ASIs, since NHAs were given statutory status under the Wildlife Act (1976).

This protection was further strengthened by the Wildlife (Amendment) Act, 2000. Ireland's programme of peatland conservation was then integrated with the European Natura 2000 system, which consolidated the legal protection of sites using new criteria and included lists of threatened species and habitats in the annexes of its main documents, the Habitats and Birds Directives. Further legislation covering fen conservation includes the Flora (Protection) Order, 1999, and the Planning and Development Act, 2000. The Environmental Impact Assessment Directive further consolidated the criminalisation of the destruction or disturbance of protected habitats and species, requiring that all development projects ensure that the ecology of a site of proposed work is thoroughly investigated before work commences, in many instances leading to the alteration or abandonment of projects on ecological grounds.

In effect, legislation protecting fens in Ireland is three-tiered: legislation is either Irish or European, forming the main two tiers. Non-legal international agreements form a third tier. To use Pollardstown Fen as an example, protection is offered by the following designations:

• Statutory Nature Reserve, with legal basis coming from the Wildlife Act, 1976, and the Wildlife (Amendment) Act, 2000, under which botanical and animal species as well as their habitats are conserved by law.
• Natural Heritage Area (NHA), with legal basis found in the Wildlife (Amendment) Act, 2000, which further conserves Irish species and habitats.
• Special Area of Conservation (SAC), under the Habitats Directive, and protecting annexed habitats and species of European importance from anthropogenic impacts.
• Ramsar Site, with no legal basis, although the convention does require parties to identify and preserve sites falling under the guidelines set out by the convention, typically of international importance, with designation made either by representativeness of the site or by the presence of a rare or endemic species.
• Biogenetic Reserve, designated by the European Council, and providing protection in  addition to that afforded by the Natura 2000 network. Precedes the Natura 2000 network, set up with the aim for scientific research and information exchange.

Of these designations, it is as an NHA and an SAC that Pollardstown Fen is afforded greatest protection, since these designations are founded in law. Any activity impacting negatively on the fen, its habitats or its supported species, may be subject to legal action.

Under the Habitats Directive, Ireland has designated a number of fens as Special Aeas of Conservation (SACs). The legal basis of the protection of SACs (and candidate, or cSACs) comes from Europe, and as such any derogations of legal protections or mitigations included in proposed works must be reported to the European Commission. Special Protection Areas (SPAs) are designated under the Birds Directive in order to conserve rare and threatened bird species, migratory species, and the habitats that they require, and these are also offered European legal protection. SPAs are classified by the presence of Annex I bird species, such as the Golden Plover, Pluvialis apricaria . Migrant species and specialist bird habitats may also be used to designate an area as an SPA. Taken together, areas designated under the Habitats Directive and the Birds Directive are referred to as the Natura 2000 network. 

Another major piece of EU legislation, the EIA Directive, requires that proposed development projects that may affect habitats or species protected under the Natura 2000 work first undertake an in-depth analysis of the ecology of the site. Together with the Natura directives themselves, this directive forms the most far-reaching and practical non-Irish-generated mechanism protecting fenland habitats and species in Ireland.   Many SACs were originally (and many remain to be) Natural Heritage Areas (NHAs). These are sites designated under the Wildlife Act, 1976, and the Wildlife (Amendment) Act, 2000, and are important habitats for botanical or animal species worthy of conservation.

Some fens in Ireland are also Natural Reserves, which are protected by Ministerial Order. National Parks are another means of conserving areas of Ireland‟s fenland, although these have no automatic legal protection. Instead, protection tends to come from any sites within these National Parks being designated as SACs, SPAs, or NHAs (NPWS, 2012). A range of international conventions have been signed by Ireland, and while many such agreements have no legal standing, these international agreements influence wildlife management and protection policymaking in the State. 

As an example, the Convention on Biological Diversity (CBD) gives individual nations sovereign rights over their biological resources. This means that nations are prevented from exploiting the resources of other nations. As part of its commitment to the CBD, Ireland prepares National Biodiversity Plan and Local Biodiversity Plans. These typically cover issues relating to biodiversity in Ireland with an emphasis on threatened habitat types and species, bringing awareness to issues which may affect fenland habitats and species among others. The Nagoya Protocol set out by the CBD then provides a framework for nations to share indigenous genetic material. While this has no direct application to fen or fen species protection, in the case of a future use being found for a fen species, for instance a type of endemic moss, then the Nagoya Protocol offers an internationally agreed best practice for the transferral of said genetic resources. This would effectively protect the species in question from over-harvesting.

The Ramsar Convention currently protects a number of Irish bogs, notably Raheenmore Bog and Clara Bog. However, conventions such as that held at Ramsar must make compromises in order to fit agreements around the disparate legal systems, and political concerns, of many nations. This weakens the objectives of such international agreements (Kruchek, 2003). 

The Bonn Convention protects migratory species, such as the Pintail and Tufted Duck. However, legislation is only as strong as its weakest link - that is to say, each migratory species is protected only so far as the law allows in each country through which it passes (de Klemm, 1994). The Bern Convention similarly protects the biological resources between nations, though its function has now been largely superseded by the Habitats Directive.

The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) is another international agreement, protecting botanical and animal species from the adverse effects of trade.  The legal framework of CITES is somewhat ambiguous, however: parties to the convention are expected to implement CITES, but each individual state must adopt its own legislation in order to do so. In effect, this means that CITES does not replace the legislation of any given state, and therefore is essentially not legally binding, the only obligation being that CITES is implemented, albeit within the pre-existing legal framework of the individual parties.

The European Water Directive acts to preserve waterbodies within the Member States, dividing countries into River Basin Districts. As such, the water quality of any river or other waterway entering aquifers and feeding fens is being managed on a European level, and so this directive could be seen as protecting fen habitats and species either directly or indirectly, depending on a site‟s hydrogeological regime.

The Common Agricultural Policy (CAP) established by the Treaty of Rome in 1957 eventually led to the creation of the Rural Environmental Protection Scheme (REPS) in 1994. All annexed habitats under the Habitats Directive found on the land of participating farms were protected under this scheme, including fens, and so REPS acted as a way of enforcing habitat protection legislation. However, since the breakup of the REPS, landowners have begun converting formerly protected land into agricultural land (IPCC, 2012), partially reversing the conservation aspect of the REPS. REPS was complemented and eventually superseded by Agri-Environmental Options Scheme (AEOS), although AEOS funding is now being withdrawn as well. 

The Irish Red Lists, drawn up in conjunction with the IUCN, protect some species associated with fens, such as the water beetles, Hydroporus scalesianus and Laccornis oblongus. Red Lists exist for other taxa, such as birds and mammals, and provide a basis for focusing conservation efforts on the most threatened species in a hierarchical manner. In summary, the main pieces of Irish legislation protecting fen habitats and species are the Wildlife Act, 1976, and the Wildlife (Amendment) Act, 2000, along with the Flora (Protection) Order, 1999. Major EU regulations that protect fen habitats and species are the Birds Directive, the Habitats Directive, and the Environmental Impact Assessment Directive, all of which have been transposed into Irish law. These mechanisms form the basis for fen protection in Ireland. 

The Flora (Protection) Order,  1999, protects those botanical species listed in Section 21 of the Wildlife Act,  1976, making it an offense to damage or uproot any of these species, to take seeds from them, or to damage their habitats. This is an important piece of legislation for fen conservation, since it is not restricted to SACs. This means that while a fen may be protected by European law, this is only good for as far as the site‟s boundary extends. The Flora (Protection) Order,  1999, protects species such as saw sedge wherever they are found, thereby protecting fenland plants regardless of SAC boundaries. It is therefore a species-based legislation, rather than site-based, such as the SACs and NHAs, which protects the site in which qualifying species are found, but not the species once it leaves that site.

Pollardstown Fen is unique in that it is the largest fen in Ireland fed by springs (O'Donnell, 2006), and also has the longest history as a fen, which it has been for at least 12,000 years. The source of these springs is the Curragh aquifer. Sandstone bedrock filters the waters which then exits the springs and seepages feeding the fen. Pollardstown Fen is an Special Area of Conservation under the Habitats Directive. Three rare species of  Vertigo snails are recorded in the fen, these being  Vertigo geyeri, V. Angustior, and V. Moulinsiana. Any one of these species would qualify the site as an SAC, but all three exist here, the only site in Europe where this occurs. Additionally, the site has three annexed habitat types, also afforded protection under the Habitats Directive, and also qualifying the site as an SAC. These habitat types are Calcareous fens with Cladium mariscus and species of the Caricion davallianae [7210] (one of the largest stands in Ireland), Petrifying springs with tufa formation (Cratoneurion) [7220], and Alkaline fens [7230]. 

The site has also had areas reclaimed from agricultural uses and reflooded, which has led to the site being used by wading birds, raising the biodiversity of the fen (NPWS, 2012), although it has not yet been designated an SPA under the Birds Directive. Examples of notable bird species found at Pollardstown Fen are sedge warblers (Acrocephalus schoenobaenus) and reed buntings (Emberiza schoeniclus), which favour the saw sedge and common reed beds of the fen, while mute swans (Cygnus olor) breed at the edges of the open water areas, as do mallard ducks (Anas platyrhynchos), coot (Fulica atra) and common teal (Anas crecca). The brook lamprey (Lampetra planeri) breeds in the waters of Pollardstown Fen, and the white-clawed crayfish (Austropotamobius pallipes) has also been recorded here, while the resident brown trout (Salmo trutta) is suited to the cold, fast-moving waters of the nearby canal. A predator of the trout, the otter (Lutra lutra) is another resident of the area. Other otter prey items, and conserved species in their own right, are also found here in abundance, the common frog (Rana temporaria) and the smooth newt (Lissotriton vulgaris).

Pollardstown Fen is also important for invertebrates. These include the raft spider (Dolomedes fimbriatus), the amber-winged hawker (Aeshna grandis) and the common darter (Sympetrum stiolatum) and two rare species, Platycherius amplus, a hoverfly, and the moth fly Panimerus goodi, the latter of which is found at Pollardstown Fen and nowhere else in the world. The silky wainscot (Chilodes maritimus) also favours fen habitats and is found at Pollardstown Fen. 

One of the most important botanical features of the fen is the stand of saw sedge (Cladium mariscus), a priority habitat listed in the Habitats Directive, and reportedly the largest in Western Europe (IPCC, 2012). This stand is situated on the north side of the fen where habitat disturbance has been the lowest. Other fen plants found at Pollardstown Fen include the common reed (Phragmites australis), (notable for supporting insect species such as the silky wainscot (Chilodes maritimus)), black bog-rush (Schoenus nigricans), blunt-flowered rush (Juncus subnodulosus), purple moor-grass (Molinia caerulea) and meadow thistle (Cirsium dissectum). Woolly feather-moss (Tomenthypnum nitens) is also found at the fen. The fen margin supports a number of rare orchids, such as fly orchid (Orphrys insectifera), marsh helleborine (Epipactis palustris) and narrow-leaved marsh orchid (Dactylorhiza traunsteineri). 

The characteristic biodiversity of the site is supported by the hydrogeology of the area. There is a constant flow between springs and groundwater seepages at the fen margins, mostly along the south-western edge, which supply the central fen. Where these springs are saturated with calcium, white deposits have formed; these springs are known as tufa (Hajek et al., 2006), and are a protected priority habitat type under the EU Habitats Directive (European Commission, 1992).  Vertigo geyeri and Tomenthypnum nitens are particularly associated with the tufa springs at Pollardstown Fen (Kuczynska et al., 2010). 

The singular nature of this site (it is the oldest of its type in Ireland, for instance) means that its biodiversity is particularly unique and is therefore of high conservation status. Its protected  Vertigo species are rare, but all come from a single genus, making the site of ecological importance. A comparison between Pollardstown Fen and other sites designated as SACs for V. Geyeri, such as Annaghmore Lough, Roscommon, show that Pollardstown Fen is uncommonly species rich for an Irish fen (NPWS, 2012). 

Pollardstown Fen is endangered by the prospect of future drainage (Golder Associates, 2011). Although the site was conserved to a large degree by mitigations to a major road-building project (Foss, 2007), the water table lowered during this construction and despite returning to normal levels, vegetation was allowed to become rank and willow encroachment occurred (Flynn, pers. comm., 2012).  Moorken (2011) noted that  Vertigo declined at the fen margin where it had previously been studied and did not return in its former territory upon normalisation of the water table levels: despite the mitigation measures taken by the road construction, a temporary drop in the level of the water table caused the higher areas of the fen to dry out. This caused an ongoing change in the hydrogeological species zonation, with two notable effects: Salix spp. began encroaching in areas of the site where it had not previously done so; vegetation became rank in areas; and the species of Vertigo for which the fen is famous became absent in the area in which they were first studied. Although Vertigo spp. are still found in the adjacent (more low-lying) area, this is most likely because they were always there and not because they have migrated to the area, although some recruitment may have occurred this way.

This situation is likely to occur again, (Golder Associates, 2011), since the membrane used in the tanking system (whereby the current road sits within a geotextile-lined furrow) is not permanent and so the question of drainage is likely to occur again in the future (Coppinger, 2004). There is currently no scheme in place to replace or upgrade the membrane system, and so permeability, and hence drainage, is likely to be a problem again once the existing geotextile membrane begins to erode (Ciara Flynn, pers. comm., 2012).

The fact that Pollardstown Fen is threatened by the future commencement of drainage means that the distinctive biodiversity of the site will be in greater need of conservation than it is currently. Conservation of this internationally unique site must be accelerated if its distinctive ecosystem and all its components are to be preserved.

References 

Allaby, M., (2010). Oxford Dictionary of Ecology. Oxford University Press, Oxford.
Coleman, D., Crossley, D., Hendrix, P., (2004). Fundamentals of Soil Ecology, 2nd Edition. Elsevier, London.
Coppinger, J., (2004). Use of bituminous geomembrane to reduce environmental impact of road in aquifer. Proceedings of the Institution of Civil Engineers - Geotechnical engineering, 157: 209-217.
Curtis, T., Downes, S., Ní Chatháin, B., (2009). The ecological requirements of water-dependent habitats and species designated under the Habitats Directive. Biology and Environment: Proceedings of the Royal Irish Academy, 109: 261–319.
de Klemm, C., (1994). The Problem of Migratory Species in International Law, in Helge Ole Bergesen and Georg Parmann (eds.), Green Globe Yearbook of International Co-operation on Environment and Development, 67–77.
Dufrene, M., Legendre, P., (1997). Species Assemblages and Indicator Species: the Need for a Flexible Asymmetrical Approach. Ecological Monographs, 67 (3): 345-366.
European Commission, (1992). EU Habitats Directive: Council Directive 92/43/EEC of 21 May 1992 on the  conservation of natural habitats and of wild fauna and flora . European Union, Brussels.
Flynn, C., (2012). Subject matter expert.
Foss, P., (2007). Study of the Extent and Conservation Status of Springs, Fens and Flushes in Ireland. National Parks & Wildlife Service, Dublin.
Fossitt, J.A., (2000). A Guide to Habitats in Ireland . The Heritage Council, Dublin.
Fuller, J., (2010). The County Meath Biodiversity Action Plan: 2008 - 2012. The Heritage Council, Dublin.
Golder Associates (2011). Natura Impact Statement: Athgarvan Septic Tank. Golder Associates, Dublin.
Hurford, C., Schneider, M., (2007). Monitoring Nature Conservation in Cultural Habitats: A Practical Guide. Springer, London.
Inland Waterways Association of Ireland, (2001). Pollardstown Fen. Newsletter Of The Inland Waterways Association Of Ireland , 28: 1-3.
Killeen, I., (2003). Ecology of Desmoulin’s Whorl Snail. Conserving Natura 2000 Rivers Ecology Series No. 6 . English Nature, Peterborough.
Kruchek, B., (2003). Extending Wetlands Protection Under The Ramsar Treaty‟s Wise Use Obligation. Arizona Journal of International and Comparative Law , 20: 410-442.
Kuczynska, A., Moorkens, E., (2010). Micro-hydrological and micro-meteorological controls on survival and population growth of the whorl snail Vertigo geyeri (Lindholm, 1925)  in groundwater fed wetlands. Biological Conservation, 143:1868– 1875.
Lindenmayer, D., Margules, C., Botkin, D., (2000). Indicators of Biodiversity for Ecologically Sustainable Forest Management. Conservation Biology, 14: 941–950.
May, R., McLean, A., eds., (2007). Theoretical Ecology: Principles and Applications. Oxford University Press, Oxford.
Moorkens, E., Killeen, I., (2011). Monitoring and Condition Assessment of Populations of Vertigo geyeri,  Vertigo angustior and  Vertigo moulinsiana in Ireland. Irish Wildlife Manuals , 55. National Parks and Wildlife Service, Department of Arts, Heritage and Gaeltacht, Dublin, Ireland.
National Parks and Wildlife Service, (2012). Site code: IE0000396 NATURA 2000 Data Form . National Parks and Wildlife Service, Department of Arts, Heritage and Gaeltacht, Dublin, Ireland.
National Parks and Wildlife Service, (2012). Site code: IE0001626 NATURA 2000 Data Form . National Parks and Wildlife Service, Department of Arts, Heritage and Gaeltacht, Dublin, Ireland.
Noss, R., (1990). Indicators for Monitoring Biodiversity: A Hierarchical Approach. Conservation Biology, 4: 355–364.
Ó Críodáin, C., Doyle, G., (1997). Schoenetum nigricantis, the Schoenus Fen and Flush Vegetation of Ireland. Biology and Environment: Proceedings of the Royal Irish Academy , 97: 203-218.
O'Donnell, C., (2006). The Kildare By-Pass And Pollardstown Fen . Friends of the Irish Environment, Wicklow.
Office of Public Works (2009). Ecological Impact Assessment of the effects of drainage maintenance on fens, mires and whorl snails. OPW Environment Section, Galway.
Scannell, Y., (2006). Environmental and Land Use Law . Thomson Round Hall, Dublin.
Schlegel, J., Rupf, R., (2010). Attitudes towards potential animal flagship species in nature conservation: A survey among students of different educational institutions. Journal for Nature Conservation , 18: 278–290.
Schulze, E., Beck, E., Müller-Hohenstein, K., (2005). Plant Ecology . Springer, Berlin.
Schwartz, M., Brigham, C.,  Hoeksema, J., Lyons, K., Mills, M., van Mantgem, P., (2000). Linking biodiversity to ecosystem function: implications for conservation ecology. Oecologia, 122: 297–305.
Serpell, J., (2003). Anthropomorphism and Anthropomorphic Selection-Beyond the “Cute Response”. Society & Animals, 11: 83-101.
Verissimo, D., MacMillan, D., Smith, R., (2011). Toward a systematic approach for identifying conservation flagships. Conservation Letters, 4: 1–8.
Wissinger, S., (1999). Ecology of Wetland Invertebrates . Wiley and Sons, San Diego.

Notes from the National Botanic Gardens, Dublin

Strelitzia reginae. Source: Jon Fern, 2009

The National Botanic Gardens are situated in Glasnevin, Dublin, and were established in 1795 by the Royal Dublin Society. The Gardens specialise in botany, science, horticulture and education. Glasnevin saw the introduction of many exotic plants from foreign countries, and a number of cultivars were created. Since 1878, the National Botanic Gardens has been a public institution. As such, it is now managed by the Office of Public Works. With partners all over the world, The Gardens work in key areas of conservation. Plants are tended and in some cases rescued. The Herbarium now holds more than 17 000 species from around the globe.

The National Herbarium is a comprehensive catalogue of all the species of flora in Ireland. In total, there are 750 000 species of indigenous plants on file. Non-native species, including invasive aliens, are being recorded all the time, so the National Herbarium is continually growing. The worldwlide collection preserved at Glasnevin covers species from areas as diverse as rainforests, deserts, marshlands, mountains and grasslands. Many of the scientists stationed at the National Botanic Gardens are involved in overseas work and have their own personal projects.

The dried plants are kept in the herbarium, which has two main sections: a series of compactors hold the world herbarium, while  the Irish collection is housed in a series of cabinets. There are 75 million specimens in total at the herbarium, of which 80,000 are Irish specimens. The Irish herbarium is the most important collection at the National Botanic Gardens since it is a record of all Irish flora. The world herbarium is incomplete and consists of collections of interest to various botanists who made studies in different locations around the globe. The Irish collection is considered to be complete, however, in that all species currently known to exist in Ireland are represented. Naturalised plants are being added, however, and so the collection is continuing to grow. There have been no major new species found in recent years, but it is believed by the curators that they exist. Numerous collectors have made donations to the museum and these are kept in their own section.

Two Genera of Note

The genus Platycerium contains around eighteen fern species in Family Polypodiaceae. These ferns are known a Stagshorn or Elkhorn ferns due to their antler-like appearance. The genus is epiphytic and native to temperate and tropical regions of South America, Australia, Southeast Asia, Africa and New Guinea. Platycerium sporophytes have tufted roots growing from a short rhizome bearing basal and fertile fronds. Basal fronds are sterile; shield (or kidney) shaped and laminate against the host tree, protecting the roots of the fern from desiccation or mechanical damage.

The uppermost margin of most Platycerium species resembles an open crown of lobes adapted to catching falling forest detritus and water. Fertile fronds have spores on their underside, projecting from the rhizome. The spores are clustered in sporangia positioned either on the lobes or between frond lobes.

Some species of the Platycerium genus have one rhizome. Other species grow in colonies with rhizomes branching or new rhizomes forming from root tips. In some conditions spores will germinate on neighbouring trees. Platycerium gametophytes are a small chordate thallus. 
Platycerium have evolved into four groups. Some Platycerium are adapted to arid conditions; the drought-tolerating mechanism Crassulacean Acid Metabolism has been reported particularly for P. veitchii.

Platycerium superbum can be found in cultivation, especially in tropical gardens. Stagshorns are propagated by spores on the underside of fertile fronds. A mature Stagshorn can grow more than a meter wide.

Sarracenia is another interesting genus that may be observed at the National Botanic Gardens. Otherwise known as Pitcher plants, species of this genus come from North America. All eight species of this genus are threatened in the wild. They require good light and tend to sit in 2 – 3 cm of water during the growing season. Like the Venus Fly Trap, the Pitcher plants are carnivorous. A trail of nectar lures insects within the ‘pitcher’ where the insect then falls in and is digested. Its presence in Ireland for over 100 years may qualify the Pitcher plant for naturalised status. It is not considered to be invasive. (Daragh Lupton, pers. comm.)

References

Botany: Basic Concepts in Plant Biology, Hufford, 1978

Trees of Britain and Europe, Aas and Riedmiller, 1994

Brief Geological and Biological Histories of the Killarney Valley

Ilex aquifolium woodland in the Killarney Valley © Jon Fern 2011

Part One: A Brief Geological History, Incorporating the Most Recent Period of Glaciation, and its Impact on the Killarney Valley and Environs

The Killarney Valley is one of the Republic of Ireland's greatest natural assets. It also has a fascinating geological history. The main contributing rock types in the geology of the Killarney Valley are Old Red Sandstone from the Devonian Age (395-345 million years old) in the south and west of the Park, and Carboniferous Limestone (345-295 million years old) in the north. These two rock types meet at an ancient geological boundary within the Park, part of which runs beneath Lough Leane (Carruthers, 1998).

Beginning with the Pleistocene Age, which began around 2 million years ago, and lasting until around 16,000 years ago, the last major period of glaciation helped to shape the bedrock of the Killarney Valley. Ice eroded the bedrock and deposited eroded material as glacial tills, forming moraines or mounds of mixed gravel and stones, which would later become hills. The massive Templenoe glacier carved out many of the mountain features we see today, including Moll’s Gap (Quirke, 2001). The Gap of Dunloe was formed when an area of ice moved across a ridge, carving out the valley beyond (Mitchell et al., 2007). Mitchell et al. (2007) also point to the striated rocks around the Upper Lake as evidence of the erosion from the ice.

Carruthers (1998) identifies several cold stages affecting Kerry, interspersed with warmer interglacial periods. During the Pleistocene Epoch, massive ice sheets formed which caused the earth’s crust to sag; during the interglacial periods, the resultant upwarping of the ground sometimes left beaches higher than sea level; an example of this is found at Ballydavid on the Dingle peninsula. These interglacial periods deposited organic material as well as inorganic tills; peat and semi-organic silts may be found within the low cliffs around Spa, near Tralee bay. Pollen from these deposits included grains from species including fir and rhododendron. Uranium-thorium disequilibrium dating determined the age of these deposits to be between 123 000 and 114 000 years BP (Carruthers, T., 1990).

Since each of the glaciers that affected Killarney likely removed the traces of those previous, the most noticeable effects of glaciation in the area come from the most recent glaciation event (Quirke, 2001). This lasted from 115 000 years ago to 10 000 years ago. Freeze-thaw action shattered mountain peaks almost continuously. Mountains of Old Red Sandstone particularly were eroded by layers of shattered rock. Snow accumulated as temperatures plummeted, and masses of ice formed. They thickened and became glaciers.

Quirke (2001) describes the Templenoe glacier as being instrumental to the formation of the Killarney landscape. More so than the mountain ice on the Macgillycuddys Reeks, the ice cap carved the Earth into now-familiar formations: north-moving tongues of ice split from the ice cap and met the Reeks – the ice split further, with some deepening Ballaghbeama Pass, down the Caragh River valley, around Caragh Lake and on towards Dingle Bay (with Cromane Point being part of the terminal moraine from this ice flow). More ice moved east past Mangerton. It also forced its way through what is now Moll’s Gap and the Gap of Dunloe. These are called glacial breaches. The ice moved through Owenreagh and Gearhameen in the lowlands, but it also flowed over higher ground as it thickened. These effects can be seen in the smoothness and width of the valley. Glacially scoured lakes such as Upper Lake are evident, as are smoothed outcrops called roch moutonnées, such as Eagle’s Nest overlooking Glaisín na Marbh.

The ice flowed north of Torc and spread in all directions, over the area containing Lough Leane, Killarney town and River Laune. It met here the glacier pushing through the Gap of Dunloe. Debris carried by the ice was deposited in moraines, the Old Red Sandstone erratic deposited on the limestone bedrock of the Park can be used to determine the direction the ice flowed in (Quirke, 2001). Different types of moraine were created as the ice began to retreat. Terminal moraines were left in corries among the Reeks as the last re-advancing of the ice subsided. As the ice melted, precipitation increased and the limestone dissolved forming cliffs and caves along the Lower and Upper Lakes, and leaving limestone islands. The cracks in the limestone pavement formed. Soil became waterlogged and peat began to build up, and blanket bog accumulated.

Part Two: A Biological History of the Killarney Valley, From the Last Period of Glaciation Onwards

As the warming trend took hold at the end of the last period of glaciation, grasslands appeared (Larner, 1992) and those trees that had survived the ice age began to flourish. These included birch, willow and hazel, and they formed the first new forests (Quirke, 2001; Mitchell et al., 2007), following the juniper that colonised the area immediately after the retreat of the ice (Larner, 1992). Pine spread widely around 9 000 years ago (Mitchell et al., 2007), and oak grew in Killarney 8 000 years ago.

Elm also moved in alongside oak on nutrient-rich soils, leaving the poorer soils for the pines, until a continual cover of trees between 8 500 years ago to 7 000 years ago. Following this period, the climate became conducive to alder colonisation, and with these wetter conditions fen-woods appeared. At around 5 000 years ago, elms declined, possibly due to a disease event (Larner, 1992).

The red deer for which the Killarney National Park is notable can be traced back to 26 000 years ago in Ireland (Ryan, 1998). The earliest evidence for the red deer in Kerry is 4 000 years ago on Ventry Beach. It was the only deer species that co-existed with humans in Ireland until the Normans later introduced the fallow deer, according to Ryan (1998). The other deer species once native (the giant Irish deer, the European elk and the reindeer) had apparently been wiped out before humans arrived. Roe deer were briefly introduced in the 1800s, only to be killed off a few decades later, and sika deer were introduced to Killarney in 1865. The Great Famine served to reduce the herd of red deer significantly (Viney, 2003).

Humans may have been living in Killarney before the last period of glaciation (Quirke, 2001), but it was not until 7 000 years ago that evidence for Mesolithic people living in Ireland exists. Evidence for human habitation in Killarney during the Bronze Age 4 000 years ago has been found at Ross Island, where copper mining took place, and a stone circle can be seen at Lissivigeen. The woodland within the park were cleared several times from the Iron Age onwards, as agriculture increased (Mitchell et al., 2007).

After 4 000 BC, there is evidence that woodland is disturbed in the Killarney National Park area (Quirke, 2001). It is around this time that the Arbutus appears in the pollen data (Viney, 2003), although this may have been from seed migration via birds. Farming increased from 3 000 BC onwards, as shown by pollen data from this period, displaying tree clearance increasing. Some hill bogs still show enclosures from this period, which would have been used to protect livestock from wolves, bears, foxes and other people. Around 2 500 BC, tribal territories were formed and there are mountain cairns in Killarney from this era.

As food supply became steadier, the local population increased, and around 2 000 BC, Killarney saw the beginning of metal working (O’Brien, 2000). This metal working continued throughout the Bronze Age. In the Late Bronze Age, tribal conflicts became common, possibly due to pressure on food sources, when soil fertility began to be problematic. Many hill forts date from this period (Clinton, 2001).

Conflict continued after the Iron Age brought new technologies related to war (Quirke, 2001). There was a resurgence in agriculture around 500 BC, when ploughing became popular (Mitchell et al., 2007). Elm and ash, previously having suffered locally, recovered when arable land declined in the area. Around 400 BC, Roman influence lead to widespread clearing of woodland for intensive farming, despite the fact that the Romans themselves did not invade the country.

According to Mitchell et al. (2007), soils that would have been well-drained with woodland now became increasingly degraded to peaty podzols, a process that had been going on wherever trees were cleared. This now became more widespread, particularly in the uplands. Ploughing practices acted to leach more nutrients from the soil, as sods were continually broken and re-broken. This may have led to the expansion of heathers. Increases in annual rainfall at this time increased the leaching process. Cattle, pigs and sheep were raised for meat, with cattle grazing on grassland that had by now been developed over hundreds of years. Soil degradation and the clearance of woodland led to a decline in plant biodiversity which is borne out by the pollen record. These areas of farmland were never again significantly colonised by woodland.

The pines disappeared around this time (Viney, 2003), and oaks became the prevalent species. A pocket of yew exists, which probably became established around 5 000 years ago (Mitchell, 1990), and similarly shows signs of having been cleared and occupied. The oak woods remained in large part untouched until the 1500s, being exploited for firewood and construction in a more or less manageable way (Larner, 1992). However, during the Elizabethan times, much of this woodland was destroyed to facilitate the passage of English troops through the country. But more so than military destruction, the onslaught of industrialisation denuded Killarney of much of the oak woodland, mainly for timber, charcoal production for iron smelting, barrel-making and boat-building.

The introduction of Rhododendron ponticum in the late 1700s (Viney, 2003), or early 1800s depending on the source, decimated the natural flora of Killarney. By 1969, half the natural woodland had been colonised by the shrub, which is not eaten by anything in the Park, and outshades and outcompetes other plants for light and nutrients. Due to the steady rain that characterises the local climate, most gaps in the woodland become waterlogged, filled with tussocky grass, and cannot nurture acorns. The deer (sika and red) graze continually on saplings, which does little for the regeneration process.

As a result of this denudation, Viney (2003) recognises that the birdlife in Killarney is missing species that are present in Britain, despite being annual passage migrants in Ireland. The loss of habitat may account for the lack of biodiversity, such as the four tits native to Ireland, compared to the seven of Britain, although this could also be due to the differences in climate. For instance, the increased rain (an effect of the retreat of the ice age), may have reduced ground invertebrates upon which small birds such as the chaffinch, wren and goldcrest feed. Heavy grazing by sika deer on brambles and ivy also serves to remove part of their habitat.

However, Killarney is notable for being home to several rare species of butterfly, such as the purple hairstreak, as well as dragonflies, including the downy emerald and the northern emerald. Another invertebrate of note in Killarney is the Kerry slug (Carruthers, 1998). It is conjectured (Viney, 2003) that it was an open-country species that became adapted to tree-cover following the postglacial warming.

The red squirrel thrived in postglacial Scots pine woodland. When this declined, the squirrels adapted to stands of hazel and oak. In medieval times, an export levy was placed on their skins, which suggests it was in abundance (Viney, 2003). However, it was considered extinct in Ireland by the end of the 1700s. It was reintroduced from England in at least ten sites between 1815 and 1876 by early ecologists. However, in 1911, the grey squirrel was introduced. Grey squirrels are better able to digest unripe acorns than the red, which explains their ability to compete so successfully. The red squirrels are more at home in Scots pine, and can feed on the kernels of their cones throughout winter, so the Park is a stronghold for them, with its stands of naturalised conifers.

In conclusion, the trend following the end of glaciation has been towards a warmer, wetter climate, with human pressure on the landscape leading to deforestation and degradation of soil. The denudation of the landscape has been at times amended, such as with the replanting of Tomies and Derricunnihy woods in the 1800s (Quirke, 2001), but more often exacerbated, as with the introduction of R. ponticum. How much of the effect on the biodiversity is due to recolonisation by plants and animals following glaciation, and how much is due to human intervention is debatable; no doubt the special climate of Ireland has a large effect, as does its being an island.

The greatest threat to the biodiversity in Killarney National Park is the spread of Rhododendron ponticum. It remains to be seen whether humans can undo the error they made in encouraging its growth here; however, it looks as though reversing the exponential spread of this shrub will take efforts beyond the economic scope of the Park as it presently stands.

If you are interested in helping to eradicate Rhododendron ponticum from the Killarney National Park, please contact Groundwork at info@groundwork.ie, or visit their website.

References

Bolton, J., (2008). Antiquities of the Ring of Kerry, Bray, Wordwell.

Carruthers, T., (1998). Kerry: A Natural History, Cork, Collins Press.

Clinton, M., (2001). The Souterrains of Ireland, Wicklow, Wordwell.

Feehan, J., O’Donovan, G., (1996). The Bogs of Ireland, Dublin, UCD Environmental Institute.

Larner, J., (1992). The Oakwoods of Killarney, Dublin, The Stationery Office.

Larner, J., (2004). The Ross Island Mining Trail, NPWS.

Mitchell, F., (1990). The history and vegetation dynamics of a yew wood (Taxus baccata L.) in S.W. Ireland. New Phytologist, 115: 573-577.

Mitchell, F., Ryan, M., (2007). Reading the Irish Landscape, Dublin, TownHouse.

O’Brien, W., (2000). Ross Island and the Mining Heritage of Killarney, Galway, National University of Ireland, Galway.

Ryan, S., (1998). The Wild Red Deer of Killarney, Kerry, Mount Eagle Publications.

Quirke, B., (2001). Killarney National Park, A Place to Treasure, Cork, Collins Press.

Viney, M., (2003). Ireland, Belfast, Blackstaff Press.

Comparisons of Irish River Water Quality Indices

Niger Delta. Source: NASA

River and stream quality may be measured by assessing the diversity of macroinvertebrates supported by the water body being surveyed (Sutherland et al., 2006). For this purpose, different biotic indices have been devised. These assign values to different biological parameters, and can sometimes take abiotic factors into account, such as siltation and dissolved oxygen. The main component of aquatic biotic indices is the identification of macroinvertebrates collected from the surveyed water body. These invertebrates act as indicator species, in that their presence and abundance indicate the quality of the water, usually due to the varying sensitivity of individual families, and sometimes individual species, with differences in tolerance to environmental impacts (Dufrene et al., 1997). By assessing the number of families present, each of which are usually assigned a value, and their abundance, the quality of the water body is given a score, indicating its quality.

The Q-value system used by the Irish Environmental Protection Agency was designed by Dr Paul Toner of An Foras Forbartha (later superseded by the EPA) in the early 1970s (Flanagan et al., 1972). An overview of the system is included in the appendices of several annual EPA reports entitled ‘Biological Survey of River Water Quality’, for example Clabby et al. (2004) and Lucey (2009). Since its development, the Q-value system has been the standard biotic index system used by the EPA to monitor the ecological quality of Irish sreams and rivers (Lucey, 2009). The Q-value system was intercalibrated with the European Union’s Ecological Quality Ratios (EQRs) as per the Water Framework Directive (Lucey, 2009). The WFD requires that biotic indices calculated by each Member State with their own systems be converted to a standardised ecological quality ratio (EQR). EQRs are the ratio between the observed and the reference conditions for the water body being surveyed and are expressed as a number between zero and one, with values close to one representing high ecological status values close to zero representing bad ecological status (McGarrigle et al., 2009).

The Biological Monitoring Working Party (BMWP) system is the main biotic index used in the UK and was first devised in 1976 (Hawkes, 1997), and has been updated a number of times, most recently in 2010 (Paisley et al., 2010).

Other indices that exist include the Trent Biotic Index, the Chandler Biotic Index, the Saprobic Index and the Hilsenhoff Biotic Index.

            Both the BMWP and the Q-value system score stream and river quality based on macroinvertebrate identification and weight families by both presence and abundance; both require habitat information, although in the BMWP system this is limited to river microhabitat type: riffles, pools and glides. The main differences between the systems are the numbers of macroinvertebrate families to which scores are assigned (more in the BMWP system), and the scoring scales themselves (narrower in the Q-value system).

Overall, while the Q-value system has the advantage of including more non-invertebrate parameters in its scoring calculations, the range of assessed invertebrates (the main function of both biotic indices) is much narrower in the Q-value system than in the BMWP system. The small number of bands (Q1-Q5) and the room for overlap between them also mean that this system is less accurate than the BMWP system.

A disadvantage of both biotic indices is the effect that sampling effort has on the final scores of surveyed water bodies. For instance, a higher score may be assigned if the sampling period is extended, and a lower score will be the result of reduced sampling times. However, the BMWP system has the advantage that it incorporates the Average Score Per Taxa (ASPT) which may be calculated by dividing the final BMWP score by the number of taxa (Hawkes, 1997).

           Good or moderate water quality may exist where faunal requirements are not met, for instance in cases where the water is either oligotrophic, very hard and calcareous, or where there is significant groundwater input (Lucey, 2009). In these cases, both biotic indices would fail to assign good quality status to water bodies which are of good physic-chemical quality, but that do not support diverse macroinvertebrate communities. Biotic indices that record macroinvertebrates also exclude some keystone species, with Margaritifera margaritifera being an example of an indicator of good water quality.

            Both the BMWP and the Q-value system test the sensitivity of a range of invertebrate species to changes in their environment. However, this is not the only measure of good water quality, since physico-chemical parameters must also be assessed, and biotic indices should not be relied upon as the sole method to test stream and river quality.

References

Ausden, M., Drake, M., (2006). Invertebrates. In: Sutherland, W., ed., (2006). Ecological Census Techniques, 2^nd Edition. Cambridge University Press, Cambridge, pp 214- 249.

Clabby, K., Lucey, J., McGarrigle, M., (2004). Interim Report on the Biological Survey of River Quality, Results of the 2003 Investigations. EPA, Wexford.

Clabby, K., Bradley, C., Lucey, J., McGarrigle, M., (2008). Water Quality in Ireland 2004- 2006. EPA, Wexford.

Chadd, R., (2010). Assessment of Aquatic Invertebrates. Springer, London.

Chalmers, N., Parker, P., (1989). The OU Project Guide: Fieldwork and Statistics for Ecological Projects. Field Studies Council, Shrewsbury.

Dufrene, M., Legendre, P., (1997). Species Assemblages and Indicator Species: the Need for a Flexible Asymmetrical Approach. Ecological Monographs, 67 (3): 345-366.

Flanagan P., Toner P., (1972). The National Survey of Irish Rivers. A Report on Water Quality. An Foras Forbartha, Dublin.

Hawkes, H., (1997). Origin and Development of the Biological Monitoring Working Party score system. Water Research, 32: 964-968.

Kerry County Council, (2010). Killarney Electoral Area Meeting Minutes, 14 April 2010. Kerry County Council, Tralee.

Luby, (2006). Guidelines on Procedures for Assessment and Treatment of Geology, Hydrology and Hydrogeology for National Road Schemes. National Roads Authority, Dublin.

Lucey, J., (2009). Water Quality In Ireland 2007-2008. Key Indicators of the Aquatic Environment. EPA, Dublin.

Mason, C., (2002). Biology of freshwater pollution. Prentice Hall, London.

McCarthy, T., (2007). Regulatory Impact Analysis of the proposed Surface Water Classification Systems including Environmental Quality Standards . EPA, Dublin.

McGarrigle, M., Lucey, J., (2009). Intercalibration Of Ecological Status Of Rivers In Ireland For The Purpose Of The Water Framework Directive. The Royal Irish Academy, 109 (3): 237-246.

Office of the Attorney General, (1998). S.I. No. 258/1998 - Local Government (Water Pollution) Act, 1977 (Water Quality Standards For Phosphorus) Regulations, 1998. The Oireachtas, Dublin.

Paisley, M., Trigg, D., Walley, W., (2010). Revision of the BMWP Score System: Derivation of Present-only and Abundance-related WHPT Scores from Field Data. Environment Agency, Bristol.

Paisley, M., Trigg, D., Walley, W., (2010). Revision of the BMWP Score System: Site Type Variations and Scores for New Taxa. Environment Agency, Bristol.

Quirke, B., (2012). Subject matter expert.

Ross, E., (2011). Subject matter expert.

Schowalter, T., (2006). Insect Ecology, 2^nd Edition. Elsevier, London.

Sutherland, W., ed., (2006). Ecological Census Techniques, 2^nd Edition. Cambridge University Press, Cambridge.