Glasgow Natural History Society

150th Anniversary Conference
15th-16th June, 2001

Alien species: friends or foes?

Friday 15th June
Prof. James Dickson (University of Glasgow)
'Alien vascular plants in Scotland: concepts and history'
The definitions of alien and native are discussed and difficulties in separating natives from long established aliens (archaeophytes) outlined. Though there are records of thousands of alien species growing in Britain as a whole only a very small proportion ever become invasive and some of these are notorious, outstanding examples being Japanese Knotweed and Giant Hogweed; the latter is discussed in detail with regard to conservation, control and toxicity.
James Dickson is Professor of Archaeobotany and Plant Systematics in the University of Glasgow and is a long-standing member and office-bearer of GNHS.

Andrew Kitchener (National Museums of Scotland)
'Alien mammals: wreaking havoc or missing the boat?'

Since the end of the last Ice Age almost 12,000 years ago, the biodiversity of mammals in Scotland has stayed fairly constant as extinctions have been balanced by introductions. However, the mean body size of mammals has declined as larger species have been lost through habitat loss and hunting and replaced by smaller incidental or deliberate introductions of smaller species. Most introduced rodents arrived incidentally as stowaways and offer potentially interesting insights into the movements of humans in the past. Other species have been introduced for hunting (e.g. deer), or economic (e.g. fur and food) and aesthetic reasons.
Introductions of alien species are widely regarded as detrimental to native species and ecosystems and there are numerous examples of this in Scotland. However, some species had a fossil record in Britain during the Pleistocene, but have been introduced to Scotland more recently. Are these species wreaking havoc or did they just miss the boat? Have some introduced species simply filled the niches left vacant by those who did not manage to colonise Britain at the end of the last Ice Age?
Dr Andrew Kitchener is Curator of Mammals and Birds at the National Museums of Scotland. His research interests include hybridisation in carnivores (e.g. wildcats and domestic cats), geographical variation in mammals (e.g. tigers, red squirrels) and radiocarbon dating of extinct Scottish mammals. He is an honorary lecturer at Glasgow University and a member of the IUCN Cat Specialist Group.

Prof. Norman Grist (University of Glasgow, emeritus)
'When aliens meet'
An imported or introduced alien is subject generally to competition, often to predation &/or parasitism in its new environment; the alien imposes similar pressures on other species in that environment. Selection pressure is mutual between the alien and these other species; it is complex and can impose genetic changes on both. Between two interacting aliens the situation is even more complex.
The best studied example of such co-evolution is the biological control of European rabbits and American myxoma virus in Australia and Europe. Initially myxomatosis was over 99% lethal, but over months and years the viruses became less virulent, the rabbits more resistant. This virus is transmitted mechanically by contaminated mouthparts of ectoparasites. The efficiency of its transmission by arthropod vectors is important. Preference for surface living, as opposed to underground in infested burrows, favours rabbits where fleas are the main vector, as in Britain. The changing population density of rabbits directly and indirectly affects crops and other vegetation, herbivores and carnivores, soil erosion, sporting and other economic interests.
Norman Grist is a retired viral epidemiologist and emeritus professor of infectious diseases; interest in ecology and host-parasite relationships widened to "natural history" especially in the Glasgow area and as member of GNHS.

Prof. Peter Maitland (Fish Conservation Centre) & Dr Colin Adams (University of Glasgow)
'Introduced freshwater invertebrates in Scotland': enhanced biodiversity or a threat to native species?'
In contrast to non-native fish, which have almost all been introduced intentionally by humans, non-native invertebrates in Scotland have mostly introduced themselves by rather surreptitious means. Of the smaller invertebrates, the crustacean, Crangonyx pseudogracilis, appears to have been brought in several decades ago from Canada, via the timber trade and is spreading through mainland Scotland, apparently displacing Gammarus pulex in some places as it does so. Several species of flatworms have been introduced accidentally - Planaria torva to waters in central Scotland (from Scandinavia, via the timber trade) and Dugesia tigrina to the River Tweed (from North America via the aquarium trade). Strangest of all perhaps is Phagocata woodworthi in Loch Ness which appears to have been brought from North America on equipment used there by monster hunters. Alien Mollusca have also been introduced at different times, notable among which are the Zebra Mussel Dreissena polymorpha and Potamopyrgus jenkinsi. Two of our largest freshwater invertebrates - crayfish - have been introduced intentionally. The two long-established populations of White-clawed Crayfish Austropotamobius pallipes - in Sutherland and Renfrewshire - were probably introduced well over a century ago and neither of them has shown any dispersal during that time. In contrast, two populations of Signal Crayfish Pacifastacus leniusculus (in the River Dee [Galloway] and the River Clyde) which appear to have been introduced in the last decade or so of the 20
th century are already spreading through these river systems and regarded as a significant threat to other biota there. As well as free-living invertebrates, a number of parasites have been unintentionally introduced to Scotland, for example the Fish Louse Argulus japonicus, which is proving to be a threat to fish both in the wild and in fish farms.
This paper reviews the status of these and other non-native invertebrate species, possible mechanisms which might be used to prevent the future entry of such biota, and what their relationship is with native plants and animals in Scotland.
Peter Maitland was educated at Bearsden Academy and the University of Glasgow where he was a Lecturer in Zoology for five years. He joined the Nature Conservancy in 1967 and saw it split into the Nature Conservancy Council and the Institute of Terrestrial Ecology in 1973. He remained with the Institute of Terrestrial Ecology until i1986 , when he 'retired' and he has worked as an independent freshwater biologist ever since. He is a Fellow of the Royal Society of Edinburgh and a visiting Professor at the University of Glasgow. He has published 9 Books, 216 papers and 79 Contract reports.
Since 1995 Dr Colin Adams has been Director of University Field Station, and Senior Lecturer, University of Glasgow, Rowardennan. He is responsible for all aspects of running the field Station and the development and implementation of its research and teaching programme. He also teaches at honour level in the degrees of Aquatic Bioscience and Zoology and is the course co-ordinator for the field courses of Freshwater Biology and Zoology course on Ecology. His research interests centre round five areas within the field of behavioural ecology and has published over 40 papers.

Saturday 16
th June

Dr. Colin Adams & Prof. Peter Maitland
'Invasion and establishment of freshwater fish populations in Scotland'
New species of fish have been invading Scottish fresh waters since the last glaciers retreated 7-8000 years ago. Some invaded Scotland naturally, most of these are species that can survive in salt water and invaded by migrations via a sea route. A few other species in the Scottish fish fauna appear to be using mechanisms that are not well understood, for migrations between unconnected fresh waters. However the vast majority of the recent additions to our fish fauna have extended their range through human intervention.
In this paper we will consider the present status of the Scottish fish fauna and why some species become successfully established when they invade new systems whereas others fail. Using a well studied example of a new fish species invasion in Loch Lomond we will show what can happen in a community invaded by a new species. Finally using data on the potential effect of global warming we will attempt to predict what the fish fauna of Scotland may look like in the future.

Miss Lynne Farrell (Scottish Natural Heritage)
Alien aquatics - where do they come from, where do they go, and what can we do about them?'
There has been a considerable increase in the number and range of alien aquatic species in recent years. Some of these are sensitive to frost so do not occur in the north of Britain. Others thrive in waterways, where they may have been 'released' from fish tanks or garden ponds. Some are listed as nuisance species, as they are vigorous, displacing our native plants, and it is illegal to introduce them into the wild. It is possible to control some species. Prevention is better than cure in most cases though, so recent information and education is being made available to make people aware of the problem. This is often displayed at garden and specialist aquatic centres.
Lynne Farrell started her career in the Nature Conservancy as a botanical assistant at Monks Wood, Huntingdonshire, where she worked on the effects of grazing on chalk grassland and rare plants population studies. After taking a Biology degree at the New University of Ulster, Coleraine, she worked in Eire for 2 years primarily on ecological surveys. Returning to Monks Wood, she produced the first British Red Data Book on Vascular Plants with Franklyn Perring. She then became a lowland heathland and plant ecologist with English Nature, and for the past 6 years has been working for Scottish Natural Heritage on European sites, and as an operational manager in Argyll & Stirling.

Dr. Roni Robbins and Prof Phil Rainbow (Natural History Museum, London)
'Mitten crabs and other crustaceans'
The Chinese mitten crab, Eriocheir sinensis, a native of China and Korea, has been introduced as an alien invader into western Europe, probably initially in ballast water in about 1912. Since the early 1990s mitten crab numbers in the Thames catchment have risen dramatically and the crab is spreading to other British estuaries. Mitten crabs begin life as planktonic larvae in estuaries. They settle on the bottom as juvenile crabs and start the long march upstream into freshwater where they live as adults. At about five years old, the crabs come into breeding condition and move downstream in large numbers in late summer, concentrating crabs from the many tributaries of a river system together in the estuary to mate. The egg-bearing females move to the estuary mouth where they release larvae into the plankton. The spent adults probably die. The invasion of the mitten crabs has potential environmental dangers. The crabs are strong burrowers and can damage banks, dams and other engineering earthworks. They are ravenous omnivores feeding on the indigenous fauna and flora, and affecting fish with benthic eggs and outcompeting native crayfish. The native crayfish is also under threat of competition from foreign crayfish, introduced since the 1960s for aquacultural, culinary and aquarist purposes, not least the Turkish narrow-clawed crayfish and the Californian signal crayfish.
Phil Rainbow is Keeper of Zoology at the NHM, a wonderfully historic term for the Head of the Department of Zoology, responsible for about one hundred researchers and curators behind the scenes in London. His own research interests centre on the biology of trace metals in crustaceans. Roni Robbins has just completed her PhD on the population ecology of the Chinese mitten crab in the Thames catchment.

Dr. Oliver Gilbert
'Figs, Japanese knotweed and Himalayan balsam enhance the urban ecology of Sheffield'.
Figs, Japanese knotweed and Himalayan balsam are all well-established beside the River Don where if flows through Sheffield. A riverside walk has recently been constructed along the river so people come into regular contact with these plants. An assessment has been made of whether each should be regarded as friend or foe with surprising results.
Oliver Gilbert has been interested in botany since a very young age. He has been fortunate enough to have spent his life in Universities, first in Botany Departments, then teaching applied ecology to landscape students. He has written books on the Ecology of Urban Habits, Habitat Creation and Lichens, and finds it stimulating to work in unfashionable areas.

Mr Geoffrey Hancock (University of Glasgow)
'Alien invertebrates'
The differing categories of alien insects will be illustrated by examples drawn mainly from Scotland. Insects can arrive here by human agency, accidental or deliberate, and through natural phenomena. After arrival their sojourn may be permanent or temporary in which latter case constant re-invasion can maintain a more or less apparent residential status. Many of these insects are reliant on our activities to provide them with food and shelter but some can survive out of doors. Familiar insects, even to the most dedicated urban dwellers, are aliens such as cockroaches, larder beetles, flour moths and carpet beetles. The largest category of established aliens are thus labelled as household or stored product pests and an attempt at eradication is the main, and generally unsuccessful, reaction to their presence. Further afield the numbers of species drop and hence awareness of their presence. Many of the alien herbivores track alien plants, their original choice from ' back home', or utilise a newly adopted food source and so gardens and fields are places to look. In the unmanaged countryside few aliens can be detected by any but the dedicated naturalist but they are there and give an extra dimension to our island's biodiversity.
After graduating in Zoology at Bristol University and a year at Leicester, Geoff Hancock embarked on a career as a museum curator in natural history in general and insects in particular. Prior to the Hunterian he worked in a number of museums, principally Liverpool, Bolton and Glasgow (Kelvingrove). Gently introduced to Glasgow's University environment by taking part in expeditions to Trinidad, becoming an Honorary Lecturer in the Division of Environmental and Evolutionary Biology (DEEB) and moved more permanently 'up the hill' three years ago.

Dr Jonathan Humphrey (Forestry Commission Research Agency)
'Sitka spruce plantations in Scotland: friends or foes to biodiversity?'

Most of Scotland was originally covered in natural woodland. Large scale conversion to other land uses such as agriculture and settlements began in Neolithic times and has continued throughout history. Now only 1-2% of the land area is occupied by ancient semi-natural woodland, the modified remnants of the original "wildwood". Many woodland species were lost over previous centuries (e.g. the beaver and the wolf) but species of open-ground habitats such as heathland and grassland have prospered. During this century there has been extensive commercial afforestation of the Scottish uplands using exotic conifer species such as Sitka spruce and native species such as Scots pine. This has resulted in the loss of open habitats, the modification of semi-natural woodland, and subsequent outcry at the loss of biodiversity. However, as these "alien" plantations have matured, there has been increasing recognition of their value as developing woodland ecosystems. In 1995, the Forestry Commission set up a Biodiversity Research Programme to assess the value of planted forests for biodiversity and to propose biodiversity enhancement strategies. This presentation will give an overview of the main findings from this research programme which suggest that Sitka spruce plantations have the potential to contribute significantly to the conservation of a range of different native flora and fauna in Scotland.
For the past 8 years, Jonathan Humphrey has been a programme manager for forest biodiversity research at the Forestry Commission's Northern Research Station. He is responsible for researching the development of biodiversity assessment tools in managed forests, and for providing guidance on the management of commercial forests for enhancing biodiversity. Jonathan is also actively involved in research relating to the ecology, and management, of native woodlands at both stand and landscape scales. A double graduate of Aberdeen University, Jonathan also spent two years working as a woodland ecologist with the Countryside Council for Wales in Bangor.

Dr. Hugh Jones (University of Manchester) & Dr. Brian Boag (Scottish Crop Research Institute)
'New Zealand flatworm'
New Zealand flatworms were first recognised in Scotland (Edinburgh) in the early 1960s, shortly after being found in Northern Ireland. It is supposed that they were transported, either as adults or as egg capsules, by means of potted plants. In New Zealand they have a limited distribution in the South Island. They are thought to feed exclusively on earthworms, and though initially they were regarded as curiosities in the UK, their subsequent spread and local abundance has raised concerns about reduced earthworm populations and consequent changes to soil structure and fertility. We will review the progress of the invasion of Scotland, give the present known distribution of New Zealand flatworms, outline their biology and summarise some of the recent and current work on the effects of New Zealand flatworms on earthworm populations. We will consider the likelihood of other species of land planarian becoming a problem in the British Isles and the probability of them becoming established on the continent of Europe. The possible knock-on effects of decreased earthworm populations on agriculture and wildlife will also be considered.
Hugh Jones' initial research interests were the physiology of intertidal and marine organisms, particularly molluscs, but has also worked on land molluscs, tunicates and sponges. He has also published many papers on the taxonomy, behaviour and ecology of land flatworms, most recently on the effect of flatworms on earthworm populations in Scotland. He proposed and organised the MEGALAB WORMS project in 1995 as part of National Science Week, in conjunction with BBC TV's Tomorrow's World and The Daily Telegraph.
Brian Boag is an ecologist working mainly on soil invertebrates especially nematodes, earthworms and flatworms but has also undertaken research on parasites of sheep, rabbits, hedgehogs and hares. He supervised the surveys of both flatworms and earthworms in Scotland in the early 1990s and is presently studying the seasonal fluctuations and population dynamics of the New Zealand flatworm in Scotland. He has made frequent trips to New Zealand to study flatworms and published over 20 papers on their distribution and biology.

Dr. John Hopkins (English Nature)
'Exotic species: questions of science and concerns of society'
Until recently, biological recording in the British Isles has heavily emphasised the documentation of species considered to be "native". In some taxonomic groups the numbers of so-called native and introduced species are now evenly balanced and a second class of non-native diversity has developed with limited comment except where economic or ecological effects have occurred. Biological invasions have been one of the most extensively studied ecological phenomena including both economic and biodiversity aspects. The lessons to emerge from this work are not simple. To characterise species which will cause economic or biodiversity problems has proved difficult. The lack of absolute rules does not however mean that there are not some trends. For example, the majority of species brought into Britain do not establish in the wild, and of those which do, a significant proportion remain rare; many of the most problematic species such rhododendron, New Zealand flatworm and grey squirrel come from areas with similar climatic features to parts of Britain. The application of risk management methods is likely to provide a more structured framework for spotting potential problem species which should be kept out of Britain. The small proportion of introductions which become problematic have had a profound effect on biodiversity, including ecosystem transformation, genetic introgression, predation, disease transmission and competition. Looking at Britain's biodiversity at a range of scales from local to international there can be little doubt that these are adverse effects.
For the great majority of society native status is an obscure concern. Where species have no defined economic or practical effect human reactions are likely to be swayed by psychological or moral factors. To many Himalayan balsam and rhododendron are seen as colourful, and the grey squirrel charming; the American bull frog and New Zealand flatworm are distasteful to most. Such values are a reflection of social mores and individual psychological traits. Members of society therefore often have divided views about individual species and human reactions may be difficult to predict. In the field of nature conservation opinion about general policy and the policy relating to single species is varied and does not separate science and philosophy. Some would like to remove all non-native species, others are content to control and eradicate problem species and some challenge the basis for branding given exotic species as problematic.
For the statutory conservation agencies there is a two fold challenge. The first challenge is to understand more precisely the effects of introduced species on biodiversity. The second challenge is to develop practical strategies for their management or eradication of established exotic species. Such control strategies will require significant scientific experimentation and structured evaluation of social and psychological factors which are likely to confound results of a purely technical analysis.
John Hopkins's education and natural history interest in primarily in the field of botany. Having been raised in a North of England cotton town, as a child he was familiar with a wide range of introduced species. Canadian pond weed was the firs water plat he knew. Japanese knotweed provided play areas: Himalayan balsam, with its strange flowers and seed pods was one of the first plants to capture my interest in botany. After a varied higher education he joined the staff of the Nature Conservancy Council in 1981 , and celebrate 20 years of employment in the statutory sector in 2001. At various times he has been particularly associated with grassland conservation and, through his work at JNCC, the implementation of the Habitats Directive which was his main employment for 8 years. Currently he is responsible for developing English Nature's science programme, particularly elements which are cross cutting, such as exotic species ecology.

Mr. Paul Walton (RSPB Scotland)
'Ruddy ducks: against...
The issue concerning the impact of North American ruddy ducks on the conservation of white-headed ducks in Europe and Asia has become a cause celebre within the wider alien species debate. Wildfowl collectors imported ruddy ducks, common and widespread in North America, to the UK. Some escaped from captivity and there is now a feral population of around 4000 birds. The species now occurs annually during the breeding season in eight other European countries, with the UK being the source population. The white-headed duck is a globally threatened species. The population closest to the UK is in Spain, where conservation efforts have increased numbers from 22 to over 2000 in the last 25 years. DNA and morphological analyses indicate that the two birds are separate species that have been geographically isolated for 2-5 million years. However, ruddy ducks and white-headed ducks interbreed, producing fertile hybrids (a common trait amongst waterfowl). Differences in mating strategy between the species, and the existence of precedents elsewhere, indicate that there is a significant risk that introgression through hybridisation will lead to the extinction of the white-headed duck. The UK government is currently conducting ruddy duck control trials, where birds are shot by government contractors, in three regions of the UK. The trials are designed to investigate whether a programme of nationwide control could successfully reduce the ruddy duck population to a level where they no longer pose a threat to the white-headed duck. Because preventing the potential extinction of the white-headed duck is seen as a very high conservation priority, the RSPB and several other national conservation organisations support the UK Government's action. The seeming contradiction of a bird conservation organisation supporting the shooting of birds has led to some opposition of this policy. The RSPB's view is that the seriousness of the threat to the white-headed duck warrants urgent action to reduce the size of the UK ruddy duck population, as part of a wider programme of measures to safeguard the white-headed duck's future.
Paul Walton was previously a researcher in the Ornithology Unit, University of Glasgow, and now works for the RSPB in Scotland as a Community Liaison Officer.

Mr Iain Gibson (Glasgow City Council)
'Ruddy ducks: for ....'
The case for controlling Ruddy Ducks, as supported by the RSPB, is unconvincing. The science is weak and fundamentally flawed. A decision was made, in advance of research, that the species needs to be controlled. Although hybrids have clearly been shown to be fertile for several generations, no studies have been implemented to demonstrate the course of behaviour of these hybrids in the wild. Nor has any model shown the likely effect of the existence of hybrids in the interspecific population. It is unproven that any species of wildfowl has ever been genetically swamped. The prime example provided by the White-headed Duck Task Force, i.e. the New Zealand Grey Duck hybridising with Mallard, on closer examination is found to be less serious than claimed. Ethically, the proposed eradication of European Ruddy Ducks is contrary to the philosophy of caring conservation, as well as introducing questionable public relations practice. The attitude of some of the scientific community towards non-native species appears to involve an undercurrent of quasi-racism.
Iain Gibson is a lifelong amateur ornithologist, and Editor of the Clyde Bird Report, with a special interest in the status and distribution of birds in the Clyde area. He has been studying the East Glasgow Lochs population of Ruddy Ducks since 1993, as well as having a particular current interest in the breeding Hen Harriers of the Clyde-Muirshiel Regional Park. He is Senior Conservation Officer with Glasgow City Council's Land Services, and has played a key role in the development of Hogganfield Park and other Local Nature Reserves.

Dr Alastair Sommerville (Scottish Wildlife Trust)
The re-introduction of the European beaver (Castor fiber)

This talk will cover the background to the idea of reintroducing the beaver to Scotland, including the evidence for the species being regarded as native and why it is not found in the country today. The prospect of beavers living here is explored by looking at their life history and their behaviour in the wild including their ability to build dams and fell trees. Key to the story is their powers of reproduction and dispersal. Finally, the pros and cons of the idea will be discussed along with an up to date account of the details of Scottish Natural Heritage's actual proposal.
Dr Alastair Sommerville is Senior Biodiversity Co-ordinator for the Scottish Wildlife Trust. He has several decades of experience of the wildlife of Scotland including survey, recording and monitoring, conservation management and site protection. Currently he is a member of the UK Biodiversity Group's species action plan group for the red squirrel and the water vole and chairs the groups for the narrow-headed ant and the small cow-wheat for which the SWT is Lead Partner. Alastair was a member of the SNH Beaver Project Steering Committee that advised on the feasibility of the reintroduction.

Prof. Christopher Smout (University of St Andrews, emeritus)
'Summing up'
Professor TC Smout is associated with the Centre for Environmental History and Policy at the Universities of St Andrews and Stirling. He is the former Deputy Chairman of Scottish Natural Heritage and an Emeritus Professor of Scottish History at the University of St Andrews. Among his books are Nature Contested: Environmental History in Scotland and Northern England since 1600, (Edinburgh University Press, 2000)
He is Historiograher Royal in Scotland.

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