A new survey of Clare Island has found Ireland is host to arange of exotic aliens, writes Juliana Adelman.
Ireland has been invaded. Stealthy colonists from as far away as New Zealand and Japan are making themselves at home here. These are not human colonists, they are foreign species of plants and animals.
New Zealand flatworms, Japanese tapeworms and Zebra mussels are among the exotic species now established in Ireland. Recent fieldwork on Clare Island is revealing just how extensive their hostile takeover may be.
The new survey of Clare Island, led by the Royal Irish Academy, also points to the importance and value of co- ordinated field studies in helping to protect Ireland's environment.
The first survey of this small island off the coast of Co Mayo took place early in the last century and was also sponsored by the Royal Irish Academy. It was led by Robert Lloyd Praeger, the Belfast naturalist and author of The Way That I Went. Conducted between 1909 and 1911, the survey was considered the first of its kind in the world.
"The original survey was very pioneering. It was an environmental study at a time when people were more interested in sticking pins in butterflies and putting them in cases," explains Dr Kieran McCarthy, a zoologist at the National University in Galway and a member of the New Survey of Clare Island Committee.
By comparing the results of the new survey to those of the first, it is possible to see changes in the environment of the island across a span of almost 100 years. When the RIA decided to re- survey Clare Island, it was prompted by an interest in what had, or had not, changed.
"Clare Island is an ecosystem that is largely unspoiled," explains Pauric Dempsey, assistant executive secretary of the RIA. "The new survey is a great opportunity, even internationally, to look at a place and track it down through time. There are few other places where you'd be able to do that."
One of the most dramatic changes is the arrival of exotic species. Some foreign species were brought over deliberately. If imports land in a new environment lacking their natural predators, the plant or animal may undergo a population explosion, unbalancing the local ecosystem.
Invading species are probably responsible for the most profound and visible environmental changes happening in Ireland today, says McCarthy, and Clare Island is no exception. "You would think that Clare Island is pretty remote, but nevertheless things are cropping up. Quite a number of unexpected exotics have appeared."
Unfortunately, the New Zealand flatworm has now made it to Clare Island. A large flatworm population can cause serious problems by feeding on and depleting the earthworms normally found in the soil. Earthworms are aerators of the soil and when their numbers drop, a field or garden can become waterlogged. The flatworm probably hitchhiked to Clare Island on plants bought at a mainland garden centre.
The original survey was also concerned with endemic and exotic species. Praeger was particularly interested in identifying species that might be unique to Ireland. Indeed, the first survey of Clare Island revealed 120 species previously unknown to science.
Because of the similarity in habitats between Ireland and Britain, most of these species were subsequently found in Britain as well. At least one species previously unknown to science has been identified in the new survey, a new type of seaweed that has since been found in one other site in Britain.
Ireland may be collecting new species, but we are losing the skills required to find and track them. Entomology (the study of insects) was once a widespread pursuit of amateur scientists such as those who did much of the pioneering survey work here. Now these and other specialists are hard to come by. "The Clare Island survey has focused attention on that gap," says McCarthy.
Praeger himself was trained as an engineer, but was a self-taught botanist and natural historian. Amateur contributions also feature in the new survey.
A staff member of the Irish Museum of Modern Art is responsible for the spider survey. He has no scientific training, but is an expert in identifying and collecting Irish spiders.
The new Clare Island survey has also demonstrated the need for centralisation of skills and information among ecologists working in Ireland. There is currently no common database into which information collected from individual surveying projects can be pooled. This could be vital in tracking pesky invaders like the flatworm.
The results of the New Survey of Clare Island are being published in parts by the RIA. The most recent volume, Marine Intertidal Ecology, was launched in May.