Impact of the New Zealand on ’s Biodiversity.

Brian Boag and Roy Neilson SCRI, Invergowrie, Dundee DD2 5DA.

Fig. 1 New Zealand flatworm. The New Zealand flatworm (Fig. 1) is an alien first

recorded in Scotland in 1963 and has subsequently spread Fig. 2 Distribution of 10 km. squares throughout the mainland and many of the western islands where the New Zealand flatworm (Fig. 2) (Boag B. et al., 1997) were recorded.

Impact on Impact on Wildlife

Initial reports from implicated the The impact of the New Zealand flatworm New Zealand flatworm with reductions in on wildlife is difficult to estimate (except in populations to below detectable limits. the case of moles where mole hills can In Scotland research has shown the presence of easily be counted). In the west of Scotland Fig 3 the New Zealand flatworm significantly reduces moles (Fig. 3) can be detected in both the numbers and biomass of the anecic approximately 70% of pasture fields but in

earthworms Lumbricus terrestis and Aporrectodea an area between Loch Eck and Dunoon present Moles present Loch Moles no longer present Eck longa (Table 1, Jones et al., 2001). These are the (where moles had been a problem) none species which feed on fresh surface litter on the of 55 New Zealand flatworm infested fields soil surface and therefore probably the main now has moles (Fig. 4) (Boag B.; Neilson Glen Massan earthworm species eaten by birds and mammals. R., 2006). The eradication of moles due to

N Strath flatworms has now also been reported Eachaig Table 1 Impact of the New Zealand flatworm on Anecic species of earthworms (numbers m-2) from Wester Ross. Earthworms are a W E New Zealand Non infested S Species flatworm Infested pasture fields fields (n=2) (n=48) major constituent of the diet of many birds

Lumbricus terrrestis 2.25 7.17 1km Aporrectodea longa 0.39 16.73 and (Tables 2 and 3, Alford et al.,

1995). Water logging and changes in Holy Fig 4 Distribution Loch of moles and flatworms The impact of the New Zealand flatworm on other vegetation e.g. increase in rushes in in Strath Eachaig Table 3. Birds likely to be and Glen Massan affected severely by earthworm species is probably less but still the infested fields has also been reported. earthworm loss (after Alford et al., 1995)

numbers of endogeic species from infested fields Moorhen Oystercatcher -2 Golden plover (6.89 per m ) were significantly less than those Table 2. Possible impact of the New Zealand flatworm on native mammals. Lapwing (after Alford et al., 1995) Stone curlew -2 Species of Mammal Possible effect Snipe from non infested fields (27.68 per m ). The Woodcock Mole Extinction Little Owl Common Shrew Population suppression, possible local extinction Blackbird deleterious impact on drainage, soil processes Badger Population suppression, possible local extinction Ring Ousel Hedgehog Population suppression, possible local extinction Redwing Stoat Possible local extinction in ‘lean’ years Song thrush and nutrient cycling is also unknown. Fox Probably unaffected Rook

Conclusions

Reports of the spread of the New Zealand flatworm throughout Meanwhile the “precautionary principle” should be promoted to Scotland continues but its deleterious impact on some earthworm control and slow down its further spread to uninfested land in species and the resulting affect of the biodiversity of wildlife found Scotland.

in Scotland is still unknown. References Alford D.V. et al., (1995). MAFF Chief Scientist Group Report. Project OCS9323. Boag B. et al., (1997). Eur. J. Soil. Biol. 33: 53-56. Boag B. & Neilson R. (2006) Proc. C