By Paul Walton, RSPB Scotland
It’s an unavoidable truth that in nature conservation, success can sometimes produce intangible results. Much of what we try to achieve inevitably comprises stopping bad things happening to the environment. A successful bridge-builder has a bridge to look at where there was none; a fund manager, funds to help spend; a medic has well people, who were previously sick. The successful environmental campaigner might find that the output of years of effort is, for example, dunes and maritime grasslands that remain just as they were before. Nothing looks different – all that’s new is the invisible knowledge that these delicate and precious habitats have not been obliterated by the golf course or power station that someone tried to build over them.
Of course, conservation must also work to actively enhance the natural environment and make positive transformations. But this preventative work is and will remain a critical basis for our shared response to the unfolding global ecological crisis – and nowhere is that more important than in the challenge of invasive non-native species.
The recent report of IPBES (the Intergovernmental Science Policy Platform for Biodiversity and Ecosystem Services) confirmed both that nature and the essential services it provides for humanity are deteriorating fast across the planet. This deterioration is caused by 5 major direct drivers: land and sea-use changes; direct exploitation; climate change; pollution; and the introduction of invasive non-native species – INNS.
People moving any animal, plant or other organism from its native range and, deliberately or accidentally, introducing it into the wild, is a potential threat to wildlife. Geographic barriers such as oceans, mountains, deserts and currents have through geological time restricted the mixing of wildlife in different regions. Species develop independently in different parts of the world, and this generates much of global biodiversity. Non-native species introductions, in effect, break down these barriers. The rate of establishment of new species is increasing at world and UK scales. INNS effects are compounded by climate change and are predicted to worsen in future. The globalisation of trade – the most important vector of INNS – is increasing species movements and rates of release.
In Scotland, we already have non-native Rhododendron and conifers damaging our most important woodland and peatland habitats; non-native predators predating seabirds and waders on our islands; invasive marine organisms threatening internationally important marine ecosystems in our sea lochs.
The graph above shows a simplified, but all-too familiar, pattern of establishment of an invasive species. It’s clear that ecological damage increases with spread – but also, critically, the costs involved in terms of both impacts and the necessary responsive action escalate dramatically. Of course, we must work to strategically manage damaging INNS that are already established. But it is hundreds, sometimes thousands of times cheaper to prevent INNS establishing in the first place than it is to manage the issue after the event. Therefore, the Convention on Biological Diversity calls for a hugely elevated emphasis on prevention – often called biosecurity – when it comes to INNS impacts on nature and economies. It is also why the EU Environmental Principle of Preventative Action is a key guiding principle for effective, informed action to protect nature, and one that we must, as a matter of national priority, be enshrined explicitly in Scottish legislation at the earliest opportunity.
Do we really need to prevent every single egg, of every tiny non-native shrimp, from ever arriving here? Thankfully, no. Research is clear that the best predictor of INNS establishment in the wild is simply the rate at which non-native organisms are released. By taking sensible, proportionate, but effective preventative action we can reduce that rate, and thus reduce establishment probability. This became clear in New Zealand through the 20th century. Firm but proportionate biosecurity measures were introduced – and the results have been spectacular:
Non-native mammals establishing in New Zealand and in Europe over recent centuries. From Armon R.H., Zenetos A. (2015) Invasive Alien Species and Their Indicators. Armon R., Hänninen O. (eds) Environmental Indicators. Springer, Dordrecht
Across the UK countries, funding for INNS biosecurity runs at around £1 million per year. That is just a tiny fraction – less than 1/200th – of biosecurity investment protecting agriculture, horticulture and aquaculture. In Scotland we have important expertise and projects developing for biosecurity issues: on islands, for example, the RSPB is leading a biosecurity project for all our most important seabird colonies. We can be leaders in this field – but for that, we must protect our environment and our economic future by investing properly in biosecurity now – and we must legislate to bring the Principle of Preventative Action squarely and unambiguously into Scots law.