Sir

Southern Ocean islands have long been considered to represent globally significant examples of pristine environments, important for the conservation of intact ecosystems. This is about to change because of environmental pressure arising from an escalation of tourism to the region (15,000 tourists in 1999)1, marked climate change, and consequent increases in the impacts of invasive species2.

Over the past three years, tourism to South Georgia has tripled1, and most southern islands now receive such visits. This trend is exemplified by the recent publication of an environmental impact assessment of tourism to Marion Island3.

Commissioned by the agency responsible for the island's administration, the South African Department of Environmental Affairs & Tourism, the impact assessment is a response to increasing demands for tourism. Although citing expert opinion that tourism poses considerable threats to the biota, because it increases the likelihood of invasive species arriving and becoming established, the assessment concludes that, in low numbers, tourism may proceed.

Among several important issues raised by the impact assessment is the compatibility of conservation and access. Just as it is becoming clear that multiple use of protected areas commonly has deleterious effects on biota, the demand for it is becoming more vociferous, and in many instances is entrenched in management policy or laws governing the areas concerned.

Thus, Marion Island was declared a special nature reserve under South Africa's Environment Conservation Act, which — in addition to its conservation clauses — also specifies that any citizen of the republic wishing to view such an area may do so, at once creating a potential conservation conflict.

The environmental impact assessment also highlights the substantial mitigation costs, usually borne by the responsible authorities rather than the tourist operators, likely to be incurred should an alien species establish itself as a result of tourist activities.

Such activities fall into a high-risk category, because they tend to involve short visits by numerous people who have frequently visited similar islands. This is likely to mean greater propagule pressure than a single landing of a few people who spend an extended time at one island, and is likely to facilitate 'island-hopping' by invasive species.

What makes the Southern Ocean islands particularly significant is that, although their isolation means that species have nowhere to go in the face of human pressure, it also means that conservation problems should be straightforward to manage.

Sadly, the latter seems not to be the case, providing a glimpse into the future as the former becomes true of increasingly fragmented mainland habitats.

Perhaps if tourism were limited now, the islands might provide sight of an alternative where conservation enjoys priority over access.