It's often said that whichever culture and environment we grow up in is the one we consider as the norm. Whilst my great-grandparents were born before the invention of heavier-than-air flying machines, I've booked numerous long-haul flights without considering much beyond their monetary and environmental cost. Yet this familiarity with our fast and efficient global transportation network masks an unpleasant side effect: it is second only to habitat loss when it comes to endangering biodiversity.
Although many environmental campaigns focus on fossil fuels, deforestation and unsustainable agricultural practices, the (mostly inadvertent) transportation of alien plants, animals and fungi from one region to another has quietly but catastrophically reduced biodiversity in many areas of the planet.
The earliest example I recall learning about was Stephen Jay Gould's heart-felt description of the extinction of French Polynesia's partulid tree snails at the hands of introduced carnivorous snails intended to control edible snail species (which were also deliberately introduced). While the nineteenth and early twentieth centuries saw large numbers of species intentionally established in areas far from their natural territories, the past half century has seen an acceleration in equally disastrous accidental introductions as a by-product of international trade.
A potential starting point for invasion ecology as a discipline in its own right was Oxford professor Charles Elton's 1958 publication The Ecology of Invasions by Animals and Plants. The International Union for Conservation of Nature's Red List of Threatened Species followed six years later. Clearly, the negative effects of our activities were starting to become known. But has enough been done to publicise it in the intervening decades?
The Red list is the most accurate data source for regional biodiversity and the population health of all organisms known to science; yet few non-specialists seem even aware of its existence. Indeed, several decades passed after the list's creation before invasive biology became an important subject in professional ecology. Over the past thirty years the topic has seen a ten-fold increase in publications and citations - a sign of recognition if ever there was one - although mainstream media appears barely aware of its existence.
The IUCN's Invasive Species Specialist Group aids governments and organisations in planning the monitoring, containment, and where possible, destruction of invasive species. It runs the publicly-available Global Invasive Species Database, but its online presence appears to be poorly funded, or at least coordinated. Rather than a central hub there is a plethora of websites featuring varying degrees of professionalism and some distinctly out-of-date content. Perhaps clients are given direct instructions, but as a member of the public I found the ISSG sites bewildering in their variety.
Needless to say, when it does come to taking action, it can be assumed that economic imperatives such as agricultural pests take precedence over preservation of other endangered species. The only country I know of that is attempting a nation-wide eradication of most invasive animals (note: not plants and fungi) is New Zealand, with our Predator Free 2050 project. However, I'm uncertain how realistic it is. Even pre-Covid it appears to have lacked a solid funding source and now - with thirty years and counting until the deadline - there's even less chance of a comprehensive removal of numerous pest species.
What the Predator Free 2050 plan doesn't include is the multitude of plants and animals that slip through the net, so to speak: the legion of species currently invading our offshore environment. It's one thing to actually see land-based plants and animals, but the ocean is largely unknown territory to most people. With over forty thousand cargo vessels moving around the globe every year there is plenty of opportunity for organisms, especially their larval forms, to be inadvertently spread to new territories via both hulls and ballast water. Whilst Killer Algae (a slight hint there in the common name for Caulerpa taxifolia) and the Chinese mitten crab aren't as well-known as Japanese knotweed and Common myna bird they are just two of the many dangerous invaders spreading ever further from their original territories.
It isn't just marine vessels that can carry such dangerous cargo: the immense amount of plastic waste in our oceans can serve as life rafts for the propagation of alien species, albeit at the whim of currents moving rather slower than diesel power. The problem of course is that the oceans are enormous and so the only time the issue becomes known about is when an invasive organism is spotted encroaching in coastal waters. Unfortunately, marine lifeforms can't be easily dealt with using the traps and poison that work on land-based entities; indeed, international regulations seem as much concerned with the dangers of anti-fouling systems as with the issues they prevent.
In 2011 the International Maritime Organization implemented guidelines to minimise vessel biofouling as it relates to the accidental incursions of invasive marine organisms. New Zealand was the first of several nations to execute their own national strategy that turned these guidelines into mandatory practice - and take them further. In addition, New Zealand's National Institute of Water and Atmospheric Research (NIWA) runs annual surveys, particularly around ports, but otherwise their funding appears inadequate to the immensity of the task.
It's all very well keeping track of the ever-increasing list of resident invasive species around the nation's coastline, but little has been done to remove them. With about 150 types of alien organism now in residence around New Zealand's coast and the same again in occasional visitors, NIWA has been a partner in international competitions aimed at finding pest management solutions, at least for coastal ecosystems if not the deep ocean. Obvious solutions such as scrubbing hulls would just lead to direct contamination of ports, so some new thinking is clearly required.
Of course, the use of cargo ships is unlikely to reduce any time soon. Our global marine transport network is far from in decline and many nations lack the stringent precautions that New Zealand and Australia are now implementing. It has been estimated that cleaning hulls to prevent biofouling could reduce global marine fuel consumption by 10%, so perhaps this commercial benefit may win over those reluctant to spend heavily on prevention measures. But just as fishing vessels are still getting away with immense amounts of by-kill, merchant shipping in many areas of the world appears to be a law unto self.
Preserving regional marine biota is just as critical as land-based environmental protection. Allowing species to proliferate outside their normal range can only lead to deleterious changes - and when combined with our warming, increasingly acidic oceans, this does not bode well for all life on Earth, especially a hungry Homo sapiens. Just because we humans spend most of our time on land, we cannot afford to ignore the far larger ecosystems of the seas.
