More shipping is sailing through thawing Arctic waters, but while these northern routes might provide opportunities for tourism, mining and cutting down delivery times, the ships may also carry stowaways on board, introducing invasive species to pristine Arctic waters.
These findings were recently published in the journal Diversity and Distributions, from research by myself and colleagues at Tromsø University Museum in Norway, University of Tasmania in Australia, and Aarhus University in Denmark. The study focused on the Svalbard archipelago in the Norwegian high-Arctic – best known for being home to the northernmost post office in the world and some 3,000 polar bears.
Invasive species have traditionally been a problem at lower latitudes; this study considered whether a growing amount of human activity in the Arctic and climate change might bring about a species invasion in the far north.
Wherever humans have travelled over the past centuries they have, deliberately or accidentally, taken creatures and plants with them. Exotic grasses now grow on Antarctica, European crabs live on both North American coasts, and Australia is filled with many millions of non-native rabbits, boar, toads and camels.
By filling and discharging ballast tanks, organisms are sucked in, transported and then deposited in other parts of the world, as are creatures that live on the bottom of the ship’s hull. Ships are responsible for most of world’s spread of invasive marine species.
Svalbard has experienced increased shipping over recent decades from tourism, scientific research, and mining. The ports there are far from the scale of those in Rotterdam or Singapore – there are more snow mobiles delivered to Svalbard every year than there are ships visiting – but nevertheless more than 500m tonnes of ballast water are discharged off Svalbard every year, from some of the 200 visiting vessels.
This means that, together with findings that Arctic oceans are warming faster than others, the region may soon lose the isolation and climatic barriers that have kept new species from invading.
Our research focused on what connections shipping visiting Svalbard has made with the rest of the world. We assessed the environmental similarities and differences between port regions the ships had visited before arriving at Svalbard, and the potential for ships to transport known invasive species. We then repeated these steps, but with the environmental conditions predicted to occur under climate change scenarios to get a picture of how the situation could change.
Species invasion warning: rising
The results showed that the present risk posed by invasive species is relatively low due to the Svalbard’s cold, 3°C seas. But a small number of ships posed a high risk due to the known invasive species in the regions they connected Svalbard to.
But under the scenarios where oceans continue to warm, the number of ships bearing invasive species will increase, and the number of species that may be able to survive in Svalbard will increase six-fold. This includes well-known invaders such as the European green crab (Carcinus maenas), the Japanese ghost shrimp (Caprella mutica), and the club sea-squirt (Styela clava).
Managing the problem
What the impact of new species on Svalbard might be is unclear, and is the subject of ongoing study. Elsewhere in the world, including in other Arctic waters, invasive species have caused severe problems, from subtle effects to threatening the collapse of fisheries
These findings give environmental managers some time to prepare barriers to potentially damaging new species. Ships in Svalbard are currently required to manage ballast water to reduce the threat of discharging non-indigenous species. Despite this, non-indigenous species are often found in samples of managed ballast water. The limitations of current management practices are acknowledged, but obstacles have prevented implementing anything better – the sooner these are overcome the better for the region.
Our results suggest that species transported on the hull are more of a threat, but removing these hull fouling organisms is more difficult. Recent guidelines developed by the International Maritime Organisation go some way towards reducing this threat, but more concrete, global measures are needed.
Shipping in the Arctic is set to increase as routes become more navigable, the tourism industry grows, and resource exploration expands. As some of the most pristine environments on earth, there is the opportunity to heed the lessons of species invasion learnt at lower latitudes, before it’s too late.