FEATURE ARTICLE: Climate change opens new frontiers for marine invaders in the Arctic

Our latest feature explores the introduction of non-native species to the changing Arctic environment and asks how the threat can be addressed.
Published: 8 May 2019

​​​​​​Farrah T. Chan, Great Lakes Laboratory for Fisheries and Aquatic Sciences, Fisheries and Oceans Canada (DFO)

Rising temperatures and melting sea ice is opening the Arctic seas, providing increased opportunities for not only human activities, but also the introduction and establishment of marine non-native species. Human activities such as shipping, aquaculture, and the building of canals facilitates the movement of non-native species to places beyond their native range and at greater rates than what could occur naturally. Although not all non-native species are harmful, many have led to changes within recipient ecosystems, causing detrimental impacts on the environment, economies, and public health. The Arctic has historically been presumed a relatively low-risk region for biological invasions due to limited access, harsh environmental conditions, and inadequate food resources that hinder dispersal, survival, and/or reproduction for many species. However, the region is now under unprecedented threat of biological invasions due to climate warming and increased human activities.

Members of ICES Working Group on Introductions and Transfers of Marine Organisms (WGITMO) and ICES/IOC/IMO Working Group on Ballast and Other Ship Vectors (WGBOSV) have recently published a review paper in the journal Global Change Biology that provides a comprehensive record of marine non-indigenous  species (NIS) in the circumpolar Arctic and identifies knowledge gaps and opportunities for biological invasion research and management in the Arctic.

​Current trends and patterns of species introductions

Along with my co-authors, we examined reports of primary introduction events (i.e. initial introductions, excluding subsequent spread within the region) in ecoregions of the marine Arctic to characterize temporal and spatial patterns of non-native species introductions. Using the Large Marine Ecosystems of the Arctic as the spatial unit, we identified regions that had the greatest number of introduction events and the likely source region(s). We also studied the pathways (processes that result in the arrival of non-native species from the source region into the recipient location) likely responsible for these introductions and the taxa involved. The dataset includes 54 introduction events representing 34 unique non-native species.

The rate of non-native species discovery ranged from zero to four species per year between 1960 and 2015. The discovery rate of non-native species in Arctic waters generally increased over time, likely coinciding with increasing human activities in the Arctic. Recent increases in non-native species detection may also be related to expanded research effort in the Arctic, though there are very few standardized or ongoing non-native species detection and monitoring programs established in the region.

The Iceland Shelf had the greatest number of introduction events (26% of all introductions), followed by the Barents Sea (20%), and the Norwegian Sea (20%). Not only do these regions have many non-native species introductions, but also many established populations of non-native species. This pattern suggests that these regions may be particularly vulnerable to biological invasions due to great diversity and abundance of species introduced, thus increased probability of successful species establishment. Additionally, these regions are becoming more hospitable for temperate non-native species, as the area is transitioning from a cold Arctic to a warm Atlantic-dominated climate regime.

A large proportion of the introduction events with known source regions were attributed to the Northeast Atlantic (39%), followed by the Northwest Pacific (29%) and the Northeast Pacific (16%). A larger spatial unit—the Food and Agriculture Organization of the United Nations (FAO)​ major fishing areas—was used for source regions because it was otherw​ise difficult to describe them, as they are generally broadly defined in the literature.

About 68% of the introduction events were attributed to a single pathway, whereas 32% were attributed to multiple pathways. Vessels, including ballast water and hull fouling, are the leading pathway for both single and multipathway introductions. This is expected because maritime transport has played an important role in expeditions and exploration, community supply/resupply, natural resource exploration and extraction, fisheries, and tourism in Arctic seas. Natural spread appears to be an important mechanism for multipathway introductions, as it is often cited as one of many possible pathways contributing to introductions. Aquaculture activities, wild fisheries, and the live food trade are also active pathways for transferring non-native species to the Arctic. 

Arthropoda (35%), Ochrophyta (22%), and Chordata (17%) are the top three phyla contributed to the greatest number of introduction events. Examples of non-native arthropods found in Arctic waters include Snow Crab, Chinese Mitten Crab, and Red King Crab. Ochrophytes detected in the Arctic include Bacillariales (diatoms), Chattonellales (raphidophytes), Fucales (brown algae), and Melosirales (diatoms). Rainbow Trout and several other salmonids species, European Flounder, and tunicate are a few examples of non-native chordates reported from the Arctic. Other taxa reported from the marine Arctic belongs to the phyla Mollusca, Rhodophyta, Platyhelminthes, Chlorophyta, and Myzozoa.

​Influence of climate change on biological invasions

Climate warming in the Arctic is expected to facilitate human activities at progressively higher latitudes, including expanded transportation to and through the region, fisheries, aquaculture, mining, and tourism. Therefore, more human-mediated movement of non-native species between temperature regions and northern seas is expected. To illustrate this point, we examined the water temperature along the shipping lane through the Suez Canal (approximately 11,200 nautical miles) and the Northern Sea Route (approximately 6,500 nautical miles) from Rotterdam to Yokohama. There are small increases in temperature along both routes since 1960 based on the global ocean water temperatures from the multiyear Simple Ocean Data Assimilation (SODA) archive. The transfer of non-native species via the northern route is likely to be tolerated by cool- and cold-temperate species, as such species are usually adapted to low temperatures and may survive Arctic waters. Climate change in combination with the shorter journey of trans-Arctic voyages may foster greater-than-expected survival rates of non-native species. Additionally, the transfer process through the Arctic route may select for populations that are pre-adapted to the cold environment, thereby increasing the potential for successful establishment once released into the Arctic. Changing environmental conditions may also allow introduced non-native species to survive and reproduce in areas where they previously could not do so and increase the magnitude of impact and/or the rate of spread.

​What could be done about the increased threat of marine invasions in the Arctic?

Management efforts that address the observed patterns and processes of biological invasions in the marine Arctic are needed to prevent new introductions and establishment of new non-native species, especially those with known negative impacts. We propose the implementation of vector management, horizon scanning, early detection, rapid response, and a pan-Arctic biodiversity inventory.

Vector management, aiming to reduce the abundance and diversity of non-native species associated with high-risk pathways, is recommended as the most cost-effective strategy to reduce invasion risks in the marine Arctic. For example, vessels should be prioritized for targeted management. While the risk of ballast-mediated introductions may be reduced via the implementation of ballast water management systems, the potential of transferring non-native species to Arctic waters via biofouling on commercial ships, leisure crafts, fishing vessels, floating platforms, and other artificial structures is expected to become increasingly important due to expanded human activities.

Horizon scanning at the circumpolar scale involves multiple nations and may be performed to develop a list of unwanted non-native species (“door-knocker" species) that have not yet established in the Arctic for a species-specific management approach. Special attention should be given to Arthropoda, Ochrophyta, and Chordata, as they are the taxa with the greatest number of non-native species in the Arctic.

Early detection of undesired non-native species at potential high-risk regions, such as the Iceland Shelf, the Norwegian Sea, and the Barents Sea, is essential for protecting the Arctic region from new invasions. We encourage the use of molecular techniques to aid in early detection of non-native species. Once harmful non-native species are detected at new locations in the Arctic, rapid response strategies to prevent or manage their establishment in a timely manner may be implemented. Allocation of contingency funds would facilitate a rapid response when required.

A comprehensive pan-Arctic inventory of biota would be useful in evaluating future changes to Arctic shelf regions. Currently, Arctic inventories are limited by relatively low search effort due to logistical challenges, high cost, and inhospitable environmental conditions. Such an inventory should be an open access and up-to-date database with records verified by taxonomic experts.

Ecosystems worldwide face dramatic changes in the coming decades. By providing the knowledge base needed to address two aspects of this change—invasive species and climate change– WGITMO and WGBOSV contribute to two of ICES science priorities:

  • Impacts of human activities
  • Conservation and management

Through their work on marine non-indigenous species, WGITMO and WGBOSV contributed to ICES Viewpoint: Biofouling on vessels – what is the risk and what might be done about it? and the supporting report, ICES Viewpoint background document: Evaluating and mitigating introduction of marine non-native species via vessel biofouling.

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​Map illustrating the Large Marine Ecosystems of the Arctic as defined by PAME, the Arctic Council's Protection of the Arctic Marine Environment Working Group. Click to enlarge.
1. Faroe Islands 2. Iceland Shelf  
3. Greenland Sea East-Greenland 4. Norwegian Sea
5. Barents Sea 6. Kara Sea 7. Laptev Sea 8. East Siberian Sea
9. East Bering Sea 10. Aleutian Islands 11. West Bering Sea
12. Northern Bering Chukchi Sea 13. Central Arctic Ocean
14. Beaufort Sea 15. Canadian High Arctic North Greenland
16. Canadian East Arctic-West Greenland 17. Hudson Bay
18. Labrador-Newfoundland
Also shown are the total number of introduction events
(n = 54) and the population status of non-native species in each introduced region.
Chan et al. 2019 Global ChangE Biology.​

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FEATURE ARTICLE: Climate change opens new frontiers for marine invaders in the Arctic

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