Benthos

What is happening and why does it matter?

• Increasing numbers of species are moving into, or shifting, their distributions in Arctic waters. These species are likely to outcompete, prey on or offer less nutritious value as prey for Arctic species.

Why are benthos important?

• Benthic invertebrates such as shrimps, crabs, sea spiders, amphipods, isopods, bristle worms, gastropods, and bivalves, live on or in the seafloor and are important food sources for fishes, marine mammals, seabirds and humans, with several commercially harvested species. Benthic organisms rely on organic material produced in the overlying water column. They break down this material and release nutrients that later become available for primary producers such as phytoplankton. Currently, there are more than 4000 known Arctic macro- and megabenthic species.
• Traditional knowledge emphasizes the link between the benthic species and their predators, such as walrus, and their significance to culture.

What should you know about the monitoring data?

• Decadal changes in benthos biodiversity have been observed in some well-studied regions, such as the Barents Sea and Chukchi Sea.

What are the most important drivers?

• Drivers related to climate change such as warming, ice decline and ocean acidification can affect the benthic community on a circumpolar scale, while drivers such as trawling, river/glacier discharge and invasive alien species have significant impact on regional or local scales.

Where is monitoring happening?

• Current monitoring efforts have focused on macro- and megabenthic species, but have been confined to the Chukchi Sea (Pacific Arctic) and the Barents Sea (Atlantic Arctic). Coordinated cross-nation efforts are increasing in the waters of Greenland, Iceland, the Canadian Arctic, and in the Norwegian Sea. All other Arctic Marine Areas are lacking long-term monitoring of benthos.

Advice for monitoring: benthos

• Develop a time- and cost-effective, long-term and standardized monitoring of megabenthic communities in all Arctic regions using regular national groundfish assessment surveys. Expanding monitoring on micro-, meio- and macrobenthic groups is encouraged.
• Gather information from research programs in regions without regular groundfish-shellfish trawl surveys. These are usually short-term and do not guarantee spatial consistency in sampling, but provide valuable information on benthic biodiversity and community patterns.
• Generate information on benthos from little-known regions, such as the Arctic Basin and Arctic Archipelago, on cryptic or difficult taxonomic groups, and on biological “hotspots”.
• Systematic studies of macrobenthos (grab investigations) and megabenthos (trawl bycatch of regular fishery surveys including both annual studies, as in the Atlantic Arctic, and periodic studies as in the Northern Bering and Chukchi Seas) are the most suitable and practical approach to long-term monitoring.
• Standardize methodology, including taxonomic identification, across regions to assist in regional comparisons. Recognize and support the use of TLK as an invaluable resource for understanding of changes in Arctic benthic communities.