ICES/PICES/PAME WORKING GROUP ON INTEGRATED ECOSYSTEM ASSESSMENT (IEA) FOR THE CENTRAL ARCTIC OCEAN (WGICA) VOLUME 2 | ISSUE 79 ICES SCIENTIFIC REPORTS RAPPORTS SCIENTIFIQUES DU CIEM ICES INTERNATIONAL COUNCIL FOR THE EXPLORATION OF THE SEA CIEM CONSEIL INTERNATIONAL POUR L’EXPLORATION DE LA MER International Council for the Exploration of the Sea Conseil International pour l’Exploration de la Mer H.C. Andersens Boulevard 44-46 DK-1553 Copenhagen V Denmark Telephone (+45) 33 38 67 00 Telefax (+45) 33 93 42 15 www.ices.dk [email protected] The material in this report may be reused for non-commercial purposes using the recommended cita- tion. ICES may only grant usage rights of information, data, images, graphs, etc. of which it has owner- ship. For other third-party material cited in this report, you must contact the original copyright holder for permission. For citation of datasets or use of data to be included in other databases, please refer to the latest ICES data policy on ICES website. All extracts must be acknowledged. For other reproduction requests please contact the General Secretary. This document is the product of an expert group under the auspices of the International Council for the Exploration of the Sea and does not necessarily represent the view of the Council. ISSN number: 2618-1371 I © 2020 International Council for the Exploration of the Sea ICES Scientific Reports Volume 2 | Issue 79 ICES/PICES/PAME WORKING GROUP ON INTEGRATED ECOSYSTEM AS- SESSMENT (IEA) FOR THE CENTRAL ARCTIC OCEAN (WGICA) Recommended format for purpose of citation: ICES. 2020. ICES/PICES/PAME Working Group on Integrated Ecosystem Assessment (IEA) for the Central Arctic Ocean (WGICA). ICES Scientific Reports. 2:79. 144 pp. http://doi.org/10.17895/ices.pub.7454 Editors Lis Lindal Jørgensen● Sei-ichi Saitoh Authors John Bengtson ● Bodil Bluhm ● Tom Christensen ● Karen Edelvang ● Hauke Flores ● Anne Kirstine Frie Yasushi Fukamachi ● Maria Gavrilo ● Harald Gjøsæter ● Jacqueline Grebmeier ● Grøsvik, Bjørn Einar Naomi Harada ● Kevin Hedges ● Martine van den Heuvel-Greve ● Taka Hirata ● Toru Hirawake ● Alf Håkon Hoel ● Randi Ingvaldsen ● Vladimir Ivanov ● Lis Lindal Jørgensen ● Kathy Kuletz ● Jan René Larsen ● Pauline Snoejis Leonmalm ● Igor Melnikov ● Anders Mosbech ● Ingeborg Mulder ● Barbara Niehoff ● Shigeto Nishino ● Fugio Ohnishi ●Natsuhiko Otsuka ● Thomas Van Pelt ● Cecilie von Quill- feldt ● Sei-ichi Saitoh ● Hyoung Chul Shin ● Hein Rune Skjoldal ● Lisa Speer ● Senjie Yang ICES | WGICA 2020 | i Contents i Executive summary .......................................................................................................................iv ii Expert group information .............................................................................................................. v iii Summary of the main conclusions ................................................................................................ 2 1 Introduction ................................................................................................................................... 5 1.1 Terms of Reference ........................................................................................................ 10 1.2 Summary of work plan ................................................................................................... 10 1.3 Summary of achievements of the WG during 3-year term ............................................ 11 2 Status for WGICA IEA report in the CAO (CRR) (Report 1).......................................................... 12 3 ToR b. Review and report on on-going and recent changes and events in the CAO ecosystem associated with changes such as in sea-ice, oceanographic circulation, and hydrographic properties .............................................................................................................. 13 3.1 Introduction ................................................................................................................... 13 3.2 Changes in Arctic Sea ice................................................................................................ 13 3.2.1 Central Arctic Ocean ...................................................................................................... 14 3.2.2 Arctic seas ...................................................................................................................... 15 3.3 Changes in the gateways ............................................................................................... 16 3.3.1 Atlantic gateways (Barents Sea, Fram Strait and Western Nansen Basin) .................... 16 3.3.2 Pacific gateway (Bering and Chukchi seas) .................................................................... 17 3.4 Changes in CAO hydrographic properties ...................................................................... 18 3.4.1 Upper ocean layer .......................................................................................................... 18 3.4.2 Halocline layer ............................................................................................................... 19 3.4.3 Intermediate and deep layers ........................................................................................ 20 3.5 Summary ........................................................................................................................ 20 3.6 Possible ecosystem implications .................................................................................... 22 3.7 References ..................................................................................................................... 22 4 ToR c. Continue to examine effects of climate change on the CAO ecosystem .......................... 29 4.1 Arctic microalgae ........................................................................................................... 29 4.1.1 General introduction...................................................................................................... 29 4.1.2 Possible effects of climate change ................................................................................. 29 References ................................................................................................................................... 32 4.2 Invertebrate ice fauna ................................................................................................... 35 4.2.1 Sea ice meiofauna .......................................................................................................... 35 4.2.2 Sea ice macrofauna ........................................................................................................ 37 4.2.3 Needs for research and monitoring ............................................................................... 38 References ................................................................................................................................... 40 4.3 Zooplankton in the Central Arctic Ocean, a linchpin to keep the system in place ........ 44 References ................................................................................................................................... 47 4.4 Benthos in the CAO ........................................................................................................ 48 4.4.1 The seabed ..................................................................................................................... 48 4.4.2 Bottom temperatures of the Central Arctic Ocean ........................................................ 49 4.4.3 Benthos .......................................................................................................................... 50 4.4.4 Climate impact on benthos ............................................................................................ 51 4.4.5 Possible human activities impacting benthos ................................................................ 51 References ................................................................................................................................... 53 4.5 Fish in the Central Arctic Ocean having to cope with unprecedented warming ........... 57 References ................................................................................................................................... 61 4.6 Marine mammals in the CAO ......................................................................................... 62 4.6.1 Ecological Effects of Climate Change ............................................................................. 62 4.6.2 Effects of anthropogenic noise ...................................................................................... 73 4.6.3 Knowledge gaps and monitoring needs for marine mammals ...................................... 74 ii | ICES SCIENTIFIC REPORTS 2: 79 | ICES References ................................................................................................................................... 76 4.7 Marine birds in the CAO ................................................................................................. 88 4.7.1 Recent information on marine birds in the CAO............................................................ 88 4.7.2 Climate and anthropogenic impacts on marine birds in the future CAO ....................... 89 4.7.3 Marine bird research, management, and monitoring resources in adjacent seas ........ 89 References ..................................................................................................................................