Arctic Ocean Biology. from the surface to the deep sea

Transcription

1 Arctic Ocean Biology from the surface to the deep sea Christina Bienhold Helmholtz Max Planck Research Group for Deep Sea Ecology and Technology ACCESS Summerschool, Bremen, Germany 23 September 2013

2 Outline Introduction Life in the Arctic The Arctic a changing ocean Marine habitats Sea ice Water column Seafloor From the surface to the deep sea Research examples Central Arctic Ocean Expedition IceArc 2012 Long-term observatory HAUSGARTEN 2

3 Animal life in the Arctic Thick fur with hollow shafts to trap warm air, dark skin, layer of blubber Polar bear up/ccr/ccrblog/2010/03/pol ar_bears_in_sweden.html IceArc team Harp seal Blubber, two sets of blood vessels to prevent heat loss e:blanchon-idlm2006.jpg 3

4 Animal life in the Arctic Beluga whale Blubber special blood vessel system to prevent heat loss Bowhead whale wwf.panda.org 4

5 Life in the Arctic Arctic fish (e.g. Polar cod) do not keep their body much warmer than the water. Need to keep ice crystals from forming in their bodies. Solution: Hauke Flores Fragilariopsis sp. Bind to small ice crystals to inhibit growth and recrystallization of ice. Found in fish, but also in ice algae, e.g. Fragilariopsis sp. Mar Fernández Méndez 5

6 The global conveyer belt Source: AWI 6

7 Arctic Ocean circulation Circulation influenced by both Atlantic and Pacific waters 7 Source: AWI

8 The Arctic a changing ocean Sea ice extent in September (National Snow and Ice Data Center) Mio km Mio km Mio km 2 8

9 The melting Arctic sea ice Average monthly Arctic sea ice extent September Ice thickness Iceextent(Miokm 2 ) Relative abundance National Snow and Ice data center S. Hendricks, AWI 9

10 The Arctic a changing ocean To understand what that may mean for Arctic organisms, we will look at the different marine habitats from the: Ice Water column Seafloor 10

11 Primary Production Photosynthesis Chl a 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Water column Melt Ponds Sea Ice Mar Fernández Méndez 11

12 Primary Production in the Arctic Seasonality in the sea ice habitat Keck & Wassmann 1993 Sea ice algae and phytoplankton are light-limited: sunlight for primary production only from May to September 12

13 Sea ice as a microbial habitat C Krembs, J Deming, University of Washington 13

14 Marine life in the Arctic 14

15 Sea-ice associated fauna Arctic cod Under-ice habitat as nursery ground Important food source for many Arctic mammals and birds Zooplankton Graze on the under-ice algae Under-ice habitat for protection (Hauke Flores) Clione limacina 15

16 Arctic seafloor 16

17 Export flux to the seafloor Sediment traps E Nöthig, C Lalande, AWI 17

18 Life at the Arctic seafloor 18

19 Biological Carbon Pump Biological carbon pump Physical carbon pump Chisolm et al., 2000 (Nature) 19

20 Primary Production Photosynthesis Chl a 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Water column Melt Ponds Sea Ice Mar Fernández Méndez 20

21 Changes in Arctic Productivity Increase in primary production in 2007: 30% attributed to decreased minimum summer ice extent, 70% to longer growing season Annual primary production (Tg C yr -1 ) Arrigo et al. 2008

22 Environmental changes in the Arctic Ocean How will changes in sea ice cover affect the carbon cycle in the Arctic? 22

23 Central Arctic Ocean Expedition IceArc RV Polarstern ARK-XXVII/3 2 August 8 October 2012 Mar Fernández-Méndez, AWI

24 Central Arctic Ocean 24

25 S Hendricks, AWI 25

26 Control of photosynthesis rates 26 M. Nicolaus, AWI

27 Control of photosynthesis rates Total transmittance Example data from ROV light measurements Nicolaus et al. GRL,

28 Control of photosynthesis rates More light will reach the Arctic Ocean 28 M.Nicolaus & C.Katlein (AWI Sea Ice Physics)

29 Sampling of algae Water column Sea Ice Melt Ponds 29 Mar Fernández-Méndez, AWI

30 Sea ice algae Pennate diatoms Melosira arctica 5 cm 5 cm Mar Fernández-Méndez, AWI 30

31 Seafloor sampling: bacteria, macrofauna, megafauna Agassiz Trawl Photos: IceArc team 31

32 Sampling seafloor: bacteria, macrofauna, megafauna TV-Multicorer Top photos: IceArc team AWI 32

33 Export flux to the seafloor AWI ~ 5 cm AWI Kolga hyalina, opportunistic holothurian (sea cucumber) AWI 33AWI

34 Benthic oxygen consumption C 6 H 12 O O 2 6 CO H 2 O + heat 34

35 Benthic oxygen consumption Oxygen is consumed below algae patches. Sediment depth (mm) F Wenzhöfer, J Felden et al., AWI/MARUM 35

36 Export of algal biomass from the sea ice Boetius et al When the ice melts, ice algae rapidly sink to the seafloor to depths of several thousand meters. Deep-sea animals feed on the algae and bacteria metabolize what is left, consuming oxygen in the seabed. Warming and the associated physical changes in the Central Arctic cause reactions in the entire ecosystem down to the deep sea. 36

37 IceArc Movie Watch it on the AWI youtube channel: 37

38 Long-term observations 38

39 HAUSGARTEN Fram Strait Circulation influenced by both Atlantic and Pacific waters 39 Source: AWI

40 HAUSGARTEN - Fram Strait T [ C] Beszczynska-Möller A et al.,

41 HAUSGARTEN Long-term observatory Established in permanent stations 9 stations along depth transect: 1000 m to 5500 m depth 8 stations at 2500 m depth Parameters: Abiotic: temperature, hydrography, ice coverage Biotic: primary productivity, carbon flux, bacterial activity, biodiversity of all size classes Soltwedel,

42 Temperature anomalies at HAUSGARTEN Oceanographic moorings across Fram Strait (Beszczynska-Möller et al., 2012)

43 Changes in phytoplankton and zooplankton Temporal variability of plankton species in sediment traps between 2000 and /1 2002/3 2004/5 2005/6 2006/7 2008/9 Coccolithophorids Diatoms Tintinnids (Bauerfeind et al., 2009, 2012) proportion of amphipods in sediment traps (%) T. Polar libellula species T. abyssorum Atlantic species 2000/01 04/05 06/07 07/08 08/09 after Kraft et al. 2012

44 Coupling of ice and organic matter flux The presence of ice influences organic matter flux. POC flux (mg C m -2 d -1 ) Ice concentration (%) Lalande et al., 2013 POC = Particulate organic carbon 44

45 Litter in the Arctic Abundance of litter Types of litter 45

46 Litter in the Arctic 46 Bergmann & Klages 2012 Marine Pollution Bulletin 64

47 To think about... Future of the Arctic Ocean Ecosystem? How can we improve predictions? Increasing or decreasing primary productivity? Increasing or decreasing stratification? Increasing or decreasing nutrient availability? Increasing or decreasing research effort? Sustainable and responsible use of Arctic resources? M. Schiller; AWI Sea ice observatory 47

48 Thank you for your attention S. Hendricks, AWI Captain and Crew RV Polarstern RV Maria S. Merian 48