How does ice cover affect the benthic fauna in the Barents Sea? (1.343Mb)

How does ice cover affect the benthic fauna in the Barents Sea?

Sabine Cochrane- Akvaplan-niva, NO

Stanislav Denisenko, Zoological Institute (ZIN), RU

Lis Lindal Jørgensen – Institute of Marine Research (IMR), NO

Collaborators:

Natalia Anisimova, PINRO, RU

Will Ambrose Jr., Bates College, USA Ingrid H. Ellingsen, SINTEF, NO

Chris Emblow, APN, NO

External funding:

Outline of presentation

• 2 examples of Norwegian-Russian benthic cooperation programmes

– ”Traditional” study: infauna and environmental variables – Pilot study - Epifauna: bycatch

• Discussion of methodologies and what they tell us (or don’t);

• Integration possibilities?

”BASICC” 2003

• Infaunal abundance

• APN-ZIN cooperation

• 47 benthic stations

• approx 400 000 km²

• 30 m² actual sediment sampled

Ice cover and faunal abundance

b) Faunal abundance (per 0.5 m²) a) Ice cover (NSIDC data; av. 3 years)

Infaunal biomass

Wet weight g/ m²

Including calcareous parts

Spitsbergen

bank Central bank

Stor bank

Environmental influences on the benthic fauna

-4 -2 0 2 4

PC1 -4

-2 0 2 4

PC2

12

3

4

5 6

7 8

9

10 11

1312

14

15

16

17 18 19

20 21

22 23

24 25 26 27 28

3029

31 32

33 34

35 36

37

38

39 40 41 42

43 44 45

46

47

depth

ice 00-03 pelite

pigments

abundance H'(loge)

PrP2003

• Production inverse to ice cover

• Production and pigments associated with faunal abundance

• Diversity not associated with production

• Ice supresses

production; leads to lower faunal abundance

• Implications for changing ice distribution

Faunal similarity

• Groupings, approx. 50%

similarity

• Foraminifera excluded

• Northern group

– Heavily ice influenced – Lower productivity

• Southern group

– Intermediate to low ice – Higher productivity

– Atlantic influenced sub- group

Ecosystem Cruise 2006

• Epifauna (bycatch)

• IMR-PINRO cooperation

• 5 ships used

- 3 Norwegian - 2 Russian

• 500 trawls

• 13.500m² per trawl

10 20 30 40

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Longitude

Latitude

Spitsbergen bank

Stor bank

Central bank

Kanin bank

Benthic by-catch: biomass distribution

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Spitsbergen bank

Stor bank

Tromsø

3 ºC isoterm at 100m depth.

Biomass (kg 0.5h-1trawled)

1 (~0,000001 kg.m-²) 40 (~0,002 kg.m^-2) 2000 (~0,14 kg.m^-2)

Central bank

Biomass fluctuations

1924-32 (warm)

1968-70 (cold)

Biomass gram m^-2

Mega-epifauna 2007

Denisenko 2001; 2004 also in Wassmann et al.2006

IMR unpublished new data

Conclusion (epifaunal studies)

•Coordinated Russian-Norwegian Cruises permit a first, near synoptic, look at the whole Barents Sea mega epifauna taken as bicatch.

•Bicatch-biomass hotspots corresponds with previously recorded hotspots from classic infauna studies

•Sponges locally dominate i biomass; might be a vulnerable habitat structuring organisms

•Erect filtrating organisms might indicate vulnerable areas

Integration: infauna/ epifauna analyses?

• Trawl and grab – selecting for different kinds and size-classes of organisms;

– Sponges, echinoderms, marine worms and bivalves

• Different representation of patchily distributed organisms;

• Some broad similarities (areas of high biomass) but many differences;

– Methods complementary, but one cannot replace the other

• Need for interdisciplinary programmes

– Need to develop standards for epifaunal analyses

Thank you for your attention