- ePIC
Ver$cal diatom flux observed in sediment traps in the Arc$c Ocean with special emphasis on Melosira arc+ca Eva-Maria Nöthig1, Eduard Bauerfeind1, Catherine Lalande1,3, Vladimir Shevshenko2, Viktoria Zernova2 1 Alfred Wegener Ins.tute Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, Bremerhaven, 27570, Germany 2 P.P. Shirshov Ins.tute of Oceanology, Russian Academy of Sciences, Nakhimovsky Prospect 36, Moscow, 117997, Russia 3 Université Laval, Québec-‐Océan, Département de Biologie, Pavillon Alexandre-‐Vachon, Québec, Québec, G1V 0A6, Canada Sampling Traps Nansen Basin id Gakkel R ge -‐> sampling area: 0.5 m2 -‐> sampling .me: ~12 month (Sept-‐Aug) -‐> sampling jars: 20, filled with sterile sea water + NaCl (psu 40) to avoid exchange of seawater -‐> sample fixa.ve: HgCl2 0.14% Moorings -‐> 2 moored sediment trap arrays were deployed -‐> northern Laptev Sea at 150m and 1550m during 1995 -‐1996 -‐> Nansen Basin at 200m and 3800m during 2011-‐2012 Amunden Basin Laptev Sea Conclusions • Melosira arc+ca dominates the flux of sea ice related diatoms in the central Arc.c Ocean • The progressively earlier ice melt affected the export fluxes of biogenic ma\er more than the ice related algal species in the region Results Ver$cal par$cle flux Photographs from trap material Diatom flux 2011/2011 Nansen Basin 200 m Ice (%) Ice (%) POC flux (mg C m-‐2 d-‐1) POC flux (mg C m-‐2 d-‐1) 1995/1996 Laptev Sea 150m 200m in July 200m in June 200m in August 200m in August Ice algae cell flux (x 106 m-‐2 d-‐1) TPM flux (mg C m-‐2 d-‐1) TPM flux (mg C m-‐2 d-‐1) Ice algae cell flux (x 106 m-‐2 d-‐1) 2011/2011 Nansen Basin 200 m Sedimenta.on pa\ern of total ma\er & par.culate organic carbon (TPM & POC) and numbers of domina.ng ice algal species • The ice cover was almost 100% during both inves.ga.ons • Ver.cal flux of organic ma\er was lower in the Nansen Basin than in the northern Laptev Sea • The higher flux in the Laptev Sea most probably reflects the input of nutrients from the Lena River Acknowledgements Ursel Schauer & oceanography group et al: Sediment trap deployments Elizabeth Bonk, Nadine Knüppel & Christiane Lorenzen for technical support in the lab AWI trainee group and several student helpers for their help with the tedious work of picking the samples 1995/1996 Laptev Sea 150m On the sea ice in September Sedimenta.on pa\ern of calculated phytoplankton carbon of the domina.ng (>90%) diatoms in the summer month • Sea ice related diatoms prevailed • Melosira arc+ca dominated diatom flux in abundances & biomass, long chains were observed during the month of July, later very short chains mainly consis.ng of res.ng spores were present • In the deep trap in the Nansen Basin more slimy Melosira aggregates were found • Other common large diatom species were Nitzschia frigida & Fragilariopsis spp. Nitzschia frigida cells sinking predominantly as single cells early in the year (June) • Less abundant were Navicula, Pseudo-‐nitzschia, Pleurosigma, Gyrosigma & Haslea species 300m in August BREMERHAVEN Am Handelshafen 12 27570 Bremerhaven Telefon 0471 4831-0 www.awi.de
© Copyright 2024