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The Functional Biology of Krill (Thysanoessa Raschii)

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The Functional Biology of Krill (Thysanoessa Raschii) with raschii) fjord The functional biology of krill (Thysanoessa raschii) Greenlandic (Thysanoessa a ‐ with focus on its ecological role in krill of role in a Greenlandic fjord biology Mette Dalgaard Agersted ecological its Supervisor: Torkel Gissel Nielsen on [email protected] functional focus The DTU Aqua, National Institute of Aquatic Resources, Technical University of Denmark, Kavalergaarden 6, 2920, Charlottenlund, Denmark. The functional biology of krill (Thysanoessa raschii) with focus on its ecological role in a Greenlandic fjord Outline • • • • • Background Summary Results Materials Aim and –who methods , what, where? Where? 3 NASA The functional biology of krill (Thysanoessa raschii) with focus on its ecological role in a Greenlandic fjord Krill • • • Diel Pelagic Large http://upload.wikimedia.org/wikipedi ‐ vertical Euphausiids schools living a/commons/b/bb/Krillanatomykils.jpg migration ‐ patchy Photo: Russ Hopcroft 4 with Krill in Western Greenland raschii) fjord • 4 species – Thysanoessa raschii Greenlandic (Thysanoessa – T. inermis a in – T. longicaudata krill of role – Meganyctiphanes norvegica biology ecological its on functional focus The wikipedia.org Thysanoessa Meganyctiphanes raschii norvegica Pedersen & Smidt 2000 Thysanoessa Thysanoessa inermis longicaudata 5 Photos: Russ Hopcroft The food web • Arctic krill not so well studied compared to Antarktic krill Phytoplankton • Key role Microplankton Copepods • Knowledge is crucial in understandingDetritus ecosystem dynamics Faecal pellets can sink hundreds of meters a day Photo: Thomas Juul Pedersen Transport of carbon 6 The functional biology of krill (Thysanoessa raschii) with focus on its ecological role in a Greenlandic fjord Combination Arctic food web To study the trophicroleof krillinthe biology ofthisspecies To gainknowledge onthefunctional of field Aim work and lab experiments 7 with In the field ECOGREEN cruise raschii) fjord ‐ july/august 2008 • Hydrography ‐ CTD Greenlandic (Thysanoessa a • Biomass data in krill of role • Difference in abundance of krill biology ecological offshore and inside its the fjord? on functional focus The • Krill vs. other zooplankton groups Photo: Colin Stedmon 8 with Laboratory raschii) fjord • Capture of krill in the Greenlandic (Thysanoessa fjord a in krill • Grazing experiments of role 1) Prey size spectrum biology experiment ecological Photo: Hannes Höffle 2) Functional response its on functional focus The 9 Photo: Russ Hopcroft Results Hydrography –july/august 2008 War Station Cold 1 2 3 4 5 6 7 8 9 10 12 13 14 15 16 17 18 19 20 m (m) Depth (m) Temperature Distance (km) (°C) Depth (m) Chl a (µg L‐1) Distance (km) Depth 10 Salinity Distance (km) Biomass of predators and prey – july/aug. 2008 Agersted et al., in press. 80 80 Phytoplankton Protozoans 70 Nauplii 70 Heterotrophs (%) • Phytoplankton biomass 60 60 50 50 largest near the fjord 40 40 entrance and inner fjord 30 30 ) -3 20 20 • Heterotrophs dominates 10 10 Heterotrophs (% of total prey) 0 0 in the middle fjord Krill 70 Copepoda 70 Gastropoda Rotifera 60 Krill (%) 60 • Copepods were the C m (mg Biomass 50 50 dominating zooplankton 40 40 group 30 30 20 20 Krill (% of total) • Krill dominates in the 10 10 0 0 inner fjord 8 9 10 11 12 13 14 16 17 18 20 Station 11 Photo: Russ Hopcroft Prey size spectrum experiment Thysanoessa raschii Foto: Signe Jung‐Madsen http://biol oc.coas.or egonstate. edu http://portal.nfrdi.re.kr/sp/saf/rts /webpage/movie/movie_01_10.js p Clearance rate Foto: Sigrún Jónasdóttir http://bioloc. coas.oregons http://microbes.limnol tate.edu/She ogy.wisc.edu/outreach rrLab/GLOBE /majorgroups.php 160 C.html Prey> 10 µm Æ 140 clearance = 86 ± 7 SE ) 120 -1 • Grazing on all d 100 organisms -1 80 from 5‐400 µm 60 40 • Mainly prey Cl (mL mg C 20 >10 µm 0 0 102030405060708090100110160170 Prey size class (ESD, µm) Agersted et al., in press. Photo: Russ Hopcroft Thalassiosira weissflogii Functional response Thysanoessa raschii Clearance rate Ingestion rate 80 Thalassiosira weissflogii 14 70 In situ phytoplankton ) ) 12 60 -1 -1 Daily ratio ~1% d d 10 50 -1 -1 Max clearance = 62 ± 8 SE 40 8 30 6 20 4 Cl (mL mg C I (µg C mg C 10 2 0 0 0 5 10 15 20 0 5 10 15 20 µg Chl a L-1 µg Chl a L-1 Agersted et al., in press Model 13 Photo: Russ Hopcroft Grazing in the fjord Phytoplankton Protozooplankton Nauplii spp. Mean carbon carbon carbon Station temperatur e ± SD (°C) % grazed d‐1 % grazed d‐1 % grazed d‐1 81 ‐ ‐ 0.001 0.001 9 2.9 ± 1.1 0.007 ‐ 0.021 10 3.1 ± 0.7 0.019 0.062 0.062 11 ‐ ‐ ‐ ‐ 12 2.9 ± 08 0.002 0.006 0.006 13 2.4 ± 0.7 0.010 0.031 0.031 14 2.5 ± 1.1 0.073 0.231 0.231 16 2.3 ± 1.2 0.020 ‐ 0.062 17 2.2 ± 1.1 ‐ ‐ ‐ 18 2.0 ± 1.3 0.005 ‐ 0.016 19 1.8 ± 0.9 ‐ ‐ ‐ 20 1.7 ± 0.6 0.092 ‐ 0.294 Alle (st. 9‐ 2.4 ± 1.1 ‐ ‐ ‐ Agersted et al., in press. 14 20) with raschii) fjord Summary Greenlandic (Thysanoessa a in • Krill are able to graze on planktonic krill of role organisms that covers several trophic levels biology • Krill did not have a significant grazing impact ecological its on the plankton populations on functional • focus The An insight into the functional biology of T. raschii 15 Thank you Acknowledgement: DTU Aqua and University of Copenhagen Greenland Climate Research Centre and Greenland Institute for Natural Resources for use of laboratory facilities KVUG and FNU for funding Bent Vismann, Kristine Engel Arendt and Peter Munk Kam Tang and Thomas Kiørboe Torkel Gissel Nielsen References: Agersted, M. D., Nielsen, T. G., Munk, P., Vismann, B. and Arendt, K. E. (in press). The functional biology and trophic role of krill (Thysanoessa raschii) in a Greenlandic fjord. Marine Biology Boyd CM, Heyraud M, Boyd CN (1984) Feeding of the Antarctic krill Euphausia superba. Journal of Crustacean Biology 14: 123‐141 Pedersen and Smidt (2000). Zooplankton Distribution and Abundance in West Greenland Water, 1950‐1984. Journal of Northwest Atlantic Fishery Science, 26: 045‐102 [email protected].
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