with raschii) fjord
The functional biology of krill (Thysanoessa raschii)
Greenlandic
(Thysanoessa a
‐ with focus on its ecological role in krill
role in a Greenlandic fjord biology of 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.
with Outline raschii) fjord
• Background –who, what, where? Greenlandic
• Aim (Thysanoessa a
in
krill •
Materials and methods role • Results biology of
• Summary ecological
its
on functional
focus The Where?
3 NASA
with Krill ‐ Euphausiids raschii) fjord
• Large schools ‐ patchy
• Pelagic living Greenlandic
(Thysanoessa a
in krill • Diel vertical migration role
Photo: Russ Hopcroft biology of
ecological
its
on functional
focus The
4
http://upload.wikimedia.org/wikipedia/commons/b/bb/Krillanatomykils.jpg with Krill in Western Greenland raschii) fjord
• 4 species – Thysanoessa raschii Greenlandic
(Thysanoessa – T. inermis a
in – T. longicaudata krill
role – Meganyctiphanes norvegica biology of
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 with raschii) fjord
Aim Greenlandic
(Thysanoessa a
To gain knowledge on the functional in krill biology of this species role biology of To study the trophic role of krill in the ecological
its Arctic food web on functional
focus The Combination of field 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
role • Difference in abundance of krill biology of
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 role
1) Prey size spectrum
biology of experiment
ecological Photo: Hannes Höffle 2) Functional response its
on
functional
focus The
9 Photo: Russ Hopcroft ( Temperature Hydrography Results ° Salinity m War C)
Depth (m) Depth (m) 1
2
3
4
5
6 7
8
9 Distance Distance
10
Station 12
–july/augus
13 (km) (km) 15 14
16 17 18 19 20 t
2008 Cold Chl
Depth (m) a (µg
L ‐ 1
) Distance
(km) 10 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
role
organisms that covers several trophic levels biology of • 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