1. VERSITET Mustafa Mantikci, Stiig Markager, Jørgen Hansen AARHUS UNIVERSITET DEPARTMENT OF BIOSCIENCE Liege, Belgium UNI The ratio of dark respiration to maximum photosynthesis and seasonal variability in two marine coastal waters

2. VERSITET Mustafa Mantikci, Stiig Markager, Jørgen Hansen AARHUS UNIVERSITET DEPARTMENT OF BIOSCIENCE Liege, Belgium UNI Seasonal variations in respiration and relationships to production and temperature

3. You can’t know production without Respiration… John Marra, 2013

4. Who respires? Robinson & Williams,2005 >95% Community Respiration

5. Unknown Respiration BacteriaPhytoplankton Light Size fractionation-antibiotics

6. ‘Global’ database of Respiration Robinson & Williams, 2005 1%6% 14 C PP45 th Liege Colloquium Presentations

7. Great Belt North sea Baltic sea Roskilde fjord monthly sampling (12 total ) (1 m & 200µM) 24 CTD profiles in 2012 Study site

8. 14 C samples (12 light + 2 dark) Dark Incubator 2 hours Linear Light Incubator 12h Respiration samples r 2 =0.997 Experimental setup

9. Results / CTD Profiles GBRF

10. Chlorophyll a GBRF

11. Community Respiration (CR) GBRF

12. P max - P max B GB RF

13. Q 10 Index r 2 = 0.38 r 2 = 0.32 r 2 = 0.72 r 2 = 0.88 GBRF 1.6 1.82.6 2.7 Lomas et al., 2002

14. R / P max % indicator of the trophic balance of the plankton community (Irriarte et al., 1991) GB RF

15. % BR as a function of Chl-a GFF filtered (Sachia et al.,unpublished)

16. Photosynthetic parameters r 2 = 0.19 r 2 = 0.46 r 2 = 0.53 p< 0.001 Webb et al, 1974 - Markager et al., 1999

17. Bacterial abundance and POC r 2 = 0.45r 2 = 0.42

18. Respiration model r 2 = 0.83 p< 0.001

19. Take home messages Phytoplankton biomass and temperature are the main factors governing community respiration Bacteria become relatively more important in open coastal waters with lower phytoplankton biomass If you measure PP don’t forget to measure R Mustafa Mantikciamm@dmu.dk

20. NCP GB-mixed layer RF (gC m -2 y -1 )GBRF  PP 143145  CR 167152  NCP 1 -25-7  NCP 2 1328 NCP 1 = GPP(PP) – CR (R a +R h ) NCP 2 = PP-R a light - R a dark -R h

21. Depth integration of PP and CR

22. Photosynthetic rates (mg C m 3 h -1 ) P est alpha P EKEK c P max =P est + c E Webb, 1974 - Markager et al., 1999

23. Respiration rates (µmol O 2 L -1 h -1 ) oxy(y) t