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![Estimate of biovolume / algal biomass
50
µm
Algal units in 10 ml subsample from a 0,275 L sample
concentrated into a 50 ml sterelin: concentration factor = 5.5
Formula used:
Biomass of algae (mg/L) = (Biovolumesubsample * 5 [um^3])/
(0.275 [L]* 1,000,000 [um^3/mm^3=mg])
Biovolume = Biomass in wet weight: mg=mm^3](https://image.slidesharecdn.com/marazzifloodpulsesymposium2010-12703317365804-phpapp02/75/Marazzi-Flood-Pulse-Symposium-2010-20-2048.jpg)
Marazzi Flood Pulse Symposium 2010
- 1. Phytoplankton biomass andbiodiversity in the Okavango Delta Luca Marazzi1 Anson W. Mackay1, Lars Ramberg2 1. Department of Geography, University College London 2. Harry Oppenheimer Okavango Research Centre Maun - 1 February 2010
- 2. Phytoplankton = basisof food webs from inflow CO2 Sunlight Nutrients water, (N, P...) dust, soil E&M Algae Algae are food for fish Energy & Zooplankton Matter E&M Fish E&M E&M Fish are food for people E&M Ecosystem Service: Birds food provision Homo sapiens 1. Introduction and aims
- 3. The Okavango Delta:a unique inland freshwater ecosystem Hydoperiod is a critical factor in shaping this ecosystem: flood pulse varies highly the inundated area Cronberg (1996) found 50 common algal species in the Boro region; several hundreds of species in the Delta (Ramberg et al., 2006) Ph.D. for a specific study to generate new knowledge 1. Introduction and aims
- 4. Aims of theresearch • Monitoring phytoplankton in seven floodplains every two months (about 100 samples in 2009-2010) • Investigating the distribution of algae across habitats and relationships with hydroperiod and other environmental variables • Generating new baseline data on phytoplankton covering vast areas of the Delta (95 samples from 2006-2007 campaigns) 1. Introduction and aims 4
- 5. Summary of sites 1. Introduction and aims Sample Date Time Flooding Pool C (G) 6.05.09 9.05 Frequently (F) Pool C (S) 9.45 F Pool C (OW) 10.30 F Water lilly pool (G1) 11.45 Intermediate (I) Water lilly pool (G2) 12.20 I Hippo pool (OW) 13.00 Frequently (F) Hippo pool (S) 13.20 F Hippo pool (G) 15.00 F Wildebeest pool (G) 7.05.09 9.00 Intermediate (I) Wildebeest pool (S) 9.40 I Aldrovanda pool (OW) 10.30 Frequently (F) Aldrovanda pool (S) 10.55 F Daunara (OW) 13.00 Rarely (R) Daunara (G) 13.15 R Buffalo fence (G) 8.05.09 12.00 Rarely (R) Buffalo fence (OW) 12.15 R 5
- 6. Map of floodplainsites 1. Introduction and aims 6 Darwin initiative project sites: P.Wolski – www.orc.ub.bw
- 7. Sampling campaign infloodplains 2-3 habitats: Open Water, Sedges and Grassland Open Water Sedges Grassland 2. Methods
- 8. Sampling of watercolumn Concentration Preservation in Lugol’s 2. Methods
- 9. Phytoplankton identification &counting Utermohl technique: inverted microscope (add picture) Sedimentation chambers: Volume: 5 ml, 10 ml or 15 ml http://www.hydrobios.de/ Counting 200-500 algal units (cells, colonies or filaments) in random fields of view at 100x and 400x magnification 2. Methods
- 10. N algal units- phyla 3. Results 16 samples from 7 floodplain sites (April/May 2009) 700 600 500 N algal units 400 300 200 100 0 Phyla Aldrovanda Hippo pool Pool C Wildebeest Waterlilly Buffalo fence Daunara 10
- 11. 3. Results Principal Component Analysis Environmental data in7 sites: depth, conductivity, TDS, Turbidity, pH, DO, %O2 sat. (measured in the field)
- 12. Physical data: turbidity(NTU) 3. Results 90 80 70 60 50 40 30 20 10 0 12
- 13. Hippo pool: frequentlyflooded site 3. Results 350 300 250 N algal units 200 Mougeotia sp. Coniugation 150 100 50 0 Phyla Open Water Sedges Grassland 13
- 14. Pool C: mostabundant taxa 3. Results 90 80 70 60 N algal units 50 40 30 20 10 0 Open Water Sedges Grassland 14
- 15. 3. Results Redundancy Analysis Pennate Diatoms, Cryptomonassp. in deeper water Desmids in flooded grasslands
- 16. Wildebeest pool: intermediateflooding frequency 350 300 250 N algal units 200 150 100 50 0 Phyla Sedges Grassland 16
- 17. Daunara pool: rarelyflooded site 3. Results 140 Cryptomonas sp. 120 100 N algal units 80 Euglena sp. 60 40 20 0 Phyla Open Water Grassland 17
- 18. Identification of speciesand genera 3. Results 100 200 10 µm µm µm Phacus longicauda Closterium dianae Goniochhloris smithii Euglenales Zygnematales (Closteriineae) Xanthophyta (Mischococcales) 60 µm 60 µm 100 µm Xanthidium sp. Stauroneis sp. Zignema sp. (Zygnemataceae) Zignematales (Desmidiinae) Bacillariophyta (Pennate Diatom)
- 19. Identification of species 3. Results 6 species & 2 varieties of Micrasterias in Pool C Grassland: 30 cells counted in the whole chamber (identified at 400x) 100 µm M. pinnatifida M. rotata M. mahabuleshwarensis M. americana M. truncata M. tropica (var. elegans) M. tropica (var. elongata)
- 20. Estimate of biovolume/ algal biomass 50 µm Algal units in 10 ml subsample from a 0,275 L sample concentrated into a 50 ml sterelin: concentration factor = 5.5 Formula used: Biomass of algae (mg/L) = (Biovolumesubsample * 5 [um^3])/ (0.275 [L]* 1,000,000 [um^3/mm^3=mg]) Biovolume = Biomass in wet weight: mg=mm^3
- 21. Algal biomass andpH... 3. Results 10 6,85 N=7 9 6,80 8 6,75 7 6,70 N=4 Biovolume (mg/l) 6 6,65 pH 5 6,60 N=5 4 6,55 3 6,50 2 6,45 1 6,40 0 6,35 Open Water Sedges Grassland 21
- 22. Conclusions Geographical and habitatdiversity results in high phytoplankton biodiversity in floodplains: 122 species and 86 genera in 16 samples Mougeotia, Cryptomonas, Cosmarium, Staurastrum and Staurodesmus are the most abundant genera Algal biomass is higher in the flooded grasslands and Desmids are the major algal group there Cyanophyta seem to be more abundant in the sites with intermediate flooding regime 22
- 23. Research development • Chemistryanalyses to understand relationships between N, P, micronutrients and algal biomass & biodiversity • Improve temporal, spatial and taxonomic resolution of the study on phytoplankton • Data exchange and integration with Nqobizitha Siziba’s Ph.D. on zooplankton to investigate the food webs in a joint project HOORC-UCL 23
- 24. References • Whitton etal. “Freshwater algae of the British Isles” • Cronberg et al. (1996). “Major ion chemistry, plankton and bacterial assemblages of the Jao/Boro river, Okavango Delta, Botswana: the swamps and the floodplains”. Archiv fur Hydrobiologie, vol. 107/3 335-407. • Ramberg et al. (2006) “Species diversity of the Okavango Delta, Botswana”. Aquat. Sci. 68 (2006) 310–337. • “Water quality – Guidance standard for the routine analysis of phytoplankton abundance and composition using inverted microscopy (Utermöhl technique)”. prEN 15204:2005 European Committee for standardization. 24
- 25. Acknowledgements Sophie desClers (co-supervisor), Thomas Davidson and Gina Clarke (UCL) Nqobizitha Siziba, Ponde Kauheva, Ineelo Mosie, Richard Mazebedi, Thebe Kemosedile, Monica Morrisson (HOORC) Royal Geographical Society (www.rgs.org) UCL Geography Department & Graduate School UK DEFRA Darwin Initiative Responding To Climate Change
- 26. Thank you foryour interest! [email protected]