Phytoplankton biomass and biodiversity
        in the Okavango Delta

                 Luca Marazzi1
        Anson W. Mack...
Phytoplankton = basis of food webs
                                                                         from inflow
  ...
The Okavango Delta: a unique inland
                    freshwater ecosystem

                            Hydoperiod is a ...
Aims of the research

• Monitoring phytoplankton in seven floodplains
  every two months (about 100 samples in 2009-2010)
...
Summary of sites                             1. Introduction and aims

        Sample             Date     Time        Flo...
Map of floodplain sites                                1. Introduction and aims




                                      ...
Sampling campaign in floodplains
2-3 habitats: Open Water, Sedges and Grassland




                         Open Water

 ...
Sampling of water column                   Concentration



                      Preservation in Lugol’s




            ...
Phytoplankton identification & counting
Utermohl technique: inverted microscope (add picture)
Sedimentation chambers: Volu...
N algal units - phyla                                                                                    3. Results

16 sa...
3. Results

Principal
Component
Analysis

Environmental
data in 7 sites:
depth, conductivity,
TDS, Turbidity, pH,
DO, %O2 ...
Physical data: turbidity (NTU)   3. Results
90
80
70
60
50
40
30
20
10
0




                                             ...
Hippo pool: frequently flooded site                       3. Results
                350


                300


         ...
Pool C: most abundant taxa                       3. Results
                90

                80

                70

  ...
3. Results
Redundancy
Analysis

Pennate Diatoms,
Cryptomonas sp. in
deeper water

Desmids in
flooded grasslands
Wildebeest pool: intermediate flooding frequency
                350


                300


                250
N algal u...
Daunara pool: rarely flooded site                                        3. Results

                140
                 ...
Identification of species and genera                                        3. Results




100                            ...
Identification of species                                           3. Results


6 species & 2 varieties of Micrasterias i...
Estimate of biovolume / algal biomass



   50
   µm



Algal units in 10 ml subsample from a 0,275 L sample
   concentrat...
Algal biomass and pH...               3. Results
                   10                                          6,85
     ...
Conclusions

Geographical and habitat diversity results in high
  phytoplankton biodiversity in floodplains: 122 species a...
Research development

• Chemistry analyses to understand relationships between
  N, P, micronutrients and algal biomass & ...
References
• Whitton et al. “Freshwater algae of the British Isles”

• Cronberg et al. (1996). “Major ion chemistry, plank...
Acknowledgements
 Sophie des Clers (co-supervisor), Thomas Davidson
  and Gina Clarke (UCL)
 Nqobizitha Siziba, Ponde Ka...
Thank you for your interest!

      l.marazzi@ucl.ac.uk
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Marazzi Flood Pulse Symposium 2010

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Presentation at Flood Pulsed Wetlands symposium in Maun, Botswana

http://www.orc.ub.bw/floodpulse/index.html

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Marazzi Flood Pulse Symposium 2010

  1. 1. Phytoplankton biomass and biodiversity 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. 2. Phytoplankton = basis of 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. 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. 4. Aims of the research • 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. 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. 6. Map of floodplain sites 1. Introduction and aims 6 Darwin initiative project sites: P.Wolski – www.orc.ub.bw
  7. 7. Sampling campaign in floodplains 2-3 habitats: Open Water, Sedges and Grassland Open Water Sedges Grassland 2. Methods
  8. 8. Sampling of water column Concentration Preservation in Lugol’s 2. Methods
  9. 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. 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. 11. 3. Results Principal Component Analysis Environmental data in 7 sites: depth, conductivity, TDS, Turbidity, pH, DO, %O2 sat. (measured in the field)
  12. 12. Physical data: turbidity (NTU) 3. Results 90 80 70 60 50 40 30 20 10 0 12
  13. 13. Hippo pool: frequently flooded site 3. Results 350 300 250 N algal units 200 Mougeotia sp. Coniugation 150 100 50 0 Phyla Open Water Sedges Grassland 13
  14. 14. Pool C: most abundant taxa 3. Results 90 80 70 60 N algal units 50 40 30 20 10 0 Open Water Sedges Grassland 14
  15. 15. 3. Results Redundancy Analysis Pennate Diatoms, Cryptomonas sp. in deeper water Desmids in flooded grasslands
  16. 16. Wildebeest pool: intermediate flooding frequency 350 300 250 N algal units 200 150 100 50 0 Phyla Sedges Grassland 16
  17. 17. Daunara pool: rarely flooded site 3. Results 140 Cryptomonas sp. 120 100 N algal units 80 Euglena sp. 60 40 20 0 Phyla Open Water Grassland 17
  18. 18. Identification of species and 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. 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. 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. 21. Algal biomass and pH... 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. 22. Conclusions Geographical and habitat diversity 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. 23. Research development • Chemistry analyses 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. 24. References • Whitton et al. “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. 25. Acknowledgements  Sophie des Clers (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. 26. Thank you for your interest! l.marazzi@ucl.ac.uk

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