marazzi flood pulse symposium 2010
DESCRIPTION
Presentation at Flood Pulsed Wetlands symposium in Maun, Botswana http://www.orc.ub.bw/floodpulse/index.htmlTRANSCRIPT
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
Algae
Fish
1. Introduction and aims
Homo sapiens
Algae are food for fish
Fish are food for people
Phytoplankton = basis of food webs
Ecosystem Service: food provision
Energy & Matter
E & M
Zooplankton
E & M
E & M
Nutrients (N, P...)
Sunlight
from inflow water, dust, soil
CO2
Birds
E & ME & M
The Okavango Delta: a unique inland freshwater ecosystem
1. Introduction and aims
Hydoperiod is a critical factor inshaping this ecosystem: flood pulsevaries highly the inundated area
Cronberg (1996) found 50 commonalgal species in the Boro region;several hundreds of species in theDelta (Ramberg et al., 2006)
Ph.D. for a specific study to generate new knowledge
Aims of the research
• Monitoring phytoplankton in seven floodplainsevery two months (about 100 samples in 2009-2010)
• Investigating the distribution of algae across habitatsand relationships with hydroperiod and otherenvironmental variables
• Generating new baseline data on phytoplankton coveringvast areas of the Delta (95 samples from 2006-2007
campaigns)
41. Introduction and aims
5
Summary of sites
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 FHippo 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
1. Introduction and aims
Map of floodplain sites
6
1. Introduction and aims
Darwin initiative project sites: P.Wolski – www.orc.ub.bw
Sampling campaign in floodplains 2-3 habitats: Open Water, Sedges and Grassland
2. Methods
Grassland
Sedges
Open Water
Sampling of water column Concentration
2. Methods
Preservation in Lugol’s
Phytoplankton identification & counting
2. Methods
Utermohl technique: inverted microscope (add picture)Sedimentation chambers: Volume: 5 ml, 10 ml or 15 ml
Counting 200-500 algal units(cells, colonies or filaments) inrandom fields of view at 100xand 400x magnification
http://www.hydrobios.de/
N algal units - phyla
16 samples from 7 floodplain sites (April/May 2009)
10
0
100
200
300
400
500
600
700
N a
lga
l u
nit
s
Phyla
Aldrovanda Hippo pool Pool C Wildebeest Waterlilly Buffalo fence Daunara
3. Results
Principal Component Analysis
Environmental data in 7 sites:depth, conductivity, TDS, Turbidity, pH, DO, %O2 sat. (measured in the field)
3. Results
12
0
10
20
30
40
50
60
70
80
90
Physical data: turbidity (NTU) 3. Results
Hippo pool: frequently flooded site
13
0
50
100
150
200
250
300
350
N a
lga
l u
nit
s
Phyla
Open Water Sedges Grassland
Mougeotia sp.
3. Results
Coniugation
0
10
20
30
40
50
60
70
80
90
N a
lga
l u
nit
s
Open Water Sedges Grassland
14
Pool C: most abundant taxa 3. Results
Pennate Diatoms, Cryptomonas sp. in deeper water
Desmids in flooded grasslands
3. Results
RedundancyAnalysis
16
Wildebeest pool: intermediate flooding frequency
0
50
100
150
200
250
300
350
N a
lga
l u
nit
s
Phyla
Sedges Grassland
Daunara pool: rarely flooded site
17
0
20
40
60
80
100
120
140
N a
lga
l u
nit
s
Phyla
Open Water Grassland
Cryptomonas sp.
Euglena sp.
3. Results
Phacus longicauda Euglenales
Closterium dianae Zygnematales (Closteriineae)
Goniochhloris smithiiXanthophyta (Mischococcales)
Xanthidium sp.Zignematales (Desmidiinae)
Stauroneis sp. Bacillariophyta (Pennate Diatom)
Identification of species and genera
Zignema sp. (Zygnemataceae)
3. Results
100 µm
200 µm
10 µm
60 µm
60 µm
100 µm
Identification of species
6 species & 2 varieties of Micrasterias in Pool C Grassland:
30 cells counted in the whole chamber (identified at 400x)
M. pinnatifida M. rotata M. mahabuleshwarensis M. americana
M. truncata M. tropica (var. elongata)M. tropica (var. elegans)
100 µm
3. Results
Estimate of biovolume / algal biomass
Algal units in 10 ml subsample from a 0,275 L sampleconcentrated 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
50 µm
6,35
6,40
6,45
6,50
6,55
6,60
6,65
6,70
6,75
6,80
6,85
0
1
2
3
4
5
6
7
8
9
10
Open Water Sedges Grassland
pH
Bio
vo
lum
e (
mg
/l)
21
Algal biomass and pH...
N=5
N=4
N=7
3. Results
Conclusions
Geographical and habitat diversity results in highphytoplankton biodiversity in floodplains: 122 species and86 genera in 16 samples
Mougeotia, Cryptomonas, Cosmarium, Staurastrumand Staurodesmus are the most abundant genera
Algal biomass is higher in the flooded grasslands andDesmids are the major algal group there
Cyanophyta seem to be more abundant in the sites withintermediate flooding regime
22
Research development
• Chemistry analyses to understand relationships betweenN, P, micronutrients and algal biomass & biodiversity
• Improve temporal, spatial and taxonomic resolution ofthe study on phytoplankton
• Data exchange and integration with Nqobizitha Siziba’sPh.D. on zooplankton to investigate the food webs in ajoint project HOORC-UCL
23
References
• Whitton et al. “Freshwater algae of the British Isles”
• Cronberg et al. (1996). “Major ion chemistry, plankton andbacterial assemblages of the Jao/Boro river, Okavango Delta,Botswana: the swamps and the floodplains”. Archiv furHydrobiologie, 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 ofphytoplankton abundance and composition using inverted
microscopy (Utermöhl technique)”. prEN 15204:2005European Committee for standardization.
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Acknowledgements
Sophie des Clers (co-supervisor), Thomas Davidsonand Gina Clarke (UCL)
Nqobizitha Siziba, Ponde Kauheva, Ineelo Mosie,Richard Mazebedi, Thebe Kemosedile, MonicaMorrisson (HOORC)
Royal Geographical Society (www.rgs.org)
UCL Geography Department & Graduate School
UK DEFRA Darwin Initiative
Responding To Climate Change
Thank you for your interest!