Near-shore biogeography and biodiversity patterns around South Africa:
setting the scene
Charles GriffithsMarine Biology Research Centre, University of Cape Town
SAMSS 2008
University of Cape Town
Presentation format:
• Marine biodiversity of South Africa.
• Geographic gradients.
• Biogeographic provinces.
• Long-shore patterns within taxa.
• Reliability of these data?
• Potential for new discoveries!
• Take home messages.
Phylum No No %RSA spp RSA endemics RSA Endemism
Algae 850 ca 340 ca 40 Placozoa 0 0 0Porifera 289 10 3Cnidaria 842 238 28Ctenophora 11 0 0Nematoda 338 30 9Platyhelminthes 28 17 61Rotifera 0 0 0Tardigrada 0 0 0Gastrotricha 0 0 0Kinorhyncha 1 0 0Gnathostomula 0 0 0Annelida 766 161 21Mollusca 3062 1592 52Crustacea 2333 719 31Chelicerata 115 57 50Brachiopoda 31 15 48Bryozoa 280 99 35Echinodermata 410 187 46Echiura 21 1 5Priapula 1 0 0Entoprocta 6 0 0Loricifera 0 0 0Sipuncula 47 0 0Pogonophora 1 1 100Phorona 0 0 0Chaetognatha 28 0 0Nemertea 17 5 29Hemichordata 11 2 18Chordata 2492 362 15
Totals 11980 3836 32.02
Overall marine biodiversity in South African(Gibbons et al. 1999 - reprints available from speaker)
Pro
du
cti
vit
y (
µg
chl-a
.cm
-2.m
o-1)
60
0
10
20
30
40
50
B.
10 20 30 400
Distance around coast (km x 100)
West Coast South Coast East Coast
Gradients in productivity and biomass:
Adapted by G Branch from Bustamante et al. 1996 J. Biogeog. 23:339-351
Alg
al b
iom
ass
(g
AF
DM
.m-2)
10 20 30 40
Distance around coast (km x 100)
0
600
0
100
200
300
400
500Sheltered shoresExposed shores
West Coast South Coast East Coast
D.
Gra
zer
bio
ma
ss
(g
AF
DM
.m-2)
Distance around coast (km x 100)
0
50
100
150
200
0 10 20 30 40
Sheltered shoresExposed shoresF.
West Coast South Coast East Coast
(Branch 2001)
Filt
er-
fee
der
bio
ma
ss (
g A
FD
M.m
-2)
10 20 30 40
Distance around coast (km x 100)
00
500
1000
1500
2000
2500
Sheltered shores
Exposed shoresE.
West Coast South Coast East Coast
Identification of provinces and plotting of biodiversity patterns
Method: Coast divided into (50 or) 100 km zones and speciesrecorded in each unit compared
Recognized marine provinces around South Africa,( based on biodiversity patterns as
originally analysed by Emanuel et al. 1992)
Source: S.A. State of the Environment Report 2004
Long-shore biodiversity patterns within faunal groups -1: Fish: species richness increases from west to east:
Namibia Cape Town Port Elizabeth Durban
Clinidae and Sparidae,two largely endemic families
Source: Turpie, Beckley & Katua 2000. Biol. Cons. 92:59-72
2: Invertebrates: Patterns differ radically between taxa (making use of ‘proxies’ dangerous!):Some groups become more species rich to the east:
Bivalves
020406080
100120140160180200
1 3 5 7 9 11 13 15 17 19 21 23 25 27
Distance around the coast (100 km units)
Number of species
Prosobranch Gastropods
0
100
200
300
400
500
1 3 5 7 9 11 13 15 17 19 21 23 25 27Distance around the coast (100 km units)
Number of species
Brachyurans
05
1015202530354045
1 3 5 7 9 11 13 15 17 19 21 23 25 27
Distance around the coast (100 km units)
Nunber of species
Echinoderms
0
10
20
30
40
50
1 3 5 7 9 11 13 15 17 19 21 23 25 27
Distance around the coast (100 km units)
Number of species
Others peak in Western Cape, declining to both E. and W.
Polychaetes
0
50
100
150
200
250
300
350
1 3 5 7 9 11 13 15 17 19 21 23 25 27
Distance around the coast (100 km units)
Number of species
Amphipods
020406080
100120140160
1 4 7 10 13 16 19 22 25 28
Distance around the coast (100 km units)
Number of Species
Endemic
Isopods
020406080
100120140160
1 3 5 7 9 11 13 15 17 19 21 23 25 27
Distance around the coast (100 km units)
Number of species
Ascidians
0
10
20
30
40
50
60
70
1 3 5 7 9 11 13 15 17 19 21 23 25 27
Distance around the coast (100 km units)
Number of species
All data: Awad, Griffiths & Turpie 2002 Diversity and Distributions 8:129-145
All groups combined
0
200
400
600
800
1000
1200
1400
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Distance around the coast (100 km units)
Number of species
Removed endemics
Endemics
0
20
40
60
80
100
120
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Distance around coast (100 km units)
Number of species
Species per 100 km stretch 1= Orange R 8= Cape Town16= Port Elizabeth24= Durban
Range-restricted species(range <300km) concentrated at ecotones!
For all invertebrates summed, species richness peaks along south coast, declining on the North East Coast
But how valid are these data ?1. Absolute species richness is certainly underestimated!If compare species counts between Africa and Europe better known groups comparable, but
poorly known ones clearly under-represented in Africa! Estimate 6 000 more species need to be described to raise level of knowledge to that of
Europe, itself far from complete! (Medd 2006)!
Taxonomic group European spp
S African spp
Well- known groups Pisces 1349 2000
Echinodermata 648 410
Mollusca 3353 3062
Decapoda 672 750
Poorly-known groups Platyhelminthes 2398 28
Nematoda 1837 338
Copepoda 2944 420
2. Are geographic patterns an artifact of unequal sampling effort?To some extent, yes, as the KwaZulu-Natal coast has most species per sample, but the species/area curve is not close to a plateau! (after Medd 2006)
0
100
200
300
400
500
600
700
800
900
1000
1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 10 10 11 11 12 12 13 13 14 14 15 15 16 16 17
Number of samples
Number of species
SWD
WCD
SCD
NAD
KZ-Natal
Namibia
West coast
South coast
Upside of this under-exploration: enormous potential for new discoveries! Recent examples include:new discoveries! Recent examples include:
New rock-lobster from Walter’s Shoal 2006
Preactiidae - endemic anemone family
Lemindidae - endemic nudibranch family
Single 2005 photograph of crinoids from False Bay revealed both:- a new Hippolyte shrimp- a new species of Myzostomida
Hippolyte n.sp. Hypomyzostoma n. sp.
Take home messages
1. South Africa has a diverse coastal environment of four main
provinces and a rich, highly endemic fauna.
2. Spatial patterns of biodiversity differ between groups.
3. Perhaps a third of macro-faunal species remain un-described!
4. There is huge potential for taxonomic discovery!
Many thanks to the Sloan Foundation and South African National Research Foundation for financial support. Also George Branch for use of data and graphics.