1. Marine Biology Research Centre, University of Cape Town
Near-shore biogeography and biodiversity patterns around South Africa: setting the scene
University of
Cape Town
Charles Griffiths
Marine Biology Research Centre, University of Cape Town
SAMSS 2008

2. 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.

3. Overall marine biodiversity in South African
(Gibbons et al reprints available from speaker)
Phylum No No %
RSA spp RSA endemics RSA Endemism
Algae 850 ca 340 ca 40
Placozoa 0 0 0
Porifera
Cnidaria
Ctenophora
Nematoda
Platyhelminthes
Rotifera 0 0 0
Tardigrada 0 0 0
Gastrotricha 0 0 0
Kinorhyncha 1 0 0
Gnathostomula 0 0 0
Annelida
Mollusca
Crustacea
Chelicerata
Brachiopoda
Bryozoa
Echinodermata
Echiura
Priapula 1 0 0
Entoprocta 6 0 0
Loricifera 0 0 0
Sipuncula
Pogonophora
Phorona 0 0 0
Chaetognatha
Nemertea
Hemichordata
Chordata
Totals

4. Gradients in productivity and biomass:
West Coast
South Coast
East Coast 60 B. 50 40
(µg chl-a.cm-2.mo-1)
Productivity 30 20 10 10 20 30 40
Distance around coast (km x 100)
Adapted by G Branch from Bustamante et al J. Biogeog. 23:

5. D. Algal biomass (g AFDM.m-2) 10 20 30 40
West Coast
South Coast
East Coast
600 D.
Exposed shores
500
Sheltered shores
400
Algal biomass
(g AFDM.m-2)
300
200
100 10 20 30 40
Distance around coast (km x 100)

6. F. West Coast South Coast East Coast Grazer biomass (g AFDM.m-2)
200 F.
Exposed shores
Sheltered shores
150
Grazer biomass
(g AFDM.m-2)
100 50 10 20 30 40
Distance around coast (km x 100)
(Branch 2001)

7. Filter-feeder biomass
West Coast
South Coast
East Coast
2500 E.
Exposed shores
2000
Sheltered shores
1500
Filter-feeder biomass
(g AFDM.m-2)
1000
500 10 20 30 40
Distance around coast (km x 100)

8. Identification of provinces and plotting of biodiversity patterns
Method: Coast divided into (50 or) 100 km zones and species
recorded in each unit compared

9. 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

10. Long-shore biodiversity patterns within faunal groups -
1: Fish: species richness increases from west to east:
Clinidae and Sparidae,
two largely endemic
families
Namibia Cape Town Port Elizabeth Durban
Source: Turpie, Beckley & Katua Biol. Cons. 92:59-72

11. 2: Invertebrates: Patterns differ radically between taxa (making use of ‘proxies’ dangerous!):
Some groups become more species rich to the east:

12. Others peak in Western Cape, declining to both E. and W.
All data: Awad, Griffiths & Turpie 2002 Diversity and Distributions 8:

13. For all invertebrates summed, species richness peaks
along south coast, declining on the North East Coast
Species per 100 km stretch
1= Orange R
8= Cape Town
16= Port Elizabeth
24= Durban
Range-restricted species
(range <300km) concentrated at ecotones!

14. But how valid are these data ?
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 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

15. 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)
South coast
KZ-Natal
West coast
Namibia

16. Upside of this under-exploration: enormous potential for new discoveries! Recent examples include:
Preactiidae - endemic anemone family
New rock-lobster from Walter’s Shoal 2006
Lemindidae - endemic nudibranch family

17. 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.

18. 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.