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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 [email protected] SAMSS 2008. Presentation format:

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near shore biogeography and biodiversity patterns around south africa setting the scene

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

[email protected]

SAMSS 2008

slide2

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.

slide3

Overall marine biodiversity in South African

(Gibbons et al. 1999 - reprints available from speaker)

Phylum No No %

RSA spp RSA endemics RSA Endemism

Algae 850 ca 340 ca 40

Placozoa 0 0 0

Porifera 289 10 3

Cnidaria 842 238 28

Ctenophora 11 0 0

Nematoda 338 30 9

Platyhelminthes 28 17 61

Rotifera 0 0 0

Tardigrada 0 0 0

Gastrotricha 0 0 0

Kinorhyncha 1 0 0

Gnathostomula 0 0 0

Annelida 766 161 21

Mollusca 3062 1592 52

Crustacea 2333 719 31

Chelicerata 115 57 50

Brachiopoda 31 15 48

Bryozoa 280 99 35

Echinodermata 410 187 46

Echiura 21 1 5

Priapula 1 0 0

Entoprocta 6 0 0

Loricifera 0 0 0

Sipuncula 47 0 0

Pogonophora 1 1 100

Phorona 0 0 0

Chaetognatha 28 0 0

Nemertea 17 5 29

Hemichordata 11 2 18

Chordata 2492 362 15

Totals 11980 3836 32.02

slide4

Gradients in productivity and biomass:

South Coast

East Coast

West Coast

B.

60

50

40

Productivity

(µg chl-a.cm-2.mo-1)

30

20

10

0

0

10

20

30

40

Distance around coast (km x 100)

Adapted by G Branch from Bustamante et al. 1996 J. Biogeog. 23:339-351

slide5

West Coast

South Coast

East Coast

600

D.

Exposed shores

500

Sheltered shores

400

Algal biomass

(g AFDM.m-2)

300

200

100

0

0

10

20

30

40

Distance around coast (km x 100)

slide6

South Coast

East Coast

West Coast

200

F.

Exposed shores

Sheltered shores

150

Grazer biomass

(g AFDM.m-2)

100

50

0

30

40

0

10

20

Distance around coast (km x 100)

(Branch 2001)

slide7

South Coast

East Coast

West Coast

2500

E.

Exposed shores

2000

Sheltered shores

1500

Filter-feeder biomass

(g AFDM.m-2)

1000

500

0

0

10

20

30

40

Distance around coast (km x 100)

slide8

Identification of provinces and plotting of biodiversity patterns

Method: Coast divided into (50 or) 100 km zones and species

recorded in each unit compared

slide9

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

slide10

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 2000. Biol. Cons. 92:59-72

slide11

2: Invertebrates: Patterns differ radically between taxa (making use of ‘proxies’ dangerous!):

Some groups become more species rich to the east:

slide12

Others peak in Western Cape, declining to both E. and W.

All data: Awad, Griffiths & Turpie 2002 Diversity and Distributions 8:129-145

slide13

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!

slide14

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 6 000 more species need to be described to raise level of knowledge to that of Europe, itself far from complete! (Medd 2006)!

slide15

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

slide16

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

slide17

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.

slide18

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.

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