Near-shore biogeography and biodiversity patterns around South Africa:

setting the scene

Charles GriffithsMarine Biology Research Centre, University of Cape Town

Charles.griffiths@uct.ac.za

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

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600

800

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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

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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.