Wilderness, June 2016 - South African National...

SIP

The condition of South Africa’s Estuaries

Lara van Niekerk

Wilderness, June 2016

Thank you

Project team

2

• CSIR

• SANBI

• NMMU

• DAFF

• ORI

• Anchor Environmental

• SAIAB

• SAEON

• Ezemvelo KZN WildlifeANCHORe n v i r o n m e n t a l

Thank you

Outline

2

• Pressures

• Measures of condition assessment

• Estuary condition

• 2009 vs 2015

• Conclusions

• Way forward

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Limited number of estuaries…

~ 300 estuaries

+/- 200 inlets/outlets

Thank you

Data collation

2

• WRC Desktop provisional EcoClassification of the

Temperate estuaries of South Africa (Orange to Mbashe)

• Mvoti to Mzimkulu WMA

• Gourits WMA Reserve study

• Usutu WMA Reserve Study

• A Desktop assessment of the Ecological Condition of South

Africa’s Temperate – Subtropical Transition Zone Estuaries

based on a Provisional EcoClassification

Estuary Health Index….

Estuarine Health

Abiotic health Biotic health

50 50

Mic

roal

gae

Ph

ysic

al h

abit

at

Wat

er

Qu

alit

y

Mo

uth

Co

nd

itio

n

Hyd

rolo

gy

Bir

ds

Mac

roal

gae

Inve

rteb

rate

s

Fish

25 252525 202020 20 20

Condition and Functionality….

Condition ≥91% 90-75 75 - 61 60 - 41 40-21 ≤20

Category

A

Natural

B

Largely natural / few

changes

C

Moderately modified

D

Largely modified

E

Highly degraded

F

Extremely degraded

State Excellent Good Fair Poor

FunctionalityRetain

Process & Pattern (representation)

Loss of Process or Pattern

No / limitedProcess & Pattern

Flow modification Bait collection

Pollution Infrastructure

Fishing pressure

Habitat degradation

Mean Annual Runoff

6 100 (45%)

5 200 (72%)

13 600 (85%)

36 900 24 900 (67% remaining)

Thank you

Emerging pressures….

• Invasive aliens

Spartina alterniflora

Tarebia granifera

• Desalination

• Aquaculture (e.g. catfish and red claw crayfish)

• Pathogens

South Africa Estuary condition

Measures of estuary condition

Estuary Condition by biogeographical region

2011 vs 2015: Estuary Condition

2011 vs 2015: Hydrology

2011 vs 2015: Water Quality

Thank you

Conclusions……

2

• Filled flow and water quality gap with models

• Revisited >95% of systems since 2009

• Only 4 system not revisited:

• Tugela/Thukela

• Siyaya

• Mhlathuze/ Richards Bay

• Nhlabane

• Desktop assessment model is becoming an official DWS

tool

• Same assessment tools for NBA, EWR and Estuary

Management Plans

Thank you

Way forward…

2

• Refine Estuary Functional Zone

• Saltmarsh and swamp forest

• What about land-estuary transitional zone????

• Revised estuary classification

• Include micro-estuaries, Langebaan

• Ecosystem threat status / Protection levels

Thank you

Van Niekerk L, Adams JB, Bate GC, Forbes AT, Forbes NT, Huizinga P, Lamberth SJ, MacKay CF, Petersen C, Taljaard S, Weerts SP, Whitfield AK and Wooldridge TH. (2013). Country-wide assessment of estuary health: An approach for integrating pressures and ecosystem response in a data limited environment, Estuarine, Coastal and Shelf Science 130: 239-251.

Veldkornet, DA, Adams, JB and van Niekerk, L (2015): Characteristics and landcover of estuarine boundaries: implications for the delineation of the South African estuarine functional zone, African Journal of Marine Science, DOI: 10.2989/1814232X.2015.1072111.