Ecosystem Guidelines for Environmental Assessment

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COASTAL ESTUARIES COASTAL ECOSYSTEMS Barry Clark What are the key ecological “drivers” in terms of maintaining ecosystem function, pattern or structure Freshwater input - quantity and variability. Freshwater water quality - nutrients, contaminants. Sediment input - terrestrial and marine sources. Oceanographic conditions - wave action, currents, water temperature, nutrients. What are the key issues, vulnerabilities and threats The primary threat to estuaries relates to changes in freshwater input and/or quality through an increase/decrease in mean annual runoff, change in seasonality of flows, change in flood frequency and/or magnitude and change in water quality. Change in the freshwater input and/or quality has typically been linked to changes in catchments: Change in land use (agriculture, forestry, urbanisation etc). Poor land use practices (increased sediment input, nutrient enrichment, contaminant input). Water abstraction (altered flow regime). Inter-basin transfers (altered flow regime). Input of contaminants (sewage, stormwater, agricultural runoff, industrial waste water). Infestation by alien vegetation (reduced freshwater input), climate change (altered freshwater inputs). Secondary threats to estuaries include: Bank stabilisation. Canalisation and other flood control measures. Modification of mouth dynamics for maintenance of water level for recreation and other purposes. Encroachment by urban development and disturbance from human activities (e.g. power boating, water skiing or swimming). Exploitation of living resources (fish, invertebrates and estuarine vegetation). What are the “bottom lines” and non-negotiables Few generic rules can be applied in respect of maintenance of estuarine biodiversity as estuaries are typically unique systems, the health of which depends on a complex interaction of many factors. For example, it is not possible to define a generic minimum proportion of the mean annual runoff required for maintenance of health for all estuaries or even for specific classes of estuaries. A comprehensive reserve determination process has been established by the Department of Water Affairs and Forestry for determination of required inputs (primarily in respect of quality and quantity of freshwater) for maintenance of estuarine health or for achieving a desired health status. Estuaries respond in a linear manner to anthropogenic disturbance over narrow tolerance ranges only, and generally respond in a ANDREW BROWN 24 : ESTUARIES
Estuaries are complex, dynamic systems affected by changes across all marine and terrestrial spectra. COASTAL
Page 1: ECOSYSTEM GUIDELINES FOR ENVIRONMEN
Page 4 and 5: CHARL DE VILLIERS (EDITOR) Conserva
Page 6 and 7: CONTENTS 7 : 8 : 10 : 14 : 22 : 24
Page 8 and 9: “Environmental Assessment provide
Page 10 and 11: PREFACE Charl de Villiers These gui
Page 12 and 13: INTRODUCTION Susie Brownlie Purpose
Page 14 and 15: The drafting process, which was co-
Page 16 and 17: INCLUDING BIODIVERSITY CONSIDERATIO
Page 18 and 19: UNEP's voluntary guidelines on biod
Page 20 and 21: Breede River valley: CAPE and SKEP
Page 22 and 23: STEP 4: WHEN SIGNIFICANT IMPACTS AR
Page 24 and 25: A NOTE ON FIRE All fynbos types req
Page 28 and 29: COASTAL non-linear manner over wide
Page 30 and 31: COASTAL SANDY BEACHES & DUNE SYSTEM
Page 32 and 33: COASTAL What are the “bottom line
Page 34 and 35: COASTAL INCORPORATING WEST AND SOUT
Page 36 and 37: COASTAL Strandveld is also increasi
Page 38 and 39: What are the critical things to mai
Page 40 and 41: LOWLAND FYNBOS INCORPORATING SAND F
Page 42 and 43: LOWLAND FYNBOS Veld clearance for r
Page 44 and 45: NICK HELME LOWLAND FYNBOS Leipoldtv
Page 46 and 47: MIDLAND & MOUNTAIN INCORPORATING AL
Page 48 and 49: MIDLAND & MOUNTAIN Altered fire reg
Page 50 and 51: MIDLAND & MOUNTAIN What are the cri
Page 52 and 53: MIDLAND & MOUNTAIN will move in fro
Page 54 and 55: RENOSTERVELD INCORPORATING COAST &
Page 56 and 57: RENOSTERVELD Urban expansion is a p
Page 58 and 59: RENOSTERVELD What, if any, reliable
Page 60 and 61: SUCCULENT KAROO INCORPORATING VYGIE
Page 62 and 63: SUCCULENT KAROO Quarrying for grani
Page 64 and 65: MAINLAND THICKET INCORPORATING THIC
Page 66 and 67: MAINLAND THICKET appear to recover
Page 68 and 69: MAINLAND THICKET What are the criti
Page 70 and 71: FRESHWATER FRESHWATER ECOSYSTEMS: W
Page 72 and 73: FRESHWATER What are the key issues,
Page 74 and 75: FRESHWATER exotic garden escapees i
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FRESHWATER INCORPORATING MINOR DRAI
Page 78 and 79:
FRESHWATER Introduction to the syst
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SCEPS SPATIAL COMPONENTS OF ECOLOGI
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JAN VLOK SCEPS Quartz patches can s
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SCEPS those characterised by mosaic
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TABLE 4: EXAMPLES OF SPATIAL COMPON
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SCEPS ecosystems (e.g. Granite Fynb
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REFERENCES & RESOURCES There is a w
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APPENDIX 1 SOUTH AFRICAN VEGETATION
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APPENDIX 2 RECOMMENDED TERMS OF REF
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SALDANHA CAPE TOWN VANRHYNSDORP CER
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Ecosystem Guidelines for Environmental Assessment

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