Download PDF - Anchor Environmental

More documents

Recommendations

Info

Verlorenvlei Estuary Management Plan Part 2: Resource Objectives & Zoning The EZP, together with the Operational Specifications, is the “Blueprint” against which any existing or future initiative, development or activity in the estuary is measured. MAPs and environmental impact assessment (EIA) studies are required to use the “Blueprint” to derive targets and limits, rather than each developing their own, which may be inconsistent or conflicting. While the overarching EZP provide comprehensive geographical information covering all the aspects, it may be more appropriate to extract the relevant information from the comprehensive plan and to produce “customised EZP” for the different MAPs. For example, compliance officers in municipalities may be more interested in a map that highlights the zones where certain types of activities/developments will be allowed/not allowed (e.g. the traditional EZP), while tourism concerns may be more interested in the demarcation of areas of ecological and heritage value. 2.5.1 Ecological Targets for Verlorenvlei The following ecological specifications for Verlorenvlei, and the associated thresholds of potential concerns (TPCs), are representative of an Ecological Category C/B. The specifications and the associated TPCs are based on a desktop health assessment of Verlorenvlei and needs to be refined during an intermediate ecological water requirement study executed by an estuarine specialist consultant team. Such teams are usually appointed by Department of Water Affairs, Resource Directed Measures Directorate. COMPONENT Water Quality Hydro-dynamics ECOLOGICAL SPECIFICATION Salinity distribution not to exceed TPCs for fish, invertebrates, macrophytes and microalgae (see below) Dissolved oxygen not to exceed TPCs for biota (see below) Turbidity levels in Verlorenvlei should not detrimentally impact biota i.t.o. reduced visibility or smother of benthic communities Inorganic nutrient concentrations in Verlorenvlei should result in excessive algal or reed growth Toxic substance concentrations in Verlorenvlei not to cause detrimental impact on biota Maintain a flow regime to create the required habitat for birds, fish, macrophytes, microalgae and water quality (see below) THRESHOLD OF POTENTIAL CONCERN (PCs) Salinity concentrations in the estuary exceed 35 PSU Salinity concentrations in the Verlorenvlei exceed 10 PSU Dissolved oxygen concentrations in Verlorenvlei decrease below 4 mg/l Average suspended solid concentrations in river inflow increase by more than 10% of present conc's (to be determined asap) Average DIN concentrations in river inflow exceed 300 ug/l Average DIP concentrations in river inflow exceed 50 ug/l Toxic substance concentrations (e.g. trace metals) in river inflow and the water column of Verlorenvlei exceed South African Water Quality guidelines for coastal marine waters (DWAF 1995) Page 2-15
Verlorenvlei Estuary Management Plan Part 2: Resource Objectives & Zoning COMPONENT Sediment dynamics Phytoplankton Benthic microalgae Macrophytes Invertebrates Fish Birds ECOLOGICAL SPECIFICATION Flood regime to maintain the sediment distribution patterns and aquatic habitat (instream physical habitat) so as not to exceed TPCs for biota (see below) Changes in sediment grain size distribution patterns not to exceed TPCs in benthic invertebrates (see below) Maintain low phytoplankton biomass. Maintain microalgal group diversity as measured for the baseline survey. Maintain high subtidal bentehic microalgal biomass during the closed mouth phase . Maintain the distribution of plant community types. Prevent excessive filamentous macroalgal growth. Ensure the long-term persistence of salt marsh species. Prevent hypersaline sediment and groundwater conditions in the salt marsh. Retain the following fish assemblages in the estuary (based on abundance): Estuarine species (10-20 %); Estuarine associated marine species (80-90 %); and Indigenous freshwater species (1 %). All numerically dominant species are represented by 0+ juveniles. Retain regular representation of waders, gulls, and terns, and overall waterbird species richness of seven or more species. THRESHOLD OF POTENTIAL CONCERN (PCs) Area covered should be less than 50 % of the open water surface area. Decline in salt marsh species. Sediment electrical conductivity should be approximately 30 mS and similar to groundwater values. Level of estuarine species increases above 60 % of total abundance. Level of estuary associated marine species drops below 60 % of total abundance. Alien Lepomis macrochirus and Micropterus spp. dominate in the upper reaches. Absence of 0+ juveniles of any of the dominant fish species. Waders or terns are absent from the estuary for five consecutive counts. 2.5.2 Heritage Targets for Verlorenvlei To be included in later version of EMP once zoning plan has been approved by the Estuary Forum Executive team in consultation forum representatives. 2.5.3 Socio-economic Targets for Verlorenvlei To be included in later version of EMP once zoning plan has been approved by the Estuary Forum Executive team in consultation forum representatives. 2.6 Overview of Existing Monitoring Programmes There is very little baseline ecological information available on Verlorenvlei. It is of the utmost importance to develop an in-depth understanding of how the ecology functions. Current monitoring initiatives include: Page 2-16
Page 1 and 2: C.A.P.E. Estuaries Programme ESTUAR
Page 3 and 4: Verlorenvlei Estuary Management Pla
Page 25 and 26: Living Resources Water Quantity & Q
Page 27 and 28: Water Quantity & Quality Land-use &
Page 29 and 30: Living Resources Water Quantity & Q
Page 31 and 32: Ecological Verlorenvlei Estuary Man
Page 37: Verlorenvlei Estuary Management Pla

Download PDF - Anchor Environmental

Create successful ePaper yourself

Delete template?

Save as template?