Uilkraals Situation Assessment - Anchor Environmental

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3.4 VegetationThere are four main vegetation communities associated with the Uilkraals Estuary: macroalgae,submerged macrophytes, reeds and sedges, and salt marsh.Heydorn & Bickerton (1982) recorded 13 species of semi‐aquatic plants in and around theUilkraals Estuary. These included Crassula glomerata, Plantago carnosa, triglochin bulbosum,Scirpus littoralis, Sebaea minutiflora, Sebaea albens, Spergularia marginata, Cotula eckloniana,Chenolea diffusa, Samolus deis and Limonium scabrum.MacroalgaeMacroalgae can be indicative of water quality and nutrient enrichment. Macroalgae may beintertidal (intermittently exposed) or subtidal (continually submerged) and can be attached tohard or soft substrata or they may float (Adams et al. 1999). Opportunistic macroalgae arefound in temporary closed estuaries like the Uilkraals as they can tolerate fluctuating salinities.During a survey in 1981 the filamentous algae Enteromorpha and Cladophora were recorded inthe estuary and Ulva beds were present under the road bridge (Heydorn & Bickerton 1982).Enteromorpha and Cladorphora belong to the family Chlorophyta, and are often found toextend further into estuaries due to their salinity tolerance (Adams et al. 1999).Submerged macrophytesThe high macrophyte diversity in the Uilkraals Estuary is of conservation importance. Thereare approximately 2 ha of submerged macrophytes in the estuary, which provide an importanthabitat for invertebrates and juvenile fish. Submerged macrophytes are plants rooted in bothsoft subtidal and low intertidal substrata, which are completely submersed for most states ofthe tide (Adams et al. 1999). Submerged macrophyte beds support diverse and abundantinvertebrate and juvenile fish communities (Whitfield 1984, 1989). Primary productivity ofsubmerged macrophytes is high and on par with the most productive plant habitats in marineand terrestrial ecosystems (Day 1981, Fredette et al. 1990). Adams et al. (1999) found in salinewaters in the region, Zostera capensis is prevalent. Submerged macrophytes are important intheir provision of food for epifaunal and benthic invertebrate species as well as nursery areasfor juvenile fish through the provision of food, shelter and protection (Adams et al. 1999).Salt marshSalt marshes in estuaries are a source of primary production and provide habitat and food for avariety of faunal species (Adams et al. 2006). The degree of tidal flushing is important indetermining how much nutrients they release into the water column (Childers & Day 1990).An open mouth is important as this maintains the intertidal salt marsh community. Salt marshplants are distributed away from the water’s edge along an inundation gradient (Figure 13).Intertidal salt marsh occurs between the limits of the high and low tide ranges, while supratidalmarsh occurs above the intertidal zone and is only normally flooded during spring tide andUilkraals Estuary Situation Assessment23Anchor Environmental
other associated high water levels. Floodplain marshes are normally elevated above the rest ofthe estuary, and are normally only covered with water during large flood events.Mucina et al. (2003) described and classified 11 salt marsh plant communities at the UilkraalsEstuary. Dominant species included Salicornia meyeriana, Sarcocornia perennis agg., S.capensis, S. decumbens, Bassia diffusa, Limonium sp. nova, Juncus kraussii subsp. kraussii,Sporobolus virginicus and Triglochin bulbosa. In a 1981, study the saltmarsh covered an area ofapproximately 1.3 ha or 0.6% of the studied estuarine region (Heydorn & Bickerton 1982) andhad the highest cover (95%) of all recorded vegetation types. A more recent vegetation studyrecorded approximately 38 ha of saltmarsh, which is still the highest cover of all recordedvegetation types and is of high conservation importance.Figure 13. Picture of the upper channel and saltmarsh area facing upstream, February 2010.Reeds and sedgesReeds and sedges act as natural biological filters, they are important for bank stabilisation asthey are rooted in soft intertidal or shallow subtidal strata (Adams et al. 1999). Reeds andsedges contribute to the diversity of aquatic life, particularly the avifauna (Coetzee et al. 1997).Terrestrial vegetationParsons (1982) identified 10 main terrestrial plant communities around the Uilkraals Estuary,including the saltmarsh (Error! Reference source not found.). These can be consolidated intofive plant formations visually: low shrubland (0.25‐1.0 m), mid‐high shrubland (1‐2 m),woodland, herbland and grassland. In the study area (205 ha) the low shrubland was the mostextensive (39 ha), followed by the herbland (37 ha) and woodland (32 ha). Mid‐high shrublandUilkraals Estuary Situation Assessment24Anchor Environmental
Page 1: C.A.P.E. Estuaries Management Progr
Page 6 and 7: Need for protection of the Uilkraal
Page 8 and 9: TABLE OF CONTENTS1. INTRODUCTION...
Page 10 and 11: 1. INTRODUCTIONThe Uilkraals Estuar
Page 12 and 13: 2. GEOGRAPHIC AND SOCIO‐ECONOMIC
Page 14 and 15: 2.2 Catchment climate, vegetation a
Page 16 and 17: Figure 7: Annual rainfall for the U
Page 18 and 19: EconomyAgriculture dominates much o
Page 20 and 21: Figure 9. An aerial view of the Uil
Page 22 and 23: Figure 12. Pictures of the exposed
Page 26 and 27: covered 19 ha and grassland 1.3 ha.
Page 28: Because the Uilkraals Estuary is ca
Page 31 and 32: For this study, a count of water‐
Page 33 and 34: iophysical variables. The current s
Page 36 and 37: Table 8. Ecosystem goods, services
Page 38 and 39: Estuaries are typically shallow and
Page 40 and 41: strands of remnant undisturbed fynb
Page 42 and 43: • to have the environment protect
Page 44 and 45: ProtectedareasUse of living resourc
Page 46 and 47: Table 11.Goals and strategies in th
Page 48 and 49: 5.3 Water quantity and quality requ
Page 50 and 51: Development planning has been rathe
Page 52 and 53: and weakening or destruction of the
Page 54 and 55: • take into consideration whether
Page 56 and 57: principles involve identifying an o
Page 58 and 59: Component Strategy with spatial imp
Page 64 and 65: Component Description PoliciesConse
Page 66 and 67: Component Description PoliciesCore
Page 68 and 69: Other recreational activities are o
Page 70 and 71: 2. Establish a Marine Protected Are
Page 72 and 73: Gillanders, B.M. & Kingsford, M.J.
Page 74 and 75:
APPENDIX 1: TERMS OF REFERENCEThe d
Page 76:
6. Monitoring and evaluationAn appr
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