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covered 19 ha and grassland 1.3 ha. Open sand, including the beach, made up 46 ha. Fynbos communities made up fairly large patches in the study area with a total cover of 56 ha or 27.3% of the study area. Dense stands of exotic vegetation surround the estuary with the main invader being the rooikrans Acacia cyclops (Heydorn & Bickerton 1982). 3.5 Invertebrates Invertebrates inhabiting estuaries can be divided into a number of sub-groups based on where they reside in the estuary. Zooplankton live mostly in the water column, benthic organisms live in the sediments on the bottom and sides of the estuary channel, and hyperbenthic organisms live just above the sediment surface. Benthic organisms are frequently further subdivided into intertidal (those living between the high and low water marks on the banks of the estuary) and subtidal groups (those living below the low water mark). Only limited information on some benthic and hyperbenthic species is available for the Uilkraals Estuary, summarised below. Benthic invertebrates During a 1955 survey, before the construction of the road bridge, a good population of bloodworms Arenicola loveni, sandprawns Callianassa kraussi and mudprawns Upogebia africana were found both up- and downstream of the foot bridge (Heydorn & Bickerton 1982, Gaigher 1984). In 1973 a strong, viable population of bloodworms was reported in the tidally exposed sandbanks of the estuary reaching at least 2 km upstream (Gaigher 1984). Three years later, after the erection of the road bridge and the long rubble embankment on which it was built, no bloodworms were found above the bridge, which is situated approximately 800 m from the mouth. Another survey in 1979 confirmed the extinction of the bloodworm in the estuary. A very small juvenile bloodworm population was found in a permanent seawater pool on the beach adjacent to the estuary mouth (Gaigher 1984). The associated change in the salinity regime of the estuary caused by the construction of the road bridge is the most likely cause of the loss of this species from the estuary. In December 1979 sandprawns and mudprawns were found up and downstream of the new road bridge, with sandprawns being more abundant and more widely distributed. Mudprawn distribution ended abruptly 100 m upstream of the bridge (Heydorn & Bickerton 1982). In March 1981, sandprawns were found in abundance from the mouth across the floodplain to where freshwater conditions prevailed. Only a few mudprawn burrows were noted (Heydorn & Bickerton 1982). Hyperbenthic invertebrates The crown crab Hymenosa orbiculare and the hermit crab Diogenes brevirostris were abundant near the road bridge in 1979, while smaller numbers of the crab Cyclograpsus punctatus were found in the same area. In 1981 large numbers of C. punctatus were found just above the bridge, as well as large numbers of the shrimp Palaemon pacificus (Heydorn & Bickerton 1982). Uilkraals Estuary Situation Assessment 25 Anchor Environmental
3.6 Fish Estuaries provide an extremely important habitat for fish in southern Africa. The vast majority of coastal habitat in southern Africa is directly exposed to the open ocean, and as such is subject to intensive wave action throughout the year (Field & Griffiths 1991). Estuaries in southern Africa are thus disproportionately important relative to other parts of the world, in that they constitute the bulk of the sheltered, shallow water inshore habitat in the region. Juveniles of many marine fish species in southern Africa have adapted to take advantage of this situation, and have developed the necessary adaptations to enable them to persist in estuaries for at least part of their life cycles. There are at least 100 species that show a clear association with estuaries in South Africa (Whitfield 1998). Most of these are juveniles of marine species that enter estuaries as juveniles, remain there for a year or more before returning to the marine environment as adults or sub-adults where they spawn, completing the cycles. Several other species also use estuaries in southern Africa, including some that are able to complete their entire life cycles in these systems, and a range of salt tolerant freshwater species and euryhaline marine species. Whitfield (1994) has developed a detailed classification system of estuary associated fishes in southern Africa. He recognized five major categories of estuary associated fish species and several subcategories (Table 1). Table 1. Classification of South African fish fauna according to their dependence on estuaries (Whitfield 1994) Category I Ia Ib II IIa IIb IIc III IV V Description Truly estuarine species, which breed in southern African estuaries; subdivided as follows: Resident species which have not been recorded breeding in the freshwater or marine environment Resident species which have marine or freshwater breeding populations Euryhaline marine species which usually breed at sea with the juveniles showing varying degrees of dependence on southern African estuaries; subdivided as follows: Juveniles dependant of estuaries as nursery areas Juveniles occur mainly in estuaries, but are also found at sea Juveniles occur in estuaries but are more abundant at sea Marine species which occur in estuaries in small numbers but are not dependant on these systems Euryhaline freshwater species that can penetrate estuaries depending on salinity tolerance. Includes some species which may breed in both freshwater and estuarine systems Obligate catadromous species which use estuaries as transit routes between the marine and freshwater environments Fish species in categories I, II, and V as defined by Whitfield (1994) are all wholly or largely dependent on estuaries for their survival and are hence the most important from an estuary conservation perspective. These species need to receive most attention from a management perspective. Uilkraals Estuary Situation Assessment 26 Anchor Environmental
Page 1 and 2: C.A.P.E. Estuaries Management Progr
Page 3 and 4: ubble spanning almost two-thirds of
Page 5 and 6: estuary’s functioning is catered
Page 7 and 8: ABBREVIATIONS AND ACRONYMS WMA BAS
Page 9 and 10: The reserve determination process .
Page 11 and 12: construction of the Kraaibosch dam
Page 13 and 14: The Uilkraals catchment lies within
Page 15 and 16: The Kraaibosch dam (Figure 6) was c
Page 17 and 18: eaches and tourism and fishing indu
Page 19 and 20: 3. ECOLOGICAL CHARACTERISTICS AND F
Page 21 and 22: The first time in recorded history
Page 23 and 24: 3.2 Water chemistry The distributio
Page 25: other associated high water levels.
Page 29 and 30: Table 2. Species composition, abund
Page 31 and 32: For this study, a count of water-as
Page 33 and 34: score of 55 (van Niekerk, unpubl. d
Page 35 and 36: 4. ECOSYSTEM SERVICES 4.1 What are
Page 37 and 38: isolation, but only inasmuch as it
Page 39 and 40: 4.8 Genetic resources Genetic resou
Page 41 and 42: 5. LEGISLATION AND MANAGEMENT ISSUE
Page 43 and 44: Land use & management Water quality
Page 45 and 46: Table 10. Provincial and local gove
Page 47 and 48: Goal # Goal Strategies practices do
Page 49 and 50: 5.4 Exploitation of living marine r
Page 51 and 52: In terms of ICMA, all land within o
Page 53 and 54: (e) stabilising walls; (f) building
Page 55 and 56: Table 14 (Overstrand Local Municipa
Page 57 and 58: Table 13. Overberg District Spatial
Page 59 and 60: Component Strategy with spatial imp
Page 61 and 62: Component Strategy with spatial imp
Page 63 and 64: Table 14. Overstrand Local Municipa
Page 65 and 66: Component Description Policies 9. S
Page 67 and 68: Issues of surrounding land use and
Page 69 and 70: protected area by a single manageme
Page 71 and 72: 6. REFERENCES Adams, J.B., Bate, G.
Page 73 and 74: Smith, N & Cullinan, C. 2000. Revie
Page 75 and 76: 8. Plan for awareness-raising and p

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