Uilkraals Situation Assessment - Anchor Environmental

1. INTRODUCTIONThe Uilkraals Estuary is one of South Africa’s approximately 279 functional estuaries (Turpie2004). It is one of 21 estuaries within the warm temperate biogeographical region to beclassified as a temporarily open/closed, mixed blackwater system (van Niekerk & Taljaard2007). A medium to large sized estuary, it is estimated to cover an area of 105 ha (Turpie &Clark 2007) (Figure 1), and before the construction of the upstream Kraaibosch Dam hadnaturally hyposaline conditions and a strong tidal exchange when open to the sea. This tidalexchange helped to maintain an open mouth state (Harrison et al. 1995b), but since theconstruction of the dam in 1999, there has been a disruption in the natural freshwater inflows.Owing to its large size, high diversity and abundance of certain biota, the estuary is rated as34 th overall in terms of conservation importance in South Africa (Turpie et al. 2002, Turpie &Clark 2007). It has been identified as a particularly important estuary for macrophyte diversity(macroalgae, submerged macrophytes and saltmarsh) and birds (both residential and migrants)(Barnes 1996).Figure 1: The Uilkraals Estuary before it became closed to the sea (Source: Google Earth).Despite the widely acknowledged conservation importance of the Uilkraals Estuary, the systemis currently under no formal protection. The estuary has been subjected to relatively highlevels of development and anthropogenic disturbance. This includes the construction of theroad bridge over the estuary which affected the natural east to west migration of the mouth.Increasing recreational use of the estuary, including natural resource use (such as fishing) andnon‐consumptive activities (birdwatching and hiking) is putting pressure on the system, whichwill most likely see a change in the character of the area. However, the most significant impacthas been the reduction in freshwater flow into the estuary due to water storage. TheUilkraals Estuary Situation Assessment9Anchor Environmental