Estuaries
Estuaries are the places where rivers enter the sea. In these dynamic and special areas life is adapted to sudden changes in salinity, water temperature and sediment loads. Although estuaries make up a very tiny portion of our marine area, they are high powered ecosystems that deliver multiple ecosystem services. Estuaries are nursery areas for young fish and because of their high productivity they are economically and ecologically valuable. Estuarine habitats such as saltmarshes and mangroves play a key role in carbon storage and climate regulation and estuaries provide food, materials for construction (reeds and wood) and safe areas during extreme weather events.
Pressures on estuaries include fresh water flow reduction (as a result of removing water upstream), fishing, coastal development and waste water discharge. South Africa has 290 estuaries that include 22 different estuary types. The status of the estuary mouth (such as permanently open versus temporarily closed) and biogeographic region influence the species and functioning of the different estuary types. Many species, including economically important and delicious species such as fish and prawns, depend on estuaries to complete their life cycles. Estuaries are vulnerable ecosystems but they can recover if their flow requirements are met, water quality, development and fishing are managed and invasive species are avoided. Outfalls and mining in estuaries should be avoided. Gill-netting in estuaries compromise the nursery function of these valuable ecosystems.
The Groenrivier estuary will be protected in Namaqua National Park MPA and uThukela river mouth in uThukela Banks MPA. Improved estuarine protection is a national priority.
