Coast KZN

Arid coastal dune systems are ever changing with storms and seasons. Many of the coastal communities may disappear in a single storm event or gradually change in response to changing environmental factors. The coastal dune communities are often quite distinct, consisting of monospecific stands of pioneer plants. In other cases there may be a graduation from the pioneers into thicket, so that the different communities are not that distinct.

Although estuaries are distinct habitats with an individual ecology, they form part of a transition gradient where freshwater from rivers meets saltwater from the sea. In the broadest sense, this is the longest standing and most universally accepted definition of an estuary. KZN has some of South Africa's finest estuaries, which provide a suite of goods and services to the province's communities. However, they are the most vulnerable of ecosystems and many of KZN's smaller estuaries are in a degraded state.

Mangroves occur on the eastern coastline of South Africa, from East London (Nahoon Estuary) to Kosi Bay, between mean sea level and mean highwater springtide level. They are inundated during high tide and exposed during low tide. Changes in freshwater inflow to estuaries, increased sedimentation due to land degradation and transformation, and prolonged closed mouth conditions all negatively affect mangroves. While the total area of mangroves in KZN has marginally increased in recent times, the geographic distribution of mangroves has unfortunately been reduced.

Rocky shores account for about 20% of the coast and are mainly located on the southern and central coast. They are composed of dolerite, granite, as well as Quaternary, Ordovician and Ecca sandstone. North of Cape Vidal, the rocky shores are interspersed between long stretches of sandy beach and are composed of Quaternary sandstone. The main threat to KZN rocky shores is coastal development, and given that they represent an important and highly vulnerable part of the coastal zone, these systems need careful protection to ensure long-term sustainability and productivity.

The KZN shelf edge, at 20 m, is a habitat that is always covered by water (subtidal) and characterised by soft sediment at the bottom. Coastal and marine sediments, ranging from large gravel elements to fine muds, occupy over 70% of the seafloor and constitute one of the largest habitats on earth. In KZN the most significant subtidal soft sediment habitat is found on the continental shelf between Richards Bay and Durban. This uncharacteristicly wide shelf section, known as the Natal Bight, has been identified as being highly productive due to the influence of local oceanographic features as well as out-welling via the Thukela River, one of the largest rivers in the country.