An Estuary - a river which meets the sea. It’s classified as a zone between fresh water and marine environments. Salinities differs according to the state of the tide, it happens more on a seasonal basis. Certain Estuaries is divided by sand during low rainfall however, usually estuaries are permanently open to the sea. Animals and plant life usually adapt to conditions of the estuaries. During high rainfall the salinity levels lower and during low level waters the saline is higher.
Rivers are usually extremely productive systems as it is nutritious and organically rich in slit from the catchment area. Primary producers are, phytoplankton, diatoms and filamentous algae which lies at the bottom sediments. Despite all the different plant species there are true herbivores in estuaries. Many fish use estuaries to protect their young and would enter the sea once they have reached maturity as the estuaries is the perfect nursery for these young for all the nutritious plant species it has. Fish eaters usually occur during certain periods of the year. Waders are seen which usually migrate to South Africa estuaries for our summers. Cape Town’s estuaries are experiencing negative impacts on the environment due to construction and buildings around the estuaries.