Image related to website content

World Oceans Day 2024 - understanding our impact on the ocean

6 Jun 2024 by CapeNature

By Pierre de Villiers, Senior Manager, Marine and Coasts Operations

The link between oceans and the land is often not well understood. People describe the ocean as that massive water space out there. Little do they know that where they live and how they live actually impacts on this ocean, so much so that they, in their small way, can contribute to a healthy ocean or a polluted ocean.

Image related to website content

The ocean is known to provide up to 80% of the moisture that eventually falls onto the land surfaces in the form of rain. Changes in ocean currents and ocean storms result in immediate changes in rainfall on the land, e.g. floods and droughts. When this rain does fall, it flows down gullies initially and eventually finds its way into streams and rivers which all flow down to the ocean. Every single space on land that gets wet during a storm is linked eventually to the ocean. A mountain may provide small rock particles that eventually become sand particles on a beach. A forest may provide leaf litter that will stain the flowing water black and create a dark plume of nutrients in the ocean where it enters the sea.

Image related to website content

The interactions from mountain catchment, rivers, wetlands to the coast and finally the ocean have been taking place for millions of years. They have resulted in the beautiful landscape you see now. They have also resulted in the characteristic near shore areas with beautiful kelp forests on rocky reefs and vast sandy beaches. The critical link between the catchments including the lands between the rivers and the ocean are the estuaries. These ecosystems form ever changing habitats that are totally dependent on freshwater inflows during the rainy season as well as the inflow of seawater when the estuary mouth opens.

The species that inhabit estuaries are adapted to live in changing salinities (salt level in the water) as well as changing water temperatures. Under natural conditions, floods result in the water level in estuaries rising and this eventually scours open the mouth. The rising water level can take from months to days depending on the rainfall and freshwater inflow into the estuary. As the water level rises it becomes fresher. When the mouth bursts open this mixed water pours into the ocean and deposits nutrients and sand in the near shore area. These form products critical to the ocean. This plume of relatively fresh water in the ocean also attracts ocean species that use an estuary as part of their life cycle. These species "smell" this water and travel far distances to enter the open estuary mouth. Many marine fish larvae enter the estuaries in this way. Estuaries form safe havens rich in food for the growing juvenile fish. They and other species like them will grow up in an estuary and go back out to sea to breed at a future date when the estuary mouth opens again. Nature and its survival is lined to these natural rhythms.

Image related to website content

Humans use water for irrigation, industry and for use in their homes. Dams have been built on rivers and sometimes as much as 50% of the available freshwater runoff is used before it reaches the estuary or ocean. The ocean was initially providing moisture in the form of rain that flowed over the land gathering essential particles to take back to the ocean again. This has now been interrupted by dams and pipelines. Freshwater flows have now been calculated by specialists in the form of an ecological reserve, This study works out how much water can be used by humans and how much is needed to sustain the aquatic ecosystems from the rivers to the ocean. It is critical from a conservation perspective to monitor these flows and the resulting water quality in the estuaries to make sure this is taking place. CapeNature has trained estuary monitoring teams supported by partners, who monitor estuaries on a monthly basis. Sometimes during critical times monitoring is more regular. Specific mouth maintenance management plans have been developed to allow managers to open the estuary mouth if specific triggers are reached. These triggers are calculated by specialists with the aim of allowing for the connectivity between the catchment and the ocean despite the use of water upstream.

Image related to website content

This is critical work carried out by a few dedicated officials. reporting is to managers who then need to make decisions and implement these with the aim of conserving our valuable natural heritage and functional catchment, estuarine and ocean ecosystems.

Share:

Related News

Newsleter blog Donation Box 1
5 Oct 2026
CapeNature visitors invited to support communities through new donation scheme

A visit to a CapeNature nature reserve can help a neighbour in need. From 5 October 2026, guests at three participating nature reserves can bring gently used clothing, blankets and other essential items for local non-profit organisations. The first phase of the donation scheme will run at Grootvadersbosch Nature Reserve near Heidelberg, Kogelberg Nature Reserve near Kleinmond, and Cederberg Wilderness Nature Reserve near Clanwilliam.
Kogelberg Nature Reserve copyright Scott Ramsay 29
1 Oct 2026
Radio network upgrade to strengthen emergency communication in Hangklip area

CapeNature and Overstrand Municipality will install a small radio repeater station near Hangklip Peak as part of an upgrade to the region’s radio communication network. The repeater will strengthen the communication networks used by both parties and improve coverage across the Overstrand municipal area, Kogelberg Nature Reserve, Betty’s Bay Marine Protected Area and parts of the City of Cape Town. Reliable radio communication is essential for the daily operations of 
2026 State of Conservation Report Front Cover
30 Sep 2026
State of Conservation Report 2026 tracks progress and pressures facing Western Cape biodiversity

The Western Cape’s biodiversity is facing mounting pressure, with a sharp increase in the area affected by fires and more ecosystems and species classified as threatened, according to the Western Cape State of Conservation Report 2026. The report records 107 fires that burned 215 936 hectares during the 2025/26 reporting period – almost three times the 75 174 hectares burned by 97 fires in the previous reporting period.
Cederberg Fire Photo Dec 2025 by Peter Hagen
29 Sep 2026
El Niño raises fire risk as Western Cape prepares for a challenging fire season

The Western Cape is preparing for a potentially challenging wildfire season, with the developing El Niño weather pattern expected to contribute to hotter and drier conditions and an increased risk of wildfires across the province. The South African Weather Service has warned of below-normal rainfall associated with the expected strong El Niño during the coming summer season. While El Niño does not automatically mean that every part of the province will experience drought
Seal Rabies
28 Sep 2026
Cape fur seal safety remains important this World Rabies Day

On World Rabies Day (28 September), CapeNature is reminding residents and visitors to keep a safe distance from Cape fur seals and to act immediately if they or their pets are bitten, scratched or exposed to a seal’s saliva. Rabies has been detected in Cape fur seals along the South African coastline and by the end of 2025, at least 176 people had been bitten by seals. While most seals do not pose a threat to people, they are wild animals and should never be approached, touched, fed or encouraged to interact with humans.
Dont Be Trashy Clean Up September 2026
21 Sep 2026
How Waste Affects Biodiversity and What We Can Do About It

Waste is more than an eyesore. Littered streets, polluted rivers and overflowing landfills are visible signs of a much wider environmental problem. Every year, people generate large volumes of waste, yet much of it is not managed effectively. In South Africa, more than 60% of waste has been reported as ending up in landfills. With service-delivery challenges and many major landfill sites approaching capacity, the pressure on communities and natural ecosystems continues to grow. Both terrestrial and aquatic biodiversity carry much of the impact.