ECOSYSTEMS

 

Three oceans surround South Africa; the Indian, the Atlantic and the Southern.

A good mix of warm, cold and even colder. This results in an incredible diversity of habitats, from the enchanting kelp forests that hug the west coast to the deep sea muds that are home to strange creatures beyond our wildest dreams.

 
 
 

SANdy shores

Sandy shores provide one of South Africa’s most valuable services….beaches! Not only are healthy beaches one of our most important tourism, recreational and cultural assets, but beaches are also important ecosystems that play a key role in nutrient cycling, food supply for humans and wildlife, breeding areas for animals such as turtles and homes to thousands of tiny animals that live among the grains of sand. Animals that live on beaches are tough creatures adapted to the shifting sand, tides and waves. Many beach animals burrow into the sand, these include plough snails, ghost crabs, giant pill bugs (or “ teddy bear “ isopods) and white mussels. Hundreds of even smaller creatures live between the sand grains, while birds and fish visit to feed on sandy shores. Seaweed and kelp washed up on beaches increases food supply and form a key part of beach ecosystems.

Healthy beaches require management of the highly connected system of dunes, beaches, and surf zone. This set of interacting habitats is known as the littoral active zone.  Beach management needs to maintain the flow of materials between the dunes, beach and surf zone. Where estuaries occur, good estuary condition contributes to beach resilience.

Inappropriate coastal development, mining, reduced fresh water flow and pollution are key pressures on South African beaches. Beach driving is no longer  a substantial pressure as vehicle access is limited. Management of resource use such as shore angling, bait collection and net fishing is also important for beach health.

Important sandy shores will be protected in Namaqua National Park MPA, iSimangaliso MPA, uThukela Banks MPA and Addo Elephant National Park MPA.

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ROCKY SHOREs

Rocky intertidal shores are among the most charismatic, colourful, accessible and interesting ecosystems in South Africa. Children and adults alike are drawn into the wonder of these magical habitats where tides and waves shape seaweed and lichen gardens, dense beds of mussels, oysters and limpets and a great diversity of other fascinating sea creatures. The shores of South Africa have fed humans since the earliest times with seafood harvested from rocky shores believed to have played a key role in human evolution, providing essential fats and nutrients critical to brain development.

South Africa’s rocky shores vary with region, wave exposure, rock type and sand cover resulting in many different ecosystem types and species. Mixed shores are those that include both rocky and sandy habitats, which usually change over time. Boulder shores, another type of rocky shore, host their own unique set of animals adapted to boulders, and not more stable rocky platforms.

Pressures on rocky shores include harvesting, invasive species, coastal development, pollution and mining. Traditional methods of selective mussel or oyster harvesting (such as by stick or screwdriver) have a lower impact than wide blade instruments such as spades. Strip harvesting that clears large areas can alter rocky shore ecosystems causing food species to be replaced with inedible seaweed turfs. Careful, selective harvesting of rocky shore animals can ensure sustainable use, without damaging the ecosystem. Managing water quality is also important for healthy shores. Preventing the introduction of invasive alien species by good management in the shipping, petroleum, yachting and aquaculture sectors will avoid the often irreversible impacts of invasive species.

The first protection of Namaqualand rocky shores will be provided in the Namaqua National Park MPA. Rocky shores in KwaZulu-Natal will receive additional protection in the expansion of the Aliwal Shoal MPA.

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BAYS

Most of South Africa's coastline is exposed to waves with relatively few sheltered areas. Bays are special because they provide shelter from waves and storms, and because they retain water and concentrate plankton (including the tiny larvae of most marine creatures including fish). They provide us with harbours, seafood, safe swimming opportunities and beautiful beaches.

St Helena Bay on the productive west coast is an important nursery ground for commercially exploited fish, and is known for its frequent low oxygen events. Cape Bays, such as Saldahna and Table Bay, have a long history in supporting trade, fisheries, aquaculture and tourism. False and Walker Bay were famous for their fishing opportunities and at night the sounds of whales breathing can sometimes be heard during whale season. Reefs in False Bay host different species to those on the Atlantic coast and are popular destinations for scuba divers. They have also supported more than 100 years of linefishing, both commercial and recreational. On the south coast, bays such as Algoa Bay near Port Elizabeth feature many endemic species found only in South Africa.

Bays are ecosystems under pressure, since port, harbour and coastal developments, fish farms and waste water discharge are often concentrated in these special places. Bays also retain pollutants and can experience increased impacts of Harmful Algal Blooms (sometimes known as red or black tides) leading to fish kills, rock lobster walkouts and human health impacts. The cause of increased Harmful Algal Blooms are not well understood, but agricultural fertilizer runoff, depletion of filter feeding fish, invasive species and climate change are likely contributing factors.

Monitoring the ecology of bays, as well as good catchment management, effective fisheries management and the prevention of invasive alien species are important measures to keep bays healthy. Effective management of bays relies on regulating coastal developments, ports and harbours, shipping and fisheries, maintaining water quality and generating opportunities for tourism. Marine Spatial Planning is a key tool that can help balance social, economic and environmental interests in these busy socio-ecological systems.

Important bay ecosystems that will receive increased protection include Algoa Bay in the Addo Elephant National Park MPA.

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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.

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Kelp forests

Kelps are large brown seaweeds that form spectacular underwater forests. Similar to terrestrial forests they have a unique three-dimensional structure and dense forest canopy. They also provide structure and homes for a diverse array of seaweeds and animals. These include valuable resources such as west coast rock lobster, abalone and fish. Animals such as turbo snails, mussels, limpets, abalone, rock lobster and fish, provided a rich source of omega-3 fatty acids, associated with brain function and development. Light filtering through a kelp forest canopy, onto a world of calm below, creates a beautiful seascape, and these kelp forest structures play an important role in buffering our coastal communities from waves and storms. Kelps are harvested and the alginate extracted is used commercially in toothpaste, soaps, ice cream and fabric printing, due to their ability to stabilize, bind, emulsify or mould. They are also harvested for use in agriculture, providing fertilizer to support food production on land and to feed abalone grown by aquaculture.

Kelps are sensitive to temperature and nutrients and they grow best in cold, nutrient-rich water. They are highly productive ecosystems with an impressive growth rate, some species reach up to 70 m in length! Four species of kelp occur in South Africa, the sea bamboo (Ecklonia maxima) is the largest of these and floats on the surface, creating large kelp forest canopies visible from the shore. The split-fan kelp (Laminaria pallida) has the greatest subtidal biomass and production contribution, while the bladder kelp (Macrocystis pyrifera) and the spiny kelp (Ecklonia radiata) are less abundant. Most of these kelps are confined to the shallow waters, but the spiny kelp grows in deeper water such as the forest found on top of the Alphard Banks, a volcanic pinnacle on the Agulhas Bank.  The ecosystem services provided by kelp forests extend beyond the coastal waters of the inner shelf where they are anchored to rocks by their holdfasts (root-like structure). Kelps play a key role in the inshore food-web, including adjacent rocky shores and sandy beaches, and even contribute to deep-sea ecosystems along the west coast, where kelp is transported offshore and into submarine canyons, providing food for other animals.

Pressures on kelp forests include fishing, pollution, kelp harvesting, diamond mining (kelps are cut to provide access for mining) and climate change. Poaching of rock lobster and abalone are serious threats to kelp forest ecosystems and their resources and services. Kelp forests are under threat in many places around the globe because of climate change and kelp forest cover has recently been declared an “essential ocean variable” by the Global Ocean Observing System (GOOS).

Important kelp forest ecosystems will be included in the Agulhas Bank Complex MPA, Robben Island MPA and Namaqua National Park MPA.

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ISLANDS

Islands are important ecosystems because of their isolation from land. Protected from land based predators, birds and seals often gather on islands in spectacular breeding colonies to raise their young. The nutrient input from these animals in the form of guano (bird droppings) and other animal waste products influence the ecology of islands and their shores. For example, increased nutrients around islands increases productivity reflected in more seaweeds, more, bigger and faster growing limpets and in some cases more west coast rock lobster. Historically guano was harvested for fertiliser (before artificial or synthetic fertilisers were produced). The removal of guano was a key threat to seabirds such as the iconic and Endangered African penguin, whose numbers are now at only 2% of original population estimates. Historically, egg harvesting also played a role in the decline of penguins, however, in more recent years changes in the distribution and decreased abundance of forage fish are the major concern for penguins. Pressures on islands include alien species and predators, climate change and overfishing. Well managed islands have effective management of invasive and potential predators and disturbance and other risks to breeding birds are minimised.

Robben and Dassen Island are two of the most important seabird islands on the west coast and although penguin numbers on these islands have declined, these are now the largest penguin colonies on the west coast. Within the West Coast National Park, Malgas Island is home to a large gannet colony. Seal Island in False Bay is world famous for the hunting behaviour of the great white shark, whose aerial displays provide incredible images for photographers from around the world. Bird and St Croix Islands in Algoa Bay are now critically important seabird areas, with St Croix hosting the largest African penguin colony in the world and Bird Island holding the world record for the largest gannet colony.

Important islands will be protected in Robben Island MPA and Addo Elephant National Park MPA.

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REEFs and banks

South Africa is blessed with cold and warm temperate reef systems and warm well-lit subtropical coral communities that attract thousands of scuba divers to our shores. Shallow reef ecosystems span three types of coral communities, hard and soft corals in the iSimangaliso Wetland Park in northern KwaZulu-Natal; the beautiful soft coral and seaweed habitats of Aliwal shoal in KwaZulu-Natal and vividly coloured temperate reefs colonised by sponges, soft and lace corals, ascidians and more on the south and west coasts. Deep reefs are less explored but recent research has revealed deep seaweed forests on the east coast, high sponge diversity across these ecosystems and more than 300 species of soft corals and seafans, many of which are endemic. Just like fynbos is special on land in South Africa, the lace coral and seafan habitats in the Cape and Agulhas ecoregions are highly diverse and unique to South Africa. These can be considered as our special 'underwater fynbos'.

Reefs and Banks support one of our oldest and most important fisheries, the line fishery, which has commercial, small scale, subsistence and recreational components. This fishery was declared in crisis in 2000 and Marine Protected Areas offer the best management option to support recovery and improved future catches of resident fishes such as the red steenbras, Miss Lucy, dageraad, poenskop or musselcracker, rockcods and roman. Alphard Banks and Protea Banks are sites where fish, sharks and rays gather and where spectacular reef structures support fisheries and eco-tourism. These special places need protection from mining, underwater noise, pollution and any activities that impact the seabed such as trawling and anchor damage. Similarly, although further offshore, Child's Bank is a unique ecosystem type whose sensitive coral-covered slopes have already been impacted by trawling. To maintain its eco-certification, the South African hake trawl fishery has committed to improved management of seabed habitats through support for protected areas in sensitive ecosystems and increased knowledge of Vulnerable Marine Ecosystems and the impact of trawling.

Important reefs and banks are included in iSimangaliso MPA, uThukela Banks MPA, Aliwal Shoal Offshore MPA, Protea Banks MPA, Child's Bank MPA, Amathole Offshore MPAAddo Elephant National Park MPA, Benguela Bank MPA, Brown's Banks Corals MPA and Brown's Bank Complex MPA.

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open ocean

This open ocean or pelagic environment is the realm of phytoplankton, microscopic plants that are responsible for half of the world’s oxygen production. Phytoplankton are the foundations for marine ecosystems, and they are eaten by animal plankton such as tiny larvae of most marine creatures including fish. Little fish eat bigger fish that are in turn eaten by larger predators such as tuna, swordfish, sharks, whales, dolphins and seabirds. Small pelagic fish such as sardines and anchovy are an important food source for humans but also feed many other animals and are often referred to as forage fish.

The seabed and open ocean ecosystems are connected and these connections are closer in shallower water (particularly on the shelf) and where seabed structures influence the flow of water such as at seamounts, canyon margins and at the shelf edge. Even though the open ocean may seem similar there are areas of difference such as areas where there are frequent fronts or eddies that may increase food availability. Pressures in open ocean ecosystems include fisheries such as those targeting forage fish and predators such as tunas and sharks. Fishing gears used in such fisheries include purse seine, mid water trawl, line and pole and pelagic long lines. South Africa has a proud tradition of effective fisheries management which is needed to ensure sustainable use. Accidental capture of animals such as seabirds, turtles and some shark species can be minimised by special management measures such as tori lines to reduce bird bycatch, turtle excluder devices and special hooks. Marine Protected Areas can also help protect important feeding areas for open ocean travellers such as turtles, whales and seabirds.

Some protection for for open ocean ecosystems and pelagic species will be provided in the Orange Shelf MPAAgulhas Front MPA, Cape Canyon MPA, Robben Island MPA, Agulhas Bank Complex MPA, Addo Elephant National Park MPA, Protea Banks MPAAmathole Offshore MPASoutheast Atlantic Seamounts MPA and Southwest Indian Seamounts MPA.

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Plateaus

An oceanic plateau is a raised area of seafloor, elevated above the adjacent abyssal plains and different from seamounts in that they are a very large, often relatively flat piece of seafloor. South Africa has only one plateau in its ocean territory, the Agulhas Plateau, a feature that formed more than 90 million years ago and a key remnant of the break up of the supercontinent Gondwana. The Agulhas Plateau formed as the moving plates passed over a hotspot, similar to how the Hawaiian Island chain has formed. The Agulhas Plateau formed near what is known as the “Triple junction” where Gondwanaland broke up into Africa, Antarctica and South America. It rises 2 500 m above the surrounding seafloor and covers an area of about 300 000 km2.

The Agulhas Plateau is bounded by a very deep abyssal channel known as the Agulhas Passage to the north; by the abyssal Agulhas Basin to the west; and by the Transkei Basin to the north-east. Nobody has ever seen the ecosystems of the Agulhas plateau but these will be protected within the proposed Agulhas Front MPA. Elsewhere in the world, plateau ecosystems are known to host distinctive biodiversity. Key pressures in these ecosystems include seabed mining and risks associated with drilling for petroleum in deep water.

The proposed Agulhas Front MPA will protect a small proportion of the Agulhas Plateau in an area most frequently visited by our Critically Endangered Leatherback Turtles.

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SEAMOUNTS

Seamounts are undersea mountains, rising from abyssal depths, usually formed by volcanic activity. Unlike islands, they don’t reach the surface and unlike plateaus they usually have a conical shape. Seamounts form stepping stones in the ocean for animal dispersal and have often been described as oases of abundance and biomass in the ocean. They provide important habitats for open ocean animals, deep-sea fish and invertebrates that thrive on the elevated position of the seabed. They provide a solid surface, something hard to find in the open ocean, for a diverse range of animals including corals, sponges, and other filter feeding animals which attach themselves in dense colonies to the seamount slopes. The open ocean above the summits and sides of seamounts are also unique, and show unique biological or biogeochemical properties.  Currents well up and swirl around the mountain, serving up a constant supply of nutrients and plankton, a phenomenon referred to as the “seamount effect”. 

Pressures on seamount ecosystems include benthic and pelagic fisheries, petroleum exploration and in some areas, seabed mining. Seamounts support vulnerable slow growing animals that are increasingly threatened by fishing and mining, so seamount ecosystems need protection. Seamount fishes such as the orange roughy are especially vulnerable to fishing because these long lived species gather in large shoals that can be targeted by high-technology fisheries that can deplete this resource from large areas. Coral dominated seamount ecosystems are not very resilient to disturbance by bottom trawling, because there are limited alternative habitats capable of supporting associated species, and because trawling typically removes entire coral habitats from large areas of individual seamounts.

Management of seamount ecosystems needs to account for changing oceanographic conditions (ocean acidification), as well as the direct impacts of human activities such as bottom trawling and mining.

Proposed MPAs that include seamounts are Southeast Atlantic Seamounts that includes Protea, Argentina and an unnamed seamount, and the Southwest Indian Seamounts that includes Natal Seamount.

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SANDY SHELF

Much of the life in sandy shelves is buried in the sand, invisible to the naked eye. Worms, snails, mussels, clams and tiny crustaceans are some of the animals that live in sandy shelves. Just as tracks on land give us clues as to who passed by, the trails, tracks and burrows of these animals can be seen on sandy seabeds. These ecosystems support important fisheries such as South Africa’s most valuable fishery which targets hake. Although kingklip was thought to prefer rocky habitats, scientists were surprised to observe these fish burrowing in soft sediments. Rays, guitarsharks and catsharks are often seen on sandy seabeds. Anemones and soft corals including seapens (corals adapted to anchoring in loose sediment) are found on sandy shelves and these attract other species to live among their tentacles. Spiny skinned animals (echinoderms), such as sea urchins, starfish, brittle stars and sea cucumbers are also characteristic of these ecosystems with more being observed with increasing depth.

Pressures on sandy shelves include trawling, mining, petroleum activities and other fisheries (e.g. demersal longlining). South African scientists are working to understand the impacts and ability of sandy seabed habitats to recover after demersal (bottom) trawling. Camera surveys and seabed samples are used to investigate this in experimental trawl closures off Hondeklipbaai. Pollution impact studies, including that from drilling petroleum wellheads, have also been undertaken to guide management of sandy shelves and ensure that healthy seafood continues to be provided by these ecosystems.

Protection for important sandy shelf ecosystems are provided in Namaqua Fossil Forest MPA, Benguela Bank MPA, Agulhas Bank Complex MPA, Protea Banks MPA, Aliwal Shoal Offshore MPAuThukela Banks MPA, Amathole Offshore MPA and iSimangaliso MPA.

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Rocky shelves, gravels & Reef mosaics

In the mid and outer shelf, rocky or hard shelf ecosystems occur. These are different from sandy or muddy ecosystems because their rocky habitats provide places for animals to anchor themselves to the seabed. South Africa has several rocky shelf areas, particularly in the current-scoured south and east coast. Sponge gardens and coral habitats are characteristic of such rocky areas. These ecosystems are sensitive to pressures that can damage the seabed, including bottom trawling, seabed mining and petroleum drilling.

Gravel habitats are not well studied, especially in South Africa. Gravel is hard like rocky reef habitat, but the rocky sediment is loose or unconsolidated like sandy habitats. Like rocky habitats, gravels provide places for animals such as soft corals to attach, but like sandy habitats, they can be subjected to movement from strong currents or physical disturbance. Gravels also support burrowing animals and seapens (soft corals with a “foot” adapted to anchor them in loose sediment). Gravel sediments have been shown to take longer to recover than sandy ecosystem types after trawling.

Protection for important rocky shelf ecosystems will be provided in Orange Shelf Edge MPA, Namaqua Fossil Forest MPA, Agulhas Bank Complex MPAAmathole Offshore MPA, iSimangaliso MPA and uThukela Banks MPA.

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MUDs

Muddy ecosystem types are different from sandy, rocky and other seabed habitats because of the high silt and clay content of muddy sediments. Visual tools such as camera surveys are seldom useful to sample muddy ecosystems as visibility is usually poor in mud habitats. Muds are rich and fertile, and home to many burrowing animals, some of which penetrate more than a metre into the seabed. The burrowing activities of animals in muddy habitats help exchange nutrients and cycle oxygen and minerals between the sediment and the water column. Key seafood species that rely on muddy habitats in South Africa include important species such as soles; kobs such as kabeljou or daga salmon; silver kob and snapper kob; spotted grunter; prawns, langoustines and crabs.

In South Africa, mud habitats are quite rare, occupying a far smaller area than most other ecosystem types on the shelf. Deep water muds are more widespread but likely to be more sensitive, as deep, calm mud habitats encounter little natural disturbance. Shallow mud habitats are more variable as they rely on river input, therefore reduced fresh water flow can threaten the very existence of the muds. Other pressures on muddy ecosystems include trawling, drilling for petroleum and seabed mining. Reference areas are needed so that South African scientists can study the role of marine muds and understand the impacts of trawling and petroleum activities. This will inform wise management of these ecosystems and their valuable resources.

Important mud ecosystems are included in uThukela Banks MPANamaqua Fossil Forest MPAAgulhas Mud MPA and Benguela Mud MPA.

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SHELF edge

The shelf edge is found where the shelf steepens and drops off into the deep sea. This steeper area is also considered as the upper section of the continental margin. In places where this descent is steepest and dramatic, the margin is like an underwater escarpment or cliff. The shelf edge can be considered the true edge of the continent, rather than the coastline which slopes rather gently in most places. The shelf edge is special because it is a productive area where the oceanography (water movement) interacts with the topography to support dense filter feeding communities, particularly in steep areas.

South Africa’s west coast has one of the deepest continental margins in the world with the shelf edge being seldom shallower than 350 m and with steep sections of the margin occurring as deep as 600 m in some places. The shelf edge is far offshore with the steepest section or shelf break occurring 250 km offshore of the Orange River and 50 km offshore of Cape Point. The west coast shelf edge is very productive and is dominated by sandy slopes with hermit crabs, raspberry starfish and fishes such as hake, dragonets and kingklip. In contrast, the east coast has the deepsea on its doorstep, with the shelf edge being very close to the coast. The narrowest shelf occurs off Maputaland and Pondoland, where the shelf break occurs at a depth of about 100 m and is closest to shore off Port St Johns at just 6km offshore! The strong scouring effect of the flow of the powerful Agulhas current means that much of the east and south coast shelf edge is rocky as sediment. Deep water corals including stony corals, lace corals, black corals and seafans characterise rocky shelf edge ecosystems on the west and south coast. Pressures on these ecosystems include shelf edge fisheries such as the hake trawl fishery, midwater trawl fishery, deep water crustacean trawl fishery and the large pelagic or longline fishery. Oil and gas activities and seabed mining is increasingly occurring on shelf edge areas in a global context. In South Africa, the first petroleum wellheads have recently been drilled at these depths and phosphate exploration has been initiated.

Protection for important shelf edge ecosystems are provided in Amathole Offshore MPA, Brown's Bank Corals MPASouthwest Indian Seamounts MPA, Protea Banks MPA, Aliwal Shoal Offshore MPA, uThukela Banks MPA and Orange Shelf Edge MPA.

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Slopes

The continental slope is the area where the shelf edge descends into the deepsea. The biodiversity of South Africa’s slopes are poorly studied due to the challenges of working below 500 m. Recent camera surveys on the west coast slopes show fishes such as rattails and spiny eels (or rippletails), lantern fish and other deep water sharks and rays. Deep water crabs and urchins have also been seen.  In some steep rocky slope areas, exposed to strong currents, deep water coral habitats have been found. No-one has seen the 30-50 m tall deep water coral mounds detected on ship echosounders on South Africa’s slopes, but sampling by dredge or accidental trawling has revealed a diversity of deep water coral species. These corals are being studied by young South African scientists. The study of deep water corals is relevant, not only because they play an important role in fisheries, but because corals are sensitive to changes in ocean temperature and acidity. Deep water corals can provide clues to our past and future climate. Fossilised corals foud in places such as Browns Bank (LINK) may provide particularly interesting insights.

Key pressures on slopes include fisheries and increasingly there is interest in deepsea mining. Fisheries are the most widespread pressure on slopes, especially those that make contact with the seabed, such as trawling for deepsea fish (hake and kingklip) and crustaceans (prawns, langoustines and crabs). Beyond the shelf edge, South Africa’s slopes are not exposed to many other pressures as yet but reference areas are needed to better study these poorly understood ecosystems, detect change and ensure that existing fisheries benefits are maintained.

Protection for important slope ecosystems is provided in Orange Shelf MPA, Southeast Atlantic Seamounts MPA, Southwest Indian Seamounts MPA, iSimangaliso MPAPort Elizabeth Corals MPA, Amathole Offshore MPA and Protea Banks MPA.

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Canyons

Submarine canyons cut into the shelf on both our west and east coasts. Cape Canyon off Saldahna is our largest shelf breaching canyon and is the same size as America’s Grand Canyon. The Cape Valley off Cape Point is also a large canyon which has sustained the highest fishing effort and catches in our hake trawl fishery for almost a century. Canyons are diverse and productive, with the canyon head often being the most rich and complex area. Rocky walls and margins are home to huge sponges, deep water corals and other fragile habitat-forming species. On the west coast, sandy areas in the canyon often have very dense colonies of animals including brittle stars and mantis shrimps. Nobody has explored the canyons off Port Elizabeth, but a recently discovered canyon near Gxulu, East London has stepped walls hosting brightly coloured deep water corals and fishes. Some of the most charismatic east coast canyon inhabitants in South Africa include our coelacanths, ancient lobe finned fishes thought to be extinct before their discovery off East London in 1938.

Key pressures in canyon ecosystems include bottom fisheries and other activities that impact the seabed such as mining, laying submarine cables, petroleum infrastructure or the anchoring of ships. Canyon margins are fragile and spatial management, such as marine protected areas, play a key role in managing multiple threats.

Protection for important canyon ecosystems is provided in Cape Canyon MPA, Amathole Offshore MPA (Gxulu and Kei), Protea Banks MPA and iSimangaliso MPA.

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Abyssal plain

These are the deepest ecosystem type in South Africa’s oceans. South Africa’s EEZ does not have deep water trenches, such as the famous Mariana trench that reaches a maximum depth of 13 000 m! Our abyssal ecosystems, spanning a depth range of 3500 to 6000 m, are largely unexplored. However, in the 1980’s, one of South Africa’s most adventurous geologists, Professor John Roger, took the first photographs of abyssal and seamount ecosystems using a camera in a special underwater housing.

Abyssal ecosystems in South Africa are currently under limited pressure but geoscientists are interested in exploring these areas for petroleum resources and deep sea minerals such as manganese. Should such minerals be found in sufficient quantities, pressure on these ecosystems will increase substantially.

Proposed MPAs that represent abyssal ecosystems include Southeast Atlantic Seamounts MPA (Cape Basin Abyss) and Agulhas Front MPA (Agulhas Basin Abyss). Southwest Indian Ocean abyssal ecosystems (Natal Basin) will be considered in future protected area planning.

 
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