As ‘busy’ humans we often fail to see the bigger picture – we take the sun for granted without realising that solar power can be the solution to the world’s energy. And on a slightly smaller scale we in Algoa Bay take the influence of the Agulhas Current for granted as well.
The Agulhas Current has a major economic impact on these Port Elizabeth industries:
- The Shipping Industry
- Food – Farming and Fishing
All industries that we benefit from in various levels.
1. The Shipping Industry
The Agulhas Current runs Southwards along the East Coast of South Africa and is responsible for much more than just ‘moving water’ which it does rather effieciently at the rate of the equivalent of 45 000 Olympic Sized Swimming pools per second.
On a surface level that current accounts for massive savings to the shipping industry who utilise the current travelling at a top speed of around 10 kilometres an hour to save fuel on their journey down the East Coast. Yachtsmen taking part in the Vasco Da Gama Ocean Race seek the current to aid them as they race from Durban to Port Elizabeth.
Many of those ships travel with the current to Algoa Bay where they find safe shelter in different anchorages close to the Port of Nqura and the islands of St Croix, Brenton and Jaheel.
Over the last 3 years, Algoa Bay has witnessed an increase in bunkering operations.
Bunkering, the ship-to-ship transfer of fuel or oil from one vessel to another while at sea, is a high risk operation. An oil spill can have major environmental consequences, impacting on other ocean industries such as tourism, water sports and fisheries.
Numerous objections were raised by marine scientists, environmentalists and tourism groups, licences to operate in the Bay were issued in 2016.
An incident took place on 6 July 2019 during offshore bunkering operations less than 10km from the Port of Nqura. It is reported that 200 – 400l of fuel was spilled into the sea due to an overflow during fuel transfer to the receiving vessel.
Even though a commercial oil spill response service provider was summoned to mitigate and contain the spread of the spill, more than 100 birds, all endangered bird species, were oiled. Algoa Bay is a marine biodiversity haven and on 1 Auguts 2019 larger portions of the bay from Bird Island to the Port of Nqura were included in the already declared Marine Protected Area.
The offshore bunkering operations pose a real and imminent threat to marine life, waters and beaches.
Benefit: The ships at anchor replenish fuel from the floating bunkering stations and are serviced by a cottage industry of service vessels from the Port of Port Elizabeth.
2. Food – Farming and Fishing
The Agulhas Current has a major influence on farming and fish stocks along the East Coast as Katherine Hutchinson, PhD Candidate, South African Environmental Observations Network, and Department of Oceanography UCT, University of Cape Town explains; “The Agulhas Current transports warm tropical Indian Ocean water southwards along the South African coast. It modulates the rainfall along the east coast and interior regions of South Africa by providing the latent heat of evaporation needed for onshore wind systems to pick up moisture and carry it inland. The current itself also sets the backdrop for local ecosystems which contribute to South African fisheries. Friction between the current and the continental shelf edge drives upwelling of nutrient rich bottom water. This in turn promotes high levels of phytoplankton – the grass of the ocean which sustains the aquatic food web.”
Approximately 30% of all rainfall along South Africa’s East Coast is attributed to the Agulhas Current.
Benefit: Coastal Farm rainfall and rich fishing in and just out of the protected bays such as Algoa Bay.
The current follows the continental shelf from Maputo to the tip of the Agulhas Bank (250 km south of Cape Agulhas). The first of the major counter currents occurs in Algoa Bay and this is the reason put forward for the source of the Sardine Run being Algoa Bay. Sardines are spotted from February in Algoa Bay and significant bait balls form. Proof of that is in the many film makers who start their Sardine Run journey off the shores of Port Elizabeth and even one that was caught in the mouth of a Brydes Whale whilst filming under permit with Expert Tours earlier this year.
The rich food and numerous islands found in Algoa Bay gave rise to major bird and fish populations. Most birds are to be found on Bird Island first named by Bartholomeu Dias as Ilhas Chaos, which is Portuguese for flat or level ground. Diaz was the first European to sail into Algoa Bay in 1488 on his quest to find the new sea route to the east. The island that he landed and erected a wooden cross on was first named Ilheu da Cruz, today known as St Croix. The two smaller islets near to St. Croix were named Jahleel and Brenton after the British Vice Admiral at the Cape who was stationed there from 1815 until 1821.
Bird Island, Stag Island, Seal Island, Black Rocks, St Croix, Brenton and Jaheel form part of a declared Marine Protected Area under the watchful eye of SANParks and the Addo Elephant Park which was expanded on 1 August 2019.
The sardine run of southern Africa occurs from March through July when billions of sardines – or more specifically the Southern African pilchard Sardinops sagax – spawn in the cool waters of the Agulhas Bank and move northward along the east coast of South Africa. Their sheer numbers create a feeding frenzy along the coastline. The run, containing millions of individual sardines, occurs when a current of cold water heads north from the Agulhas Bank up to Mozambique where it then leaves the coastline and goes further east into the Indian Ocean.
The Agulhas Current reaches its maximum transport near the Agulhas Bank. It is hypothesised that the humpback whales migrating North from the Southern Ocean use the Agulhas Bank and the warmer current as a ‘marker’ to follow on their migratory path.
In Algoa Bay three main whale species are spotted on a regular basis: Brydes Whales, Humpback Whales and Southern Right Whales.
Humpback whales can be seen from April to August moving north to their breeding grounds on the east and west coasts of Southern Africa and from September to December moving south to their feeding grounds in the Southern Ocean. There is a difference in offshore distribution between the two migrations, with the Northerly migration closer inshore than the Southerly migration. This may be due to the whales avoiding the southward flowing Agulhas current during their Northerly migration, and swimming with it during their Southerly migration.
Humpback whales dive to about 200m. They can stay underwater for 30 minutes, but on average their dives only last about 15 minutes. As a consequence they are unlikely to use the Agulhas Undercurrent which flows towards the equator. The undercurrent begins at a depth of 800m, is 2000m deep, 40km wide and can reach 90cm/s at 1400 metres, one of greatest speeds observed in any current at this depth.
Tourists booking cruises in the bay are likely to see: Humpback Whales, Southern Right Whales, Bryde’s Whales, Bottlenose Dolphins, Common Dolphins, Humpback Dolphins, African Penguins, African Black Oystercatchers, Cape Gannets, Cape Fur Seals, Cape Cormorants, White-Breasted Cormorants, various shark species and various pelagic birds including Terns, Skuas, Petrels, Shearwaters And Albatrosses.
Benefit: Many international Tourists visit to see the Sardine run and to travel into the bay to see Whales and Dolphins with one of the two licensed Boat Based Whale and Dolphin Watching Outfits.
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