“We have to alert the world to the impending food security, livelihoods and marine ecosystems disaster in the Western Indian Ocean (WIO), which extends from South Africa all the way up the east coast of Africa. We probably have about 15 years before things get very serious. It is not a lot of time if you think how slowly things move in terms of politics.”
These are the words of Professor Mike Roberts, head of the South African Research Chairs Initiative (SARChI) in Ocean Science and Marine Food Security, jointly hosted by Nelson Mandela University, the University of Southampton and the Southampton-based National Oceanography Centre in the United Kingdom.
“Over the past five years we’ve done enough research to expose and determine the seriousness of the impending disaster in the WIO, which is warming faster than any other part of the global ocean,” says Roberts who is also the recipient of the 2020 Newton Prize, worth R4million. This international award is given to teams of people making an essential contribution to the world, and was made for the Chair’s research in the WIO.
“Sixty million people in the WIO directly depend on the ocean for food and livelihoods, and fish abundance projections clearly demonstrate that the amount of fish in the region, as well as species diversity, is rapidly declining as a result of overfishing, ocean warming, pollution and population growth,” Roberts explains.
“We are looking at widespread starvation in the WIO by 2035, and it is the duty of this Chair to shock people and governments into facing the reality of this very serious situation, backed by considerable research,” says Roberts.
With money from the Newton prize his team has retrieved five of the seven underwater temperature recorders that Roberts deployed off the Mozambique coast 20 years ago, which are still working and have recorded hourly water temperatures over this time period. Roberts explains the data from the recorders as well as satellite data already clearly shows that the resource-rich Mozambique channel is warming. Northern Mozambique, for example, is on course to reach 5°C by 2100. This will devastate the coral reef system and the ecosystems that depend on it. This directly impacts the livelihoods and food security of artisanal fishers in the WIO region who depend on the shallow coral reefs for their food source.
Roberts and his team are currently facilitating joint planning and mitigation measures with the Mozambican government. A Memorandum of Understanding is in place between Nelson Mandela University and the Mozambican government for assistance in building research capacity in ocean science and fisheries.
The models the researchers use further show that by 2035 the tropical WIO’s marine heat waves that would normally last a few days up to about ten days will extend for far longer periods, at times spanning 12 months, with devastating consequences for the ocean. “These marine heat waves intensify the partition or thermocline between the warm upper and cold lower layers of the ocean, inhibiting the upwelling of nutrients from the deep levels of the ocean into the upper layer where phytoplankton (microplants) production takes place,” Roberts explains.
Upwelling is the upward movement of deep, cold, nutrient-rich water to the ocean surface, encouraging the growth of phytoplankton, which forms the base of the marine food web. Reduced productivity in phytoplankton impacts the entire food-web, meaning there is less food for fish larvae, and hence fewer juvenile fish and fewer of all species, all the way up the food chain to the top marine predators. Together with ocean physics, upwelling directly underpins marine food security. As the planet’s climate is changing, so is the ocean’s upwelling systems.
“We make use of satellites, ocean models, marine robotics, and other state-of-the-art technologies capable of studying complex marine ecosystems and the upwelling systems in the WIO,” says Roberts. Nelson Mandela University recently established a marine robotics unit to support this research.
To tackle the immense ocean science challenges in the WIO and southern hemisphere, the Chair has established the Innovation Bridge and Regional Hub Network (IB-RHN) which builds research partnerships between institutions in Africa and the Global North. An equally important innovation bridge the Chair has established is with leading French marine research institutions, notably the Institut de Recherche pour le Développement (IRD) in Marseille and the Université de Bretagne Occidentale (UBO) in Brest.
“To find solutions to address the WIO’s problems requires intensive transdisciplinary, global research,” says Roberts. “This encompasses research in physical oceanography, biogeochemistry, plankton, trophic ecology, fisheries and food resources, quantified by end-to-end ecosystem and socio-economic modelling.”
The Ocean Science Campus at Nelson Mandela University, which specialises in ocean physics and productivity (ecosystem functioning), forms the principal southern footprint of the IB-RH in partnership with Rhodes University, which provides expertise in fisheries science and ocean governance to the alliance.
Another key role of the Chair is to increase the number of master’s and PhD students in ocean sciences throughout Africa. As Roberts says: “You cannot build the research capacity required to innovate Africa’s solutions on food security and other ocean challenges and opportunities without top researchers.”
The Chair’s research on marine ecosystems in the WIO includes Madagascar, Kenya, Tanzania, Mozambique and South Africa.
South Africa’s Agulhas Bank is the widest shelf area on the African continent and supports the chokka/squid fishery. This research undertaken by SOLSTICE project, funded by the UK Global Challenges Research Fund, looked at why the squid fishery collapsed in the Eastern Cape between in 2013, when over 2 500 squid fishermen lost their livelihoods, affecting an estimated 35 000 family dependants. and whether it can happen again.
“The data from the research, satellite observations and ocean models reveal a regime shift in the Agulhas Bank ecosystem, probably as result of climate change,” says Roberts. “We need big state-of-the-art models, to help us anticipate future shifts and if or when the squid fishery crash could happen again.” The research on the chokka fishery collapse will be featured in 18 papers published in a special issue of the international journal Deep Sea Research II in 2022.
Another research project in KwaZulu-Natal is looking at where cyclonic eddies and turbulences in the Agulhas Current impact the coastal ecosystems along the coast between Port Alfred and Durban. This project is currently being done through the IB-RHN with the French institutions, and is called CYCLOPS. “These eddies appear to drive the ocean productivity on this narrow shelf, supporting a huge amount of biodiversity, including many species of fish on which coastal communities rely, as does the commercial fishing sector,” Roberts explains.
Of concern here is that because the Agulhas Current is showing signs of change over several decades, this will probably affect the productivity of the Transkei and KZN coastal ecosystems. One of these is the annual sardine run which benefits communities all along the east coast of South Africa.
Roberts hypothesises that the strength of the sardine run (how may fish reach Durban beaches) depends on the behaviour of eddies and turbulence passing Waterfall Bluff near Port St Johns. Here, the shelf becomes very narrow and the northward migrating sardines get stuck if there are no eddies to open “a gate” for them to swim along the shelf into KZN.
Roberts’ team is also looking at the possible loss of fish larvae from the shelf caused by eddies. They have shown that large eddies passing the Thukela Bank can remove the entire water column from this shelf, and with it all the important fish larvae that are essential for fisheries recruitment. A worry is if this happens more frequently with climate change.
The team’s research off Kenya and Tanzania, published in 2021 in the international journal Ocean and Coastal Management, has shown how upwelling will diminish in the future there and will negatively impact fisheries, especially the North Kenya Bank (NKB) and the Pemba Channel small pelagic fisheries. These are large artisanal fisheries, supporting thousands of coastal and island communities. “We now need to figure out if this will happen more often in the future,” says Roberts. “Our modelling studies show that this region will heat up by 5°C and that all fish stocks will collapse by 2100. This is a super serious situation given that droughts will increase too.”
Another major research project called MADRidge, also done with the partners though the IB-RHN and completed in 2020, focused on three submarine seamounts around Madagascar. “Seamounts, which are essentially huge reef systems, are exceedingly important for marine food security as the vertical movement of deeper, nutrient-rich water against the abrupt topography induces regular upwelling which stimulates primary production in the upper layer of the ocean,” Roberts explains. This is where many of the large pelagic fish are found such as tuna and in the near bottom zone species like the orange roughy.
Results from this research are being used to engage international bodies to try and protect this area from foreign fleets plundering fisheries at these seamounts as no country owns them. They are in the open ocean and classified as Areas Beyond National Jurisdiction (ABNJ), therefore no one is policing them – and they have been plundered since the 1970s by several nations, including the, long French, Russians and Asians, and since the 1990s by fisheries operating out of Reunion.
The slow growth, late maturity and low fecundity of species like the orange roughy, contributes to their decimation. Added to this is the emerging threat of mining. This brings into focus important bodies like the International Seabed Authority (ISA). These threats have raised a number of questions like the legal status of seamounts both within and beyond national jurisdiction, which laws apply, and who will implement the legislation and control this at these faraway isolated sites.
Roberts and the Chair’s team of researchers are developing a policy brief that they aim to put on the 2022 agenda of the UN World Food Security Committee in order to raise the issue of marine food security in the WIO, and to catalyse planning and action.
“WIO governments and the international community urgently need to collaborate on understanding the rate at which changes are manifesting and, critically, mitigation measures have to happen. Time is running out quickly!”
