‘Nature not designed for seismic blasting’ – marine expert

The South African Association for Marine Biological Research (SAAMBR) says it has serious concerns about the risks of potential drilling for oil offshore of the Wild Coast because the region is influenced by one of the fastest-flowing and most powerful oceanic currents in the world: the Agulhas Current.

This comes after Shell’s recent announcement that it has appointed Shearwater GeoServices to conduct a three-dimensional (3D) offshore seismic survey from Morgan Bay to Port St Johns, to map potential deposits of oil and gas under the seabed, which has triggered public outrage.

On Sunday, the Amazon Warrior, the seismic vessel commissioned by Shell, entered the Cape Town harbour, where several hundred environmental activists and local residents protested its arrival. The vessel is due to start underwater seismic blasting operations next month. 

The survey, which will take four to five months to complete depending on weather and current conditions, is more than 20km from the coast at its closest point in water depths ranging from 700m to 3 000m. The survey area covers 6 011 square kilometres.

Dr Judy Mann of the SAAMBR told the Mail & Guardian: “It’s the Wild Coast, the place of shipwrecks and unpredictable ocean currents. It’s not the Gulf of Mexico. We shouldn’t be looking there [for oil and gas] in the first place.”

In her piece, she voiced the SAAMBR’s concerns if viable oil and gas reserves are found. “The Agulhas Current is not static. It meanders up to 100km in width, and while it generally flows from north to south, current reversals are not uncommon, particularly in deeper water. 

“Large-scale eddies peeling off the current complicate the flow, with offshore water frequently reaching our coast. The power of the current is such that attempts to contain any accidental spillage or normal operational spillage would likely be unsuccessful.” 

Clear evidence of this was seen, Mann wrote, when plastic nurdles spilled in the Durban Harbour spread along the entire coast of KwaZulu-Natal and the Eastern Cape within days of the disaster.

“While internationally, the risk of a catastrophic blowout (large-scale oil spill) is rated as very low by environmental impact assessments, this does not consider the increased risks posed by the harsh, unique, physical environment found off the Wild Coast (as its name implies).” 

Mann described how the potential impacts of developing and running shore-based facilities for the processing and transport of oil and gas should they be found in viable quantities, “have not yet even been considered”.

Seismic surveys, she said, are used by mining companies to find and estimate the size of offshore oil and gas reserves. These marine seismic surveys determine if there is oil or gas, in sufficient quantities, to start exploratory drilling, the next phase in the process before extraction or mining. A ship tows multiple airgun arrays that emit thousands of high-decibel explosive impulses to map the seafloor and rock strata. 

Hydrophones attached to long cables pick up the signal reflected off the seafloor. Based on the return time of the reflected or refracted impulses to the hydrophones, the underlying structure of the ocean floor can be mapped in 3D.

“The bottom line is that nature is not designed for these sorts of impacts … Just because we don’t see the immediate evidence, doesn’t mean that there isn’t an impact,” she told the M&G. 

The ocean is an acoustic world. “Unlike light, sound travels extremely efficiently in seawater, and marine mammals and many fish and invertebrates depend on sound to find mates, find food, avoid predators, navigate and communicate.

“We know that many of the marine and coastal habitats off the South African east coast are unique and support a high ecological diversity, much of which is not found elsewhere. Deep-water habitats (> 500 m), in particular, are largely unexplored ecologically, so we do not know exactly what occurs or what ecological processes take place there,” said Mann.

Internationally, she wrote how seismic surveys have been demonstrated to have negative impacts on a range of marine organisms, from smaller creatures, which live in sediments or as plankton, to larger animals such as fishes and marine mammals. 

Marine mammals, in particular, appear to be most affected because of their reliance on sound for communication, to find food and to navigate. 

While research has shown that the impacts on fish themselves is likely to be localised, seismic surveys may have serious consequences for the health of fisheries and different fisheries are impacted in different ways. In some fisheries decreases in catches have been observed.

“We are just starting to discover what life lives in the seabed of the deep oceans and underneath it. Those are the ecosystems that are going to be affected by the seismic blasting, but because they’re out of sight and out of mind, people generally don’t care about them,” Mann said.

“My concerns are about the impacts of the survey itself, but my real fear is what happens if they do discover something and decide they want to start mining that area — that’s when we really have to be concerned.”

Several unique marine protected areas (MPAs) — Amathole Offshore, Dwesa-Cwebe, Hluleka and Pondoland — are adjacent to Shell’s proposed survey area. Each safeguards unique marine biodiversity, featuring a high number of endemic species, found nowhere else on the planet.

“The impacts of the sound from the seismic survey travels great distances through water, meaning that the marine life in the MPAs may be affected,” said Mann.

An incredible amount of work went into getting these MPAs proclaimed. “Some of them are biggish areas, but most of them, particularly along this coast, are reasonably small but they are very valuable … And if mineral extraction happens off that coast they would be vulnerable.”

Kevin Cole, principal scientist at the East London Museum, pointed out how in South Africa, there is only a single study on the impact of seismic surveys, which was undertaken off Port Elizabeth within the foraging area of the African penguin

The research, by professor Lorien Pichegru of Nelson Mandela University, found that the endangered seabirds avoided their preferred feeding areas during seismic surveys, feeding further from the survey vessel when in operation.

“Apart from Pichegru’s 2017 study, no research or experimental studies have been undertaken within South African waters on the impact of seismic surveys,” Cole said. “Scientific studies need to be undertaken in situ to provide quantifiable data on this subject before considering the permitting of seismic surveys.”

Dr Els Vermeulen, the research manager of the Mammal Research Institute’s whale unit at the University of Pretoria, said seismic surveys have an effect on the marine environment and fauna, “which will go from behavioural changes to possible hearing damage if too close to the source of the sound”.

“However, that said, the plain reality is that we still do need oil and gas until the country ( or world) can go 100% on alternative energy sources, so it’s a give-and-take, I suppose … The impact will largely depend on the species/habitat of interest.”

According to Mann, the best way forward for environmental sustainability and local job creation is to expand technology that makes use of renewable energy. 

“The global market is moving away from fossil fuels given the catastrophic effects of human-induced climate change. Indeed, if South Africa and the world are to meet the goals set by COP26, which has recently concluded in Glasgow, to limit global warming to less than 1.5°C, it is urged that we move away from our reliance on fossil fuels.” 

The international community has just pledged R131-billion to help South Africa decrease its reliance on fossil fuels. 

“We thus consider that the potential short-term, non-sustainable benefits to be gained from oil and gas are largely outweighed by the environmental risks posed by exploring for, and using these non-renewable energy resources, especially along this vulnerable coastline.”

Shell said a significant amount of research has been conducted globally on seismic surveys, and their effects on the marine environment. “The impacts are well understood and mitigated against when performing seismic surveys. This is supported by decades of scientific research and the establishment of international best practice guidelines.” 

Shell adopts the most stringent of controls and follows international best practice from the UK’s joint nature conservation committee guidelines for conducting seismic operations.

“This, in combination with the mitigation measures outlined in the environmental management programme, ensures we are conducting seismic surveys safely with regard to marine animals and the environment.”  

These include an exclusion zone of 500m around the sound source that is monitored 24 hours a day by independent marine mammal observers on board the seismic vessel. No seismic operations will take place in MPAs and there is a buffer area around MPAs where no seismic activities may take place, it said.

Mann added: “All of us use fuel. We need to think consciously about our use of that fuel. Each of our decisions can help or harm the environment. So many people are speaking up — if we can harness that into conservation and caring for our oceans, there’s definitely a positive to come from this.”

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Sheree Bega
Sheree Bega is an environment reporter at the Mail & Guardian.

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