Marine phosphate mining is nothing like diamond dredging and will have extreme and irreversible consequences for millennia to come, says an expert.
Catherine Sasman | Namibian Sun | 26 October 2016
Marine biologist and former director of the Sam Nujoma Marine and Coastal Resources Research Centre of Unam, Professor Edosa Omoregie, has warned that marine phosphate mining, however small or large the scale, will lead to devastating and long-lasting effects on the marine ecosystem.
He said this could cause serious damage to the productivity of the Namibian marine environment and the country’s fisheries.
Omoregie made these remarks at the first annual research conference of the Sam Nujoma campus at Henties Bay in late September.
Despite strong resistance from environmental groups, environmental clearance has been granted to start with marine phosphate mining.
The Ministry of Environment and Tourism has granted the certificate to Namibia Marine Phosphate, which is developing the world”s first marine phosphate project off the coast of Namibia.
Omoregie said marine phosphate mining involves massive seabed dredging that removes as much as 20 metres of the top sediments that have accumulated for millions of years.
With massive removal of this large quantity of sediments, reclamation after mining would be practically impossible, hence other countries with huge marine phosphate deposits have refused to allow mining.
The presentation noted that the high productivity of the Namibian marine ecosystem is dependent on the biological and chemical processes taking place in these sediments.
Once these sediments are disturbed and eventually removed, the consequences could be extremely devastating to marine life.
Another concern raised by Omoregie is that marine sediments rich in phosphorite are known breeding grounds for several commercial fish species and other marine life. The removal of these sediments would, therefore, directly affect fish stocks.
There is currently no scientific data on the effects of marine phosphate mining on fish productivity because it has never been done anywhere in the world.
And for good reason, figured Omoregie, because of what is known about disturbances of the seabed, which should concern everyone, including decision-makers and politicians.
“Remedying phosphate mining on land is easy but in the deep sea reclamation would be practically zero and will take several million years to recover,” was Omoregie’s apocalyptic prognosis.
Another concern he raised is the release of several types of nutrients into the water column, including inorganic phosphates that have been locked up within aggregates in these sediments.
One consequence of this release would be red tide and sulphur eruptions, which the mariculture industry is scared of. Another consequence would be the direct toxic effects of nutrient over-loading.
Omoregie and others have investigated the effects of varying concentrations of a single superphosphate fertiliser on the survival and respiratory dynamics of Nile tilapia under laboratory conditions.
They concluded that fertilisers in water bodies stimulate growth of phytoplankton and waterweeds, which in turn provide food for fish.
However, at certain concentrations of these fertilisers, algae and waterweeds grow wildly, clogging the waterways and depleting the dissolved oxygen present in the system.
In short; aquatic life suffocates as a result.
Moreover, said Omoregie, the geology of the seabed is poorly understood and for this, it is not clear to what extent massive removal of seabed sediments would disrupt underlying rock formations.
It is a known scientific fact that there are several vents within underlying rocks of seabed sediments. Massive sediment dredging could expose some of these vents, making whatever has been locked up within the vents erupt into the water column.
Omoregie likened this eventuality to the 2010 Deepwater Horizon oil spill in the Gulf of Mexico, recognised as the worst oil spill in the history of the USA, in which an estimated 3.19 million barrels of oil spilled into the sea.
“The incident in the Gulf of Mexico will be child’s play if anything should happen here,” he warned, as it is a known fact that there are massive gas reserves beneath the sea bedrock.
He said while taking cognisance of rapid economic development in several countries and the global need for more food production both for human and bio-fuel production, extensive removal of deep seabed sediments would set up disruptive events that cannot be reverted for millions of years to come.
“Why would Namibia want to play the guinea pig?” he asked, since no other country has allowed massive removal of deep seabed sediments for whatever reason, be it marine phosphate mining or any other kind of mining based on the outcry from the scientific community.
“What we as scientists refer to is what can be proven scientifically but the choice lies with decision-makers and politicians,” Omoregie said.