Elephant’s Ear, by Guy Rogers
THERE’s more to this red tide than meets the eye.
I thought it was dwindling. But on Monday tourism consultant Peter Myles, who has a bird’s eye view from his Lovemore Park house over Sardinia Bay and up and down the coast, mailed me to say he had never seen such a sight in his 30 years in Port Elizabeth with the sea blanketed in red in all directions.
Then on Tuesday morning I got a call from dive operator and Herald Citizen of the Year Rainer Schimpf who told me he had just returned from a trip down the coast from Noordhoek. He and his passenger travelled 20km south and offshore 10-20kms and were shocked by what they saw. “Amongst the dead plankton there was dead jellyfish, dead penguins and gannets… It was bad.”
NMMU botany department head and red tide expert Dr Derek du Preez notes that since the early 90’s Australian researcher Geoffrey Hallegraeff has been saying that red tides are on the increase globally and he has largely blamed the spread of these harmful organisms on them being transported in the ballast water of ships.
One thinks immediately of the increase in shipping related to Ngqura but Du Preez says that, while there is no doubt ballast transport is a general red tide factor – there is likely a more powerful driver here.
The red tide that has engulfed our waters for the past month from Knysna to Port Alfred is “unlike anything we have seen along this part of our coast”, he says.
The plankton Lingulodinium polyedrumthat is causing it has been present in our waters for many years but it has never been very abundant. “Something has happened that is unusual. It would appear there has been an unusually intense upwelling of cold nutrient rich water along the coast that has fuelled the bloom. Coupled with warm surface waters and relatively still conditions, this has intensified the effect and the result is the spectacular event we have been witnessing.
“It could be that it is a very rare natural one-in-a-thousand-year event. But I think it is more likely that it has been caused by climate change.”
The algae need nutrients to bloom and without nutrients they will die, he explains. What seems to be happening is that the bloom starts to weaken because the algae have used up all the nutrients, and then there is another upwelling event bringing fresh nutrients into the system, and the bloom intensifies again.
When the nutrients are used up, the bloom will dissipate. The problem is that as the bloom decomposes it releases nutrients that can trigger the whole thing again, he notes. “What we need to reduce the bloom is a good storm that will mix the waters, dilute the system and cool the surface.”
Du Preez says he believes we have been very lucky and the situation would have been much worse if one of the more toxic dinoflaggelates had been involved. Although he cannot say with absolute certainty, he believes that “what we have seen this year could become a common event.” And if this prediction is correct – “it is just a matter of time before a different set of conditions presents itself and one of the really toxic species blooms.”
Du Preez’s forecast correlates with the view of the American National Oceanic and Atmospheric Administration whose studies are showing how warming oceans, the result of climate change, appear to be increasing the frequency and severity of red tides.
In an e-mail before I spoke to Du Preez, Myles said he was concerned that pollution might be the cause of our mega-red tide event. Schimpf argued that the seismic testing for oil and gas deposits underway off our coast might have been the trigger.
A little reading indicated to me neither possibility is far-fetched. More and more study findings are showing that red tide can indeed be triggered by man-made problems as well as natural events.
A recent study by University of Connecticut marine scientist Prof Hans Dam, for example, found that “pollution from rivers is partly to blame”. As Myles notes, one immediately thinks of our heavily polluted Swartkops and there are of course similarly sewage-laden rivers up and down the coast.
Exploring Schimpf’s concern, I found a paper by Irma van der Vyver and senior red tide expert Dr Grant Pitcher which describes how dinoflagellate cysts “lying dormant in sediment on the sea floor” are whisked upwards together with that cold nutrient-rich upwelling.
Now, I wonder: could seismic activity not disturb the seabed in the same way, thrusting up the dormant dinoflaggelates together with the nutrients they need to grow and divide?
Endorsing the call from Van der Vyver and Pitcher, Du Preez says there is a need for a comprehensive investigation into the expansion of these blooms, and NMMU would be in full support of such a study.
Red tide is a perfect example of a modern day environmental problem, it seems to me. The intertwining possible contributors and the potential havoc it can wreak on human health, fisheries, tourism and ecosystems would take our researchers to the core of many things. We have the expertise at NMMU. Any sponsors out there?