25/02/2014
For the past six weeks or so, a major red tide event has been the focus of much media attention in the Port Elizabeth press. This red tide extends from Knysna through to Port Alfred and all the way from the coast to about 15 km offshore. The culprint is a tiny microalga belonging to a group of algae called dinoflagellates. It is about 20 micrometres in size (about 20 thousandths of a mm) and has the awkward sounding scientific name of Lingulodinium polyedrum. In very concentrated parts of the red tide there are about 20 million of these tiny cells per litre of seawater. You can imagine how many of them there must be in the area described above!!
Red tides are badly named because they are not always red (they can be orange, brown, yellow and even green in colour) and they have nothing to do with the tide. Under favourable conditions, in this case upwelled, nutrient rich water, and warmer than usual water temperature, the cells divide rapidly and result in a bloom of these microalgae.
At this stage we, at NMMU, together with our colleagues at SAEON, are still studying the phenomenon and trying to understand why it has occurred now and never before in recorded history. This does not mean that it has never occurred anywhere else in the world before. Blooms of Lingulodinium polyedrum are reasonably common around the world, but have never been recorded off our coast before.
As we learn more about the bloom we will provide more information and insights and make them available here.
Derek du Preez, Head - CMR