West Coast red tides clearing
18 February 2015
The Department of Environmental Affairs has been monitoring the red tide in the West Coast inshore area and this appears to be gone. The red tide is no longer covering a big area and there have been no further impacts on marine species. However, sampling of some of the areas is continuing to monitor the extent of the red tide and to look out for any further impact on marine species and the environment.
Water conditions have been improving and since Sunday, 15 February, the water has started to clear. There has been no further walk outs or washing up of West Coast Rock Lobsters or even dead animals observed. At St Helena Bay the red tide is moving more offshore possibly as a result of the Easterly wind (5 to 10 knots) pushing the water. In Elands Bay the water inshore is clean unlike last week when the water was completely dark. In Lamberts Bay, there are patches of darkish brown water extending towards Doring Bay, but there is no longer a big coverage of the water area.
In light of the annual walkouts and growing concern with the presence of Harmful Algal Blooms (HABs), also known as Red Tides, in the upwellig region of the west coast southern Africa, the Department has proposed a research programme to assess and monitor the formation and impacts of HABs. The department hopes that this will complement existing efforts by the Department of Agriculture, Forestry and Fisheries.
The proposed DEA programme for the assessment and monitoring of HABs, has the following actions which are currently being considered for implementation:
- Add an oxygen sensor to the data buoy that is already deployed at Elands Bay to provide real-time data on the occurrence of anoxic events;
- Continue with the monitoring of winds at key coastal localities, and improve the information readiness by setting up real-time availability of wind information;
- Monitor the presence of HAB species and bloom formation in relation to environmental variables during quarterly research cruises currently conducted on the west coast as part of the existing DEA Ocean and Coasts Integrated Ecosystem Programme (IEP);
- Monitor the formation and spatial extent of algal blooms by satellite remote sensing;
- Assess the impacts of environmental and human-induced drivers on anoxic events caused by HABs (through empirical studies);
- Develop indicators for long-term HAB monitoring based on empirical findings;
- Assess the effects of HABs on marine ecosystem health and functioning (small-boat based sampling, e.g. from Elands Bay)
- Integrate HAB monitoring in DEA’s Plankton Monitoring and Water Quality Monitoring Programmes;
- Continue monitoring HAB indicators in coastal waters (e.g. on IEP quarterly cruises);
- Gather predictive understanding of HAB formation and decay to contribute to an observational tool for HAB detection (This will be included in the National Oceans & Coasts Information System towards an early warning system. This Information System is one of the planned deliverables of Phakisa Oceans initiatives, and is to be developed with the DST – CSIR Meraka Institute of Innovation).
HABs are natural phenomena in coastal waters caused by a dense accumulation of microscopic algae. These minute organisms carry pigments to photosynthesize which give HABs their typical reddish-brown appearance. HABs occur in most coastal regions of the world, and are particularly common in the productive west coast upwelling regions, such as the California, Humboldt, Canary, Somali and Benguela upwelling systems.
Some of the 29 algal species that are known worldwide for forming HABs are harmful because they contain toxins, which are poisonous to humans. Poisoning may either take place through the consumption of seafood that is contaminated by toxic algae, or by toxic aerosols or waterbound compounds that cause respiratory and skin irritation. Other HABs cause harm through the depletion of oxygen (anoxia), which affects all marine creatures and can lead to mass mortalities of entire marine communities or mass walkouts of rock lobsters that try to escape the anoxic conditions. Therefore HABs events can potentially have major environmental as well as societal implications, with knock-on effects on coastal economies.
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