Build-up of large harmful algal bloom (Red Tides) in the greater St. Helena Bay Region over the past few weeks
A Harmful Algal Bloom (Red Tides) has been building up at Elands Bay, on the West coast of the South and has resulted in several marine species washing on the beach.
These include, rock lobsters, octopus, white mussels and some fish species. Weather conditions are not favourable at the moment as a North westerly (NW) wind is currently blowing and keeping the algal bloom concentrated in the bay.
Notwithstanding the Red Tides, West coast rock lobster catches are still good and this indicates that oxygen levels are still high. The new moon spring tide occurred 2 days ago, thus limiting the possibility of a mass stranding within the next 10 days.
The Department of Environment, Forestry and Fisheries (DEFF) has immediately, in terms of its West Coast Rock Lobster Contingency Plan (“the Contingency Plan”) activated the Contingency Plan, issued a Situation Yellow alert and placed all government role-players on standby.
In terms of the Contingency Plan, the Department of Environment, is the lead department, supported by the following organs of state: West Coast District Municipality, Cederberg Municipality, South African Police Services, SANDF and Western Cape Provincial Administration. These role-players are currently preparing for a Situation Red because beaching has taken place and there is a possibility that there may be beaching in excess of 10 tons at a single or multiple localities in the area
As is often the case in summer and late summer, there has been a build-up of large Red Tides in the greater St. Helena Bay region over the past few weeks. These blooms of phytoplankton presently extend 50-60 kilometres in the vicinity of Elands Bay, Lambert’s Bay and Doring Bay.
Notes for the Editor:
Red Tides are a natural phenomenon in coastal waters caused by a dense accumulation of microscopic algae. Some of the algal species 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 water bound compounds that cause respiratory and skin irritation. Other Red Tides cause harm through the depletion of oxygen (anoxia), which affects all marine creatures and can lead to mass mortalities of the entire marine communities or mass walkouts of rock lobsters that try to escape the anoxic conditions. Red Tides occurrences can therefore have major environmental, as well as societal implications, with knock-on effects on coastal economies. Fisheries and Aquaculture industries suffer from the episodic mortalities of stocks caused by Red Tides, while poor water quality and foul smells associated with these occurrences affect coastal tourism.
Red Tides are particularly common in the productive West coast upwelling regions, such as the Benguela, California, Humboldt, Canary and Somali upwelling systems.
In the Benguela upwelling region off the West Coast of Southern Africa, Red Tides have periodically led to rock lobster strandings. The most famous examples are the strandings of hundreds of tonnes of rock lobsters in Elands Bay in 1997 and 2000. In 2014, an extensive and long-lasting Red Tide occurred for the first time along the South Coast, extending from Knysna to beyond Port Elizabeth and causing wide-scale mortalities of fish.
These blooms are dominated by a group of phytoplankton known as dinoflagellates and their inshore accumulation, particularly during periods of calm, often leads to their decay and the subsequent development of low oxygen conditions which cause marine mortalities. Such mortalities were observed on the beaches of Elands Bay earlier today and with the prediction of light westerly winds over the next few days, the risk of further mortalities is high.
For media enquiries please contact:
Zolile Nqayi: 082 898 6483
E-mail: znqayi@environment.gov.za
