The effect harmful algal blooms (red tides) have on the Namibian mariculture industry

Abstract

Abstract by author:

The threat of HABs and their consequences exists throughout the Benguela region. Although HABs were present long before human activities began to impact coastal ecosystems, a survey of affected regions and of economic losses and human poisoning throughout the world demonstrates clearly that mere has been a dramatic increase in the impacts of HABs over the last few decades (GEOHAB, 2001). The HAB problem is now widespread and serious. Harmful effects attributed to HABs extend well beyond impacts on human health and direct economic losses. When HABs contaminate or destroy coastal resources, the livelihoods of local residents are threatened and the sustenance of human population is compromised. Among the harmful effects, die-offs resulting from anoxia or hypoxia following large blooms of relative ungrazed species are well known. In some instances marine fauna in the Northern Benguela are killed by micro algal species tat release toxins and other compounds directly into the water. For many years shellfish poisoning was not reported in the Namibian coast. Recently, however, attempts to market mussels grown in the Luderitz region failed (Pitcher, 1999) as bioassays for Paralytic Shellfish Poisoning (PSP) regularly tested positive as a consequence of blooms of the toxic Dinoflagellates, Alexandrian catenella. Various species of Dinophysis, known to cause Diarrhetic Shellfish Poisoning (DSP), have been recorded on the Namibian coast but shellfish in the Northern Benguela have yet to be tested for DSP (Pitcher, 1999)

Clearly, there is a pressing need to develop effective response to the threat of HABs through management and mitigation. This requires knowledge of the ecological and oceanographic factors that control the distribution and population dynamics of HAB species. Namibia has the statutes on which a more detailed regulatory framework can be built and an acceptable program. The Ministry of Trade and Industry is already the EU-recognized Competent Authority for other fishing products, while the Ministry of Fisheries and Marine Resources (MFMR) will be the lead agency in the implementation of the monitoring program