NOAA holds that “Seaweed is chock-full of vitamins, minerals, and fiber, and can be tasty. For at least 1,500 years, the Japanese have enrobed a mixture of raw fish, sticky rice and other ingredients in a seaweed called nori. The delectable result is a sushi roll.”
Seaweeds have also been found to contain anti-cancer agents that researchers believe can eventually prove effective in the treatment of tumours and certain cancers including leukemia.
A study conducted by Robertson-Anderson in 2007 indicated that red seaweed derivative had the potential of blocking the transmission of HIV/AIDS. Thus, the prevalence rates of HIV/AIDS and some cancers are low in Japan and Korea due to high consumption of dietary seaweeds.
Apart from their medicinal qualities, multipurpose marine plants and algae, they have also contributed to economic growth in the manufacturing industry.
NOAA classifies them as “effective binding agents (emulsifiers) in such commercial goods as toothpaste and fruit jelly, and popular softeners (emollients) in organic cosmetics and skin-care products.” They are also used as excipients in certain pharmaceutical products.
Despite the numerous benefits highlighted, a team of researchers from the United Kingdom (UK) has warned of some dangers associated with seaweed consumption.
They summed it up by saying “those of you who have been swept along by the latest sushi craze or who can’t visit a Chinese restaurant without indulging in deep-fried seaweed may be getting a higher dose of arsenic than you think.”
The researchers have identified thio-organoarsenate, a compound in the urine of sheep after they were fed a diet of seaweed, leading to concerns that previous estimates of the amount of arsenic that people consumed might have been too low.
Seaweeds in Ghana
Unlike West African countries such as Senegal and The Gambia, the commercial and dietary benefits of seaweed are not very well known in Ghana, notwithstanding the recent frequent accumulation of large swamps of seaweed in Ghana’s offshore coastal belt as well as along the beaches, particularly near Ghana’s oilfields.
Some have attributed these swamps to oil exploration activities, while others claim they travelled from Cote d’Ivoire to Ghana. Some fishermen have also blamed low yield to the presence of seaweeds.
Seaweed invasion of the coast of Ghana is not new. There have been incidents in the past, albeit in relatively limited quantities. But in recent times incidents have increased. For example, brown seaweeds (Sargassum) began invading the coastal region beaches and estuaries of Ghana in 2009, but large amounts of these weeds were observed between January and October 2012 and from January to June 2014.
The most recent has been the increased influx of the seaweeds along the inshore coastal waters and beaches particularly in the Jomoro, Ahanta West and Nzema East districts of the Western Region and some parts of the Central, Greater and Volta Regions of Ghana.
“This has impacted negatively on biodiversity, tourism and the livelihoods of coastal communities, especially the fisher folks whose lives are dependent on fishing activities,” a recent study on seaweeds, conducted by the Centre for Scientific and Industrial Research – Water Research Institute (CSIR-WRI) to identify and analyse seaweeds collected along some selected fishing communities within the coastal areas in the Western Region revealed.
The study referred to this adverse impact on economic activities of the fishing community. The situation is not different on the international scene.
In 2011 in Antigua, a $600-a-night St James’ Club and Villas was forced to close for the month of September, while it removed 10,000 tons of seaweed from its beaches with revenue losses and clean up costs of $1 million.
The CSIR-WRI also cited similar situations in the coastal regions of Bermuda, Anguilla, Tobago and Texas. In West Africa, similar conditions have been reported in Sierra Leone, Cote d’Ivoire and Liberia where volumes of Sargassum have invaded the respective shores of these countries.
Seaweeds and farming
Seaweed invasion of communities and towns such as Half Assini, Egbazo, Bakanta, Esiama, Asenda, Egyan, Miamia, Busua Africa Beach and South of Shama were studied.
Analysis of samples of Sargassum collected from these communities revealed significant quantities of heavy metals such as Copper, Zinc, Iron, Lead, Cadmium, and Mercury. The samples also contained phosphates, nitrates and chlorides. Also present were various compounds of ammonia and potassium.
The presence of phosphates, nitrates and potassium suggest that Sargassum could be a potential source of nitrogen and phosphate fertilisers, but “the nutrition content and utility of the seaweed cannot be considered alone without taking cognisance of the potentially harmful levels of heavy metals found in all samples evaluated in this study.”
According to the CSIR study, these heavy metals could be transported in food when they are applied on edible plants as manure and in turn cause serious health risks.
Investigate source of seaweed
Nigeria has more than 80 active oilfields, while Norway has more than 60, but both do not record heavy masses of seaweeds and for that reason the emergence of seaweeds at Ghana’s coastal regions cannot be attributed to oil exploration, the CSIR-WRI report noted. “The Western Region has been a long time hub of the gold industry and the coastal areas are at the terminus of the inland drainage system from renowned mining locations such as Prestea, Tarkwa, Daman and Bogoso.
The Western Region is now also the hub of oil exploration and drilling activities and all efforts must be made to thoroughly investigate the sources of these heavy metals so as to be clear as to where they originate from.”
Based on the findings of the report and what pertains in other oil rich countries and mining activities in the Western Region, it would be inconclusive for anyone to attribute the growing number of seaweeds to oil exploration activities.
This is particularly so, when seaweeds are also believed to have migrated from the Sargasso Sea and along the Gulf of Guinea from Senegal to Ghana, according to the CSIR-WRI report.
As has been noted, seaweeds have been proven to be of tremendous use despite their potential health risks when consumed in large quantities over a long period of time. China and Japan rake in millions of dollars annually through the commercialisation of seaweeds.
Ghana can strengthen its scientific research institutions to conduct thorough studies into seaweeds to make maximum use of them. Farmers need to be educated on the dangers of using raw seaweeds as fertiliser.
These seaweeds can be harnessed and processed to remove the heavy metals that make them potentially harmful to plants and humans. Further investigations should be conducted to find the sources of seaweeds and how they can be either brought under control or utilised for profit.