The arrival of the invasive brown seaweed Sargassum in the Western Region of Ghana was first reported in 2009. This impacted negatively on biodiversity, tourism and the livelihoods of the coastal communities. The objectives of the study among others were to identify and determine the nutritional and toxicological contents of the seaweed. Twenty four samples collected from 6 zones along the Western Region were analysed. Nutritional and toxicological analyses were carried out using an Atomic Absorption Spectrophotometer (AAS) 900T. Results of the study indicated that the Sargassum samples analyzed contained low concentrations of nitrogen. However, nitrogen utilized by plants, namely, nitrate and ammonia were very high, together with phosphates. This makes the Sargassum a good source organic fertilizer. However, the high concentrations of toxic heavy metals in the Sargassum defeat this assertion. Heavy metals have implications in both the growth and metabolic activities of plants. Most heavy metals, especially arsenic and lead are carcinogenic and are capable of causing skin, lung, liver and bladder cancers and miscarriages. Indiscriminate domestic and industrial wastes disposal, oil and gas activities, mining and high shipping traffic may have contributed to the heavy metal concentrations in the seaweeds.
The 26 communities surrounding the rim of the largest Crater Lake in Africa, the Lake Bosomtwe, depend on the lake for livelihood support. Water sources such as lake, streams and boreholes used as drinking water sources were collected quarterly for a period of 2 years. These were analysed bacteriologically for the determination of total and faecal coliform, Escherichia coli, Aeromonas sp., Enterococcus sp., Salmonella sp., Pseudomonas sp. and total heterotrophic bacteria (THB) using membrane filtration and pour plate techniques. The seasonal variations of these bacteria in the water sources were determined. The results showed variation of bacteria counts in all the water sources. The highest E. coli counts of 2.9 × 10 3 cfu/100 ml were recorded in the lake and the least in the borehole 2.1 × 10 1 cfu/100 ml. The difference between the total coliform, faecal coliform and E. coli counts and the water sources was significant (p < 0.05). All the bacteria count with the exception of THB, in the different water sources, had higher bacteria counts during the dry season than the wet season which are statistically significant (p < 0.05). The bacteria contamination of these water sources renders them bacteriologically not suitable for drinking purposes; therefore, drinking these waters without any form of treatments could pose health risk to consumers. These water sources can, however, be used for domestic purposes.
Although cyanobacterial blooms and cyanotoxins represent a worldwide-occurring phenomenon, there are large differences among different countries in cyanotoxin-related human health risk assessment, management practices and policies. While national standards, guideline values and detailed regulatory frameworks for effective management of cyanotoxin risks have been implemented in many industrialized countries, the extent of cyanobacteria occurrence and cyanotoxin contamination in certain geographical regions is underreported and not very well understood. Such regions include major parts of tropical West and Central Africa, a region constisting of more than 25 countries occupying an area of 12 million km 2 , with a total population of 500 milion people. Only few studies focusing on cyanotoxin occurrence in this region have been published so far, and reports dealing specifically with cyanotoxin contamination in drinking water are extremely scarce. In this study, we report seasonal data on cyanobacteria and microcystin (MC) contamination in drinking water reservoirs and adjacent treatment plants located in Ghana, West Africa. During January-June 2005, concentrations of MCs were monitored in four treatment plants supplying drinking water to major metropolitan areas in Ghana: the treatment plants Barekese and Owabi, which serve Kumasi Metropolitan Area, and the plants Kpong and Weija, providing water for Accra-Tema Metropolitan Area. HPLC analyses showed that 65% samples of raw water at the intake of the treatment plants contained intracellular MCs (maximal detected concentration was 8.73 µg L -1 ), whereas dissolved toxins were detected in 33% of the samples. Significant reduction of cyanobacterial cell counts and MC concentrations was achieved during the entire monitoring period by the applied conventional water treatment methods (alum flocculation, sedimentation, rapid sand filtration and chlorination), and MC concentration in the final treated water never exceeded 1 µg L -1 (WHO guideline limit for MC-LR in drinking water). However, cyanobacterial cells (93-3,055 cell mL -1 ) were frequently found in the final treated water and intracellular MCs were detected in 17% of the samples (maximal concentration 0.61 µg L -1 ), while dissolved MCs were present in 14% of the final treated water samples (maximal concentration 0.81 µg L -1 ). It indicates a borderline efficiency of the water treatment, thus MC concentrations in drinking water might exceed the WHO guideline limit if the treatment efficiency gets compromised. In addition, MC concentrations found in the raw water might represent significant human health risks for people living in areas with only a limited access to the treated or underground drinking water.
This work reveals new, important insights about the influence of broad spatial variations on the phylogenetic relationship and chemical characteristics of Ghanaian Hypnea musciformis-a carrageenan-containing red seaweed. DNA barcoding techniques alleviate the difficulty for accurate morphological identification. COI barcode sequences of the Ghanaian H. musciformis showed <0.7% intraspecies divergence, indicating no distinct phylogenetic variation, suggesting that they actually belong to the same species. Thus, the spatial distribution of the sampling sites along the coast of Ghana did not influence the phylogenetic characteristics of H. musciformis in the region. The data also showed that the Ghanaian Hypnea sp. examined in this work should be regarded as the same species as the H. musciformis collected in Brazilian Sao Paulo (KP725276) with only 0.8%-1.3% intraspecies divergence. However, the comparison of COI sequences of Ghanaian H. musciformis with the available COI sequence of H. musciformis from other countries showed intraspecies divergences of 0%-6.9% indicating that the COI sequences for H. musciformis in the GenBank may include different subspecies. Although samples did not differ phylogenetically, the chemical characteristics of the H. musciformis differed significantly between different sampling locations in Ghana. The levels of the monosaccharides, notably galactose (20%-30% dw) and glucose (10%-18% dw), as well as the seawater inorganic salt concentration (21-32 mg/L) and ash content (19%-33% dw), varied between H. musciformis collected at different coastal locations in Ghana. The current work demonstrated that DNA-based identification allowed a detailed understanding of H. musciformis phylogenetic characteristics and revealed that chemical compositional differences of H. musciformis occur along the Ghanaian coast which are not coupled with genetic variations among those samples.
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