Lake Bosomtwe has been subjected to anthropogenic perturbations that provide different scales of ... more Lake Bosomtwe has been subjected to anthropogenic perturbations that provide different scales of environmental stimuli in response to seasonal variation. This situation can overwhelm the capacity of lake to mitigate the impact on the water quality. Knowledge of seasonality will enhance the predictability of the water quality trends to advance management of the lake. The seasonal pattern of levels of physicochemical and nutrient parameters was examined, from March 2018 to February 2020, using the Canadian Council of Ministers of the Environment Water Quality Index model. Temperature, pH, alkalinity, turbidity, dissolved oxygen, total hardness, total dissolved solids, total suspended solids, biochemical oxygen demand, nitrate, phosphate, sulphate, iron, lead, and zinc were studies. The results showed a decline in water quality from ‘fair’ status in the pre-rainy (65.7%) and rainy (67.2%) seasons through ‘marginal’ in the pre-dry seasons (46.5%) to poor in the dry seasons (44%). The la...
Fishery characteristics and livelihood status of fishers at Tono Reservoir, Ghana, were investiga... more Fishery characteristics and livelihood status of fishers at Tono Reservoir, Ghana, were investigated between January 2015 and June 2016. Data on fisher demography, fishing gears, fishing methods, perceptions of the state of fish stocks, management practices, income and consumption of fishers were obtained through structured interviews. Censuses of fishers and fishing gears were conducted through direct observation and counts. The population of fishers was 950 and the majority (74%) of the sampled respondents fell within the ages of 24–41 years. Gillnet, cast net, trap and hook and line were the four main gears utilised. Illegal methods of fishing observed included the use of mosquito nets (nets with mesh <1.0 cm) and the use of brewer’s waste (pito mash) as bait. Brycinus nurse, Synodontis spp., Parailia spiniserrata and Chrysichthys spp. were perceived to have disappeared from the reservoir. The fishers were unaware of the existence of any fisheries regulations, hence there was no adherence to management practices. Their daily income was derived mainly from fishing. The incidence of poverty among fishers was low (8%). The Tono Reservoir has a great potential for supporting livelihood if it is properly managed.
The study was carried out to characterize potential larval habitats in the city of Sekondi with t... more The study was carried out to characterize potential larval habitats in the city of Sekondi with the aim of assessing the relative importance of anthropogenic and natural water bodies as larval habitats. Insecticide-resistance status of Anopheles gambiae senso lato in the southwestern part of the coastal savannah zone in Ghana was also assessed against four different classes of insecticides. Larval surveys were carried out in two communities that are separated by a lagoon. Although the lagoon was a potential mosquito larval habitat, we showed that it was not an important mosquito breeding site. The major larval habitats were anthropogenic, resulting from human behavior. Some of the organically polluted breeding sites were inhabited by both An. gambiae s.l. and Culex quinquefasciatus larvae. The data also showed that An. gambiae s.l. has currently developed a strong resistance to DDT and pyrethroid insecticides in southwestern Ghana, where the species was reported to be susceptible about a decade ago. The use of insecticides in households was implicated as a possible cause of the development of resistance among An. gambiae s.l. populations in the area. The management of insecticide resistance among malaria vectors needs urgent attention if insecticide-treated materials can continue to be used for malaria control.
Journal of Aquaculture Research and Development, 2019
Background: The development of aquaculture management areas (AMAs) is opined as one of the strate... more Background: The development of aquaculture management areas (AMAs) is opined as one of the strategies to ensure sustainable aquaculture. AMAs allows collaborative management of individual fish farms in a coordinated manner within a demarked space, where water resources and aquaculture impacts are shared in an environmentally harmonised way. This study seeks to evaluate the trophic status and develop potential AMAs for the Tono and Vea reservoirs in the Upper East Region of Ghana.Materials and Methods: Reservoir water depth, transparency, chlorophyll-a, nitrate-nitrogen, nitrite-nitrogen, ammonium-nitrogen and phosphorus concentrations was monitored for 15 months (February 2015-April 2016). The trophic status of the water was estimated from the concentrations of the water quality parameters after laboratory analysis. The composite values obtained were integrated into a tropic level index (TLI) equation and values compared to standard nutrient enrichment categories. The AMAs were dem...
General contamination of heavy metals in the environment is a major global concern, which has pro... more General contamination of heavy metals in the environment is a major global concern, which has provoked the emergence of phytoremediation technologies for cleaning aquatic environment. Heavy metals are released into the environment from a wide range of natural and anthropogenic sources. Macrophytes are known as good indicators of heavy metal contamination in aquatic ecosystems and they act as biological filters by accumulating heavy metals from the surrounding environments. Concentrations of heavy metals such as Hg, Cd, Co, Cu, Mo, Ni, Pb, Tl and Zn were measured in macrophytes and water samples from the mouth of five rivers namely; Gavaraget, Argichi, Makenis, Masrik each of them meeting the Lake Sevan, Armenia. The collected plants were Batrachium rionii, Myosotis palustris, Lythrum salicaria, Scrophularia alata, Calamagrostis epigeios, Lepidium latifolium, Glyceria plicata, Veronica anagallis-aquatica, Butomus umbellatus, Sparganium erectum. The highest concentration of Ni (5.5 mg/kg) was observed in Glyceria plicata whereas concentrations (mg/kg) of all other metals were highest (Hg, 0.02; Cd, 0.46; Co, 3; Cu, 18.9; Pb, 6.9; Tl, 0.13 and Zn, 113) in Batrachium rionii. Range and trend in concentrations of Co (<0.5μg/l), Cd (<0.5μg/l), Tl (<0.1μg/l) and Hg (<0.3μg/l) in water samples were similar at all the sites. Occurrence of heavy metals was much higher in macrophytes and water from Gavaraget and Masrik than that of the Argichi and Makenis due to the discharge of sewage into the river Gavaraget and industrial wastewaters into the river Masrik. The fact that the concentrations of different heavy metals in these macrophytes were far higher than in their respective water column indicates to their role in the biogeochemical cycles of heavy metals. This study aimed at understanding the importance of macrophytes in accumulation of heavy metals and suggesting remedial measures for the preservation and restoration of the lake ecosystem.
Physics-based remote sensing in littoral environments for ecological monitoring and assessment is... more Physics-based remote sensing in littoral environments for ecological monitoring and assessment is a challenging task that depends on adequate atmospheric conditions during data acquisition, sensor capabilities and correction of signal disturbances associated with water surface and water column. Airborne hyper-spectral scanners offer higher potential than satellite sensors for wetland monitoring and assessment. However, application in remote areas is often limited by national restrictions, time and high costs compared to satellite data. In this study, we tested the potential of the commercial, high-resolution multi-spectral satellite QuickBird for monitoring littoral zones of Lake Sevan (Armenia). We present a classification procedure that uses a physics-based image processing system (MIP) and GIS tools for calculating spatial metrics. We focused on classification of littoral sediment coverage over three consecutive years (2006–2008) to document changes in vegetation structure associated with a rise in water levels. We describe a spectral unmixing algorithm for basic classification and a supervised algorithm for mapping vegetation types. Atmospheric aerosol retrieval, lake-specific parameterisation and validation of classifications were supported by underwater spectral measurements in the respective seasons. Results revealed accurate classification of submersed aquatic vegetation and sediment structures in the littoral zone, documenting spatial vegetation dynamics induced by water level fluctuations and inter-annual variations in phytoplankton blooms. The data prove the cost-effective applicability of satellite remote-sensing approaches for high-resolution mapping in space and time of lake littoral zones playing a major role in lake ecosystem functioning. Such approaches could be used for monitoring wetlands anywhere in the world.
Lake Bosomtwe has been subjected to anthropogenic perturbations that provide different scales of ... more Lake Bosomtwe has been subjected to anthropogenic perturbations that provide different scales of environmental stimuli in response to seasonal variation. This situation can overwhelm the capacity of lake to mitigate the impact on the water quality. Knowledge of seasonality will enhance the predictability of the water quality trends to advance management of the lake. The seasonal pattern of levels of physicochemical and nutrient parameters was examined, from March 2018 to February 2020, using the Canadian Council of Ministers of the Environment Water Quality Index model. Temperature, pH, alkalinity, turbidity, dissolved oxygen, total hardness, total dissolved solids, total suspended solids, biochemical oxygen demand, nitrate, phosphate, sulphate, iron, lead, and zinc were studies. The results showed a decline in water quality from ‘fair’ status in the pre-rainy (65.7%) and rainy (67.2%) seasons through ‘marginal’ in the pre-dry seasons (46.5%) to poor in the dry seasons (44%). The la...
Fishery characteristics and livelihood status of fishers at Tono Reservoir, Ghana, were investiga... more Fishery characteristics and livelihood status of fishers at Tono Reservoir, Ghana, were investigated between January 2015 and June 2016. Data on fisher demography, fishing gears, fishing methods, perceptions of the state of fish stocks, management practices, income and consumption of fishers were obtained through structured interviews. Censuses of fishers and fishing gears were conducted through direct observation and counts. The population of fishers was 950 and the majority (74%) of the sampled respondents fell within the ages of 24–41 years. Gillnet, cast net, trap and hook and line were the four main gears utilised. Illegal methods of fishing observed included the use of mosquito nets (nets with mesh <1.0 cm) and the use of brewer’s waste (pito mash) as bait. Brycinus nurse, Synodontis spp., Parailia spiniserrata and Chrysichthys spp. were perceived to have disappeared from the reservoir. The fishers were unaware of the existence of any fisheries regulations, hence there was no adherence to management practices. Their daily income was derived mainly from fishing. The incidence of poverty among fishers was low (8%). The Tono Reservoir has a great potential for supporting livelihood if it is properly managed.
The study was carried out to characterize potential larval habitats in the city of Sekondi with t... more The study was carried out to characterize potential larval habitats in the city of Sekondi with the aim of assessing the relative importance of anthropogenic and natural water bodies as larval habitats. Insecticide-resistance status of Anopheles gambiae senso lato in the southwestern part of the coastal savannah zone in Ghana was also assessed against four different classes of insecticides. Larval surveys were carried out in two communities that are separated by a lagoon. Although the lagoon was a potential mosquito larval habitat, we showed that it was not an important mosquito breeding site. The major larval habitats were anthropogenic, resulting from human behavior. Some of the organically polluted breeding sites were inhabited by both An. gambiae s.l. and Culex quinquefasciatus larvae. The data also showed that An. gambiae s.l. has currently developed a strong resistance to DDT and pyrethroid insecticides in southwestern Ghana, where the species was reported to be susceptible about a decade ago. The use of insecticides in households was implicated as a possible cause of the development of resistance among An. gambiae s.l. populations in the area. The management of insecticide resistance among malaria vectors needs urgent attention if insecticide-treated materials can continue to be used for malaria control.
Journal of Aquaculture Research and Development, 2019
Background: The development of aquaculture management areas (AMAs) is opined as one of the strate... more Background: The development of aquaculture management areas (AMAs) is opined as one of the strategies to ensure sustainable aquaculture. AMAs allows collaborative management of individual fish farms in a coordinated manner within a demarked space, where water resources and aquaculture impacts are shared in an environmentally harmonised way. This study seeks to evaluate the trophic status and develop potential AMAs for the Tono and Vea reservoirs in the Upper East Region of Ghana.Materials and Methods: Reservoir water depth, transparency, chlorophyll-a, nitrate-nitrogen, nitrite-nitrogen, ammonium-nitrogen and phosphorus concentrations was monitored for 15 months (February 2015-April 2016). The trophic status of the water was estimated from the concentrations of the water quality parameters after laboratory analysis. The composite values obtained were integrated into a tropic level index (TLI) equation and values compared to standard nutrient enrichment categories. The AMAs were dem...
General contamination of heavy metals in the environment is a major global concern, which has pro... more General contamination of heavy metals in the environment is a major global concern, which has provoked the emergence of phytoremediation technologies for cleaning aquatic environment. Heavy metals are released into the environment from a wide range of natural and anthropogenic sources. Macrophytes are known as good indicators of heavy metal contamination in aquatic ecosystems and they act as biological filters by accumulating heavy metals from the surrounding environments. Concentrations of heavy metals such as Hg, Cd, Co, Cu, Mo, Ni, Pb, Tl and Zn were measured in macrophytes and water samples from the mouth of five rivers namely; Gavaraget, Argichi, Makenis, Masrik each of them meeting the Lake Sevan, Armenia. The collected plants were Batrachium rionii, Myosotis palustris, Lythrum salicaria, Scrophularia alata, Calamagrostis epigeios, Lepidium latifolium, Glyceria plicata, Veronica anagallis-aquatica, Butomus umbellatus, Sparganium erectum. The highest concentration of Ni (5.5 mg/kg) was observed in Glyceria plicata whereas concentrations (mg/kg) of all other metals were highest (Hg, 0.02; Cd, 0.46; Co, 3; Cu, 18.9; Pb, 6.9; Tl, 0.13 and Zn, 113) in Batrachium rionii. Range and trend in concentrations of Co (<0.5μg/l), Cd (<0.5μg/l), Tl (<0.1μg/l) and Hg (<0.3μg/l) in water samples were similar at all the sites. Occurrence of heavy metals was much higher in macrophytes and water from Gavaraget and Masrik than that of the Argichi and Makenis due to the discharge of sewage into the river Gavaraget and industrial wastewaters into the river Masrik. The fact that the concentrations of different heavy metals in these macrophytes were far higher than in their respective water column indicates to their role in the biogeochemical cycles of heavy metals. This study aimed at understanding the importance of macrophytes in accumulation of heavy metals and suggesting remedial measures for the preservation and restoration of the lake ecosystem.
Physics-based remote sensing in littoral environments for ecological monitoring and assessment is... more Physics-based remote sensing in littoral environments for ecological monitoring and assessment is a challenging task that depends on adequate atmospheric conditions during data acquisition, sensor capabilities and correction of signal disturbances associated with water surface and water column. Airborne hyper-spectral scanners offer higher potential than satellite sensors for wetland monitoring and assessment. However, application in remote areas is often limited by national restrictions, time and high costs compared to satellite data. In this study, we tested the potential of the commercial, high-resolution multi-spectral satellite QuickBird for monitoring littoral zones of Lake Sevan (Armenia). We present a classification procedure that uses a physics-based image processing system (MIP) and GIS tools for calculating spatial metrics. We focused on classification of littoral sediment coverage over three consecutive years (2006–2008) to document changes in vegetation structure associated with a rise in water levels. We describe a spectral unmixing algorithm for basic classification and a supervised algorithm for mapping vegetation types. Atmospheric aerosol retrieval, lake-specific parameterisation and validation of classifications were supported by underwater spectral measurements in the respective seasons. Results revealed accurate classification of submersed aquatic vegetation and sediment structures in the littoral zone, documenting spatial vegetation dynamics induced by water level fluctuations and inter-annual variations in phytoplankton blooms. The data prove the cost-effective applicability of satellite remote-sensing approaches for high-resolution mapping in space and time of lake littoral zones playing a major role in lake ecosystem functioning. Such approaches could be used for monitoring wetlands anywhere in the world.
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Co, Cu, Mo, Ni, Pb, Tl and Zn were measured in macrophytes and water samples from the mouth of five rivers namely; Gavaraget, Argichi, Makenis, Masrik each of them meeting the Lake Sevan, Armenia. The collected plants were Batrachium rionii, Myosotis palustris, Lythrum salicaria, Scrophularia alata, Calamagrostis epigeios, Lepidium latifolium, Glyceria plicata, Veronica anagallis-aquatica, Butomus umbellatus, Sparganium erectum. The highest concentration of Ni (5.5 mg/kg) was observed in Glyceria plicata whereas concentrations (mg/kg) of all other metals were highest (Hg, 0.02; Cd, 0.46; Co, 3; Cu, 18.9; Pb, 6.9; Tl, 0.13 and Zn, 113) in Batrachium rionii. Range and trend in concentrations of Co (<0.5μg/l), Cd (<0.5μg/l), Tl (<0.1μg/l) and Hg (<0.3μg/l) in water samples were similar at all the sites. Occurrence of heavy metals was much higher in macrophytes and water from Gavaraget and Masrik than that of the Argichi and Makenis due to the discharge of sewage into the river Gavaraget and industrial wastewaters into the river Masrik. The fact that the concentrations of different heavy metals in these macrophytes were far higher than in their respective water column indicates to their role in the biogeochemical cycles of heavy metals. This study aimed at understanding the importance of macrophytes in accumulation of heavy metals and suggesting remedial measures for the preservation and restoration of the lake ecosystem.
Co, Cu, Mo, Ni, Pb, Tl and Zn were measured in macrophytes and water samples from the mouth of five rivers namely; Gavaraget, Argichi, Makenis, Masrik each of them meeting the Lake Sevan, Armenia. The collected plants were Batrachium rionii, Myosotis palustris, Lythrum salicaria, Scrophularia alata, Calamagrostis epigeios, Lepidium latifolium, Glyceria plicata, Veronica anagallis-aquatica, Butomus umbellatus, Sparganium erectum. The highest concentration of Ni (5.5 mg/kg) was observed in Glyceria plicata whereas concentrations (mg/kg) of all other metals were highest (Hg, 0.02; Cd, 0.46; Co, 3; Cu, 18.9; Pb, 6.9; Tl, 0.13 and Zn, 113) in Batrachium rionii. Range and trend in concentrations of Co (<0.5μg/l), Cd (<0.5μg/l), Tl (<0.1μg/l) and Hg (<0.3μg/l) in water samples were similar at all the sites. Occurrence of heavy metals was much higher in macrophytes and water from Gavaraget and Masrik than that of the Argichi and Makenis due to the discharge of sewage into the river Gavaraget and industrial wastewaters into the river Masrik. The fact that the concentrations of different heavy metals in these macrophytes were far higher than in their respective water column indicates to their role in the biogeochemical cycles of heavy metals. This study aimed at understanding the importance of macrophytes in accumulation of heavy metals and suggesting remedial measures for the preservation and restoration of the lake ecosystem.