Pub Date : 2023-07-03DOI: 10.2989/16085914.2023.2236646
A. Hamza, A. T. M. Mohammed
The study was conducted to barcode five freshwater fish species obtained from Nile River tributaries (the Atbara River and the Blue Nile), in March 2019, using analysis of partial CO1 gene sequences. Fish samples were identified morphologically as Nile perch Lates niloticus, Nile labeo Labeo vulgaris, North African catfish Clarias gariepinus, Cornish jack Mormyrops anguilloides and bebe mormyrid Hyperopisus bebe. Following DNA extraction, universal primers were used for amplification of the CO1 barcode region. The PCR products were sequenced and used for molecular identification. Each sequence was matched to corresponding GenBank sequences using the BLAST technique. Sequences of all specimens were aligned along with the GenBank published sequences and polymorphic sites were identified. The analysed sequences were uploaded to GenBank under the accession numbers OL804282– OL804286. The analysed partial CO1 barcode gene showed a readable length of ∼548–669 base pairs. Sequence comparison of CO1 gene sequences with sequences published in GenBank revealed 99.27–100% identities at the species level. Therefore, the CO1 barcodes accurately identified all the studied freshwater fishes. This is the first molecular DNA barcode characterisation of freshwater fish species found in Sudan. The fish CO1 gene sequences revealed in this study will serve as barcode references for future characterisations of Nile River fishes.
{"title":"DNA barcoding of five economically important freshwater fish species from the Nile River, Sudan","authors":"A. Hamza, A. T. M. Mohammed","doi":"10.2989/16085914.2023.2236646","DOIUrl":"https://doi.org/10.2989/16085914.2023.2236646","url":null,"abstract":"The study was conducted to barcode five freshwater fish species obtained from Nile River tributaries (the Atbara River and the Blue Nile), in March 2019, using analysis of partial CO1 gene sequences. Fish samples were identified morphologically as Nile perch Lates niloticus, Nile labeo Labeo vulgaris, North African catfish Clarias gariepinus, Cornish jack Mormyrops anguilloides and bebe mormyrid Hyperopisus bebe. Following DNA extraction, universal primers were used for amplification of the CO1 barcode region. The PCR products were sequenced and used for molecular identification. Each sequence was matched to corresponding GenBank sequences using the BLAST technique. Sequences of all specimens were aligned along with the GenBank published sequences and polymorphic sites were identified. The analysed sequences were uploaded to GenBank under the accession numbers OL804282– OL804286. The analysed partial CO1 barcode gene showed a readable length of ∼548–669 base pairs. Sequence comparison of CO1 gene sequences with sequences published in GenBank revealed 99.27–100% identities at the species level. Therefore, the CO1 barcodes accurately identified all the studied freshwater fishes. This is the first molecular DNA barcode characterisation of freshwater fish species found in Sudan. The fish CO1 gene sequences revealed in this study will serve as barcode references for future characterisations of Nile River fishes.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"48 1","pages":"338 - 343"},"PeriodicalIF":1.4,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48608994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-03DOI: 10.2989/16085914.2023.2231486
Emmanuel Mzungu, A. Sifuna, W. Shivoga
The current study investigated the relationship between sediment grain sizes and macroinvertebrate distribution along the Isiukhu River, a tropical stream in western Kenya. Ten sites in total were selected from the upstream, midstream and downstream areas. Sampling of sediments and macroinvertebrates was carried out twice a month from March 2018 to March 2019. Sediment was characterised as polymodal and extremely poorly sorted at the upstream; trimodal and extremely poorly sorted in the midstream; and polymodal and extremely poorly sorted towards the downstream of the river. Upstream sediments were fine gravelly mud and very coarse gravelly mud, while downstream sediments were very coarse gravelly muddy very fine sand and very fine gravelly, clayey very fine sand, indicating sediments became finer downstream. The study identified 993 individual macroinvertebrates from 21 families. Highest mean abundance (100 ± 9.2) was recorded at Kimangeti (upstream) while least was at Mutono (11 ± 0.7) (downstream). A regression model of the relationship between mean sediment grain size and mean macroinvertebrate abundance indicated that sediment grain size accounted for 28.7% of the spatial variability of macroinvertebrate abundance. The connection between sediment size and macroinvertebrate abundance and diversity in the Isiukhu River highlights that control of soil erosion in this catchment is important for the ecology of this river.
{"title":"Relationship between sediment grain sizes and macroinvertebrate distribution along the Isiukhu River, western Kenya","authors":"Emmanuel Mzungu, A. Sifuna, W. Shivoga","doi":"10.2989/16085914.2023.2231486","DOIUrl":"https://doi.org/10.2989/16085914.2023.2231486","url":null,"abstract":"The current study investigated the relationship between sediment grain sizes and macroinvertebrate distribution along the Isiukhu River, a tropical stream in western Kenya. Ten sites in total were selected from the upstream, midstream and downstream areas. Sampling of sediments and macroinvertebrates was carried out twice a month from March 2018 to March 2019. Sediment was characterised as polymodal and extremely poorly sorted at the upstream; trimodal and extremely poorly sorted in the midstream; and polymodal and extremely poorly sorted towards the downstream of the river. Upstream sediments were fine gravelly mud and very coarse gravelly mud, while downstream sediments were very coarse gravelly muddy very fine sand and very fine gravelly, clayey very fine sand, indicating sediments became finer downstream. The study identified 993 individual macroinvertebrates from 21 families. Highest mean abundance (100 ± 9.2) was recorded at Kimangeti (upstream) while least was at Mutono (11 ± 0.7) (downstream). A regression model of the relationship between mean sediment grain size and mean macroinvertebrate abundance indicated that sediment grain size accounted for 28.7% of the spatial variability of macroinvertebrate abundance. The connection between sediment size and macroinvertebrate abundance and diversity in the Isiukhu River highlights that control of soil erosion in this catchment is important for the ecology of this river.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"48 1","pages":"274 - 286"},"PeriodicalIF":1.4,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42831854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-03DOI: 10.2989/16085914.2023.2218411
A. Dagne, H. Tadesse, K. Teshome
We conducted a study in Lake Abaya and Lake Chamo, the two largest Ethiopian Rift Valley lakes, between 2016 and 2019, to evaluate their limnological features and infer longer-term changes in some water-quality parameters. Data generated through in situ measurements and laboratory analyses of physico-chemical parameters and the plankton communities were compared with results from the literature. Turbidity, salinity, nitrates and soluble reactive phosphorous showed an increasing trend in Lake Abaya, while in Lake Chamo conductivity, salinity, nitrates and soluble reactive phosphorous showed an increasing trend. In both lakes the water transparency and chlorophyll a concentration showed a declining trend. Despite higher available nutrients in Lake Abaya compared with Lake Chamo, higher turbidity with suspended solids contributed to lower chlorophyll-a concentrations and lower zooplankton abundance. The abundances of rotifers and crustaceans were lower in Lake Abaya compared with Lake Chamo. The mean trophic state index using total phosphorus, Secchi depth and chlorophyll-a shows that both lakes are in a eutrophic state. Our findings are consistent with previous studies and indicate that changes in major limnological features are a signal to take intervention measures to prevent further ecological degradation and to sustain the ecological services and livelihoods of fishers who are directly dependent on the lakes.
{"title":"Limnological features and water-quality changes of two Ethiopian Rift Valley lakes, Lake Abaya and Lake Chamo","authors":"A. Dagne, H. Tadesse, K. Teshome","doi":"10.2989/16085914.2023.2218411","DOIUrl":"https://doi.org/10.2989/16085914.2023.2218411","url":null,"abstract":"We conducted a study in Lake Abaya and Lake Chamo, the two largest Ethiopian Rift Valley lakes, between 2016 and 2019, to evaluate their limnological features and infer longer-term changes in some water-quality parameters. Data generated through in situ measurements and laboratory analyses of physico-chemical parameters and the plankton communities were compared with results from the literature. Turbidity, salinity, nitrates and soluble reactive phosphorous showed an increasing trend in Lake Abaya, while in Lake Chamo conductivity, salinity, nitrates and soluble reactive phosphorous showed an increasing trend. In both lakes the water transparency and chlorophyll a concentration showed a declining trend. Despite higher available nutrients in Lake Abaya compared with Lake Chamo, higher turbidity with suspended solids contributed to lower chlorophyll-a concentrations and lower zooplankton abundance. The abundances of rotifers and crustaceans were lower in Lake Abaya compared with Lake Chamo. The mean trophic state index using total phosphorus, Secchi depth and chlorophyll-a shows that both lakes are in a eutrophic state. Our findings are consistent with previous studies and indicate that changes in major limnological features are a signal to take intervention measures to prevent further ecological degradation and to sustain the ecological services and livelihoods of fishers who are directly dependent on the lakes.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"48 1","pages":"237 - 246"},"PeriodicalIF":1.4,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69845799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-03DOI: 10.2989/16085914.2023.2215267
EO Akindele, S. Olaniyan, AM Adedapo
Deforestation in the Afrotropical realm is extensively encroaching on riparian corridors, causing increasingly negative impacts on freshwater biota. This study aimed to assess the biological water quality of an Afrotropical river in southwestern Nigeria whose riparian corridor is threatened by numerous environmental stressors. Water and macroinvertebrate samples from the Ojutu River, Osun State, were collected from March to November in 2019. The river’s extent of degradation was determined based on criteria such as riparian vegetation removal, grazing, farming, solid waste dumping, water abstraction and in-channel structures. Macroinvertebrate samples were scored using the International Organization for Standardization (ISO) Biological Monitoring Working Party (BMWP) system, which uses the presence of macroinvertebrate groups as a bioindicator of water quality in a river. The values obtained indicate that the water quality of the Ojutu River varied from an altered system (36 ≤ WQ ≤ 60) to a much-altered system (16 ≤ WQ ≤ 35) in the wet season, with evidence of mild pollution (61 ≤ WQ ≤ 100) in the dry season. The main drivers of biological water quality were in-channel structures, water abstraction, riparian vegetation removal and solid waste dumping. This study underscores the need to initiate resource management measures and enforce laws that could improve the ecological integrity of degraded riparian corridors in the Afrotropical realm.
{"title":"Environmental stressors influence the biological water quality of a lotic system in southwestern Nigeria","authors":"EO Akindele, S. Olaniyan, AM Adedapo","doi":"10.2989/16085914.2023.2215267","DOIUrl":"https://doi.org/10.2989/16085914.2023.2215267","url":null,"abstract":"Deforestation in the Afrotropical realm is extensively encroaching on riparian corridors, causing increasingly negative impacts on freshwater biota. This study aimed to assess the biological water quality of an Afrotropical river in southwestern Nigeria whose riparian corridor is threatened by numerous environmental stressors. Water and macroinvertebrate samples from the Ojutu River, Osun State, were collected from March to November in 2019. The river’s extent of degradation was determined based on criteria such as riparian vegetation removal, grazing, farming, solid waste dumping, water abstraction and in-channel structures. Macroinvertebrate samples were scored using the International Organization for Standardization (ISO) Biological Monitoring Working Party (BMWP) system, which uses the presence of macroinvertebrate groups as a bioindicator of water quality in a river. The values obtained indicate that the water quality of the Ojutu River varied from an altered system (36 ≤ WQ ≤ 60) to a much-altered system (16 ≤ WQ ≤ 35) in the wet season, with evidence of mild pollution (61 ≤ WQ ≤ 100) in the dry season. The main drivers of biological water quality were in-channel structures, water abstraction, riparian vegetation removal and solid waste dumping. This study underscores the need to initiate resource management measures and enforce laws that could improve the ecological integrity of degraded riparian corridors in the Afrotropical realm.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"48 1","pages":"261 - 273"},"PeriodicalIF":1.4,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48063571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-03DOI: 10.2989/16085914.2023.2249507
Frank O. Masese, Augustine Sitati, Mourine J. Yegon, Elizabeth W. Wanderi, P. Raburu
Habitat quality and diversity strongly influence the composition of macroinvertebrate communities in lotic ecosystems. We evaluated the functional organization of macroinvertebrates in response to changes in habitat type and seasonality in the Afromontane Moiben River in western Kenya. In-stream substrate characteristics were evaluated at the reach, channel unit/habitat and microhabitat scales at nine sites in different land-use areas. Water and habitat quality were assessed during the dry (January–March) and wet (April–June) seasons. A total of 81 macroinvertebrate samples were collected every month from three channel units (pools, riffles and runs) defined by different substrate types and classified into five functional feeding groups (FFGs): collector-filterers, collector-gatherers, predators, scrapers and shredders. Numerical abundance differed significantly between FFGs, with gatherers > filterers > predators > scrapers > shredders. Coarse substrate (bedrock, boulders and cobbles) in riffles had the highest richness and abundance of filterers and scrapers while sand, mud and detritus in pools recorded the lowest richness and abundance. Shredders and scrapers occurred predominantly in upstream sites with minimal human disturbance, while gatherers were most abundant at disturbed sites. The greatest variability in FFGs was at the smallest microhabitat scale, and not at the reach scale. This study shows that attention should be given to both reach-scale and in-stream disturbances when assessing the ecological condition of streams and rivers.
{"title":"Habitat scale and seasonality influence macroinvertebrate functional feeding groups in a tropical Kenyan montane stream","authors":"Frank O. Masese, Augustine Sitati, Mourine J. Yegon, Elizabeth W. Wanderi, P. Raburu","doi":"10.2989/16085914.2023.2249507","DOIUrl":"https://doi.org/10.2989/16085914.2023.2249507","url":null,"abstract":"Habitat quality and diversity strongly influence the composition of macroinvertebrate communities in lotic ecosystems. We evaluated the functional organization of macroinvertebrates in response to changes in habitat type and seasonality in the Afromontane Moiben River in western Kenya. In-stream substrate characteristics were evaluated at the reach, channel unit/habitat and microhabitat scales at nine sites in different land-use areas. Water and habitat quality were assessed during the dry (January–March) and wet (April–June) seasons. A total of 81 macroinvertebrate samples were collected every month from three channel units (pools, riffles and runs) defined by different substrate types and classified into five functional feeding groups (FFGs): collector-filterers, collector-gatherers, predators, scrapers and shredders. Numerical abundance differed significantly between FFGs, with gatherers > filterers > predators > scrapers > shredders. Coarse substrate (bedrock, boulders and cobbles) in riffles had the highest richness and abundance of filterers and scrapers while sand, mud and detritus in pools recorded the lowest richness and abundance. Shredders and scrapers occurred predominantly in upstream sites with minimal human disturbance, while gatherers were most abundant at disturbed sites. The greatest variability in FFGs was at the smallest microhabitat scale, and not at the reach scale. This study shows that attention should be given to both reach-scale and in-stream disturbances when assessing the ecological condition of streams and rivers.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"7 1","pages":"287 - 299"},"PeriodicalIF":1.4,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139363803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-03DOI: 10.2989/16085914.2023.2207098
Margaret Waturu, L. Sitoki, J. Lalah, Stanley Chasia, E. Mbao
The unprecedented pollution of Athi River has negatively impacted the downstream communities who depend on the river's waters. Moreover, the Upper Athi River Catchment has recently experienced an increase in human population coupled with rapid industrialisation, which has led to encroachment of wetlands, riparian areas and forests. The objective of the present study was to investigate the impact of land use/land cover changes (LULCC) on the spatial-temporal distribution of water quality (WQ) in the Upper Athi River Catchment. The research stations were each allocated a GPS position, overlaid onto a 2018 LULCC map of the area. WQ data were analysed using PCA and further subjected to Kruskai-Wallls tests that resulted in six significant WQ parameters at (p < 0.05). The multiple regression model output showed that EC, DO, Zn and Pb, with R 2 values of 0.983, 0.918, 0.938 and 0.961 respectively, were significantly associated with urban area land use (p < 0.009, p < 0.042, p < 0.031 and p < 0.02 respectively). The results of our study suggest that significant land cover degradation is expected to occur in the Upper Athi River Catchment in future if mitigation activities are not undertaken, posing a great threat to biodiversity conservation, and the survival of local communities and urban dwellers in Athi River town.
{"title":"Effect of land use/land cover changes on water quality in the Upper Athi River sub-catchment in Kenya","authors":"Margaret Waturu, L. Sitoki, J. Lalah, Stanley Chasia, E. Mbao","doi":"10.2989/16085914.2023.2207098","DOIUrl":"https://doi.org/10.2989/16085914.2023.2207098","url":null,"abstract":"The unprecedented pollution of Athi River has negatively impacted the downstream communities who depend on the river's waters. Moreover, the Upper Athi River Catchment has recently experienced an increase in human population coupled with rapid industrialisation, which has led to encroachment of wetlands, riparian areas and forests. The objective of the present study was to investigate the impact of land use/land cover changes (LULCC) on the spatial-temporal distribution of water quality (WQ) in the Upper Athi River Catchment. The research stations were each allocated a GPS position, overlaid onto a 2018 LULCC map of the area. WQ data were analysed using PCA and further subjected to Kruskai-Wallls tests that resulted in six significant WQ parameters at (p < 0.05). The multiple regression model output showed that EC, DO, Zn and Pb, with R 2 values of 0.983, 0.918, 0.938 and 0.961 respectively, were significantly associated with urban area land use (p < 0.009, p < 0.042, p < 0.031 and p < 0.02 respectively). The results of our study suggest that significant land cover degradation is expected to occur in the Upper Athi River Catchment in future if mitigation activities are not undertaken, posing a great threat to biodiversity conservation, and the survival of local communities and urban dwellers in Athi River town.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"48 1","pages":"247 - 260"},"PeriodicalIF":1.4,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47800991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-03DOI: 10.2989/16085914.2023.2232411
Judith G Makombu, Cynthia A Bih, G. Nkongho, P. M. Oben, Rollins N Ndi, Clovis N Chombe, Mercy B Verkijika, Gerry K Sonkeng, Tekou Guegang, Janet H Brown
Macrobrachium vollenhovenii (Herklots, 1857), the largest of the indigenous West African Palaemonidae prawns, has a high potential for aquaculture. This work was carried out to assess the effect of temperature on embryonic development and offspring quality of this species. In the phase one experiment, females at stage V of gonadal development incubated their eggs at three experimental temperatures and their embryonic development was evaluated. Seven embryonic developmental stages were observed: fertilisation, mitosis, morula, blastula, gastrula, nauplius and larvae. The incubation periods were 19, 14 and 13 days at 26 °C, 28 °C and 30 °C, respectively. A temperature of 30 °C resulted in higher broodstock mortality (33.33%). In phase two, larvae were reared at the respective temperatures for 30 days at a stocking density of 30 larvae per litre of water. Offspring quality was significantly different between treatments from day five onwards, with the fastest development at 30 °C followed by 28 °C. However, larval survival rate was significantly higher at 26 °C (31.7%) followed by 28 °C (27.6%). A temperature of 28 °C could therefore be recommended as the most favourable for embryonic development and larviculture of M. vollenhovenii. These findings will help bridge the knowledge gap with respect to captive breeding and hatchery technology for M. vollenhovenii.
{"title":"Effect of temperature on embryonic development and offspring performance of the African river prawn, Macrobrachium vollenhovenii","authors":"Judith G Makombu, Cynthia A Bih, G. Nkongho, P. M. Oben, Rollins N Ndi, Clovis N Chombe, Mercy B Verkijika, Gerry K Sonkeng, Tekou Guegang, Janet H Brown","doi":"10.2989/16085914.2023.2232411","DOIUrl":"https://doi.org/10.2989/16085914.2023.2232411","url":null,"abstract":"Macrobrachium vollenhovenii (Herklots, 1857), the largest of the indigenous West African Palaemonidae prawns, has a high potential for aquaculture. This work was carried out to assess the effect of temperature on embryonic development and offspring quality of this species. In the phase one experiment, females at stage V of gonadal development incubated their eggs at three experimental temperatures and their embryonic development was evaluated. Seven embryonic developmental stages were observed: fertilisation, mitosis, morula, blastula, gastrula, nauplius and larvae. The incubation periods were 19, 14 and 13 days at 26 °C, 28 °C and 30 °C, respectively. A temperature of 30 °C resulted in higher broodstock mortality (33.33%). In phase two, larvae were reared at the respective temperatures for 30 days at a stocking density of 30 larvae per litre of water. Offspring quality was significantly different between treatments from day five onwards, with the fastest development at 30 °C followed by 28 °C. However, larval survival rate was significantly higher at 26 °C (31.7%) followed by 28 °C (27.6%). A temperature of 28 °C could therefore be recommended as the most favourable for embryonic development and larviculture of M. vollenhovenii. These findings will help bridge the knowledge gap with respect to captive breeding and hatchery technology for M. vollenhovenii.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"10 1","pages":"315 - 326"},"PeriodicalIF":1.4,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139363523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-03DOI: 10.2989/16085914.2023.2231513
S. Janse van Vuuren, A. Swanepoel
During 2012, aerial photographs of the Vaal River, South Africa, showed differences in water colour on either side of the Lethabo Weir. Water upstream of the weir was muddy brown, while water downstream was olive-green. Physical and chemical analyses indicated water quality differences upstream and downstream from the weir; furthermore, microscopic examination of water samples revealed that the colour difference were the result of different types of phytoplankton blooms. The upstream section was dominated by cryptophytes and green algae, while the downstream section experienced a cyanobacterial bloom dominated by Microcystis aeruginosa. The same phenomenon was again observed regularly between 2012 and 2022, and routine monitoring of the phytoplankton assemblage likewise indicated differences in the phytoplankton community composition upstream and downstream of the weir. The upstream section was characterised by various eukaryotic algae; in contrast, frequent and intensive cyanobacteria blooms occurred in the downstream section. Multivariate analyses showed a correlation between the different phytoplankton assemblages and physico-chemical properties of the river water. Many freshwater cyanobacteria and algae taxa are problematic: Microcystis and Dolichospermum produce potent cyanotoxins; flagellated green algae, cryptomonads and dinoflagellates produce substances that cause bad tastes and odours, plus the cells can cause floc disruption during drinking water treatment processes; and certain filamentous green algae and diatoms are known for clogging filters.
{"title":"Role of the Lethabo Weir in altering the phytoplankton community structure of the Vaal River, South Africa","authors":"S. Janse van Vuuren, A. Swanepoel","doi":"10.2989/16085914.2023.2231513","DOIUrl":"https://doi.org/10.2989/16085914.2023.2231513","url":null,"abstract":"During 2012, aerial photographs of the Vaal River, South Africa, showed differences in water colour on either side of the Lethabo Weir. Water upstream of the weir was muddy brown, while water downstream was olive-green. Physical and chemical analyses indicated water quality differences upstream and downstream from the weir; furthermore, microscopic examination of water samples revealed that the colour difference were the result of different types of phytoplankton blooms. The upstream section was dominated by cryptophytes and green algae, while the downstream section experienced a cyanobacterial bloom dominated by Microcystis aeruginosa. The same phenomenon was again observed regularly between 2012 and 2022, and routine monitoring of the phytoplankton assemblage likewise indicated differences in the phytoplankton community composition upstream and downstream of the weir. The upstream section was characterised by various eukaryotic algae; in contrast, frequent and intensive cyanobacteria blooms occurred in the downstream section. Multivariate analyses showed a correlation between the different phytoplankton assemblages and physico-chemical properties of the river water. Many freshwater cyanobacteria and algae taxa are problematic: Microcystis and Dolichospermum produce potent cyanotoxins; flagellated green algae, cryptomonads and dinoflagellates produce substances that cause bad tastes and odours, plus the cells can cause floc disruption during drinking water treatment processes; and certain filamentous green algae and diatoms are known for clogging filters.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"48 1","pages":"300 - 314"},"PeriodicalIF":1.4,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46880326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-03DOI: 10.2989/16085914.2023.2188166
Yadesa Chibsa, S. Mengistou, D. Kifle
This study assessed the spatio-temporal dynamics of the phytoplankton community in backwaters of the Ketar River, central Ethiopia, in relation to water quality and macrophyte coverage. Phytoplankton samples and physicochemical information were collected at six sites along the river over 1 year (December 2017 to November 2018). Phytoplankton was collected using a 15-μm mesh net. A total of 56 species belonging to three algal phyla were identified; the most diverse phylum was Bacillariophyta (35 species), followed by Chlorophyta (13 species) and Euglenophyta (eight species). Bacillariophyta had the highest abundance and contributed 80.08% of the total phytoplankton abundance. Site 6 in the downstream portion had the highest abundance and greatest diversity of phytoplankton species. The algal phyla present showed significant differences in species diversity and abundance both spatially and temporally. Redundancy analysis results revealed that the spatial distribution of phytoplankton in the river positively correlated with pH, electrical conductivity, dissolved oxygen and nitrate-nitrogen, while water temperature and total suspended solids correlated negatively. Some indicators of organic pollution suggest that the water quality of the river is progressively declining, meriting close monitoring.
{"title":"Spatio-temporal variation in phytoplankton community structure in backwaters of the Ketar River, central Ethiopia","authors":"Yadesa Chibsa, S. Mengistou, D. Kifle","doi":"10.2989/16085914.2023.2188166","DOIUrl":"https://doi.org/10.2989/16085914.2023.2188166","url":null,"abstract":"This study assessed the spatio-temporal dynamics of the phytoplankton community in backwaters of the Ketar River, central Ethiopia, in relation to water quality and macrophyte coverage. Phytoplankton samples and physicochemical information were collected at six sites along the river over 1 year (December 2017 to November 2018). Phytoplankton was collected using a 15-μm mesh net. A total of 56 species belonging to three algal phyla were identified; the most diverse phylum was Bacillariophyta (35 species), followed by Chlorophyta (13 species) and Euglenophyta (eight species). Bacillariophyta had the highest abundance and contributed 80.08% of the total phytoplankton abundance. Site 6 in the downstream portion had the highest abundance and greatest diversity of phytoplankton species. The algal phyla present showed significant differences in species diversity and abundance both spatially and temporally. Redundancy analysis results revealed that the spatial distribution of phytoplankton in the river positively correlated with pH, electrical conductivity, dissolved oxygen and nitrate-nitrogen, while water temperature and total suspended solids correlated negatively. Some indicators of organic pollution suggest that the water quality of the river is progressively declining, meriting close monitoring.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"48 1","pages":"166 - 177"},"PeriodicalIF":1.4,"publicationDate":"2023-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41517049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-03DOI: 10.2989/16085914.2023.2200816
J. Sirunda, P. Oberholster, G. Wolfaardt, Christoff Truter, Sean van der Merwe
Rising temperatures and increased occurrences of droughts, brought on by climate change, are expected to affect reservoir water levels. We hypothesised that the decrease in reservoir volumes in dams with desert climates will favour the growth of phytoplankton biomass, measured as chlorophyll a (Chl a), under drought conditions. Using the threshold levels method of Q50, ten drought years were recorded in the Von Bach Dam (VB) in comparison to seven in the Swakoppoort Dam (SWP). Both dams had significant reduction in percentage volume (vol %). The Chl a in SWP was 81 µg l−1 in drought and 48 µg l−1 in AAR years, compared to VB with 21 µg l−1 in drought and 24 µg l−1 in AAR years. Cyanobacterial cell counts in drought and AAR years in SWP were 129 704 and 77 838 cells ml−1, respectively, while cell counts in drought and AAR years in VB were 5 925 cells ml−1 and 20 070 cells ml−1, respectively. Decreases in phytoplankton biomass and total cyanobacteria were observed in SWP but not in VB. The pattern and magnitude of the statistically significant responses (t-test, p < 0.05) between physico-chemical and biological water quality variables varied among drought and AAR years. We conclude that that there is no clear correlation between drought and phytoplankton biomass from this study and that other anthropogenic–environmental drivers, such as land use impacts, will be needed to further elucidate the response of water quality to droughts.
{"title":"Long-term study of the drought impact on the phytoplankton concentration and assemblages in two water supply reservoirs in Namibia","authors":"J. Sirunda, P. Oberholster, G. Wolfaardt, Christoff Truter, Sean van der Merwe","doi":"10.2989/16085914.2023.2200816","DOIUrl":"https://doi.org/10.2989/16085914.2023.2200816","url":null,"abstract":"Rising temperatures and increased occurrences of droughts, brought on by climate change, are expected to affect reservoir water levels. We hypothesised that the decrease in reservoir volumes in dams with desert climates will favour the growth of phytoplankton biomass, measured as chlorophyll a (Chl a), under drought conditions. Using the threshold levels method of Q50, ten drought years were recorded in the Von Bach Dam (VB) in comparison to seven in the Swakoppoort Dam (SWP). Both dams had significant reduction in percentage volume (vol %). The Chl a in SWP was 81 µg l−1 in drought and 48 µg l−1 in AAR years, compared to VB with 21 µg l−1 in drought and 24 µg l−1 in AAR years. Cyanobacterial cell counts in drought and AAR years in SWP were 129 704 and 77 838 cells ml−1, respectively, while cell counts in drought and AAR years in VB were 5 925 cells ml−1 and 20 070 cells ml−1, respectively. Decreases in phytoplankton biomass and total cyanobacteria were observed in SWP but not in VB. The pattern and magnitude of the statistically significant responses (t-test, p < 0.05) between physico-chemical and biological water quality variables varied among drought and AAR years. We conclude that that there is no clear correlation between drought and phytoplankton biomass from this study and that other anthropogenic–environmental drivers, such as land use impacts, will be needed to further elucidate the response of water quality to droughts.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"48 1","pages":"152 - 165"},"PeriodicalIF":1.4,"publicationDate":"2023-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41312510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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