Pub Date : 2021-07-14DOI: 10.2989/16085914.2021.1933375
Amelework Zewudu, G. Beneberu, Minwyelet Minigst, A. Mezgebu
A multimetric index was developed using benthic macroinvertebrates to assess the ecological health of selected rivers and streams in the north-eastern part of Lake Tana subbasin, Ethiopia. One-time extensive sampling was carried out during the post-rainy season (November–December) of 2016. Macroinvertebrates were collected using a Surber sampler and a D-frame net at twenty sites. Based on the measured physico-chemical variables, sampling sites were clustered into references (n = 8) and test sites (n = 4). Approximately thirty potential candidate metrics were tested, and five metrics were selected as core metrics: number of Ephemeroptera Plecoptera Trichoptera taxa, percentage of Ephemeroptera individuals, percentage of EPT individuals, percentage that were shredders, and the percentage that were filter-feeders. These metrics were scored on a continuous scale from 0 to 10. To develop Lake Tana subbasin multimetric index (LTSBMI), scores were added and scaled to produce a score from 0 to 100. The final index was divided into five water quality classes: 'very good', 'good', 'fair', 'poor' and 'very poor'. The LTSBMI was effective in discriminating sites with different levels of impacts, but should be checked to other localities. The current LTSBMI could be used for ecosystem health assessment and monitoring in different Aftropical river systems with similar agroecology.
{"title":"Development of a multimetric index for assessing the ecological integrity of some selected rivers and streams in the north-eastern part of Lake Tana sub-basin, Ethiopia","authors":"Amelework Zewudu, G. Beneberu, Minwyelet Minigst, A. Mezgebu","doi":"10.2989/16085914.2021.1933375","DOIUrl":"https://doi.org/10.2989/16085914.2021.1933375","url":null,"abstract":"A multimetric index was developed using benthic macroinvertebrates to assess the ecological health of selected rivers and streams in the north-eastern part of Lake Tana subbasin, Ethiopia. One-time extensive sampling was carried out during the post-rainy season (November–December) of 2016. Macroinvertebrates were collected using a Surber sampler and a D-frame net at twenty sites. Based on the measured physico-chemical variables, sampling sites were clustered into references (n = 8) and test sites (n = 4). Approximately thirty potential candidate metrics were tested, and five metrics were selected as core metrics: number of Ephemeroptera Plecoptera Trichoptera taxa, percentage of Ephemeroptera individuals, percentage of EPT individuals, percentage that were shredders, and the percentage that were filter-feeders. These metrics were scored on a continuous scale from 0 to 10. To develop Lake Tana subbasin multimetric index (LTSBMI), scores were added and scaled to produce a score from 0 to 100. The final index was divided into five water quality classes: 'very good', 'good', 'fair', 'poor' and 'very poor'. The LTSBMI was effective in discriminating sites with different levels of impacts, but should be checked to other localities. The current LTSBMI could be used for ecosystem health assessment and monitoring in different Aftropical river systems with similar agroecology.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"47 1","pages":"1 - 10"},"PeriodicalIF":1.4,"publicationDate":"2021-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48986752","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 : 2021-07-14DOI: 10.2989/16085914.2021.1924609
John Peter Obubu, S. Mengistou, T. Fetahi, W. Graf, R. Odong
Worldwide, water resources have an impact on all forms of life as lotic systems are networks that interconnect water resources and land. They are important for navigation, water supplies, agriculture, recreation, and industrial development and help to regulate changes in climate and support social, spiritual, educational, and ecosystem health services. These ecosystems are, however, facing both natural and anthropogenic threats. Anthropogenic threats are driven by population increase, economic development, and catchment degradation. They are now the most threatened resources worldwide, and in Africa in particular. To design proper management strategies, the causes and impacts of the threats must be properly diagnosed. Monitoring and assessment approaches that show degradation and integrate it over time are essential to generate data and information required by water managers for decision making. Biomonitoring using macroinvertebrates is an effective tool in this regard, because it integrates causes of degradation and aquatic biotic responses to the impacts thereof. This review summarises the needs, challenges, and legal implications of biomonitoring in Africa using lessons from countries with successful biomonitoring as benchmarks.
{"title":"A critical review of macroinvertebrate-based bioassessment approaches in Africa’s lotic systems: developments, challenges, and legal requirements","authors":"John Peter Obubu, S. Mengistou, T. Fetahi, W. Graf, R. Odong","doi":"10.2989/16085914.2021.1924609","DOIUrl":"https://doi.org/10.2989/16085914.2021.1924609","url":null,"abstract":"Worldwide, water resources have an impact on all forms of life as lotic systems are networks that interconnect water resources and land. They are important for navigation, water supplies, agriculture, recreation, and industrial development and help to regulate changes in climate and support social, spiritual, educational, and ecosystem health services. These ecosystems are, however, facing both natural and anthropogenic threats. Anthropogenic threats are driven by population increase, economic development, and catchment degradation. They are now the most threatened resources worldwide, and in Africa in particular. To design proper management strategies, the causes and impacts of the threats must be properly diagnosed. Monitoring and assessment approaches that show degradation and integrate it over time are essential to generate data and information required by water managers for decision making. Biomonitoring using macroinvertebrates is an effective tool in this regard, because it integrates causes of degradation and aquatic biotic responses to the impacts thereof. This review summarises the needs, challenges, and legal implications of biomonitoring in Africa using lessons from countries with successful biomonitoring as benchmarks.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"46 1","pages":"377 - 389"},"PeriodicalIF":1.4,"publicationDate":"2021-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46539843","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 : 2021-07-06DOI: 10.2989/16085914.2021.1941743
R. van Deventer, C. Morris, T. Hill, N. Rivers-Moore
Urban and agricultural land uses have the potential to severely compromise the quality of impoundments, if ineffectively managed and operated. A case in point is the upper uMngeni Catchment, including Midmar Dam, which is integral to the freshwater supply infrastructure in KwaZulu-Natal, South Africa. Monitoring sites were established in varying land use types in three subcatchments of the upper uMngeni Catchment to assess water quality and ecosystem health impacts of current land uses. Conclusions about water quality were drawn using pairing of SASS5 and spot water quality data. Water quality and ecological condition were highest in commercial plantations and upstream of a high-density settlement where natural land cover and sparse settlement occurred. Although marked declines in water quality and ecological condition were observed under commercial agriculture. The most notable declines in water quality and ecological condition were observed downstream of the settlement with elevated nutrient loads. Shifts in aquatic biota were highly correlated with seasonal shifts in water quality, influenced markedly by land use. The cumulative effects of current land use activities, urban development and agriculture on Midmar Dam’s water quality should be viewed with concern. Additional development in the form of additional social housing projects may exacerbate impacts.
{"title":"Use of biological and water quality indices to evaluate conditions of the Upper uMngeni Catchment, KwaZulu-Natal, South Africa","authors":"R. van Deventer, C. Morris, T. Hill, N. Rivers-Moore","doi":"10.2989/16085914.2021.1941743","DOIUrl":"https://doi.org/10.2989/16085914.2021.1941743","url":null,"abstract":"Urban and agricultural land uses have the potential to severely compromise the quality of impoundments, if ineffectively managed and operated. A case in point is the upper uMngeni Catchment, including Midmar Dam, which is integral to the freshwater supply infrastructure in KwaZulu-Natal, South Africa. Monitoring sites were established in varying land use types in three subcatchments of the upper uMngeni Catchment to assess water quality and ecosystem health impacts of current land uses. Conclusions about water quality were drawn using pairing of SASS5 and spot water quality data. Water quality and ecological condition were highest in commercial plantations and upstream of a high-density settlement where natural land cover and sparse settlement occurred. Although marked declines in water quality and ecological condition were observed under commercial agriculture. The most notable declines in water quality and ecological condition were observed downstream of the settlement with elevated nutrient loads. Shifts in aquatic biota were highly correlated with seasonal shifts in water quality, influenced markedly by land use. The cumulative effects of current land use activities, urban development and agriculture on Midmar Dam’s water quality should be viewed with concern. Additional development in the form of additional social housing projects may exacerbate impacts.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"47 1","pages":"11 - 22"},"PeriodicalIF":1.4,"publicationDate":"2021-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43909128","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 : 2021-07-03DOI: 10.2989/16085914.2021.1991694
N. Rivers-Moore, K. Frith
{"title":"African Journal of Aquatic Science as a window for research surrounding the Grand Ethiopian Renaissance Dam","authors":"N. Rivers-Moore, K. Frith","doi":"10.2989/16085914.2021.1991694","DOIUrl":"https://doi.org/10.2989/16085914.2021.1991694","url":null,"abstract":"","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"46 1","pages":"iii - iv"},"PeriodicalIF":1.4,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41321372","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 : 2021-06-29DOI: 10.2989/16085914.2021.1922348
TV Mmako, A. Addo-Bediako, W. Luus-Powell, M. Kekana
The study assessed the impact of water and sediment quality on benthic macroinvertebrate assemblages in the Dwars River, a tributary of the Olifants River, Limpopo province, South Africa. Physico-chemical variables, heavy metals and macroinvertebrates were collected using standard methods. A multivariate analysis, Canonical Correspondence Analysis (CCA), was used to examine the macroinvertebrate community structure. Based on the selected physico-chemical variables and metal concentrations assessed, the water quality and sediment quality are deteriorating mainly in the downstream areas. The number of taxa and the Average Score per Taxon (ASPT) were significantly different between sites and seasons, with more taxa recorded in the upstream section of the river and in winter. A higher proportion of sensitive and high-scoring taxa (Ephemeroptera, Plecoptera and Trichoptera) were recorded in upstream and midstream sites and in winter. The CCA analysis showed an association of heavy metal concentration in the sediment with the distribution of macroinvertebrate taxa tolerant to poor water quality in the downstream section of the river. Because of the potential impacts of rapid economic development in the catchment, regular monitoring of the river is recommended, to detect potential river health problems early.
{"title":"Assessment of river health using benthic macroinvertebrates in the Dwars River, Olifants Water Management Area, Limpopo province, South Africa","authors":"TV Mmako, A. Addo-Bediako, W. Luus-Powell, M. Kekana","doi":"10.2989/16085914.2021.1922348","DOIUrl":"https://doi.org/10.2989/16085914.2021.1922348","url":null,"abstract":"The study assessed the impact of water and sediment quality on benthic macroinvertebrate assemblages in the Dwars River, a tributary of the Olifants River, Limpopo province, South Africa. Physico-chemical variables, heavy metals and macroinvertebrates were collected using standard methods. A multivariate analysis, Canonical Correspondence Analysis (CCA), was used to examine the macroinvertebrate community structure. Based on the selected physico-chemical variables and metal concentrations assessed, the water quality and sediment quality are deteriorating mainly in the downstream areas. The number of taxa and the Average Score per Taxon (ASPT) were significantly different between sites and seasons, with more taxa recorded in the upstream section of the river and in winter. A higher proportion of sensitive and high-scoring taxa (Ephemeroptera, Plecoptera and Trichoptera) were recorded in upstream and midstream sites and in winter. The CCA analysis showed an association of heavy metal concentration in the sediment with the distribution of macroinvertebrate taxa tolerant to poor water quality in the downstream section of the river. Because of the potential impacts of rapid economic development in the catchment, regular monitoring of the river is recommended, to detect potential river health problems early.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"46 1","pages":"441 - 451"},"PeriodicalIF":1.4,"publicationDate":"2021-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49260919","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 : 2021-06-24DOI: 10.2989/16085914.2021.1924110
G. Nwonumara, O. Okogwu
This study assessed the impacts of human activities and naturogenic processes on the water quality and phytoplankton of four rivers proximal to rice farms in Ebonyi State, south-eastern Nigeria. A range of water quality parameters were measured in conjunction with phytoplankton samples that were collected and identified in the laboratory using microscope and standard keys. The results showed that mean water temperature (30.32 ± 3.34 °C), conductivity (199.11 ± 118.70 μS cm−1) and total dissolved solids (102.60 ± 58.5 mg l−1) were highest in the dry season, while mean flow rate (0.7 ± 0.1 ms−1) and dissolved oxygen (6.15 ± 1.88 mg l−1) were highest in the wet season. Bacillariophyta had the highest mean abundance (6 611 ind. l−1) and biomass (5.52 μg l−1) in the dry season, whereas Chlorophyta had the highest mean diversity (Hʹ = 4.55) and species richness (MI = 1.1) in the wet season. Canonical correspondence analysis showed that hydrologic and climatic factors (temperature, water clarity and discharge) predominantly controlled phytoplankton community structure during the wet season while anthropogenic related factors (phosphate, nitrate and conductivity) regulated phytoplankton during the dry season. Consequently, sustainable management plans for these rivers must prioritise these factors in order to succeed.
{"title":"Seasonal dynamics in water quality and phytoplankton of four tropical rivers in Ebonyi State, southeastern Nigeria","authors":"G. Nwonumara, O. Okogwu","doi":"10.2989/16085914.2021.1924110","DOIUrl":"https://doi.org/10.2989/16085914.2021.1924110","url":null,"abstract":"This study assessed the impacts of human activities and naturogenic processes on the water quality and phytoplankton of four rivers proximal to rice farms in Ebonyi State, south-eastern Nigeria. A range of water quality parameters were measured in conjunction with phytoplankton samples that were collected and identified in the laboratory using microscope and standard keys. The results showed that mean water temperature (30.32 ± 3.34 °C), conductivity (199.11 ± 118.70 μS cm−1) and total dissolved solids (102.60 ± 58.5 mg l−1) were highest in the dry season, while mean flow rate (0.7 ± 0.1 ms−1) and dissolved oxygen (6.15 ± 1.88 mg l−1) were highest in the wet season. Bacillariophyta had the highest mean abundance (6 611 ind. l−1) and biomass (5.52 μg l−1) in the dry season, whereas Chlorophyta had the highest mean diversity (Hʹ = 4.55) and species richness (MI = 1.1) in the wet season. Canonical correspondence analysis showed that hydrologic and climatic factors (temperature, water clarity and discharge) predominantly controlled phytoplankton community structure during the wet season while anthropogenic related factors (phosphate, nitrate and conductivity) regulated phytoplankton during the dry season. Consequently, sustainable management plans for these rivers must prioritise these factors in order to succeed.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"46 1","pages":"402 - 413"},"PeriodicalIF":1.4,"publicationDate":"2021-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44540128","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 : 2021-06-22DOI: 10.2989/16085914.2021.1914537
J. Izegaegbe, L. Vivier, H. Mzimela
Bioaccumulation of metals in an endemic ocypodid burrowing mud crab, Paratylodiplax blephariskios, was investigated in contaminated mudflats of the subtropical Richards Bay Harbour (RBH), South Africa. Following sampling of water, sediment and mud crabs from three sites (Bhizolo, Mzingazi and Richards Bay Coal Terminal) in RBH during 2016/2017, tissue and sediment samples were oven dried for 48 hours, weighed and digested in an advanced microwave digester. Samples were then analyzed in triplicate for Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn using inductively coupled plasma optical emission spectrometry (ICP-OES). Highest tissue concentrations of Co, Cu, Mn, Ni, Pb and Zn were recorded at Bhizolo. High Biota Sediment Accumulation Factor (BSAF) values for Cd, Cu, Mn, Ni and Zn at all sites confirmed that crabs bioaccumulated these metals. The high Cr concentration in sediment (Bhizolo: 104 ± 18.2 µg g−1; Richards Bay Coal Terminal (RBCT): 104 ± 29.2 µg g−1; Mzingazi: 94.1 ± 38.7 µg g−1) was not reflected in the biota-sediment accumulation factor (BSAF) value, suggesting low bioavailability of Cr. High BSAF values for Cd, Cu, Mn, Ni and Zn suggest that the threshold of regulation in P. blephariskios was exceeded, resulting in net bioaccumulation.
{"title":"Bioaccumulation of trace metals in the ocypodid burrowing crab, Paratylodiplax blephariskios, in Richards Bay Harbour, South Africa","authors":"J. Izegaegbe, L. Vivier, H. Mzimela","doi":"10.2989/16085914.2021.1914537","DOIUrl":"https://doi.org/10.2989/16085914.2021.1914537","url":null,"abstract":"Bioaccumulation of metals in an endemic ocypodid burrowing mud crab, Paratylodiplax blephariskios, was investigated in contaminated mudflats of the subtropical Richards Bay Harbour (RBH), South Africa. Following sampling of water, sediment and mud crabs from three sites (Bhizolo, Mzingazi and Richards Bay Coal Terminal) in RBH during 2016/2017, tissue and sediment samples were oven dried for 48 hours, weighed and digested in an advanced microwave digester. Samples were then analyzed in triplicate for Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn using inductively coupled plasma optical emission spectrometry (ICP-OES). Highest tissue concentrations of Co, Cu, Mn, Ni, Pb and Zn were recorded at Bhizolo. High Biota Sediment Accumulation Factor (BSAF) values for Cd, Cu, Mn, Ni and Zn at all sites confirmed that crabs bioaccumulated these metals. The high Cr concentration in sediment (Bhizolo: 104 ± 18.2 µg g−1; Richards Bay Coal Terminal (RBCT): 104 ± 29.2 µg g−1; Mzingazi: 94.1 ± 38.7 µg g−1) was not reflected in the biota-sediment accumulation factor (BSAF) value, suggesting low bioavailability of Cr. High BSAF values for Cd, Cu, Mn, Ni and Zn suggest that the threshold of regulation in P. blephariskios was exceeded, resulting in net bioaccumulation.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"46 1","pages":"485 - 491"},"PeriodicalIF":1.4,"publicationDate":"2021-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47332154","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 : 2021-06-22DOI: 10.2989/16085914.2021.1930999
S. Wagaw, S. Mengistou, A. Getahun
Phytoplankton communities responses to physico-chemical factors were studied in Lake Shala from January to December 2018. Distinct spatial and seasonal variations were observed for all physico-chemical parameters, except DO (ANOVA: p < 0.05). In total, 72 taxa, Bacillariophyta (55 taxa), Chlorophyta (seven taxa), Cyanobacteria (six taxa), Euglenophyta (two taxa), Dinophyta (one taxon) and Charophyta (one taxon) were identified. Phytoplankton abundance and biomass ranged from 5 789.3 cells ml–1 to 1 516.2 cells ml–1, with a mean of 8 756.9 cells ml–1 and 9.8 μg l−1 to 25.8 μg l−1, with a mean of 17.1 μg l−1, respectively, and showed seasonal variations (p < 0.05). Based on RDA analysis, most species were abundant in Shala Gike Shore station. Their distribution was negatively correlated with salinity and EC, whereas pH, alkalinity, NO3–N, SRP, TP, NH3–N and SiO2 had a positive correlation. Previously Lake Shala was dominated by Cryptophyta but this has switched to a diatom-dominant community. Such changes in phytoplankton taxa may be suggestive of ecological change. This study provides baseline data on the phytoplankton community structure of Lake Shala associated with physico-chemical changes, against which future community structure can be evaluated.
{"title":"Phytoplankton community structure in relation to physico-chemical factors in a tropical soda lake, Lake Shala (Ethiopia)","authors":"S. Wagaw, S. Mengistou, A. Getahun","doi":"10.2989/16085914.2021.1930999","DOIUrl":"https://doi.org/10.2989/16085914.2021.1930999","url":null,"abstract":"Phytoplankton communities responses to physico-chemical factors were studied in Lake Shala from January to December 2018. Distinct spatial and seasonal variations were observed for all physico-chemical parameters, except DO (ANOVA: p < 0.05). In total, 72 taxa, Bacillariophyta (55 taxa), Chlorophyta (seven taxa), Cyanobacteria (six taxa), Euglenophyta (two taxa), Dinophyta (one taxon) and Charophyta (one taxon) were identified. Phytoplankton abundance and biomass ranged from 5 789.3 cells ml–1 to 1 516.2 cells ml–1, with a mean of 8 756.9 cells ml–1 and 9.8 μg l−1 to 25.8 μg l−1, with a mean of 17.1 μg l−1, respectively, and showed seasonal variations (p < 0.05). Based on RDA analysis, most species were abundant in Shala Gike Shore station. Their distribution was negatively correlated with salinity and EC, whereas pH, alkalinity, NO3–N, SRP, TP, NH3–N and SiO2 had a positive correlation. Previously Lake Shala was dominated by Cryptophyta but this has switched to a diatom-dominant community. Such changes in phytoplankton taxa may be suggestive of ecological change. This study provides baseline data on the phytoplankton community structure of Lake Shala associated with physico-chemical changes, against which future community structure can be evaluated.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"46 1","pages":"428 - 440"},"PeriodicalIF":1.4,"publicationDate":"2021-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46924385","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 : 2021-06-21DOI: 10.2989/16085914.2021.1892577
H. Souley Adamou, B. Alhou, M. Tackx, F. Azémar
A first study of the rotifers of the Niger River in Niger is reported here. Two surveys took place under contrasting hydrological conditions: low-water level (16 April to 8 May 2018) and high-water level (1 to 15 February 2019). Zooplankton and physico-chemical parameters were sampled at eight stations spread over 520 km from Ayorou to Gaya. In total, 32 taxa were identified, including 26 at species level. During the low-water sampling, Polyarthra sp. (31%), Brachionus caudatus (23%), Synchaeta longipes (11%), Keratella tropica (7%) and Filinia longiseta (5%) were the most abundant, whereas Brachionus quadridentatu s (26%), Lecane hastata (25%), Keratella cochlearis (9%), Keratella lunaris (5%), Hexarthra sp. (3%) were dominant during the high-water sampling. The mean abundance of rotifers ranged between 14 × 103 ind. m−3 during the high-water sampling and 244 × 103 ind. m−3 during the low-water sampling. The highest diversity was observed in the three stations located upstream from the city of Niamey. The results reflect the difference in environmental parameters between the downstream and upstream Niamey stations. RDA analyses showed that the main environmental factors explaining the distribution of rotifers were dissolved oxygen, orthophosphate and nitrate concentrations.
{"title":"Rotifers in the Niger River, Niger: diversity and abundance in relation to environmental parameters","authors":"H. Souley Adamou, B. Alhou, M. Tackx, F. Azémar","doi":"10.2989/16085914.2021.1892577","DOIUrl":"https://doi.org/10.2989/16085914.2021.1892577","url":null,"abstract":"A first study of the rotifers of the Niger River in Niger is reported here. Two surveys took place under contrasting hydrological conditions: low-water level (16 April to 8 May 2018) and high-water level (1 to 15 February 2019). Zooplankton and physico-chemical parameters were sampled at eight stations spread over 520 km from Ayorou to Gaya. In total, 32 taxa were identified, including 26 at species level. During the low-water sampling, Polyarthra sp. (31%), Brachionus caudatus (23%), Synchaeta longipes (11%), Keratella tropica (7%) and Filinia longiseta (5%) were the most abundant, whereas Brachionus quadridentatu s (26%), Lecane hastata (25%), Keratella cochlearis (9%), Keratella lunaris (5%), Hexarthra sp. (3%) were dominant during the high-water sampling. The mean abundance of rotifers ranged between 14 × 103 ind. m−3 during the high-water sampling and 244 × 103 ind. m−3 during the low-water sampling. The highest diversity was observed in the three stations located upstream from the city of Niamey. The results reflect the difference in environmental parameters between the downstream and upstream Niamey stations. RDA analyses showed that the main environmental factors explaining the distribution of rotifers were dissolved oxygen, orthophosphate and nitrate concentrations.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"46 1","pages":"473 - 484"},"PeriodicalIF":1.4,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46041309","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 : 2021-06-07DOI: 10.2989/16085914.2021.1924608
L. Mofu, T. Dalu, R. Wasserman, D. Woodford, D. Khosa, O. Weyl
Irrigation ponds are increasingly abundant globally, particularly in water-stressed countries with limited natural surface waters, yet knowledge of their ecology is limited. Here, we assessed zooplankton, macroinvertebrate, and littoral fish communities from irrigation ponds located in the Sundays River Valley in South Africa. This study assessed the seasonal community patterns in response to physico-chemical and biotic components. Water temperature, water depth, Secchi depth, and ammonium concentrations differed significantly across seasons. Similarly, Chlorophyll-a concentrations differed seasonally, with water transparency identified as the main driver. Zooplankton was dominated by Rotifera, Copepoda and Cladocera. Seasonal changes in temperature and subsequent fluctuations in water levels resulted in changes in zooplankton community. Macroinvertebrates were dominated by insects, notably the families Corixidae and Naucoridae. The littoral fish community comprised of Glossogobius callidus, Oreochromis mossambicus and Gambusia affinis. Zooplankton, macroinvertebrates and littoral fish abundances, species richness, diversity and assemblage composition differed significantly across seasons with temperature identified as the main driver of these differences. This study demonstrates that bottom-up processes are the dominant drivers of the irrigation pond communities in the Sundays River Valley and highlights the relevance of seasonal abiotic drivers in structuring these communities, particularly G. callidus and G. affinis.
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