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.
{"title":"Seasonal variation and drivers of zooplankton, macroinvertebrate and littoral fish communities from irrigation ponds in a semi-arid region in the Eastern Cape (South Africa)","authors":"L. Mofu, T. Dalu, R. Wasserman, D. Woodford, D. Khosa, O. Weyl","doi":"10.2989/16085914.2021.1924608","DOIUrl":"https://doi.org/10.2989/16085914.2021.1924608","url":null,"abstract":"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.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"46 1","pages":"452 - 463"},"PeriodicalIF":1.4,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48449903","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 : 2021-06-03DOI: 10.2989/16085914.2021.1898927
M. Omoigberale, I. Ezenwa, E. Biose, C. Okoye
The impact of a rubber effluent on the water quality of Oken River, Nigeria, was assessed. Surface water was analysed for water quality parameters at four sites; one upstream and three downstream. Significantly raised (p ≤ 0.05) levels of electrical conductivity, salinity, colour, turbidity, TSS, TDS, DO, COD, HCO3 -, Ca, Cl, P, Mn, Cu, Pb and THC at the site immediately downstream of the pollution point source were recorded, with levels of colour, turbidity, Cd and Ni in all the stations higher than the WHO permissible limits. Principal component analysis (PCA) yielded 28 variables under six components that accounted for 92.33% of the total variance between sites. The PCA and water quality index (WQI) revealed significant influence by anthropogenic activities on the water quality of the river. Furthermore, the WQI output showed that the river water was not fit for human consumption. The cluster analysis revealed similarity in the physico-chemical conditions at Stations 1 and 4, whereas Stations 1 and 2 were the most dissimilar. This study advocates monitoring and protection of water bodies upstream and downstream of the influx of untreated effluents.
{"title":"The impact of rubber effluent discharges on the water quality of a tropical rain forest river in Nigeria","authors":"M. Omoigberale, I. Ezenwa, E. Biose, C. Okoye","doi":"10.2989/16085914.2021.1898927","DOIUrl":"https://doi.org/10.2989/16085914.2021.1898927","url":null,"abstract":"The impact of a rubber effluent on the water quality of Oken River, Nigeria, was assessed. Surface water was analysed for water quality parameters at four sites; one upstream and three downstream. Significantly raised (p ≤ 0.05) levels of electrical conductivity, salinity, colour, turbidity, TSS, TDS, DO, COD, HCO3 -, Ca, Cl, P, Mn, Cu, Pb and THC at the site immediately downstream of the pollution point source were recorded, with levels of colour, turbidity, Cd and Ni in all the stations higher than the WHO permissible limits. Principal component analysis (PCA) yielded 28 variables under six components that accounted for 92.33% of the total variance between sites. The PCA and water quality index (WQI) revealed significant influence by anthropogenic activities on the water quality of the river. Furthermore, the WQI output showed that the river water was not fit for human consumption. The cluster analysis revealed similarity in the physico-chemical conditions at Stations 1 and 4, whereas Stations 1 and 2 were the most dissimilar. This study advocates monitoring and protection of water bodies upstream and downstream of the influx of untreated effluents.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"46 1","pages":"390 - 401"},"PeriodicalIF":1.4,"publicationDate":"2021-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44844670","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 : 2021-05-31DOI: 10.2989/16085914.2021.1922349
A. Degsera, M. Minwyelet, T. Yosef
Nile tilapia Oreochromis niloticus is a commercially important fish species in the Lake Tana fishery and contributes to 65% of the total annual catch. This study estimated the maximum sustainable yield (MSY) and effort at maximum sustainable yield (fMSY) for the O. niloticus fishery using the Thompson and Bell yield prediction model. Catch and effort data from four representative landing sites were collected daily from June 2016 to May 2017 and used to estimate the total mortality coefficient (Z) using catch curve analysis, natural mortality (M) using Pauly’s empirical formula, and fishing mortality (F) as F = Z − M. Population abundance was evaluated using the Jones length-based cohort analysis model. The estimated Z, M and F values were 1.1, 0.52, and 0.49 per year, respectively. In total, 5 077 tons of O. niloticus were produced, which exceeds the MSY of 4 904 tons per year that could be obtained from the fishery at an F0.1. Consequently, the recommendation is to reduce the fishing effort by 15%. Collection of catch-and- effort data from more landing sites, over an extended period, could improve the yield estimates and this should be considered in conjunction with a bioeconomic analysis in future.
{"title":"Stock assessment of Nile tilapia Oreochromis niloticus (Linnaeus 1758) in Lake Tana, Ethiopia","authors":"A. Degsera, M. Minwyelet, T. Yosef","doi":"10.2989/16085914.2021.1922349","DOIUrl":"https://doi.org/10.2989/16085914.2021.1922349","url":null,"abstract":"Nile tilapia Oreochromis niloticus is a commercially important fish species in the Lake Tana fishery and contributes to 65% of the total annual catch. This study estimated the maximum sustainable yield (MSY) and effort at maximum sustainable yield (fMSY) for the O. niloticus fishery using the Thompson and Bell yield prediction model. Catch and effort data from four representative landing sites were collected daily from June 2016 to May 2017 and used to estimate the total mortality coefficient (Z) using catch curve analysis, natural mortality (M) using Pauly’s empirical formula, and fishing mortality (F) as F = Z − M. Population abundance was evaluated using the Jones length-based cohort analysis model. The estimated Z, M and F values were 1.1, 0.52, and 0.49 per year, respectively. In total, 5 077 tons of O. niloticus were produced, which exceeds the MSY of 4 904 tons per year that could be obtained from the fishery at an F0.1. Consequently, the recommendation is to reduce the fishing effort by 15%. Collection of catch-and- effort data from more landing sites, over an extended period, could improve the yield estimates and this should be considered in conjunction with a bioeconomic analysis in future.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"46 1","pages":"499 - 507"},"PeriodicalIF":1.4,"publicationDate":"2021-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44617221","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：