Pub Date : 2021-11-06DOI: 10.2989/16085914.2021.1989572
K. Kanu, N. Amaeze, A. Otitoloju
The acute toxicity of the pesticides atrazine, mancozeb, chlorpyrifos and lambda-cyhalothrin, acting singly and jointly, was assessed on Nile tilapia (Oreochromis niloticus) fingerlings. Median lethal concentration (LC50), median lethal time (LT50), and mixture interaction were estimated, whereas survival analysis was used to model time-to-death. The most toxic single and joint mixture was lambda-cyhalothrin and chlorpyrifos-lambda cyhalothrin, respectively. The risk of death (RoD) of fingerlings exposed to 9.22 mg l−1 atrazine-mancozeb mixture was 1.76 times higher than fingerlings exposed to 9.0 mg l−1 atrazine (p > 0.05). However, RoD of fingerlings exposed to 9.95 mg l−1 atrazine-chlorpyrifos was 5.59 times higher than fingerlings exposed to 9.0 mg l−1 atrazine (p < 0.01). The risk of death of fingerlings exposed to 20.8 mg l−1 atrazine-lambda cyhalothrin was 2.81 times higher than 21.0 mg l−1 atrazine. The toxicity of 2.3 mg l−1 mancozeb-chlorpyrifos was 254.25 higher than 2.2 mg l−1 mancozeb (p < 0.01). Fingerlings exposed to 4.33 mg l−1 mancozeb-lambda cyhalothrin and 0.177 mg l−1 chlorpyrifos-lambda cyhalothrin mixture were 0.02 and 0.14 times less likely to die than those exposed to 4.8 mg l−1 mancozeb and 0.17 mg l−1 chlorpyrifos, respectively (p < 0.01). Atrazine-mancozeb, atrazine-chlorpyrifos, atrazine-lambda cyhalothrin, and mancozeb-chlorpyrifos interaction were synergistic, and their relative risk was >1. Both mancozeb-lambda cyhalothrin and lambda-cyhalothrin-chlorpyrifos mixtures were antagonistic, and their relative risk was less than 1. Survival analysis can show interaction in complex pesticide mixtures.
{"title":"Estimation of pesticide mixture interaction in Nile tilapia (Oreochromis niloticus) using survival analysis","authors":"K. Kanu, N. Amaeze, A. Otitoloju","doi":"10.2989/16085914.2021.1989572","DOIUrl":"https://doi.org/10.2989/16085914.2021.1989572","url":null,"abstract":"The acute toxicity of the pesticides atrazine, mancozeb, chlorpyrifos and lambda-cyhalothrin, acting singly and jointly, was assessed on Nile tilapia (Oreochromis niloticus) fingerlings. Median lethal concentration (LC50), median lethal time (LT50), and mixture interaction were estimated, whereas survival analysis was used to model time-to-death. The most toxic single and joint mixture was lambda-cyhalothrin and chlorpyrifos-lambda cyhalothrin, respectively. The risk of death (RoD) of fingerlings exposed to 9.22 mg l−1 atrazine-mancozeb mixture was 1.76 times higher than fingerlings exposed to 9.0 mg l−1 atrazine (p > 0.05). However, RoD of fingerlings exposed to 9.95 mg l−1 atrazine-chlorpyrifos was 5.59 times higher than fingerlings exposed to 9.0 mg l−1 atrazine (p < 0.01). The risk of death of fingerlings exposed to 20.8 mg l−1 atrazine-lambda cyhalothrin was 2.81 times higher than 21.0 mg l−1 atrazine. The toxicity of 2.3 mg l−1 mancozeb-chlorpyrifos was 254.25 higher than 2.2 mg l−1 mancozeb (p < 0.01). Fingerlings exposed to 4.33 mg l−1 mancozeb-lambda cyhalothrin and 0.177 mg l−1 chlorpyrifos-lambda cyhalothrin mixture were 0.02 and 0.14 times less likely to die than those exposed to 4.8 mg l−1 mancozeb and 0.17 mg l−1 chlorpyrifos, respectively (p < 0.01). Atrazine-mancozeb, atrazine-chlorpyrifos, atrazine-lambda cyhalothrin, and mancozeb-chlorpyrifos interaction were synergistic, and their relative risk was >1. Both mancozeb-lambda cyhalothrin and lambda-cyhalothrin-chlorpyrifos mixtures were antagonistic, and their relative risk was less than 1. Survival analysis can show interaction in complex pesticide mixtures.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"47 1","pages":"66 - 77"},"PeriodicalIF":1.4,"publicationDate":"2021-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48086971","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 : 2021-11-03DOI: 10.2989/16085914.2021.1982671
C. Nsor, Rockson Acolatse, J. Mensah, S. Oppong, D. Dompreh, Louis Addai-Wireko
Anthropogenic activities as predictors of species assemblages in the Owabi Ramsar Wetland were investigated between May and September 2019. Data were collected in 154 plots at five different sites. The prevalence index method was used to categorise the species into wetland and non-wetland indicators. Log series and Hill number models were applied to quantify community assemblages, whereas the CCA technique was used to examine the relationship between anthropogenic activities and species presence or absence. In all, 2 185 individuals, belonging to 32 families and 68 species were recorded. Paspalum orbiculare and Persicaria lanigera were the most abundant, indicating their wide distribution. Mean number of individuals were highest at Atafua and lowest at Owabi. An abundance of terrestrial species (41.2%; i.e. plant species not listed as obligate wetland plants) and facultative species (30.9%), compared with obligate wetland species (27.9%), suggests a dominance of species from dryland habitats into the wetland. Farming activities, increased levels of NH4 +, PO4 3+ and NO3–N, were the predictors that explained 72.01% of the overall variability in community assemblages. The results revealed the impact of the anthropogenic activities on the ecological integrity of the Owabi Ramsar Wetland and the need to institute conservation measures outlined in this study.
{"title":"Structural assemblages of plant species in the Owabi Ramsar Wetland in the Ashanti Region of Ghana","authors":"C. Nsor, Rockson Acolatse, J. Mensah, S. Oppong, D. Dompreh, Louis Addai-Wireko","doi":"10.2989/16085914.2021.1982671","DOIUrl":"https://doi.org/10.2989/16085914.2021.1982671","url":null,"abstract":"Anthropogenic activities as predictors of species assemblages in the Owabi Ramsar Wetland were investigated between May and September 2019. Data were collected in 154 plots at five different sites. The prevalence index method was used to categorise the species into wetland and non-wetland indicators. Log series and Hill number models were applied to quantify community assemblages, whereas the CCA technique was used to examine the relationship between anthropogenic activities and species presence or absence. In all, 2 185 individuals, belonging to 32 families and 68 species were recorded. Paspalum orbiculare and Persicaria lanigera were the most abundant, indicating their wide distribution. Mean number of individuals were highest at Atafua and lowest at Owabi. An abundance of terrestrial species (41.2%; i.e. plant species not listed as obligate wetland plants) and facultative species (30.9%), compared with obligate wetland species (27.9%), suggests a dominance of species from dryland habitats into the wetland. Farming activities, increased levels of NH4 +, PO4 3+ and NO3–N, were the predictors that explained 72.01% of the overall variability in community assemblages. The results revealed the impact of the anthropogenic activities on the ecological integrity of the Owabi Ramsar Wetland and the need to institute conservation measures outlined in this study.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"47 1","pages":"100 - 114"},"PeriodicalIF":1.4,"publicationDate":"2021-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42364982","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 : 2021-10-26DOI: 10.2989/16085914.2021.1978380
N. Asare, JL Javier
This study assessed the effects of tidal stages and habitat conditions on nekton assemblage and distribution in the Kakum River estuarine mangrove system in the Central Region of Ghana. Teleosts and crustaceans were sampled using pole seine and cast net from a tidal mangrove pond and a channel, and characterised using morphometry and ecological guilds concept. In total, 1 146 specimens were collected, with 35 species from 19 families represented. The most abundant species encountered were Liza spp. (Mugilidae; 36%), Sarotherodon melanotheron (Cichlidae; 16%), Elops lacerta (Elopidae; 6%) and Sardinella aurita (Clupeidae; 5%), which exhibited pronounced spatial distribution. Sarotherodon melanotheron showed preference for ponds with minimal water flow and depth, Sardinella aurita occurred only in deeper sections of the mangrove channel with significant flow velocity, and Elops lacerta in the pond and all channel stations. Mugilids were found exclusively in the channel, whereas Palaemonidae (Macrobrachium macrobrachion and M. vollenhoveni) occurred in specific locations in the channel, with species- specific preferences for tidal stages. Most species encountered were identified to be predominantly marine migrants with bentophagous feeding habit. Site selection and tidal stages were found to affect the occurrence and distribution of fishes over a tidal cycle and interactively influence species diversity.
{"title":"Tidal influence on fish faunal occurrence and distribution in an estuarine mangrove system in Ghana","authors":"N. Asare, JL Javier","doi":"10.2989/16085914.2021.1978380","DOIUrl":"https://doi.org/10.2989/16085914.2021.1978380","url":null,"abstract":"This study assessed the effects of tidal stages and habitat conditions on nekton assemblage and distribution in the Kakum River estuarine mangrove system in the Central Region of Ghana. Teleosts and crustaceans were sampled using pole seine and cast net from a tidal mangrove pond and a channel, and characterised using morphometry and ecological guilds concept. In total, 1 146 specimens were collected, with 35 species from 19 families represented. The most abundant species encountered were Liza spp. (Mugilidae; 36%), Sarotherodon melanotheron (Cichlidae; 16%), Elops lacerta (Elopidae; 6%) and Sardinella aurita (Clupeidae; 5%), which exhibited pronounced spatial distribution. Sarotherodon melanotheron showed preference for ponds with minimal water flow and depth, Sardinella aurita occurred only in deeper sections of the mangrove channel with significant flow velocity, and Elops lacerta in the pond and all channel stations. Mugilids were found exclusively in the channel, whereas Palaemonidae (Macrobrachium macrobrachion and M. vollenhoveni) occurred in specific locations in the channel, with species- specific preferences for tidal stages. Most species encountered were identified to be predominantly marine migrants with bentophagous feeding habit. Site selection and tidal stages were found to affect the occurrence and distribution of fishes over a tidal cycle and interactively influence species diversity.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"47 1","pages":"88 - 99"},"PeriodicalIF":1.4,"publicationDate":"2021-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43097179","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 : 2021-09-07DOI: 10.2989/16085914.2021.1952158
Wesley. Evans, C. Downs, M. Burnett, G. O’Brien
The degradation of freshwater ecosystems can be attributed to stressors associated with the increased demand for water and other aquatic resources. Freshwater ecosystems face such challenges in supporting agriculture, industry, and high-density urban areas in KwaZulu-Natal (KZN) province, South Africa. In this study, the presence of fish species and their abundance was quantified at 40 sites in KZN on 16 major rivers systems. Surveys were done during a drought period between February 2015 and April 2016, as part of the River Health Programme, a national river monitoring assessment. The Fish Response Assessment Index (FRAI) was used to evaluate the condition of the sites, and redundancy analysis was used to evaluate the habitat, water quality and fish community relationships. The FRAI scores showed four sites to be in a ‘Seriously Modified’ condition. These areas were associated with intensive agricultural activities and urban environments. The presence of invasive fish species, abstraction and industrial use all had negative impacts on the ecological state of the rivers. When compounded by excessive water use, the drought resulted in poor fish community integrity, highlighting the vulnerability of fish communities in this region. The absence or low abundances of some indigenous fish alongside the high presence of invasive fish requires additional investigation. Results highlight the importance of mitigation measures against anthropogenic impacts should be enforced to ensure sustainable use of KZN water resources.
{"title":"Assessing fish community response to water quality and habitat stressors in KwaZulu-Natal, South Africa","authors":"Wesley. Evans, C. Downs, M. Burnett, G. O’Brien","doi":"10.2989/16085914.2021.1952158","DOIUrl":"https://doi.org/10.2989/16085914.2021.1952158","url":null,"abstract":"The degradation of freshwater ecosystems can be attributed to stressors associated with the increased demand for water and other aquatic resources. Freshwater ecosystems face such challenges in supporting agriculture, industry, and high-density urban areas in KwaZulu-Natal (KZN) province, South Africa. In this study, the presence of fish species and their abundance was quantified at 40 sites in KZN on 16 major rivers systems. Surveys were done during a drought period between February 2015 and April 2016, as part of the River Health Programme, a national river monitoring assessment. The Fish Response Assessment Index (FRAI) was used to evaluate the condition of the sites, and redundancy analysis was used to evaluate the habitat, water quality and fish community relationships. The FRAI scores showed four sites to be in a ‘Seriously Modified’ condition. These areas were associated with intensive agricultural activities and urban environments. The presence of invasive fish species, abstraction and industrial use all had negative impacts on the ecological state of the rivers. When compounded by excessive water use, the drought resulted in poor fish community integrity, highlighting the vulnerability of fish communities in this region. The absence or low abundances of some indigenous fish alongside the high presence of invasive fish requires additional investigation. Results highlight the importance of mitigation measures against anthropogenic impacts should be enforced to ensure sustainable use of KZN water resources.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"47 1","pages":"47 - 65"},"PeriodicalIF":1.4,"publicationDate":"2021-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46871325","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 : 2021-09-03DOI: 10.2989/16085914.2021.1949260
Lerato T. Maimela, C. Chimimba, T. Zengeya
This study investigated the effects of rainbow trout (Oncorhynchus mykiss) invasion on native fish communities in the upper Blyde River catchment. A fish survey was undertaken between September 2017 and October 2018 from 11 sites in the Blyde and Treur Rivers using electrofishing and fyke nets. Differences in species composition, relative abundance, and community structure among sites were tested using multivariate analysis. A total of ten fish species were captured. There were significant differences in composition and abundance between fish communities that could be attributed to O. mykiss invasion and variation in habitats. Populations of native species that historically occurred throughout the upper catchment, such as Enteromius treurensis, were greatly reduced and fragmented in the presence of O. mykiss. However, instream migration barriers such as waterfalls have prevented upstream migration of O. mykiss, and these invasion-free areas have remnant populations of native fishes that appear to be largely intact. This finding is consistent with other studies that have shown that introduced alien predatory fish can have a significant effect on fish communities and highlighted the need to prevent human-facilitated introductions in biodiversity sensitive areas, such as mountain headwater streams, that are inhabited by endemic and range-restricted minnows.
{"title":"The effect of rainbow trout (Oncorhynchus mykiss) invasions on native fish communities in the subtropical Blyde River, Mpumalanga province, South Africa","authors":"Lerato T. Maimela, C. Chimimba, T. Zengeya","doi":"10.2989/16085914.2021.1949260","DOIUrl":"https://doi.org/10.2989/16085914.2021.1949260","url":null,"abstract":"This study investigated the effects of rainbow trout (Oncorhynchus mykiss) invasion on native fish communities in the upper Blyde River catchment. A fish survey was undertaken between September 2017 and October 2018 from 11 sites in the Blyde and Treur Rivers using electrofishing and fyke nets. Differences in species composition, relative abundance, and community structure among sites were tested using multivariate analysis. A total of ten fish species were captured. There were significant differences in composition and abundance between fish communities that could be attributed to O. mykiss invasion and variation in habitats. Populations of native species that historically occurred throughout the upper catchment, such as Enteromius treurensis, were greatly reduced and fragmented in the presence of O. mykiss. However, instream migration barriers such as waterfalls have prevented upstream migration of O. mykiss, and these invasion-free areas have remnant populations of native fishes that appear to be largely intact. This finding is consistent with other studies that have shown that introduced alien predatory fish can have a significant effect on fish communities and highlighted the need to prevent human-facilitated introductions in biodiversity sensitive areas, such as mountain headwater streams, that are inhabited by endemic and range-restricted minnows.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"47 1","pages":"78 - 87"},"PeriodicalIF":1.4,"publicationDate":"2021-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42960863","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 : 2021-08-31DOI: 10.2989/16085914.2021.1940823
H. Tesfaye, B. Warkineh
The Cheleleka Wetland is located in the Ethiopian Rift Valley on the upper shore of Lake Hawassa, after which the regional capital is named. This study investigated the relationship between water quality and the occurrence and diversity of macrophyte species of the wetland. Spatio-temporal variability in terms of water quality and macrophytes were studied in the wet and dry seasons at purposely-selected sites selected based on human disturbance levels. Six sites were selected, two from each of ‘severely’, ‘moderately’ and ‘least disturbed’, and data collected on water quality parameters, macrophytes richness and abundance. The results showed 25 macrophyte species dominated by Cyperaceae (24%), Poaceae (20%) and Nymphaeaceae (12%). Species diversity and abundance were significantly different between seasons and among the sampling sites (p < 0.05), with the richest taxa recorded at the least disturbed sites. A redundancy analysis of the species–environment relationships identified nutrient loads as significant drivers of macrophyte diversity and abundance in the wetland. Generally, the results showed the spatial and temporal variation of macrophyte diversity and abundance are affected by water quality, and poor water quality has resulted in poor ecological conditions of the Cheleleka Wetland.
{"title":"Macrophyte species diversity and distribution in relation to water quality of the Cheleleka Wetland in Ethiopia","authors":"H. Tesfaye, B. Warkineh","doi":"10.2989/16085914.2021.1940823","DOIUrl":"https://doi.org/10.2989/16085914.2021.1940823","url":null,"abstract":"The Cheleleka Wetland is located in the Ethiopian Rift Valley on the upper shore of Lake Hawassa, after which the regional capital is named. This study investigated the relationship between water quality and the occurrence and diversity of macrophyte species of the wetland. Spatio-temporal variability in terms of water quality and macrophytes were studied in the wet and dry seasons at purposely-selected sites selected based on human disturbance levels. Six sites were selected, two from each of ‘severely’, ‘moderately’ and ‘least disturbed’, and data collected on water quality parameters, macrophytes richness and abundance. The results showed 25 macrophyte species dominated by Cyperaceae (24%), Poaceae (20%) and Nymphaeaceae (12%). Species diversity and abundance were significantly different between seasons and among the sampling sites (p < 0.05), with the richest taxa recorded at the least disturbed sites. A redundancy analysis of the species–environment relationships identified nutrient loads as significant drivers of macrophyte diversity and abundance in the wetland. Generally, the results showed the spatial and temporal variation of macrophyte diversity and abundance are affected by water quality, and poor water quality has resulted in poor ecological conditions of the Cheleleka Wetland.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"47 1","pages":"36 - 46"},"PeriodicalIF":1.4,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42215683","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 : 2021-07-26DOI: 10.2989/16085914.2021.1931000
Ihuoma N. Anyanwu, Confidence A Ezema, Sowechi Ebi, C. Nwajiuba, O. Nworie, C. Anorue
Seasonal changes significantly affect tropical ecosystems; hence, verification of how these changes affect water quality is important for waterbodies that serve as water and food sources, particular as such changes are often associated with shifts in plankton diversity and microbial loads. This study assessed the seasonal changes in water quality, plankton diversity and microbial load in four lakes serving as sources of drinking water. Temperature, hardness and phosphate concentration were elevated in the dry season, and pH, biochemical oxygen demand, transparency, turbidity, total dissolved solids, conductivity, alkalinity and nitrate concentrations were elevated in the wet season. A phytoplankton analysis revealed that Chlorophyta, Bacillariophyta, Cyanophyta and Dinophyta were most common, with the families Desmidiaceae, Microcystaceae and Euglenaceae (phylum Euglenophyta) displaying dominance. For zooplankton, Rotifera was most common, with Branchionidae dominating the lakes in both seasons. In the wet season, Chlorophyta, Cyanophyta, Bacillariophyta and Dinophyta dominated, with Aphanizomenonaceae and Microcystaceae the most diverse families. Disease-causing pathogens, Ascaridae, Trichuridae and Ancylostomatidae (phylum Nematoda), were detected during periods of high rainfall. The waters in the dry season had higher microbial loads than in the wet season, ranging from 1.50 to 233.50 CFU g−1 (p < 0.05). This demonstrates the seasonal variations in risk to users and underlies the importance of regular assessment of water quality particularly given the threat of seasonal changes elated to climate change.
{"title":"Seasonal variation in water quality, plankton diversity and microbial load of tropical freshwater lakes in Nigeria","authors":"Ihuoma N. Anyanwu, Confidence A Ezema, Sowechi Ebi, C. Nwajiuba, O. Nworie, C. Anorue","doi":"10.2989/16085914.2021.1931000","DOIUrl":"https://doi.org/10.2989/16085914.2021.1931000","url":null,"abstract":"Seasonal changes significantly affect tropical ecosystems; hence, verification of how these changes affect water quality is important for waterbodies that serve as water and food sources, particular as such changes are often associated with shifts in plankton diversity and microbial loads. This study assessed the seasonal changes in water quality, plankton diversity and microbial load in four lakes serving as sources of drinking water. Temperature, hardness and phosphate concentration were elevated in the dry season, and pH, biochemical oxygen demand, transparency, turbidity, total dissolved solids, conductivity, alkalinity and nitrate concentrations were elevated in the wet season. A phytoplankton analysis revealed that Chlorophyta, Bacillariophyta, Cyanophyta and Dinophyta were most common, with the families Desmidiaceae, Microcystaceae and Euglenaceae (phylum Euglenophyta) displaying dominance. For zooplankton, Rotifera was most common, with Branchionidae dominating the lakes in both seasons. In the wet season, Chlorophyta, Cyanophyta, Bacillariophyta and Dinophyta dominated, with Aphanizomenonaceae and Microcystaceae the most diverse families. Disease-causing pathogens, Ascaridae, Trichuridae and Ancylostomatidae (phylum Nematoda), were detected during periods of high rainfall. The waters in the dry season had higher microbial loads than in the wet season, ranging from 1.50 to 233.50 CFU g−1 (p < 0.05). This demonstrates the seasonal variations in risk to users and underlies the importance of regular assessment of water quality particularly given the threat of seasonal changes elated to climate change.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"46 1","pages":"414 - 427"},"PeriodicalIF":1.4,"publicationDate":"2021-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42585248","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 : 2021-07-26DOI: 10.2989/16085914.2021.1946383
H. Getnet, S. Mengistou, B. Warkineh
The influence of environmental factors on the diversity of macroinvertebrates was studied in the wetlands of the Gilgel Abay River (GAR) catchment in Ethiopia. The study was done between September 2017 and March 2018, encompassing both wet and dry seasons. Six study wetlands from the GAR catchment were selected in a targeted manner based on the surrounding land use, exposure to anthropogenic disturbances and accessibility to conduct a quantitative study. The relationships between biological and environmental variables were evaluated by using multivariate analyses. Altogether, 36 families of macroinvertebrates were identified. Macroinvertebrate diversity indices were significantly higher at less impaired sites, compared with more impaired sites. Several families of Ephemeroptera, Odonata and Trichoptera taxa, including Corduliidae, Calopterygidae, Baetidae, Aeshnidae, Polymitarcyidae, Hydropsychidae, Heptageniidae, Polycentrapodidae, Hydroptilidae and Philopotamidae were negatively correlated with organic and inorganic pollutants and human disturbances and might be considered as potential indicators of less impaired sites. Conversely, the families Chironomidae, Hirudinidae and Libellulidae were positively correlated with biological oxygen demand, ammonium and human disturbance score and negatively correlated with dissolved oxygen. Generally, results of macroinvertebrate diversity and composition in this study indicate poor ecological condition of the wetlands, particularly those adjacent to agricultural and urban areas.
{"title":"Macroinvertebrate community structure and diversity in relation to environmental factors in wetlands of the lower Gilgel Abay River catchment, Ethiopia","authors":"H. Getnet, S. Mengistou, B. Warkineh","doi":"10.2989/16085914.2021.1946383","DOIUrl":"https://doi.org/10.2989/16085914.2021.1946383","url":null,"abstract":"The influence of environmental factors on the diversity of macroinvertebrates was studied in the wetlands of the Gilgel Abay River (GAR) catchment in Ethiopia. The study was done between September 2017 and March 2018, encompassing both wet and dry seasons. Six study wetlands from the GAR catchment were selected in a targeted manner based on the surrounding land use, exposure to anthropogenic disturbances and accessibility to conduct a quantitative study. The relationships between biological and environmental variables were evaluated by using multivariate analyses. Altogether, 36 families of macroinvertebrates were identified. Macroinvertebrate diversity indices were significantly higher at less impaired sites, compared with more impaired sites. Several families of Ephemeroptera, Odonata and Trichoptera taxa, including Corduliidae, Calopterygidae, Baetidae, Aeshnidae, Polymitarcyidae, Hydropsychidae, Heptageniidae, Polycentrapodidae, Hydroptilidae and Philopotamidae were negatively correlated with organic and inorganic pollutants and human disturbances and might be considered as potential indicators of less impaired sites. Conversely, the families Chironomidae, Hirudinidae and Libellulidae were positively correlated with biological oxygen demand, ammonium and human disturbance score and negatively correlated with dissolved oxygen. Generally, results of macroinvertebrate diversity and composition in this study indicate poor ecological condition of the wetlands, particularly those adjacent to agricultural and urban areas.","PeriodicalId":7864,"journal":{"name":"African Journal of Aquatic Science","volume":"47 1","pages":"23 - 35"},"PeriodicalIF":1.4,"publicationDate":"2021-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46865138","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: 10.2989/16085914.2021.1933375
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}
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