Benthic diatom-based indices and isotopic biomonitoring of nitrogen pollution in a warm temperate Austral river system
- Dalu, Tatenda, Cuthbert, Ross N, Taylor, Jonathan C, Magoro, Mandla L, Weyl, Olaf L F, Froneman, P William, Wasserman, Ryan J
- Authors: Dalu, Tatenda , Cuthbert, Ross N , Taylor, Jonathan C , Magoro, Mandla L , Weyl, Olaf L F , Froneman, P William , Wasserman, Ryan J
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466917 , vital:76798 , https://doi.org/10.1016/j.scitotenv.2020.142452
- Description: Rivers are impacted by pollutants from anthropogenic activities such as urbanisation and agricultural practices. Whilst point source pollution has been widely studied and in some cases remediated, non-point pollutant sources remain pervasive, particularly in developing countries that lack economic and human specialist capacity. Monitoring of pollution levels in many regions is additionally challenged by a lack of robust indicators for nitrogen inputs, however, diatom community indices and analysis of variation in microphytobenthos (MBP) stable isotope analysis variations have potential. The present study investigates variations and utilities in benthic diatom indices and MPB δ15N along different river sections (n = 31) of an austral river between two seasons (wet and dry), testing for relationships with key environmental variables (physical, water and sediment), in the context of N monitoring. One hundred and eighteen diatom taxa belonging to 36 genera were identified, with physical (water flow), water (nitrate, P and total dissolved solids) and sediment (B, Ca, Cr, Na, N, P, SOM, Pb and Zn) variables correlating to one or more of the 12 diatom indices presented. In particular, Biological Diatom Index, Biological Index of Water Quality, Central Economic Community, Index of Artois-Picardie Diatom (IDAP) and Sládeček's Index were strongly explained by sediment variables, whilst Descy's Pollution Index and Schiefele and Schreiner's Index were explained by water and physical variables.
- Full Text:
- Date Issued: 2020
- Authors: Dalu, Tatenda , Cuthbert, Ross N , Taylor, Jonathan C , Magoro, Mandla L , Weyl, Olaf L F , Froneman, P William , Wasserman, Ryan J
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466917 , vital:76798 , https://doi.org/10.1016/j.scitotenv.2020.142452
- Description: Rivers are impacted by pollutants from anthropogenic activities such as urbanisation and agricultural practices. Whilst point source pollution has been widely studied and in some cases remediated, non-point pollutant sources remain pervasive, particularly in developing countries that lack economic and human specialist capacity. Monitoring of pollution levels in many regions is additionally challenged by a lack of robust indicators for nitrogen inputs, however, diatom community indices and analysis of variation in microphytobenthos (MBP) stable isotope analysis variations have potential. The present study investigates variations and utilities in benthic diatom indices and MPB δ15N along different river sections (n = 31) of an austral river between two seasons (wet and dry), testing for relationships with key environmental variables (physical, water and sediment), in the context of N monitoring. One hundred and eighteen diatom taxa belonging to 36 genera were identified, with physical (water flow), water (nitrate, P and total dissolved solids) and sediment (B, Ca, Cr, Na, N, P, SOM, Pb and Zn) variables correlating to one or more of the 12 diatom indices presented. In particular, Biological Diatom Index, Biological Index of Water Quality, Central Economic Community, Index of Artois-Picardie Diatom (IDAP) and Sládeček's Index were strongly explained by sediment variables, whilst Descy's Pollution Index and Schiefele and Schreiner's Index were explained by water and physical variables.
- Full Text:
- Date Issued: 2020
River nutrient water and sediment measurements inform on nutrient retention, with implications for eutrophication
- Dalu, Tatenda, Wasserman, Ryan J, Magoro, Mandla L, Froneman, P William, Weyl, Olaf, L F
- Authors: Dalu, Tatenda , Wasserman, Ryan J , Magoro, Mandla L , Froneman, P William , Weyl, Olaf, L F
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/467222 , vital:76841 , https://doi.org/10.1016/j.scitotenv.2019.05.167
- Description: The consideration of nutrients in pollution dynamics is important for environmental management and conservation. Developing countries are yet to appreciate the aquatic ecosystem pollution impacts on their economies and as such, information on water pollution dynamics is limited. This study assessed the spatio-temporal dynamics of nutrient loading and retention in stream water and sediments in the Bloukrans River system, Eastern Cape province, South Africa over the course of the wet and dry season. Sediment and water samples were analysed for total phosphorus (TP) and nitrogen (TN) concentrations, and were used in combination with river flow discharge, to determine nutrient loads. The study results highlight that river discharge plays a significant role in temporal differences in sediment and water column nutrient concentrations.
- Full Text:
- Date Issued: 2019
- Authors: Dalu, Tatenda , Wasserman, Ryan J , Magoro, Mandla L , Froneman, P William , Weyl, Olaf, L F
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/467222 , vital:76841 , https://doi.org/10.1016/j.scitotenv.2019.05.167
- Description: The consideration of nutrients in pollution dynamics is important for environmental management and conservation. Developing countries are yet to appreciate the aquatic ecosystem pollution impacts on their economies and as such, information on water pollution dynamics is limited. This study assessed the spatio-temporal dynamics of nutrient loading and retention in stream water and sediments in the Bloukrans River system, Eastern Cape province, South Africa over the course of the wet and dry season. Sediment and water samples were analysed for total phosphorus (TP) and nitrogen (TN) concentrations, and were used in combination with river flow discharge, to determine nutrient loads. The study results highlight that river discharge plays a significant role in temporal differences in sediment and water column nutrient concentrations.
- Full Text:
- Date Issued: 2019
Impact of an introduced predator (Micropterus salmoides, Centrarchidae) on native estuarine fish elucidated through fatty acid analyses
- Carassou, Laure, Magoro, Mandla L, Whitfield, Alan K, Richoux, Nicole B
- Authors: Carassou, Laure , Magoro, Mandla L , Whitfield, Alan K , Richoux, Nicole B
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/456247 , vital:75496 , xlink:href="https://hal.inrae.fr/hal-04177984/document"
- Description: The introduction of alien fish species can have contrasting impacts on local aquatic communities. The largemouth bass Micropterus salmoides (Centrarchidae; Fig.1) was introduced in 1928 in South Africa for recreational anglers. Concerns about its impact on local indigenous freshwater and estuarine fish populations are raised (Gratwicke and Marshall, 2001; Weyl and Lewis, 2006; Wasserman et al., 2011). In particular, the predatory impact of M. salmoides on estuary-associated juveniles of marine fish species must be elucidated.
- Full Text:
- Date Issued: 2017
- Authors: Carassou, Laure , Magoro, Mandla L , Whitfield, Alan K , Richoux, Nicole B
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/456247 , vital:75496 , xlink:href="https://hal.inrae.fr/hal-04177984/document"
- Description: The introduction of alien fish species can have contrasting impacts on local aquatic communities. The largemouth bass Micropterus salmoides (Centrarchidae; Fig.1) was introduced in 1928 in South Africa for recreational anglers. Concerns about its impact on local indigenous freshwater and estuarine fish populations are raised (Gratwicke and Marshall, 2001; Weyl and Lewis, 2006; Wasserman et al., 2011). In particular, the predatory impact of M. salmoides on estuary-associated juveniles of marine fish species must be elucidated.
- Full Text:
- Date Issued: 2017
Variation partitioning of benthic diatom community matrices: Effects of multiple variables on benthic diatom communities in an Austral temperate river system
- Dalu, Tatenda, Wasserman, Ryan J, Magoro, Mandla L, Mwedzi, Tongayi, Froneman, P William, Weyl, Olaf L F
- Authors: Dalu, Tatenda , Wasserman, Ryan J , Magoro, Mandla L , Mwedzi, Tongayi , Froneman, P William , Weyl, Olaf L F
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/467182 , vital:76837 , https://doi.org/10.1016/j.scitotenv.2017.05.162
- Description: This study explores diatom community dynamics in a highly modified semi-arid temperate region river system characterised by inconsistent river flow. Various water and sediment environmental variables were assessed using a multi-faceted analysis approach to determine the spatio-temporal drivers of benthic diatom communities in the river system. Overall, the diatom community was generally dominated by pollution tolerant species, reflecting the anthropogenic intensity and activities on the river system. Diatom community composition was found to be largely determined by water column chemistry variables particularly nutrient concentrations in comparison to sediment chemistry and physical variables. Strong seasonal diatom species composition was also observed and this was driven by strong seasonal variations in nutrient loads and metal concentrations, a result of the variable water flow across the two seasons. However, the greater temporal variation in communities was observed in the smaller systems with the mainstream river system being more homogenous over time. In addition, diatom community composition and environmental variables were found to be different and more pronounced between streams and mainstream sites, than between canals and streams. The study highlights the complex interaction between water column, sediment and physical variables in determining the diatom species composition in small river systems. It also highlights the importance of river flow inconsistency as an indirect variable that alters primary drivers such as nutrient concentrations in the water column and heavy metal levels in the sediment.
- Full Text:
- Date Issued: 2017
- Authors: Dalu, Tatenda , Wasserman, Ryan J , Magoro, Mandla L , Mwedzi, Tongayi , Froneman, P William , Weyl, Olaf L F
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/467182 , vital:76837 , https://doi.org/10.1016/j.scitotenv.2017.05.162
- Description: This study explores diatom community dynamics in a highly modified semi-arid temperate region river system characterised by inconsistent river flow. Various water and sediment environmental variables were assessed using a multi-faceted analysis approach to determine the spatio-temporal drivers of benthic diatom communities in the river system. Overall, the diatom community was generally dominated by pollution tolerant species, reflecting the anthropogenic intensity and activities on the river system. Diatom community composition was found to be largely determined by water column chemistry variables particularly nutrient concentrations in comparison to sediment chemistry and physical variables. Strong seasonal diatom species composition was also observed and this was driven by strong seasonal variations in nutrient loads and metal concentrations, a result of the variable water flow across the two seasons. However, the greater temporal variation in communities was observed in the smaller systems with the mainstream river system being more homogenous over time. In addition, diatom community composition and environmental variables were found to be different and more pronounced between streams and mainstream sites, than between canals and streams. The study highlights the complex interaction between water column, sediment and physical variables in determining the diatom species composition in small river systems. It also highlights the importance of river flow inconsistency as an indirect variable that alters primary drivers such as nutrient concentrations in the water column and heavy metal levels in the sediment.
- Full Text:
- Date Issued: 2017
Connectivity through allochthony: Reciprocal links between adjacent aquatic and terrestrial ecosystems in South Africa
- Richoux, Nicole B, Moyo, Sydney, Chari, Lenin D, Bergamino, Leandro, Carassou, Laure, Dalu, Tatenda, Hean, Jeffrey W, Sikutshwa, Likho, Gininda, Simphiwe, Magoro, Mandla L, Perhar, Gurbir, Ni, Felicity, Villet, Martin H, Whitfield, Alan K, Parker, Daniel M, Froneman, P William, Arhonditsis, George, Craig, Adrian J F K
- Authors: Richoux, Nicole B , Moyo, Sydney , Chari, Lenin D , Bergamino, Leandro , Carassou, Laure , Dalu, Tatenda , Hean, Jeffrey W , Sikutshwa, Likho , Gininda, Simphiwe , Magoro, Mandla L , Perhar, Gurbir , Ni, Felicity , Villet, Martin H , Whitfield, Alan K , Parker, Daniel M , Froneman, P William , Arhonditsis, George , Craig, Adrian J F K
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438363 , vital:73454 , ISBN 978-1-4312-0679-7 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2186-1-15.pdf
- Description: An important aspect of the dynamics of nutrients and pollutants in natural systems is captured in the concept of allochthony, founded on the observation that nutrients and energy in a variety of forms are transferred between adjacent habitats, com-munities and ecosystems that are not routinely considered as connected. Different forms of nutrients and energy move across the conceptual boundaries of habitats via organisms’ activities or physical processes such as wind or water currents, and these transfers can represent important food subsidies. Such cross-partition ecolog-ical subsidies can augment the nutritional condition, biomass and biodiversity of communities, particularly where local production (or autochthony) alone may be inadequate to support local food webs. Furthermore, organic subsidies can influ-ence population dynamics, community interactions and ecosystem processes, and can represent dominant flux inputs in ecosystem budgets. Our intention was to ex-plore organic nutrient fluxes in relation to a primarily lotic (i.e. flowing) aquatic sys-tem at the scale of a hydrological catchment.
- Full Text:
- Date Issued: 2015
- Authors: Richoux, Nicole B , Moyo, Sydney , Chari, Lenin D , Bergamino, Leandro , Carassou, Laure , Dalu, Tatenda , Hean, Jeffrey W , Sikutshwa, Likho , Gininda, Simphiwe , Magoro, Mandla L , Perhar, Gurbir , Ni, Felicity , Villet, Martin H , Whitfield, Alan K , Parker, Daniel M , Froneman, P William , Arhonditsis, George , Craig, Adrian J F K
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438363 , vital:73454 , ISBN 978-1-4312-0679-7 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2186-1-15.pdf
- Description: An important aspect of the dynamics of nutrients and pollutants in natural systems is captured in the concept of allochthony, founded on the observation that nutrients and energy in a variety of forms are transferred between adjacent habitats, com-munities and ecosystems that are not routinely considered as connected. Different forms of nutrients and energy move across the conceptual boundaries of habitats via organisms’ activities or physical processes such as wind or water currents, and these transfers can represent important food subsidies. Such cross-partition ecolog-ical subsidies can augment the nutritional condition, biomass and biodiversity of communities, particularly where local production (or autochthony) alone may be inadequate to support local food webs. Furthermore, organic subsidies can influ-ence population dynamics, community interactions and ecosystem processes, and can represent dominant flux inputs in ecosystem budgets. Our intention was to ex-plore organic nutrient fluxes in relation to a primarily lotic (i.e. flowing) aquatic sys-tem at the scale of a hydrological catchment.
- Full Text:
- Date Issued: 2015
Movement behaviour of alien largemouth bass Micropterus salmoides in the estuarine headwater region of the Kowie River, South Africa
- Murray, Taryn S, Magoro, Mandla L, Whitfield, Alan K, Cowley, Paul D
- Authors: Murray, Taryn S , Magoro, Mandla L , Whitfield, Alan K , Cowley, Paul D
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443194 , vital:74087 , https://doi.org/10.1080/15627020.2015.1079141
- Description: The movement behaviour of largemouth bass Micropterus salmoides in the estuarine headwater region of the Kowie River, South Africa, was investigated using passive acoustic telemetry. Ten adult fish were tagged and released in four discrete pools below a weir that precluded possible upriver migration. Their residency and movement patterns were monitored using 27 moored acoustic receivers spanning both riverine and estuarine habitats between January and November 2013. Small-scale movements ranging from 50 to 400 m occurred between pools in the headwater region, where tagged fish remained resident (did not leave their tagging pool) during the warmer (summer) months. The onset of autumn and winter correlated with declining water temperatures and half of the tagged largemouth bass made downstream excursions into the slightly warmer upper reaches of the estuary. The penetration of these alien piscivores into estuarine headwaters potentially provide additional predator pressure on the juveniles of migratory estuary-associated native marine fish species, which utilise these areas as nurseries. The presence of the alien fish in South African estuarine headwaters may impair the migration of juvenile fishes between the estuarine and freshwater environments.
- Full Text:
- Date Issued: 2015
- Authors: Murray, Taryn S , Magoro, Mandla L , Whitfield, Alan K , Cowley, Paul D
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443194 , vital:74087 , https://doi.org/10.1080/15627020.2015.1079141
- Description: The movement behaviour of largemouth bass Micropterus salmoides in the estuarine headwater region of the Kowie River, South Africa, was investigated using passive acoustic telemetry. Ten adult fish were tagged and released in four discrete pools below a weir that precluded possible upriver migration. Their residency and movement patterns were monitored using 27 moored acoustic receivers spanning both riverine and estuarine habitats between January and November 2013. Small-scale movements ranging from 50 to 400 m occurred between pools in the headwater region, where tagged fish remained resident (did not leave their tagging pool) during the warmer (summer) months. The onset of autumn and winter correlated with declining water temperatures and half of the tagged largemouth bass made downstream excursions into the slightly warmer upper reaches of the estuary. The penetration of these alien piscivores into estuarine headwaters potentially provide additional predator pressure on the juveniles of migratory estuary-associated native marine fish species, which utilise these areas as nurseries. The presence of the alien fish in South African estuarine headwaters may impair the migration of juvenile fishes between the estuarine and freshwater environments.
- Full Text:
- Date Issued: 2015
- «
- ‹
- 1
- ›
- »