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A glimpse into the littoral nutrient dynamics of a lake system connected to the sea

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dc.contributor.author Taljaard, Susan
dc.contributor.author Van Niekerk, Lara
dc.contributor.author Lemley, DA
dc.date.accessioned 2018-02-21T08:31:27Z
dc.date.available 2018-02-21T08:31:27Z
dc.date.issued 2018-01
dc.identifier.citation Taljaard, S., Van Niekerk, L. and Lemley, D.A. 2018. A glimpse into the littoral nutrient dynamics of a lake system connected to the sea. Water SA, vol. 44(1): http://dx.doi.org/10.4314/wsa.v44i1.08 en_US
dc.identifier.issn 0378-4738
dc.identifier.uri https://www.ajol.info/index.php/wsa/article/view/166142
dc.identifier.uri http://www.wrc.org.za/Lists/Knowledge%20Hub%20Items/Attachments/12263/3298%20abstract.pdf
dc.identifier.uri http://hdl.handle.net/10204/10053
dc.description Article published in Water SA, vol. 44(1): http://dx.doi.org/10.4314/wsa.v44i1.08 en_US
dc.description.abstract In South Africa more than 80% of estuaries are small, dynamic and predominantly linear systems. Nutrient characteristics in these systems are mostly influenced by external catchment processes, except during extended periods of closure. However, a small percentage of the country’s estuaries (< 3%) comprise larger estuarine lakes mostly evolved from drowned river valleys. The physical properties of these systems suggest relatively low flushing rates, and the potentially stronger influence of in-situ processes on nutrient characteristics. This study investigates dissolved inorganic nutrient dynamics in the littoral zones of these estuarine lake systems, and potential influencing factors, using the Wilderness Lake System as a case study. Comparison of inter-annual and seasonal trends in dissolved inorganic nutrients (NOx-N, NH4-N and PO4-P) in river inflow and in the three lakes confirmed that external catchment fluxes are most likely not the sole, or even the dominant drivers of average long-term or seasonal dissolved inorganic nutrient patterns in the lake littoral zones. Relatively low NOx:NH4 ratios (mostly less than 1) in the lakes (especially in Eilandvlei and Langvlei) indicated a stronger influence of in-situ processes, such as bacteriological remineralisation, similar to observations in other lake type systems with low flushing rates. Low NO3:NH4 ratios are known to stimulate cyanobacteria, having the metabolic ability to potentially produce microcystins. Therefore, incremental dissolved inorganic nutrient and organic matter enrichment may cause these systems to tip into eutrophic, possibly toxic, aquatic states that will be difficult, if not impossible, to reverse given their weak flushing mechanisms. The findings from this study highlight the importance of appropriate water resource management, both in the catchments and within the floodplains of estuarine lake systems. en_US
dc.language.iso en en_US
dc.publisher Water Research Commission en_US
dc.relation.ispartofseries Worklist;20206
dc.subject Wilderness en_US
dc.subject Estuarine lake en_US
dc.subject Littoral zone en_US
dc.subject Dissolved inorganic nutrients en_US
dc.subject Catchment fluxes en_US
dc.subject In-situ processes en_US
dc.title A glimpse into the littoral nutrient dynamics of a lake system connected to the sea en_US
dc.type Article en_US
dc.identifier.apacitation Taljaard, S., Van Niekerk, L., & Lemley, D. (2018). A glimpse into the littoral nutrient dynamics of a lake system connected to the sea. http://hdl.handle.net/10204/10053 en_ZA
dc.identifier.chicagocitation Taljaard, Susan, Lara Van Niekerk, and DA Lemley "A glimpse into the littoral nutrient dynamics of a lake system connected to the sea." (2018) http://hdl.handle.net/10204/10053 en_ZA
dc.identifier.vancouvercitation Taljaard S, Van Niekerk L, Lemley D. A glimpse into the littoral nutrient dynamics of a lake system connected to the sea. 2018; http://hdl.handle.net/10204/10053. en_ZA
dc.identifier.ris TY - Article AU - Taljaard, Susan AU - Van Niekerk, Lara AU - Lemley, DA AB - In South Africa more than 80% of estuaries are small, dynamic and predominantly linear systems. Nutrient characteristics in these systems are mostly influenced by external catchment processes, except during extended periods of closure. However, a small percentage of the country’s estuaries (< 3%) comprise larger estuarine lakes mostly evolved from drowned river valleys. The physical properties of these systems suggest relatively low flushing rates, and the potentially stronger influence of in-situ processes on nutrient characteristics. This study investigates dissolved inorganic nutrient dynamics in the littoral zones of these estuarine lake systems, and potential influencing factors, using the Wilderness Lake System as a case study. Comparison of inter-annual and seasonal trends in dissolved inorganic nutrients (NOx-N, NH4-N and PO4-P) in river inflow and in the three lakes confirmed that external catchment fluxes are most likely not the sole, or even the dominant drivers of average long-term or seasonal dissolved inorganic nutrient patterns in the lake littoral zones. Relatively low NOx:NH4 ratios (mostly less than 1) in the lakes (especially in Eilandvlei and Langvlei) indicated a stronger influence of in-situ processes, such as bacteriological remineralisation, similar to observations in other lake type systems with low flushing rates. Low NO3:NH4 ratios are known to stimulate cyanobacteria, having the metabolic ability to potentially produce microcystins. Therefore, incremental dissolved inorganic nutrient and organic matter enrichment may cause these systems to tip into eutrophic, possibly toxic, aquatic states that will be difficult, if not impossible, to reverse given their weak flushing mechanisms. The findings from this study highlight the importance of appropriate water resource management, both in the catchments and within the floodplains of estuarine lake systems. DA - 2018-01 DB - ResearchSpace DP - CSIR KW - Wilderness KW - Estuarine lake KW - Littoral zone KW - Dissolved inorganic nutrients KW - Catchment fluxes KW - In-situ processes LK - https://researchspace.csir.co.za PY - 2018 SM - 0378-4738 T1 - A glimpse into the littoral nutrient dynamics of a lake system connected to the sea TI - A glimpse into the littoral nutrient dynamics of a lake system connected to the sea UR - http://hdl.handle.net/10204/10053 ER - en_ZA


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