Impact of trace metals (Cu, Cd, Zn) on phytoplankton in open and coastal oceans: a Southern African perspective

Simple item page
dc.contributor.advisorFietz, Susanneen_ZA
dc.contributor.authorWium, Emtiaen_ZA
dc.contributor.otherStellenbosch University. Faculty of Science. Dept. of Earth Sciences.en_ZA
dc.date.accessioned2023-02-20T16:40:01Z
dc.date.accessioned2023-05-18T06:59:07Z
dc.date.available2023-02-20T16:40:01Z
dc.date.available2023-05-18T06:59:07Z
dc.date.issued2023-03
dc.descriptionThesis (MSc)--Stellenbosch University, 2023. en_ZA
dc.description.abstractENGLISH ABSTRACT: This study reflects on the understanding of marine trace metal concentrations and their impacts on growth of marine phytoplankton. The aim was to better understand the oceanic concentrations of copper (Cu), cadmium (Cd) and zinc (Zn) and their potential toxicity effects on phytoplankton in general, and the ubiquitous Nannochloropsis sp. The data for Paper 1 was obtained from previously published literature and focussed on (1) oceanic Cu, Cd and Zn concentrations worldwide, and in seawater near Southern Africa, (2) toxicity threshold concentrations of Cu and Cd for marine phytoplankton, and (3) threshold concentrations of Cu, Cd and Zn for phytoplankton used in incubation studies, and were used to determine the risk of metal toxicity in oceans around Southern Africa, at less than or equal to 200m water depth. Paper 1 shows the concentrations for Cu, Cd and Zn in the coastal water around Southern Africa, at aforementioned depths, were 1.1 – 240 nM, 0.20 – 180 nM and 0.40 – 8300 nM, respectively. These concentrations vary worldwide, as metal concentrations in seawater are influenced by a number of factors, e.g., human pressure, distance to shore, water depth, resident biological community and chemical-physical interaction. Paper 1 showed a range of threshold concentrations of Cu, Cd, and Zn on phytoplankton species and revealed that picoeukaryotes, nanoplankton, cyanobacteria, dinoflagellates and diatoms may be at risk of trace metal toxicity in coastal seawater around Southern Africa. Paper 1 showed the need for further studies and easily accessible data to better understand the impact of high Cu, Cd and Zn concentrations on marine phytoplankton. Therefore, in Paper 2, a key phytoplankton in the marine realm was selected, the ubiquitous Nannochloropsis sp. Paper 1 furthermore served to inform experiments of Paper 2, where 0 – 9.0 μM Cu, 0 – 5.5 μM Cd and 0 – 20 μM Zn were investigated. The parameters tested on Nannochloropsis sp. in the incubation experiments were dry weight biomass, chlorophyll-a (chl-a) concentration, chl-a content, density of single living cells, percent contributing dead cells, growth rate of single living cells, and trace metal and nitrate change in the solution. It was established that 0.94 – 1.7 μM Cu caused decline in chl-a concentrations and chl-a content, while increasing the dead cell contribution. A range of 4.0 – 5.5 μM Cd decreased the biomass. The Zn range of 4 – 11 μM decreased the chl-a concentration, while 11 – 20 μM Zn decreased the biomass, single cell density and growth rate. Combining the results of Paper 1 and Paper 2, it was established that Nannochloropsis sp. may face toxicity risks in the coastal oceans around Southern Africa, especially if future concentrations increase. This study therefore highlighted the importance of trace metal monitoring and in maintaining phytoplankton growth in the marine environments.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Hierdie studie handel oor die kennis van marine spoormetale konsentrasies en hul effek op die groei van marine fitoplankton. Die doelwit was om kennis te verbeter rakende die konsentrasies van koper (Cu), kadmium (Cd) en sink (Zn) in die oseaan, asook die potensiële toksiese effek daarvan op fitoplankton en Nannochloropsis sp. Manuskrip 1 data was saamgestel uit gepubliseerde literatuur en fokus op (1) Cu, Cd en Zn konsentrasies in die oseaan en rondom Suidelike Afrika, (2) Cu en Cd toksiese drempel konsentrasies vir fitoplankton, en (3) Cu, Cd en Zn drempel konsentrasies op fitoplankton van inkubasie eksperimente, en was gebruik om die risiko te evalueer van fitoplankton in die oseaan aan die kus van Suidelike Afrika. Manuskrip 1 het konsentrasies van 1.1 – 240 nM (Cu), 0.20 – 180 nM (Cd) en 0.40 – 8300 nM (Zn) gewys. Hierdie konsentrasies wissel wêreldwyd, afhangende van faktore soos menslike drukking, afstand van die kus, water diepte, residensiële biologiese gemeenskap en chemiese-fisiese interaksie. Manuskrip 1 het ‘n breë verskeidenheid drempel konsentrasies van Cu, Cd en Zn op fitoplankton gewys, waar pikoeukariote, nanoplankton, sianobakterieë, dinoflagellate en diatome die risiko het om negatief beïnvloed te word deur metale in die seewater naby die kus van Suidelike Afrika. Manuskrip 1 het daarop gewys dat daar ‘n behoefte is vir maklik toeganklike studies, en verdere studies, om die impak van Cu, Cd en Zn op marine fitoplankton beter te verstaan. Vir hierdie rede, in Manuskrip 2, is a fundamentele fitoplankton in die oseaan ryk gebruik, die alomteenwoordige Nannochloropsis sp. Manuskrip 1 het verder gedien as informasie vir die eksperimente in Manuskrip 2, waar die konsentrasies 0 – 9.0 μM Cu, 0 – 5.5 μM Cd en 0 – 20 μM Zn ondersoek was. Die kriteria het ingesluit: droë gewig biomassa, chlorofil-a (chl-a), chl-a inhoud, digtheid van enkele lewende selle, persentasie van dooie selle, groeikoers, en metaal en nitraat verandering in die oplossing van die eksperiment. Gedurende die eksperimente het 0.94 – 1.7 μM Cu ‘n afname in chl-a konsentrasies en chl-a inhoud gehad, en ‘n toename in die dooie sel bydrae. Die biomassa was verlaag deur 4.0 – 5.5 μM Cd. Vir Zn, het 4 – 11 μM die chl-a konsentrasie verlaag, en 11 – 20 μM die biomassa, enkel sel digtheid en groeikoers verlaag. Die kombinasie van resultate van Manuskrip 1 en Manuskrip 2 het bewys dat Nannochloropsis sp. die risiko van toksisiteit mag hê in die seewater aan die kus van Suidelike Afrika, veral indien toekomstige konsentrasies verhoog. Hierdie studie het dus weereens die belangrikheid van monitering van spoormetaal konsentrasies uitgelig, asook die handhawing van fitoplankton groei in die mariene omgewing.af_ZA
dc.description.versionMastersen_ZA
dc.format.extentxvi, 140 pages : illustrations (some color), mapsen_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/126991
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshPhytoplankton -- Africa Southern -- Coastal oceansen_ZA
dc.subject.lcshMarine phytoplankton -- Effect of cadmium onen_ZA
dc.subject.lcshMarine phytoplankton -- Effect of chemicals onen_ZA
dc.subject.lcshTrace elementsen_ZA
dc.subject.lcshNannochloropsisen_ZA
dc.subject.lcshPhytoplankton -- Environmental aspectsen_ZA
dc.subject.nameUCTDen_ZA
dc.titleImpact of trace metals (Cu, Cd, Zn) on phytoplankton in open and coastal oceans: a Southern African perspectiveen_ZA
dc.typeThesisen_ZA
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
wium_impact_2023.pdf
Size:
5.79 MB
Format:
Adobe Portable Document Format
Description:
Download
Collections
Masters Degrees (Earth Sciences)