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Effect of long-term exposure to cadmium on the earthworm Eisenia fetida (Oligochaeta) : possible resistance
Thesis (M.Sc.) -- University of Stellenbosch, 1999.
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| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2012
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| _version_ | 1867613986864758784 |
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| access_status_str | Open Access |
| author | Prinsloo, Manfred Wilhelm |
| author2 | Reinecke, S. A. |
| author_browse | Prinsloo, Manfred Wilhelm Reinecke, S. A. |
| author_facet | Reinecke, S. A. Prinsloo, Manfred Wilhelm |
| author_sort | Prinsloo, Manfred Wilhelm |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (M.Sc.) -- University of Stellenbosch, 1999. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/51251 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:44:52.037Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/51251 Effect of long-term exposure to cadmium on the earthworm Eisenia fetida (Oligochaeta) : possible resistance Prinsloo, Manfred Wilhelm Reinecke, S. A. Reinecke, A. J. Stellenbosch University. Faculty of Science. Dept. of Botany & Zoology. Cadmium -- Environmental aspects Earthworms -- Effect of chemicals on Dissertations -- Zoology Thesis (M.Sc.) -- University of Stellenbosch, 1999. ENGLISH ABSTRACT: Environmental cadmium is the result of emissions from non-ferrous smelters and mining activities, as well as disposal of Cd-containing household waste Cd-containing sewage sludge and phosphate fertilisers. In polluted soil, the Cd associates with the biological fraction and therefore is relatively available for uptake by soil dwelling organisms Animals living in contaminated soil are subjected to selection pressures caused by the pollutant and can either acclimate (the pressure is overcome by natural individual resistance), or develop a tolerance/adaptation (genetic increase in the mean resistance of the population). Numerous studies on soil invertebrates show that some species are capable of developing resistance to heavy metal pollution. For earthworms however, such data is non-existent. The aim of this study was to determine whether a population of Eisenia fetida that had been exposed in the laboratory to sublethal concentrations of Cd for four years, had developed resistance to Cd. This was done by subjecting pre-exposed and control worms to various experiments and comparing the results. The first parameter under investigation was biomass change of the different groups in uncontaminated, moderately contaminated, and heavily contaminated substrates. During these experiments, the pre-exposed worms displayed signs of Cd-dependency by performing worse in the uncontaminated substrate than in the moderately contaminated substrate. This was also reflected when cocoon production was monitored, the control worms showing a linear decrease in cocoon production as the concentration of CdS04 in the substrate rose, while the pre-exposed worms had the highest cocoon production in the moderately contaminated substrate. Physiologically, the osmolality- as well as the cell percentage of the coelomic fluid for pre-exposed and control worms, exposed to high concentrations of CdS04 was measured. Although no differences between the two groups were observed when looking at the osmolality, a possible resistance was observed for the pre-exposed worms when looking at the differences in cell percentage. Total body accumulation did not differ between the pre-exposed and control worms after exposure to Cd. The pre-exposed worms did however show a marked increase in the nephridial accumulation of Cd as shown by PIXE analyses of the organs, when compared to the control groups. This study has shown that there is definite evidence of an increased resistance to Cd in the form of CdS04 in the pre-exposed worms when compared to unexposed control worms. Whether this resistance is the result of acclimation or a genetic adaptation could however not be determined by this study and further research in that direction is recommended. AFRIKAANSE OPSOMMING: Kadmium beland in die omgewing deur emissies atkomstig van nie-fereuse smelterye en mynaktiwiwteite, asook deur die kadmiumbevattende huishoudelike afval, riool en fosfaatkunsmisse. In die besoedelde grond assosieer die kadmium met die biologiese fraksie en is dus relatief beskikbaar vir opname deur grondlewende organismes. Diere in besoedelde grond word blootgestel aan seleksiedruk. Diegene wat kan oorleef, het of geakklimeer (oorkoming deur die individu se natuurlike weerstand), of geadapteer ('n genetiese toename in die gemiddelde weerstand van die populasie). Verskeie studies is gedoen op grondinvertebrate wat aantoon dat sekere spesies wei 'n verhoogde weerstand ten opsigte van swaarmetaalbesoedeling kan ontwikkel. Baie min inligting is egter beskikbaar oor erdwurms in hierdie verband. Die doel van hierdie studie was om vas te stel of 'n populasie van Eisenia jetida, wat oor 'n tydperk van vier jaar in die laboratorium blootgestel is aan subletale· konsentrasies van Cd, 'n verhoogde weerstand ten opsigte van Cd toon. Dit is gedoen deur vooratblootgestelde en kontrole wurms aan verskeie eksperimente te onderwerp en die resultate te vergelyk. Die eerste parameter waarna gekyk is, is die verandering in biomassa van die ondersreie groepe in 'n ongekontamineerde ,matige of swaar gekontamineerde substraat. Hierdie eksperimente het getoon dat die voorafblootgestelde wurms tekens van Cd-afhanklikheid toon deurdat hulle swakker gevaar het in die ongekontamineerde as in die matig gekontamineerde substraat. Tekens van 'n Cd-afhanklikheid is ook waargeneem toe daar na kokonproduksie gekyk is. Die kontrolewurms het 'n liniere afname in die kokonproduksie getoon namate die konsentrasie van die Cd in die substraat toegeneem het, terwyl die voorafblootgestelde wurms die hoogste kokonproduksie getoon het in die matig gekontamineerde substraat. Fisiologies is daar gekyk na die osmolaliteit en die selpersentasie van die seloomvloeistof van die voorafblootgestelde en kontrole wurms by blootstelling aan hoe konsentrasies van Cd. Alhoewel daar geen verskille tlissen die twee groepe waargeneem was, wat osmolaliteit betref nie, was daar wel aanduidings van 'n verhoogde weerstand gevind in die voorafblootgestelde wurms toe die selpersentasies ondersoek is. Die totale liggaamskonsentrasie van Cd het me verskil tussen die voorafblootgestelde en kontrole wurms na blootstelling aan Cd me. Die voorafblootgestelde wurms het egter 'n duidelike toename in nefridiale akkumulasie, van Cd getoon na PlXE analise van die organe. Hierdie studie het aangetoon dat daar 'n definitiewe aanduiding is van 'n verhoogde weerstand t.o.v. Cd in die voorafblootgestelde wurms. Of hierdie weerstand die gevolg van akklimasie of geneties ontwikkelde toleransie (weerstand) is, kon egter nie deur hierdie studie aangetoon word nie, en verdere navorsing op hierdie gebied word voorgestel. Master 2012-08-27T11:34:24Z 2012-08-27T11:34:24Z 1999-10 Thesis http://hdl.handle.net/10019.1/51251 en_ZA Stellenbosch University 103 pages : ill. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Cadmium -- Environmental aspects Earthworms -- Effect of chemicals on Dissertations -- Zoology Prinsloo, Manfred Wilhelm Effect of long-term exposure to cadmium on the earthworm Eisenia fetida (Oligochaeta) : possible resistance |
| title | Effect of long-term exposure to cadmium on the earthworm Eisenia fetida (Oligochaeta) : possible resistance |
| title_full | Effect of long-term exposure to cadmium on the earthworm Eisenia fetida (Oligochaeta) : possible resistance |
| title_fullStr | Effect of long-term exposure to cadmium on the earthworm Eisenia fetida (Oligochaeta) : possible resistance |
| title_full_unstemmed | Effect of long-term exposure to cadmium on the earthworm Eisenia fetida (Oligochaeta) : possible resistance |
| title_short | Effect of long-term exposure to cadmium on the earthworm Eisenia fetida (Oligochaeta) : possible resistance |
| title_sort | effect of long term exposure to cadmium on the earthworm eisenia fetida oligochaeta possible resistance |
| topic | Cadmium -- Environmental aspects Earthworms -- Effect of chemicals on Dissertations -- Zoology |
| url | http://hdl.handle.net/10019.1/51251 |
| work_keys_str_mv | AT prinsloomanfredwilhelm effectoflongtermexposuretocadmiumontheearthwormeiseniafetidaoligochaetapossibleresistance |