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The implications of a changing environment for fouling biota
Thesis (PhD)--Stellenbosch University, 2023.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2023
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| _version_ | 1867613774488272896 |
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| access_status_str | Open Access |
| author | Matikinca, Phikolomzi |
| author2 | Robinson-Smythe, Tamara B |
| author_browse | Matikinca, Phikolomzi Robinson-Smythe, Tamara B |
| author_facet | Robinson-Smythe, Tamara B Matikinca, Phikolomzi |
| author_sort | Matikinca, Phikolomzi |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhD)--Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/128373 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:41:29.531Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/128373 The implications of a changing environment for fouling biota Matikinca, Phikolomzi Robinson-Smythe, Tamara B Stellenbosch University. Faculty of Science. Dept. of Botany & Zoology. Ocean acidification -- South Africa -- Western Cape West Coast(South Africa) -- Environmental conditions Fouling -- Environmental aspects -- South Africa -- Western Cape Climatic changes -- West Coast(South Africa) Marine ecology -- South Africa -- Saldanha Bay Saldanha Bay (South Africa) -- Environmental conditions UCTD Thesis (PhD)--Stellenbosch University, 2023. ENGLISH ABSTRACT: In marine systems climate change manifests primarily in altered thermal and carbonate chemistry regimes. Temperature and carbonate chemistry can vary across spatial and temporal scales. However, there is limited understanding of how this variability manifests in most regions or what the implications are for marine biota. This is especially true in relation to Africa. This thesis aimed to quantify spatial and temporal dynamics in carbonate chemistry along the temperate west coast of South Africa, assess how future cooling and acidification might affect fouling biota, and investigate how co-occurring stressors might modulate tolerance of these taxa to acidification. Carbonate chemistry was monitored on rocky shores, sandy shores and in marinas. Temporal variability was considered at the scale of diurnal fluctuations, days and months in different seasons, while spatial variability was captured among four locations and between two depths in marinas. All carbonate chemistry parameters varied among months in different seasons, with reduced temperature, pH and aragonite saturation, and elevated partial pressure of carbon dioxide and dissolved inorganic carbon in winter. The low levels of pH and very low aragonite saturation (7.64 (± 0.14 SD ) and 0.5 (± 0.2 SD) respectively (in Saldanha Bay)) highlight the vulnerability of this region to ocean acidification . Spatial variability was driven by differences among locations, indicating the importance of accounting for local conditions when designing laboratory experiments assessing effects of acidification. Our understanding of community-level responses to the predicted changes in future environments remains limited. Fouling communities from Saldanha Bay and Table Bay were used to assess the effects of future cooling and acidification. Communities were exposed to two temperatures (13℃ (current) and 9℃ (future cooling)) and three pH treatments (7.9 (current), 7.6 and 7.4) for 18 days. Acidification was more detrimental to fouling communities than cooling, resulting in altered community structure and reduced diversity particularly at 7.4 pH. Declining pH reduced the abundance of both calcifying and soft bodied taxa, demonstrating the vulnerability of taxa like ascidians to acidification. These findings highlight that reduced pH along the cooling west coast will be a greater threat to fouling communities than altered temperatures. Responses to acidification can be life stage specific and be modulated by temperature and energetic context. To understand how co-occurring changes in temperature and food supply, together with ontogeny might affect tolerance of fouling biota to declining pH, juveniles and adults of the colonial ascidians Diplosoma listerianum, Botryllus schlosseri and Botryllus gregalis, as well as the solitary sea vase Ciona robusta were exposed to two temperatures (13℃ and 9℃), at which two food levels (unrestricted and restricted food supply) were investigated. Juveniles were less tolerant to acidic conditions than adults. Notably, regardless of ontogeny or species, cooling and restricted food supply additively reduced tolerance of ascidians to low pH. These results suggest that cooling along the west coast may amplify the effects of declining pH on ascidians, particularly in the juvenile stage. However, this effect may be buffered by enriched food supply during periods of high productivity along this coast. AFRIKAANSE OPSOMMING: In mariene stelsels manifesteer klimaatsverandering hoofsaaklik in veranderde termiese en karbonaatchemie-regimes. Temperatuur- en karbonaatchemie kan oor ruimtelike en tydelike skale verskil. Daar is egter beperkte begrip van hoe hierdie veranderlikheid in die meeste streke manifesteer of wat die implikasies vir mariene biota is. Dit is veral waar met betrekking tot Afrika. Hierdie tesis het die volgende doelle gehad (1) kwantifiseer ruimtelike en tydelike dinamika in karbonaatchemie langs die gematigde weskus van Suid-Afrika, bepaal hoe toekomstige verkoeling en versuring vervuilingsbiota kan beïnvloed, en (3) ondersoek hoe mede-voorkomende stressors die verdraagsaamheid van hierdie taksa teenoor versuring kan moduleer. Karbonaatchemie is op rotsagtige en sanderige kusse en in marinas gemonitor. Temporele variasie is oorweeg op die skaal van daaglikse skommelinge, dae en maande in verskillende seisoene, terwyl ruimtelike variasie tussen vier plekke en tussen twee dieptes in marinas vasgelê is. Alle karbonaatchemie-parameters het tussen maande in verskillende seisoene gewissel, met verlaagde temperatuur, pH en aragonietversadiging, en verhoogde parsiële druk van koolstofdioksied en opgeloste anorganiese koolstof in die winter. Die lae vlakke van pH en baie lae aragonietversadiging (7.64 (± 0.14 SD ) en 0.5 (± 0.2 SD) onderskeidelik (in Saldanhabaai)) beklemtoon die kwesbaarheid van hierdie streek vir oseaanversuring. Ruimtelike veranderlikheid is gedryf deur verskille tussen plekke, wat die belangrikheid aandui om plaaslike toestande in ag te neem wanneer laboratoriumeksperimente ontwerp word wat die effekte van versuring bepaal. Ons begrip van reaksies op gemeenskapsvlak op die voorspelde veranderinge in toekomstige omgewings bly beperk. Bevuilende gemeenskappe vanaf Saldanhabaai en Tafelbaai was gebruik om die uitwerking van toekomstige verkoeling en versuring te bepaal. Gemeenskappe was vir 18 dae aan twee temperature (13 ℃ (stroom) en 9 ℃ (toekomstige verkoeling)) en drie pH-behandelings (7.9 (huidig), 7.6 en 7.4) blootgestel. Versuring was meer nadelig vir die bevuiling van gemeenskappe as afkoeling, wat gelei het tot veranderde gemeenskapstruktuur en verminderde diversiteit, veral by 7.4 pH. Dalende pH het die oorvloed van beide verkalkende en sagte liggaamstaksa verminder, wat die kwesbaarheid van taksa soos ascidiane vir versuring toon. Hierdie bevindinge beklemtoon dat verlaagde pH langs die verkoelende weskus 'n groter bedreiging vir bevuiling van gemeenskappe sal wees as veranderde temperature. Reaksies op versuring kan lewensfasespesifiek wees en gemoduleer word deur temperatuur en energiekonteks. Om te verstaan hoe gepaardgaande veranderinge in temperatuur en voedselvoorsiening, tesame met ontogenie die verdraagsaamheid van bevuilende biota vir dalende pH, jeugdiges en volwassenes van die koloniale ascidians Diplosoma listerianum, Botryllus schlosseri en Botryllus gregalis, sowel as die eensame seevaas Ciona robusta was aan twee temperature (13℃ en 9℃) blootgestel, waarby twee voedselvlakke (onbeperkte en beperkte voedselvoorraad) ondersoek is. Jeugdiges was minder verdraagsaam teenoor suur toestande as volwassenes. Veral, ongeag ontogenie of spesie, het verkoeling en beperkte voedselvoorsiening additief die toleransie van ascidiane tot lae pH verminder. Hierdie resultate dui daarop dat afkoeling langs die weskus die effek van dalende pH op ascidiane kan versterk, veral in die jeugdige stadium. Hierdie effek kan egter gebuffer word deur verrykte voedselvoorsiening gedurende periodes van hoë produktiwiteit langs hierdie kus. Doctoral 2023-01-22T16:39:13Z 2023-08-30T13:05:33Z 2023-01-22 2023-01-22T16:39:13Z 2023-08-31T09:18:31Z 2023-01-22T16:39:13Z 2023-08-31T09:18:31Z 2023-03 Thesis https://scholar.sun.ac.za/handle/10019.1/128373 en Stellenbosch University application/pdf vii, 117 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Ocean acidification -- South Africa -- Western Cape West Coast(South Africa) -- Environmental conditions Fouling -- Environmental aspects -- South Africa -- Western Cape Climatic changes -- West Coast(South Africa) Marine ecology -- South Africa -- Saldanha Bay Saldanha Bay (South Africa) -- Environmental conditions UCTD Matikinca, Phikolomzi The implications of a changing environment for fouling biota |
| title | The implications of a changing environment for fouling biota |
| title_full | The implications of a changing environment for fouling biota |
| title_fullStr | The implications of a changing environment for fouling biota |
| title_full_unstemmed | The implications of a changing environment for fouling biota |
| title_short | The implications of a changing environment for fouling biota |
| title_sort | implications of a changing environment for fouling biota |
| topic | Ocean acidification -- South Africa -- Western Cape West Coast(South Africa) -- Environmental conditions Fouling -- Environmental aspects -- South Africa -- Western Cape Climatic changes -- West Coast(South Africa) Marine ecology -- South Africa -- Saldanha Bay Saldanha Bay (South Africa) -- Environmental conditions UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/128373 |
| work_keys_str_mv | AT matikincaphikolomzi theimplicationsofachangingenvironmentforfoulingbiota AT matikincaphikolomzi implicationsofachangingenvironmentforfoulingbiota |