File Download
  Links for fulltext
     (May Require Subscription)
Supplementary

postgraduate thesis: Corals in a variable physical environment : impacts on growth and the [delta]¹¹B pH-proxy

TitleCorals in a variable physical environment : impacts on growth and the [delta]¹¹B pH-proxy
Authors
Issue Date2013
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Yang, T. T. [杨婷婷]. (2013). Corals in a variable physical environment : impacts on growth and the [delta]¹¹B pH-proxy. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5223959
AbstractCoral reefs are important to sustain marine ecosystems and provide a reliable resource for studying past climate. Corals are increasingly challenged by changing environments. The marginal corals of Hong Kong provide a natural laboratory to study the combination of environmental conditions controlling coral distribution and growth. Salinity and pH were found to impact corals in studies of coral distribution, extension, and culture. Hong Kong corals have low extension rates (1.2-11.4 mm/yr) and do not colonize in areas of low in salinity and pH. Ten years of instrumental records showed extension related positively to summer salinity and dissolved oxygen. Winter seawater temperature was inversely related to extension, while chlorophyll a showed positive relationship in autumn and winter. Culture results show low salinity negatively impacted coral calcification, photosynthesis, and extension. Corals exhibited reduced growth, paling and bleached. In contrast, coral growth increased under high pCO2, but corals decalcified in dark indicating underlying mechanisms may be altering coral physiology. The boron isotope (δ11B) proxy in corals is able to reconstruct past seawater pH when the pH of the extracellular calcifying fluid (ECF) is considered. A pH offset (ΔpH) was recorded in reconstructed pHsw due to ion pumping to ensure the ECF is saturated with respect to aragonite. By incorporating carbon isotopes (δ13C) into the δ11B-ΔpH relationship, δ11B can be corrected to remove ECF processes and reconstruct seawater pH. Culture results indicated δ11Baxial from axial tip recorded pH similar to other studies while low salinity impacted δ11Bbasal at the base. The different relationship shown from the same colony within the same cultured conditions suggested vital effects with differing coral metabolisms. δ11Baxial and δ11Bbasal related to extension but insignificantly. The large isotopic offset between δ11Baxial and δ11Bbasal indicated different growth mechanisms could possibly affected boron incorporation. The δ11B variation within a coral colony suggested careful and precise sampling for pH reconstructions is important.
DegreeDoctor of Philosophy
SubjectCorals - Effect of water acidification on - China - Hong Kong
Dept/ProgramEarth Sciences
Persistent Identifierhttp://hdl.handle.net/10722/209621

 

DC FieldValueLanguage
dc.contributor.authorYang, Teng Teng-
dc.contributor.author杨婷婷-
dc.date.accessioned2015-05-08T23:12:56Z-
dc.date.available2015-05-08T23:12:56Z-
dc.date.issued2013-
dc.identifier.citationYang, T. T. [杨婷婷]. (2013). Corals in a variable physical environment : impacts on growth and the [delta]¹¹B pH-proxy. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5223959-
dc.identifier.urihttp://hdl.handle.net/10722/209621-
dc.description.abstractCoral reefs are important to sustain marine ecosystems and provide a reliable resource for studying past climate. Corals are increasingly challenged by changing environments. The marginal corals of Hong Kong provide a natural laboratory to study the combination of environmental conditions controlling coral distribution and growth. Salinity and pH were found to impact corals in studies of coral distribution, extension, and culture. Hong Kong corals have low extension rates (1.2-11.4 mm/yr) and do not colonize in areas of low in salinity and pH. Ten years of instrumental records showed extension related positively to summer salinity and dissolved oxygen. Winter seawater temperature was inversely related to extension, while chlorophyll a showed positive relationship in autumn and winter. Culture results show low salinity negatively impacted coral calcification, photosynthesis, and extension. Corals exhibited reduced growth, paling and bleached. In contrast, coral growth increased under high pCO2, but corals decalcified in dark indicating underlying mechanisms may be altering coral physiology. The boron isotope (δ11B) proxy in corals is able to reconstruct past seawater pH when the pH of the extracellular calcifying fluid (ECF) is considered. A pH offset (ΔpH) was recorded in reconstructed pHsw due to ion pumping to ensure the ECF is saturated with respect to aragonite. By incorporating carbon isotopes (δ13C) into the δ11B-ΔpH relationship, δ11B can be corrected to remove ECF processes and reconstruct seawater pH. Culture results indicated δ11Baxial from axial tip recorded pH similar to other studies while low salinity impacted δ11Bbasal at the base. The different relationship shown from the same colony within the same cultured conditions suggested vital effects with differing coral metabolisms. δ11Baxial and δ11Bbasal related to extension but insignificantly. The large isotopic offset between δ11Baxial and δ11Bbasal indicated different growth mechanisms could possibly affected boron incorporation. The δ11B variation within a coral colony suggested careful and precise sampling for pH reconstructions is important.-
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.subject.lcshCorals - Effect of water acidification on - China - Hong Kong-
dc.titleCorals in a variable physical environment : impacts on growth and the [delta]¹¹B pH-proxy-
dc.typePG_Thesis-
dc.identifier.hkulb5223959-
dc.description.thesisnameDoctor of Philosophy-
dc.description.thesislevelDoctoral-
dc.description.thesisdisciplineEarth Sciences-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.5353/th_b5223959-

Export via OAI-PMH Interface in XML Formats


OR


Export to Other Non-XML Formats