Isotopic Logs of The Sea of Cortez: Oxygen and Carbon Stable Isotopes in Otoliths of Marine Fish Record the Impact of Diverting the Colorado River from the Sea

Persistent Link:
http://hdl.handle.net/10150/194512
Title:
Isotopic Logs of The Sea of Cortez: Oxygen and Carbon Stable Isotopes in Otoliths of Marine Fish Record the Impact of Diverting the Colorado River from the Sea
Author:
Rowell, Kirsten
Issue Date:
2006
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
I use microchemistry in fish otoliths to test the hypothesis that diverting Colorado River flow from reaching the Gulf of California has impacted two endemic fish: the threatened gulf Corvina, (Cynoscion othonopterus) and the endangered totoaba (Totoaba macdonaldi). The oxygen and carbon stable isotope ratios in otoliths help to reconstruct conditions of the environment during key life history stages before and after the damming and diverting the Colorado River. The δ¹⁸O in otoliths illustrate that both C. othonopterus and T. macdonaldi seek out brackish habitat provided by the Colorado River during their early life history. The δ¹⁸O of C. othonopterus otolith have a strong negative correlation with Colorado River flow. I found that previously published relationships between otolith δ¹⁸O and ambient temperature along with δ¹⁸O of the water are sufficient to predict ranges of expected δ¹⁸O values for T. macdonaldi in the field. The δ¹⁸O in pre-dam T. macdonaldi otoliths show significant divergence from modern T. macdonaldi otoliths’ values, indicating that these fish used the brackish waters of the Colorado River estuary. The δ¹³C in T. macdonaldi otoliths has a significant proportion of its δ¹³C derived from diet. Pre-dam T. macdonaldi juveniles have a significantly different diet, which reflects that the Colorado River estuary had higher productivity before diversion of the river. Lastly, T. macdonaldi grew faster before the dams and in association with Colorado River flow measured by the δ¹⁸O.
Type:
text; Electronic Dissertation
Keywords:
Gulf of California; Colorado River; totoaba; corvina; estuary; otoliths; isotope
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Geosciences; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Flessa, Karl W.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleIsotopic Logs of The Sea of Cortez: Oxygen and Carbon Stable Isotopes in Otoliths of Marine Fish Record the Impact of Diverting the Colorado River from the Seaen_US
dc.creatorRowell, Kirstenen_US
dc.contributor.authorRowell, Kirstenen_US
dc.date.issued2006en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractI use microchemistry in fish otoliths to test the hypothesis that diverting Colorado River flow from reaching the Gulf of California has impacted two endemic fish: the threatened gulf Corvina, (Cynoscion othonopterus) and the endangered totoaba (Totoaba macdonaldi). The oxygen and carbon stable isotope ratios in otoliths help to reconstruct conditions of the environment during key life history stages before and after the damming and diverting the Colorado River. The δ¹⁸O in otoliths illustrate that both C. othonopterus and T. macdonaldi seek out brackish habitat provided by the Colorado River during their early life history. The δ¹⁸O of C. othonopterus otolith have a strong negative correlation with Colorado River flow. I found that previously published relationships between otolith δ¹⁸O and ambient temperature along with δ¹⁸O of the water are sufficient to predict ranges of expected δ¹⁸O values for T. macdonaldi in the field. The δ¹⁸O in pre-dam T. macdonaldi otoliths show significant divergence from modern T. macdonaldi otoliths’ values, indicating that these fish used the brackish waters of the Colorado River estuary. The δ¹³C in T. macdonaldi otoliths has a significant proportion of its δ¹³C derived from diet. Pre-dam T. macdonaldi juveniles have a significantly different diet, which reflects that the Colorado River estuary had higher productivity before diversion of the river. Lastly, T. macdonaldi grew faster before the dams and in association with Colorado River flow measured by the δ¹⁸O.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectGulf of Californiaen_US
dc.subjectColorado Riveren_US
dc.subjecttotoabaen_US
dc.subjectcorvinaen_US
dc.subjectestuaryen_US
dc.subjectotolithsen_US
dc.subjectisotopeen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGeosciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairFlessa, Karl W.en_US
dc.contributor.committeememberFlessa, Karl W.en_US
dc.contributor.committeememberDettman, David L.en_US
dc.contributor.committeememberGerber, Leahen_US
dc.contributor.committeememberGlenn, Eden_US
dc.contributor.committeememberReinthal, Peteren_US
dc.identifier.proquest1679en_US
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