Physiological consequences of environmental contamination in an elasmobranch with matrotrophic histotrophy, the Round Stingray (Urobatis halleri)

Lyons, Katherine

Physiological consequences of environmental contamination in an elasmobranch with matrotrophic histotrophy, the Round Stingray (Urobatis halleri)

dc.contributor.advisor	Wynne-Edwards, Katherine
dc.contributor.author	Lyons, Katherine
dc.contributor.committeemember	Syme, Douglas
dc.contributor.committeemember	Cobb, John
dc.contributor.committeemember	Anderson, Gary
dc.contributor.committeemember	Smits, Judit
dc.date	2018-02-16
dc.date.accessioned	2018-01-25T19:03:51Z
dc.date.available	2018-01-25T19:03:51Z
dc.date.issued	2018-01-15
dc.description.abstract	A range of physiological biomarkers were compared in two populations of Round Stingray (Urobatis halleri) that differed primarily in PCB exposure. Females, and their embryos, were sampled each month of pregnancy at both sites, while adult males were matched with a 40-day subset of females to investigate the effect of sex and its interaction with PCB exposure. I hypothesized that exposure would have negative energetic outcomes for PCB-exposed, compared to reference population, stingrays. Adverse impacts were widespread. Number of offspring was not affected by PCB exposure; however, exposure exacerbated maternal tissue mass, and quality, loss during pregnancy. PCB-exposed females also compromised osmoregulation with urea, an important osmolyte, reduced in maternal plasma. Higher liver quality in contaminant-exposed females was not associated with higher embryo quality, suggesting contaminants increase metabolic demands in adult females and lead to inefficiencies in embryos’ use of maternal resources. Embryos also influenced their uterine environment, as they were steroidogenic and capable of osmoregulating very early in development. I found sex- related differences in embryo mass only at the reference site, suggesting that contaminant effects on males begin in utero. These contaminant sex-related effects extended into adulthood, as relative liver mass and energy content were lower in comparably-sized adult males than females, whereas fewer differences were found between adults at the reference site. Higher energy generation potential, combined with lower tissue quality in contaminant-exposed adult males suggests they are more energetically compromised than females, despite the latter’s costly pregnancy demands. Regardless of sex, contaminant exposure had negative impacts on the ability of adult stingrays to mount a robust secondary stress response as reflected by lower plasma glucose levels after stress, thus potentially impairing their ability to respond to acute stressors. Effects found both in utero and in adulthood suggest that contaminants have a significant, and potentially life-long, impact on Round Stingray homeostasis. This has implications for other species with greater contaminant burdens. Contaminant exposure, and its interactive effects with sex and age, should be included as part of effective elasmobranch management.	en_US
dc.identifier.citation	Lyons, K. (2018). Physiological consequences of environmental contamination in an elasmobranch with matrotrophic histotrophy, the Round Stingray (Urobatis halleri) (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.	en_US
dc.identifier.doi	http://dx.doi.org/10.11575/PRISM/5412
dc.identifier.uri	http://hdl.handle.net/1880/106331
dc.language.iso	en	en_US
dc.publisher.faculty	Science	en_US
dc.publisher.institution	University of Calgary	en
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.	en_US
dc.subject.classification	Biology	en_US
dc.title	Physiological consequences of environmental contamination in an elasmobranch with matrotrophic histotrophy, the Round Stingray (Urobatis halleri)	en_US
dc.type	doctoral thesis	en_US
thesis.degree.discipline	Biological Sciences	en_US
thesis.degree.grantor	University of Calgary	en_US
thesis.degree.name	Doctor of Philosophy (PhD)	en_US
ucalgary.item.requestcopy	true
ucalgary.thesis.checklist	I confirm that I have submitted all of the required forms to Faculty of Graduate Studies.	en_US