Dissertations / Theses on the topic 'Chondrichtyan'
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Crawford, Callie Hendricks. "Skeletal anatomy in the chondrichthyan tree of life." Thesis, College of Charleston, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1585540.
Full textChondrichthyans (sharks, rays, skates, and chimaeras) are a diverse taxonomic clade inhabiting bodies of water all over the world. As a lineage, chondrichthyans split from the other jawed vertebrates 450 million years ago, the most basal split in the gnathostome vertebrate tree. Although they have been studied for centuries, knowledge about these animals lags behind that of many other vertebrate groups. This work uses Computed Tomography (CT) to explore morphological variation across phylogenetically diverse species of chondrichthyans. CT imaging is a nondestructive method for viewing internal structures of extant and fossilized specimens. After CT scan data acquisition, reconstruction software was used to manually segment the skeletal anatomical into constituent structures, creating 3-Dimensional representations of the structures. In most groups of vertebrate organisms, skeletal structures are made of calcified bone which has high radiopacity, leading to greater contrast between the skeleton and soft tissues. Chondrichthyans, by comparison, have skeletons composed of cartilage which is much less radiopaque than bone, resulting in lower contrast with surrounding tissues. Variations in the skeletal structures are discussed along with notes on calcification within the chondrichthyan orders. This work is presented as a summary of the variation observed in the skeletal anatomy, building upon previous works in chondrichthyan anatomy, expanding the current state of knowledge of the diversity in chondrichthyan fish skeletons. This project is part of a collaborative effort to develop a phylogenetic tree of life for modern chondrichthyans.
Cotton, Charles F. "Age, growth, and reproductive biology of deep-water chondrichthyans." W&M ScholarWorks, 2010. https://scholarworks.wm.edu/etd/1539791561.
Full textHansen, Michael C. "Microscopic chondrichthyan remains from Pennsylvanian marine rocks of Ohio and adjacent areas /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487266011222677.
Full textau, wwhite@murdoch edu, and William Toby White. "Aspects of the biology of elasmobranchs in a subtropical embayment in Western Australia and of chondrichthyan fisheries in Indonesia." Murdoch University, 2003. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20040510.154948.
Full textKoot, Martha Beatrijs. "Effects of the Late Permian mass extinction on Chondrichthyan palaeobiodiversity and distribution patterns." Thesis, University of Plymouth, 2013. http://hdl.handle.net/10026.1/1584.
Full textWatson, Ralph Gareth Andrew. "Baited remote underwater survey of chondrichthyans in False Bay, South Africa." Master's thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/14022.
Full textCrozier, Paul. "The impact of fishing on populations of deep-water chondrichthyan fishes of the northeast Atlantic." Thesis, Open University, 2006. https://pure.uhi.ac.uk/portal/en/studentthesis/the-impact-of-fishing-on-populations-of-deepwater-chondrichthyan-fishes-of-the-northeast-atlantic(f2c996d4-ebfe-41b3-8577-f438e8417de6).html.
Full textHoenig, Matthew Michael James. "Chondrichthyan Diversity within the Burlington-Keokuk Fish Bed of Southeast Iowa and Northwest Illinois (Mississippian: Osagean)." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1567706794231779.
Full textOliveira, Carlos. "Exploring the physiological variables of oxygen isotope composition in chondrychthyan teeth." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-395647.
Full textPethybridge, Heidi. "Ecology and physiology of deepwater chondrichthyans off southeast Australia : mercury, stable isotope and lipid analysis." Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14050/document.
Full textAnalyse de spéciation a montré que le mercure est présent à plus de 91 % sous forme de MeHg, et même avec des taux supérieurs à 95 % chez les espèces des environnements les plus profonds. Les concentrations maximales en THg ont été trouvés dans les tissus musculaires (59 à 82 % de charge corporelle). Les reins et le foie possèdent aussi des taux élevés, respectivement de 0,3 à 4,2 et 0,5 à 1,5 mg kg-1 (ph), tandis que la peau enregistre les concentrations les plus faibles (> 0,3 mg kg-1, ph). Cette étude de l’organotropisme permet de conclure que les reins et le foie sont associés au métabolisme du métal, à l'élimination et au stockage à court terme, alors que le muscle est le sites le plus important du stockage du mercure à long terme. Les isotopes stables de carbone et d’azote ont été utilisés pour évaluer l'influence de la position trophique (d15N) et de la source de carbone (d13C) sur l'accumulation du THg chez les chondrichthiens. Le d15N varie entre 12,4 à 16,6 ‰ démontrant la large gamme de positions trophiques occupées par ces espèces. La variation interspécifique du d13C est quant à elle minimale (–18,7 à –17,1 ‰). Les concentrations en mercure notées chez la plupart des requins augmentent en fonction de la taille, de la position trophique (d15N) et du stade de maturité de l’animal. Dans la communauté des chondrichthiens des profondeurs on observe des taux modérés de bioamplification du mercure, ceci est révélé par la faible pente de la relation, log (THg mg kg-1 ww) = 0,2 (d15N) – 2,4 (R2 = 0,35 ; P <0,05). Le THg et les acides gras de 61 espèces appartenant aux niveaux trophiques intermédiaires ont été analysés dans le but d’étudier les régimes alimentaires des proies et la bioaccumulation de ce métal à travers la chaîne alimentaire démersale. L'utilisation intégrée de ces techniques biochimiques a fourni des données fondamentales sur la reproduction, l'accumulation en mercure et l'écologie trophique des chondrichthiens des profondeurs. La compréhension de ces fonctions est impérative non seulement pour la mise en place d’une gestion durable des pêcheries, mais aussi pour la protection des habitats des chondrichthiens et leurs écosystèmes associés
For most deepwater chondrichthyans, fisheries and conservation management is problematic, largely due to the lack of scientific data resulting from inherent logistical challenges working within deep-sea environments. Furthermore, many conventional analytical techniques (stomach content analysis and morphometrics) require large sample sizes and are often quantitatively inadequate. Thus, new and more robust methods requiring fewer specimens are needed. Biochemical ‘tracer’ techniques are increasingly being used to resolve complex ecological and biological questions at individual species and population levels. This research explored the integrated use of multiple biochemical techniques (lipid and fatty acid profiling, stable nitrogen and carbon isotope and mercury analysis) to understand aspects of the reproduction, feeding ecology, metal accumulation and physiology of deepwater chondrichthyans. Most were from the Order Squaliformes. Other species include those from the Families: Chimaeridae, Rhinochimaeridae, Scyliorhinidae and Hexanchidae. All specimens were caught as fisheries bycatch from the continental slope waters off southeast Australia. The examination of lipid composition and partitioning revealed that deepwater chondrichthyans have large, lipid rich (38–70 % wet weight, ww) livers high in neutral lipids and monounsaturated fatty acids. Liver is a multifunctional tissue, playing a vital role in lipid distribution and biosynthesis, buoyancy regulation and storage. In contrast, muscle is a structural organ, low in lipid (<2 %) and consisting primarily of polar lipids. Lipid composition of kidney and pancreas show that they, too, have complex roles in lipid metabolism and storage. Lipid analysis of reproductive tissues revealed high maternal investment in deepwater chondrichthyans as indicated by high lipid content in mature pre-ovulated ovarian follicles (18–34 %). Variable levels of triacylglycerols (8–48 %), diacylglyceryl ethers (0.2–28 %) and wax esters (0.5–20 %) were observed in all specimens, demonstrating the use of multiple lipid classes to fuel embryonic development. The maternal provisions differed between oviparous and viviparous species and between elasmobranchs and holocephalans. Greater lipid investment was displayed by sharks living in deeper environments, suggesting lower fecundity and increased vulnerability to fishing. Diet was examined by complementary lipid biomarker and traditional stomach content techniques. A total of 41 prey taxa were identified using stomach content analysis and consisted mainly of bathyal-demersal fish and cephalopods. Using multidimensional scaling analysis, the extent of variability in composition within each species was determined by grouping the signature fatty acid profiles of shark tissues with profiles for demersal fish, squid and crustaceans. Both techniques showed that deepwater chondrichthyans are opportunistic predators, and that there is some degree of specialisation and overlap between them. Total (THg) and inorganic (monomethyl, MeHg) mercury concentrations and tissue distribution were examined to determine the extent of biomagnification and evaluate levels for human consumption. Mean THg levels for most species were above the regulatory threshold (>0.1 mg kg-1 ww) and levels as high as 6.6 mg kg-1 ww were recorded. Speciation analysis demonstrated that 91% mercury was bound as MeHg with higher percentages (>95%) observed in species occupying deeper environments. Higher levels of THg were stored in muscle which accounted for between 59–82% of the total body burden of mercury. High levels were also found in kidney (0.3–4.2 mg kg-1 ww) and liver (0.5–1.5) with lower levels observed in skin (>0.3). Both the kidney and liver are likely to be associated in metal metabolism, short term storage and elimination procedures, while the muscle is the major site for long term storage. Stable isotopes were used as natural dietary tracers, to further evaluate dietary relationships and to assess the influence of trophic position (d15N) and carbon sources (d13C) on THg accumu
lation. Isotopic nitrogen (d15N) values ranged from 12.4 to 16.6 ‰ demonstrating a broad range of trophic positions. Minor variation in carbon (d13C) enrichment was observed between species (–18.7 to –17.1‰). In most shark species, mercury concentrations increased with size, trophic position (d15N), and maturity stage, but not between location or collection period. As a community, deepwater sharks demonstrated moderate rates of THg biomagnification, as indicated by the regression slope (log (THg) = 0.2 d15N – 2.4, R2 = 0·35, P < 0·05). THg and fatty acid analyses of 61 mid-trophic species were measured for their usage in studies of diet in high-order predators and mercury bioaccumulation in the extended demersal food chain. The integrated use of these biochemical techniques has provided fundamental data on the reproduction, metal accumulation and trophic ecology of deepwater chondrichthyans. Understanding these parameters is imperative not only for the implementation of sustainable management but for habitat protection of deepwater chondrichthyans and their associated ecosystems
White, William T. "Aspects of the biology of elasmobranchs in a subtropical embayment in Western Australia and of chondrichthyan fisheries in Indonesia /." Access via Murdoch University Digital Theses Project, 2003. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20040510.154948.
Full textWhite, William Toby. "Aspects of the biology of elasmobranchs in a subtropical embayment in Western Australia and of chondrichthyan fisheries in Indonesia." Thesis, White, William Toby (2003) Aspects of the biology of elasmobranchs in a subtropical embayment in Western Australia and of chondrichthyan fisheries in Indonesia. PhD thesis, Murdoch University, 2003. https://researchrepository.murdoch.edu.au/id/eprint/402/.
Full textWhite, William Toby. "Aspects of the biology of elasmobranchs in a subtropical embayment in Western Australia and of chondrichthyan fisheries in Indonesia." White, William Toby (2003) Aspects of the biology of elasmobranchs in a subtropical embayment in Western Australia and of chondrichthyan fisheries in Indonesia. PhD thesis, Murdoch University, 2003. http://researchrepository.murdoch.edu.au/402/.
Full textBest, Lauren Nicole. "The historical exploitation of chondrichthyans in False Bay, South Africa and assessment of their conservation status." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/12085.
Full textIncludes bibliographical references.
Commercial fishing in False Bay, South Africa, began in the 1600s. Today chondrichthyans are regularly taken in multiple fisheries throughout the Bay. Using time series data and life history information I assessed the vulnerability of chondrichthyans to exploitation in False Bay. Extensive time series from five fishing methods, between 1897 and 2011, enabled catch trend analyses for chondrichthyans as a whole as well as for specific species. Commercial linefish, beach seine, and recreational angling provided the best source of data because they cover the range of habitats found in the Bay and are the least selective methods.
Best, Lauren Nicole. "The historical exploitation of chondrichthyans in False Bay, South Africa and assessment of their conservation status." Master's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/12085.
Full textIncludes bibliographical references.
Commercial fishing in False Bay, South Africa, began in the 1600s. Today chondrichthyans are regularly taken in multiple fisheries throughout the Bay. Using time series data and life history information I assessed the vulnerability of chondrichthyans to exploitation in False Bay. Extensive time series from five fishing methods, between 1897 and 2011, enabled catch trend analyses for chondrichthyans as a whole as well as for specific species. Commercial linefish, beach seine, and recreational angling provided the best source of data because they cover the range of habitats found in the Bay and are the least selective methods.
Mussgnug, Robert Sebastian. "An assessment of the long-term changes in chondrichthyan abundance on the inshore trawl grounds of the Agulhas Bank, South Africa." Master's thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/14017.
Full textEnault, Sébastien. "Évolution et diversité des structures minéralisées chez les sélaciens : approche paléo-développementale." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS234/document.
Full textChondrichthyans exhibit a number of interesting features which make them valuable organisms to investigate from an evo-devo perspective. However, due to their cartilaginous skeleton, isolated teeth are usually the only available fossil material to reconstruct their evolutionary history. Their teeth are covered by enameloid, a hypermineralized tissue whose microstructure has proven a useful taxonomic tool to differentiate between modern forms (neoselachians) and their extinct relatives. However it is poorly known in several groups, thus casting doubts on the validity of such characters.In this work, I first describe the enameloid microstructure of batoids based on an extensive sampling of both their extant and extinct diversity. I highlight unexpected diversity in the microstructural organization of enameloid which was thought to be very stable in neoselachians. The developmental basis for this diversity was then investigated in two extant chondrichthyan models through classic histological techniques and in situ hybridization. The results highlight differences in their enameloid organic matrix, as well as important differences with enameloid formation in osteichthyans, casting doubts on the homology of the two tissues. Finally I investigate skeletogenesis in the lesser spotted catshark from both a morphological and molecular perspective. Using X-Ray microtomography and in situ hybridization, I highlight both the mineralization sequence of the cartilaginous skeleton and the molecular context in which it calcifies over the course of embryonic development. I find that skeletal calcification in chondrichthyans appears to be much more versatile than in osteichthyans
Deynat, Pascal. "Applications de l'etude du revetement cutane des chondrichtyens a la systematique taxinomique et phylogenetique des pristiformes et rajiformes sensu compagno, 1973 (elasmobranchii, batoidea)." Paris 7, 1996. http://www.theses.fr/1996PA077354.
Full textLteif, Myriam. "Biology, distribution and diversity of cartilaginous fish species along the Lebanese coast, eastern Mediterranean." Thesis, Perpignan, 2015. http://www.theses.fr/2015PERP0026/document.
Full textThe aim of this study is to contribute to a better knowledge of cartilaginous fish in the Lebanese coastal waters, Eastern Mediterranean. Emphasis was placed on various aspects of the distribution, diversity, biology and ecology of these species. In this study, a total of 314 specimens of cartilaginous fish were sampled. These specimens constituted of 25 cartilaginousfish species, 11 shark species and 14 batoid species. No chimaeras were recorded. The data was collected from two sources: (a) an experimental survey in the framework of the CIHEAM PESCA-Libano project and (b) periodic observation of fisheries and catches of hired fishermen. Spatiotemporal distribution was evaluated using the Catch Per Unit Effort of the experimental survey data. Spatiotemporal diversity was also estimated taking into account the total number of species caught in the survey and fisheries/fishermen data. Length-weight relationships for three sharks and five batoids were also presented for species of the combined data sources having more than 10 individuals. Finally, the biology and ecology of two commercially significant and exploited species were also presented as a first step in their fishery management andconservation
Izzo, Christopher. "Patterns of telomere length change with age in aquatic vertebrates and the phylogenetic distribution of the pattern among jawed vertebrates." Thesis, 2010. http://hdl.handle.net/2440/63477.
Full textThesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2010
Deets, Gregory B. "Copepod-chondrichthyan coevolution : a cladistic consideration." Thesis, 1995. http://hdl.handle.net/2429/8770.
Full textOsgood, Geoffrey J. "Chondrichthyan conservation in marine protected areas: elucidating species associations in two chondrichthyan hotspots using non-invasive techniques." Thesis, 2020. http://hdl.handle.net/1828/11775.
Full textGraduate
2021-05-08
Rigby, Cassandra Louise. "Life histories of deepwater chondrichthyans." Thesis, 2015. https://researchonline.jcu.edu.au/46298/7/46298-rigby-2015-thesis.pdf.
Full text"Origin, Form, and Function of Follicle Cell Processes in Chondrichthyan Fishes." Tulane University, 2020.
Find full textIn this dissertation, I characterize the origins, phylogenetic distribution, and function of Follicle Cell Processes (FCP) in Class Chondrichthyes. FCP are actin associated tubes that have been detected in the intercellular space between a developing oocyte and the surrounding follicle cells in chondrichthyan fishes. Using light microscopy, I describe the presence FCP in Hydrolagus colliei, a species of Subclass Holocephali, a divergent lineage at the base of the chondrichthyan phylogeny. FCP were also detected in species representing six of nine studied orders of Subclass Elasmobranchii, the sister group of holocephalans, but absent in three examined batoid orders. To establish the role FCP play in vitellogenesis - the process of providing yolk to developing oocytes - I performed fluorescent microscopy, staining specifically for myosin, an actin-associated transport protein previously identified in vitellogenic oocytes. The detection of myosin in oocytes during vitellogenesis and its association with actin in FCP are inconclusive. I performed RNA sequencing on follicles and ovarian tissues from Mustelus sinusmexicanis, using Illumina Hi-Seq 4000 profiling with the specific aim of identifying the types of myosins and actins involved in yolk transport. Three (MYH9, MYH10, and MYO5A) of particular interest and one actin (ACTG1L) were differentially expressed in the tissues. MYO5A is a class V myosin that has been associated with cytoplasmic vesicle transport, though it is most abundant in melanocytes and nerve cells. MYH9 and MYH10 are membrane associated non-muscle class II myosin paralogs, and MYH9 was upregulated in the ovarian tissues; MYH10 was upregulated in the corresponding follicle tissues. ACTG1L, the only actin transcript differentially expressed codes for a gamma actin isoform involved in internal cell mobility.
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Lydia Crawford
Vaughan, David Brendan. "Review of South African genera of the family hexabothriidae price, 1942, parasites of chondrichthyan fishes." 2009. http://hdl.handle.net/11394/3171.
Full textThe oligonchoinean monogenean family Hexabothriidae Price, 1942 currently consists of approximately 60 valid species, representing 15 genera. Hexabothriids are gill parasites of chondrichthyan fishes (sharks, rays and chimaeras). Some hexabothriid species have been reported as problematic in public aquaria, directly responsible for host pathology and subsequent host mortalities. However, without information on specific hexabothriid species and their host associations, accurate captive management of hexabothriids in public aquaria is hindered. Hexabothriid taxonomy is in a state of confusion. The historic taxonomic restoration of the priority of Hexabothrium sees the beginning of the taxonomic uncertainty of the hexabothriids, and is continued into the present literature particularly among lower-level taxa in Hexabothriidae. In addition, there is currently no consensus for a single accepted morphometric protocol for the discrimination of hexabothriid taxa, which leads to unnecessary ambiguity of character variable nomenclature, measurement and interpretation. A call for stability in the nomenclature and morphometric discrimination of species is therefore proposed. A novel morphometric protocol is tested for the sclerotised haptoral armature, supported by the proteolytic digestion of structures for optimal representation. Character variables, subjected to univariate and multivariate analyses were systematically accepted or rejected based on their potential to discriminating species of Callorhynchocotyle Suriano and Incorvaia, 1986. The hexabothriid genera Callorhynchocotyle and Branchotenthes, represented by South African taxa, are reviewed, using these variables. Four Callorhynchocotyle species and 2 Branchotenthes species are redescribed with the inclusion of some new voucher specimens.
Claeson, Kerin Michele. "Trends in evolutionary morphology : a case study in the relationships of angel sharks and batoid fishes." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-05-1347.
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