| dc.contributor.author | Hunt von Herbing, Ione de B. | en_US |
| dc.date.accessioned | 2014-10-21T12:36:12Z | |
| dc.date.available | 1994 | |
| dc.date.issued | 1994 | en_US |
| dc.identifier.other | AAINN93819 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/55426 | |
| dc.description | The physiological energetics of the early life history of Atlantic cod, Gadus morhua were investigated in laboratory studies for two genetically discrete populations (Newfoundland and Scotian Shelf), by integrating information from the fields of ecology, physiology and functional morphology. Laboratory studies were designed to simulate temperatures that eggs and larvae of different stocks experience in the ocean. Functional morphological landmarks important to feeding and respiration were derived from specimens treated by clearing and staining, histology, and scanning electron microscopy. These landmarks defined 12 developmental stages at two temperatures, 5$\sp\circ$C and 10$\sp\circ$C, from hatching to metamorphosis, in larval cod. Results showed that staging is a more accurate way of determining developmental state than days post-hatch or degree days. Staging of specific structures such as the jaw and alimentary canal illustrated that variation in structural complexity may be influenced by intrinsic (genetic) factors and/or extrinsic (environmental) factors. Detailed anatomical and functional analysis revealed that while the yolk-sac serves as a food resource, primary skeletal structures and mechanisms for feeding are simple and non-integrated and respiration is cutaneous. As ontogeny progresses, requirements for exogenous food are met by the development of new skeletal elements, ligaments and muscles. Together these changes allow increases in jaw coordination and suction pressure generation necessary for prey capture and eventually for branchial respiration. | en_US |
| dc.description | Landmarks and developmental stages were also used to mark major life history transitions in energy acquisition. At these transitions, changes occur in the allocation of finite energy resources between growth and activity metabolism. In addition, the energy allocated to growth and activity metabolism differed between populations. Larvae from the Newfoundland population were more cost-effective in conditions that reflected their native environment; these larvae appeared to be physiologically 'cold-adapted'. In contrast, larvae from the Scotian Shelf population appeared to be 'warm-adapted' but spent more energy on activity metabolism and less on growth at all temperatures. This suggests that the physiological energetics underlying the dynamics of production and survivorship are different between cod populations in Canada. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 1994. | en_US |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | | en_US |
| dc.subject | Biology, Zoology. | en_US |
| dc.subject | Agriculture, Fisheries and Aquaculture. | en_US |
| dc.title | Form, function and energetics of the early life history of Atlantic cod (Gadus morhua). | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
