dc.contributor.advisor |
Babcock, Russ |
en |
dc.contributor.advisor |
Sewell, Mary |
en |
dc.contributor.author |
Morgan, Andrew David |
en |
dc.date.accessioned |
2007-12-06T06:59:05Z |
en |
dc.date.available |
2007-12-06T06:59:05Z |
en |
dc.date.issued |
2003 |
en |
dc.identifier |
THESIS 04-074 |
en |
dc.identifier.citation |
Thesis (PhD--Environmental and Marine Science)--University of Auckland, 2003 |
en |
dc.identifier.uri |
http://hdl.handle.net/2292/2213 |
en |
dc.description |
Full text is available to authenticated members of The University of Auckland only. |
en |
dc.description.abstract |
Major gaps existing in our knowledge of aspidochirote sea cucumber life history have impeded the development of commercial scale aquaculture and conservation of this group. Little is known about the regulation of gamete shedding and spawning or the causes of variation in larval developmental life history. The purpose of the present study was to quantify these in captivity using the sea cucumber stichopus mollis as a model animal.
The induction of spawning of S. mollis in captivity using thermal shock augmented spawning periodicity and was not successful when animals were not ready to spawn. Spawning of S. mollis occurred at dusk in the week following the full moon and early in the 3rd quarter. However, changes in the gonad index and the presence of shed gametes did not always indicate that animals were going to spawn. Broodstock with more mature non-shed gametes at the start of a 2-week period in captivity were more reliable spawners. A yellow coloured gonad in females and little movement of motile spermatozoa in wet mounts of mashed gonad tissue in males indicated animals coming into spawning condition. Oocyte germinal vesicle breakdown was greater in non-spawners than spawners after a 2-week period in captivity and may indicate spawning readiness. No difference between new (less than 1 week) and old (greater than 4 weeks) broodstock was observed.
S. mollis larvae were very susceptible to being overfed as full guts and high feeding regimes did not contribute to the successful completion of the larval cycle. Larvae in more optimal feeding regimes adjusted their size and shape during growth and development and completed the larval cycle. Larvae on low feeding regimes increased ciliated band length relative to other larval structures but their ability to complete the larval cycle was significantly reduced. The timing of appearance and number of hyaline spheres in the folds of the ciliated band in late auricularia larvae appeared to be related to differences in larval size rather than being solely related to food availability.
The ability to complete the larval cycle was related to the proportion of normally developing embryos, which in turn was correlated with egg numbers and egg size. Furthermore, the relationship between the size and shape of the larval gut and maternal origin was important and may contribute to successful completion of the larval cycle. This also appeared to be related to the appearance and number of hyaline spheres and the rate at which larvae metamorphosed. Larger larval guts relative to larval size may indicate superior larvae and better broodstock condition. These attributes could be used to select hardy strains of sea cucumber for aquaculture and further domesticate sea cucumber production. |
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dc.language.iso |
en |
en |
dc.publisher |
ResearchSpace@Auckland |
en |
dc.relation.ispartof |
PhD Thesis - University of Auckland |
en |
dc.relation.isreferencedby |
UoA99120161014002091 |
en |
dc.rights |
Restricted Item. Available to authenticated members of The University of Auckland. |
en |
dc.rights |
Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. |
en |
dc.rights.uri |
https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm |
en |
dc.title |
Variation in reproduction and development of the temperate sea cucumber Stichopus mollis |
en |
dc.type |
Thesis |
en |
thesis.degree.discipline |
Environmental and Marine Sciences |
en |
thesis.degree.grantor |
The University of Auckland |
en |
thesis.degree.level |
Doctoral |
en |
thesis.degree.name |
PhD |
en |
dc.rights.holder |
Copyright: The author |
en |
dc.identifier.wikidata |
Q112858855 |
|