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Understanding reproduction and energy storage, for broodstock conditioning, in Mytilus galloprovincialis

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Fearman, J (2010) Understanding reproduction and energy storage, for broodstock conditioning, in Mytilus galloprovincialis. PhD thesis, University of Tasmania.

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Abstract

Synchronous seasonal reproduction in Mytilus galloprovincialis has been
well documented, however asynchronous reproduction is also observed in many
populations. These reproductive events occur at different times of year, and therefore
under different environmental conditions. Experimental evidence regarding the
influence of environmental parameters, such as temperature and food, on
reproduction and energy storage in this species is limited. Therefore, this research
aimed to determine the important environmental conditions that influence the timing
and rate of reproductive maturation in relation to energy storage and use in mussels,
which can be used for broodstock conditioning in the mussel aquaculture industry.
Monthly samples of the population were collected over two years, and the
timing and rate of maturation and energy storage was different between years and at
different depths. Mussels used energy from food for reproduction in 2006, and used
stored energy (glycogen) for reproduction in 2007. The use of these different
reproductive strategies was potentially influenced by differences in temperature and
food (phytoplankton concentration).
Diet composition was tested for its effect on reproduction and energy storage.
Mussels were able to spawn more readily when fed a combination of Chaetoceros
calcitrans and Pavlova lutheri. A monospecific diet of Pavlova lutheri provided
PUFAs necessary for maturation, but may have provided less energy; and
Chaetoceros calcitrans provided sufficient energy, which increased glycogen
storage, but may have been limited in PUFAs.
The effects of temperature and ration were also tested, and the rate of
maturation was fastest at 7°C and reduced in warmer water, up to 19°C, when held at
constant temperature. When held in temperatures that mimicked seasonal
temperature changes in spring, summer and autumn, mussels produced oocytes and
stored energy during summer, but during autumn production of oocytes was greater
and stored glycogen was depleted. Mussels fed a higher ration in this experiment
allocated greater amounts of energy to storage or energy demands, but oocytes were
not increased, which suggests that temperature rather than ration regulates
reproductive maturation.
The effects of food and temperature may be synergistic during seasonal
cycles of reproduction. Reproduction appears to be prioritised over energy storage in
mussels, which should result in year round reproduction in this species if energy
(food or glycogen) is not a limiting factor. However warmer seasonal temperatures
limit reproduction, therefore available energy is stored as glycogen. This information
can be used to control the rate and timing of maturation of broodstock in a hatchery.

Item Type: Thesis (PhD)
Copyright Holders: The Author
Copyright Information:

Copyright 2010 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
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Additional Information:

Available for use in the Library and copying in accordance with the Copyright Act 1968, as amended. Thesis (PhD)--University of Tasmania, 2010. Includes bibliographical references

Date Deposited: 09 Dec 2014 00:14
Last Modified: 16 Feb 2017 00:24
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