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A study on the feeding of the pot-bellied seahorse (Hippocampus abdominalis : reducing the reliance on brine shrimp (Artemia)

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Wardley, TR (2006) A study on the feeding of the pot-bellied seahorse (Hippocampus abdominalis : reducing the reliance on brine shrimp (Artemia). PhD thesis, University of Tasmania.

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Abstract

The primary aim of this study is to reduce the reliance on Artemia during the
culture of pot-bellied seahorses. The results demonstrate that reliance can be
reduced significantly if not totally replaced. Early juvenile seahorses can be
fed on alternative live diets such as copepods as the growth (F = 0.054, df 1, p
> 0.05) and condition (F = 0.416, df 1, p > 0.05) of 3-week old seahorses fed
copepods was similar to those fed enriched Artemia. It was also found that
seahorses as young as newborns readily consumed copepods and gammarid
amphipods (Hippomedon sp and Biribus sp) from the biofouling panels. Later
juveniles can continue to be fed on biofouling crustaceans as the growth (F =
0.982, df 1, p > 0.05) and condition (F = 7.401, df 1, p < 0.05) of 17-week old
seahorses fed biofouling was similar to those fed Artemia or weaned onto
frozen diets.
The best predictor for determining prey size was the total length of the
seahorse. Based on Cheeson's standardised forage ratio the preferred prey type
of 5, 21 and 49 day old seahorses showed a particular preference for copepods
with 21 and 49 day old seahorses also positively selecting both amphipod
species (Hippomedon sp and Biribus sp). Larger 147 and 175-day old
seahorses positively selected both amphipod species and 203-day old
seahorses' positively selected Biribus sp and caprellids (Caprella sp).
Thirteen week old seahorses were weaned onto either a frozen mysid or
amphipod diet with a nil, 10 day and 16 day weaning period and it was found
that the growth of seahorses weaned onto frozen diets over a 16 day period had
similar growth (F = 83.922, df 7, p < 0.05) to those seahorses fed enriched
Artemia. It is possible that younger seahorses could be weaned onto frozen
diets if appropriate sized feeds can be attained. It was also found that although
a range of commercial enrichment diets had no affect on the growth (F = 0.671,
df 5, p > 0.05) and condition (F = 1.637, df 5, p > 0.05) of seahorses, Artemia
should be enriched as the liver condition in seahorses fed unenriched Artemia
was poor and the optimal feed rate for seahorses was between 5 and 7 % body
weight daf1 (F = 0.47, df 5, p < 0.05).
This study also examined the anatomy of the digestive system and ontogenetic
development of digestive enzymes to provide a better understanding of the potbellied
seahorses' nutritional requirements and digestive capacity. Seahorses
are released with a near fully developed digestive tract and could be said to be
fully developed between day 21 and 35 after the intestinal valve develops on
day 7 and the intestine starts to loop around itself on day 21. Trypsin, lipase
and amylase were present at every stage studied. The presence of enzymes in
unfed newborn seahorses indicates that they are capable of digesting protein,
lipid and carbohydrates prior to the onset of feeding, however the digestive
system may not be fully functional until around day 28 to 35 when enzyme
activities appeared to plateau. It was also found that trypsin and lipase
activities were greater than amylase activities indicating that seahorses rely
more heavily on protein and lipid than carbohydrate for their early nutrition.
Lastly a cost benefit analysis of alternative feed sources was prepared which
demonstrated that significant savings in costs can be achieved.

Item Type: Thesis (PhD)
Keywords: Sea horses, Sea horses, Sea horses
Copyright Holders: The Author
Copyright Information:

Copyright 2006 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 would be pleased to hear from the copyright owner(s).

Additional Information:

Available for library use only and copying in accordance with the Copyright Act 1968, as amended. Thesis (PhD)--University of Tasmania, 2006. Includes bibliographical references

Date Deposited: 04 Feb 2015 23:32
Last Modified: 11 Mar 2016 05:54
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