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Chronic effects of adverse water quality on the greenlip abalone, Haliotis laevigata Donovan

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Harris, James Owen (1999) Chronic effects of adverse water quality on the greenlip abalone, Haliotis laevigata Donovan. PhD thesis, University of Tasmania.

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Abstract

Bioassays were undertaken to assess the effects of ammonia, nitrite, dissolved oxygen
and pH on greenlip abalone, Haliotis laevigata. At the end of each chronic bioassay,
oxygen consumption, haemolymph ionic concentration and tissue microstructure were
documented, relative to toxicant concentration.
EC5 data (concentration causing a 5% growth reduction; whole wet body weight
unless stated) indicated that these abalone were very sensitive to elevated levels of
ammonia (0.041 mg FAN.1 -1 ), low dissolved oxygen (7.36 mg DO.l-1') and low (7.78)
and high (8.77) pH. Most of these variables affected shell growth relative to whole
body growth, indicating some independence of nett shell and soft tissue growth rates.
Greenlip abalone were also sensitive to nitrite on a growth basis. Modeling of the
whole weight data indicated relatively uniform growth depression regardless of
concentration in the range 0.56-7.80 mg NO2-N.1-1 .
The influence of nutritional history on the susceptibility of abalone to ammonia was
determined in an acute bioassay. The abalone had been maintained on either a mixture
of three commercial diets, or the same mixture treated at 110°C for two days. No
significant difference in mortality occurred between the two diet groups (p>0.05). At
1.025 mg FAN.1-1, an LT50 value of 125.3 h was estimated by probit analysis.
Oxygen consumption patterns were similar to growth trends (depressed consumption
per unit whole weight per unit time in slow growing groups) for nitrite, dissolved
oxygen and pH. However, oxygen consumption was elevated at higher ammonia
concentrations.
In general, tissue histology was a relatively insensitive indicator of growth rate
inhibition as structural changes were usually only pronounced at extreme
concentrations. Gill structure was affected by exposure to high nitrite and low
dissolved oxygen levels, with ciliates occurring between the gill lamellae of abalone
exposed to low dissolved oxygen. Kidney tissue exhibited changes from exposure to
ammonia and nitrite.
Haemolymph ionic patterns did not provide any apparent stress specific indicators of
growth depression. However, reduced haemolymph sodium and chloride
concentrations were found in abalone exposed to ammonia, and nitrite respectively.
In most chronic bioassays, control groups exposed to saturated seawater survived
well (>95%). Growth rates were progressively improved throughout the series of
bioassays by adding heaters and later, submersible pumps to increase current flow.
However, growth rates were depressed in the absence of within-tank aeration in the
dissolved oxygen bioassay

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

Copyright 1999 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:

Pocket contains 4 reprinted articles. Thesis (PhD )--University of Tasmania, 1999. Includes bibliographical references

Date Deposited: 09 Dec 2014 00:05
Last Modified: 03 Nov 2016 03:56
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