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

Harris, JO 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.
EC$$_5$$ 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.I$$^{-1}$$), 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 NO$$_2$$-N.I$$^{-1}$$.
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.I$$^{-1}$$, 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 Harris, JO Abalones 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). Chapter 3 appears to be the equivalent of a pre-print version of an article published as: Harris, J. O., Maguire, G. B., Edwards, S. J., Hindrum, S. M., 1998. Effect of ammonia on growth rate and oxygen consumption for juvenile greenlip abalone, Haliotis laevigata Donovan. Aquaculture, 160(3-4), 259-272Chapter 5 appears to be the equivalent of a pre-print version of an article published as: Harris, J. O., Maguire, G. B., Edwards, S. J., Johns, D. R., 1999. Low dissolved oxygen reduces growth rate and oxygen consumption rate of juvenile greenlip abalone, Haliotis laevigata Donovan, Aquaculture, 174(3-4), 265-278 View statistics for this item