Investigating the Immunology of Stressed Abalone (Haliotis Species)

Investigations on the immunology of stressed abalone R. Day, C. Hooper, K. Benkendorff, R. Slocombe and J. Handlinger Project No. 2004/233 1 Investigations on the immunology of stressed abalone Final report for FRDC project number: 2004/233 By Rob Day Zoology Department, University of Melbourne, Parkville 3010, Australia. Celia Hooper Zoology Department, University of Melbourne, Parkville 3010, Australia. Kirsten Benkendorff School of Biological Sciences, Flinders University, GPO BOX 2100, Adelaide, SA 5001, Australia. Ron Slocombe Faculty of Veterinary Science, University of Melbourne, Parkville, Vic. 3010, Australia. Judith Handlinger DPIWE Animal Health Laboratory, 165 Westbury Rd, Prospect, Tasmania 7250, Australia. April 2010 Published by The University of Melbourne ISBN 978-0-646-52921-9 Copyright Fisheries Research and Development Corporation and The University of Melbourne. 2010 This work is copyright. Except as permitted under the Copyright Act 1968 (Cth), no part of this publication may be reproduced by any process, electronic or otherwise, without the specific written permission of the copyright owners. Information may not be stored electronically in any form whatsoever without such permission. Disclaimer The authors do not warrant that the information in this document is free from errors or omissions. The authors do not accept any form of liability, be it contractual, tortious, or otherwise, for the contents of this document or for any consequences arising from its use or any reliance placed upon it. The information, opinions and advice contained in this document may not relate, or be relevant, to a readers particular circumstances. Opinions expressed by the authors are the individual opinions expressed by those persons and are not necessarily those of the publisher, research provider or the FRDC. The Fisheries Research and Development Corporation plans, invests in and manages fisheries research and development throughout Australia. It is a statutory authority within the portfolio of the federal Minister for Agriculture, Fisheries and Forestry, jointly funded by the Australian Government and the fishing industry. 2 CONTENTS: Non-Technical Summary 3 Acknowledgements 5 Background 6 Need 8 Objectives 9 Methods 10 Results and Discussion 20 Heat Stress - experiment and on-farm sampling, 2007 20 Heat Stress - long term experiment 32 Heat Stress – on-farm sampling, summer 2008 35 Discussion of heat stress experiments and monitoring 37 Stressors associated with stock movements 42 Discussion of stock movement stress effects 48 Benefits and Adoption 51 Further Development 52 Planned Outcomes 53 Conclusions 54 References 56 Appendix 1: Intellectual Property 64 Appendix 2: Staff 64 Appendix 3: A glossary of technical terms in this report 65 Appendix 4: A review of stress and immunity in abalone 70 NON-TECHNICAL SUMMARY 2004/233 Investigations on the immunology of stressed abalone PRINCIPAL INVESTIGATOR: Dr Rob Day ADDRESS: The University of Melbourne Department of Zoology Parkville, Vic. 3010 Telephone: 03 8344 6262 Fax: 03 8344 7909 OBJECTIVES: 1. To establish the most useful immunological parameters of abalone haemolymph (blood), and the best methods to use to assess immune function in abalone on abalone farms. 2. To determine the effects of a series of common on-farm stresses by monitoring the changes in immune function and histology (micro-structure of body tissues). 3. To establish a list of repeatable laboratory tests on abalone haemolymph and see if these indices correlate with the development of histological changes. OUTCOMES ACHIEVED TO DATE 1. A set of well-described tests that can be applied on farms is now available, to assess the immune status of abalone. These methods can be employed to compare different management procedures and how much stress they are likely to cause to their stock. 2. The project has led to a better understanding of the nature and effects of summer heat stress, and the stress that occurs during stock movements, as a result of experiments conducted on a farm. 3. These methods to evaluate stress and model designs of on-farm experiments and analyses have established a process for future trials of stress reduction strategies. We provide a pathway for many more outcomes to come. 4. Farmers have attended a training session to set up a surveillance program. Several Victorian and South Australian farms now use diagnostic pathology services set up as a result of this project. The response at Abalone Growers Association workshops where the work was presented has been very favourable. NON TECHNICAL SUMMARY: In aquaculture, as in other kinds of stock production, outbreaks of disease can damage profits both due to large die-offs of stock and due to reduced growth during periods with low grade disease. Because abalone farming is relatively new, little is known of how abalone protect themselves – their immune sytem, or of how stresses, such as warm water in summer or being moved from one tank to another, might reduce their capacity to resist infection. This project set out first to find the best ways to measure how well an abalone’s immune system is functioning, and to develop and define these assays so that they can be used to monitor the effects of procedures on abalone on farms. We have shown that small samples of blood can be drawn from abalone and small amounts 4 used in three reliable assays that measure different aspects of stress or disease resistance. Together these provide a good assessment of immune function. Next, experiments and monitoring were done using these assays, to discover how much abalone immune defences are affected by some common stressors on farms, namely elevated summer temperatures and stock movement. Moving abalone from one tank to another when the tanks become too full as the abalone grow is a stressful process. Part of the movement procedure is anaesthetizing the abalone to release their grip on the tank floor. We showed that one of the commonly used anaesthetics was the most stressful part of the movement process on the farm studied, although handling during movement is also important. This will prompt farmers to find less stressful ways to move abalone. In summer, when water temperatures rise, farms often experience increased mortality. We found that abalone are only affected by a severe elevation in temperatures and they apparently can adjust to heat stress. This suggests that the summer mortality problem involves not just elevated water temperatures but other factors are likely to be involved that were not part of this investigation. Other possible problems not covered in this project include water quality problems such as decreased dissolved oxygen and increased numbers of bacteria in the water. Further work on these factors, by farmers via management experiments, or in a further project, is recommended. Our work also defined and trialed a large number of laboratory tests, as well as the on-farm assays; and we examined the ways in which the tissues of abalone are damaged by stress, which could affect the long-term recovery of the abalone. While the assays used on the farm showed different results with different stressors, the tissue damage found was similar for various types of stress, although quantitative scoring might reveal differences. We have designed experiments to work on the farm and have shown how to use powerful methods to analyse the information. Others can now use our designs, methods and assays to investigate other situations on farms where stress reduces stock survival or growth. We have also provided farmers with a review of what was known about how abalone immune systems work and our subsequent results, plus a glossary of technical terms, so they can build on this knowledge. Further, the publication of our review and experiments on farms provides a stimulus and a foundation for more work elsewhere that will further help farmers to grow abalone more productively, and with fewer disease problems. KEYWORDS: abalone, aquaculture, immune function, stress assays. 5 ACKNOWLEDGMENTS This work would not have been possible without the extensive support and facilities provided by Great Southern Waters abalone farm (GSW). We wish to thank in particular Anton Krsinich, Adam Clark and Matt Van der Graaff from GSW. A number of other GSW staff helped over the years in different ways. We acknowledge also support from Coastal Sea Farms, Southern Ocean Mariculture, and the Australian Abalone Growers Association. The support and encouragement of Ann Fleming was pivotal in setting up this study. We thank also Gribbles Veterinary Pathology, Flinders University, and The University of Melbourne for the use of facilities, and especially John Ahern and Bruce Abaloz (Zoology Department, University of Melbourne) for help with aquarium experiments and histology, and Dr Jeremy Carson (DPIWE, Launceston) for assistance with the preparation of bacterial cultures. We are grateful to Julian Goulias, who came to Australia from France to undertake a ‘stage’ in his Masters Degree with Rob Day, and who set up some of the biochemical assays used in France. We are grateful also to a number of volunteers who assisted with setting up experiments and immune assays, including particularly Matthew Wassnig, Nicole Currie and Athol Whitten. 6 BACKGROUND Commercial aquaculture, like all farming, involves raising animals at relatively high densities. High densities however, increase the likelihood of transmission of diseases and other parasites between the animals, and the provision of plentiful food to the tanks can encourage opportunistic bacteria. Under these conditions it is important that the animals are in good physiological condition and able to resist infections. Resistance to infectious disease is an important role of the immune system. Knowledge of the physiology and immune systems of the species in culture is essential for maximising health and productivity in aquaculture. The immune system provides the principle line of defense against a broad spectrum of pathogens, so that studies on immune functions can provide an indication of the potential to resist disease under different culture regimes (Benkendorff, 2003).

Load more