Biofouling in Salmon Aquaculture: the effectiveness of alternative netting materials and coatings in coastal British Columbia by Courtney D. Edwards BSc. University of Victoria, 2008 A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE in the Department of Geography © Courtney D. Edwards, 2012 University of Victoria All rights reserved. This thesis may not be reproduced in whole or in part, by photocopy or other means, without the permission of the author. i Biofouling in Salmon Aquaculture: the effectiveness of alternative netting materials and coatings in coastal British Columbia by Courtney D. Edwards BSc. University of Victoria, 2008 Supervisory Committee Co-Supervisor Dr. S.F. Cross (Department of Geography) Co-Supervisor Dr. M. Flaherty (Department of Geography) ii Supervisory Committee Co-Supervisor Dr. S.F. Cross (Department of Geography) Co-Supervisor Dr. M. Flaherty (Department of Geography) Abstract Biofouling in salmon aquaculture is an important issue. The use of copper based antifoulants contributes to marine pollution and managing biofouling on untreated nets incurs a heavy cost on the industry. What is needed is an antifoulant coating that balances the needs of the industry with good environmental practices. This study describes the effectiveness of seven alternative netting treatments and two copper based treatments as compared to an untreated nylon net. Effectiveness was measured in terms of percent net occlusion, percent cover of major fouling groups and biomass. Following eight months immersion, results show that the alternative treatments did not out-perform the untreated nylon control, and that the two copper treatments significantly outperformed the control and all of the alternative treatments tested in this study. The results demonstrate that the alternative treatments tested in this study were unable to meet the performance standards set by industry, that more research is needed into alternative antifoulant coatings for aquaculture, and that the effectiveness of copper based treatments will continue to be a barrier to the implementation of alternative antifouling treatments. keywords: biofouling; salmon; copper antifoulant; image analysis iii Table of Contents Abstract .......................................................................................................................................... iii Table of Contents ........................................................................................................................... iv List of Tables ................................................................................................................................. vi List of Figures .............................................................................................................................. viii Acknowledgements ......................................................................................................................... x CHAPTER 1: Introduction .............................................................................................................. i CHAPTER 2: Biofouling ................................................................................................................ 7 2.1 The Biology of Biofouling .................................................................................................... 7 2.2 Biofouling in Salmon Aquaculture ..................................................................................... 11 2.3 Historical Context of Antifoulants ...................................................................................... 14 2.4 Environmental Concerns of Antifoulants ........................................................................... 15 2.5 Alternative Treatments........................................................................................................ 17 2.6 Summary ............................................................................................................................. 20 CHAPTER 3: Materials and Methods .......................................................................................... 22 3.1 Test Materials...................................................................................................................... 22 3.1.2 Net Materials ................................................................................................................ 22 3.1.3 Coatings ....................................................................................................................... 23 3.2 Study Site ............................................................................................................................ 25 3.3. Experimental Design .......................................................................................................... 27 3.4. Analysis.............................................................................................................................. 30 CHAPTER 4: Results ................................................................................................................... 33 4.1 Succession ........................................................................................................................... 33 4.2 Percent Net Occlusion......................................................................................................... 34 4.3 Percent Cover ...................................................................................................................... 38 4.4 Biomass ............................................................................................................................... 42 CHAPTER 5: Discussion .............................................................................................................. 44 5.1 Percent Net Occlusion......................................................................................................... 44 5.2 Percent Cover ...................................................................................................................... 45 5.3 Biomass ............................................................................................................................... 46 5.4 Multiple Measures .............................................................................................................. 46 iv 5.4.1 Time ............................................................................................................................. 49 5.4.2 Depth ............................................................................................................................ 49 5.4.3 Treatment by Depth Interaction ................................................................................... 49 5.4.4 Treatment ..................................................................................................................... 50 5.4.5 Dyneema and Sancure.................................................................................................. 51 5.4.6. Netrex and Flexgard .................................................................................................... 52 5.6 Challenges in Aquaculture Field Research ......................................................................... 53 5.7 Better Management Practices ............................................................................................. 56 CHAPTER 6: Conclusion ............................................................................................................. 59 References ..................................................................................................................................... 61 Appendix A: SPSS v.17 Syntax .................................................................................................... 69 v List of Tables: Table 1: Copper based antifoulant coatings that are available in Canada for use in aquaculture (PMRA 2012)……………………………………………………………………………………17 Table 2: Summary of netting materials and coatings tested in this study. Including the treatment name used throughout this document in both the text and figures. Because there are two treatments with Dyneema netting they are sometimes referred to as ‘untreated Dyneema’ and ‘Dyneema with Sancure.’ The control is untreated nylon……………………………………………………………………………22 Table 3: Dominant taxa by fouling group……………………………………………………....38 Table 4: Summary table for PERMANOVA analysis showing significance tests for treatment, depth and treatment*depth. Table 5: Mean percent cover of major fouling groups (< 3% coverage; Untransformed data) for the treatments found to be significantly different at each depth. Untransformed data. Column labels: mus = mussel, barn = barnacle, tuni = tunicate, hyd = hydroid, sabe = sabellid, capr = caprellid, diat = diatom…………………………………………………………………………..38 Table 6: PERMANOVA pairwise comparisons showing significant differences in treatment as compared to the control, separated by depth…………………………………………………….40 Table 7: Significant results for indices used in this study (PNO over time, PNO for the final month of September, percent cover, and biomass), where ‘X’ marks a significant result for the associated index. Including treatment, depth and the treatment*depth interaction. Super-script represents, when relevant, the depths where the significance was found and whether it was higher (↑) or lower (↓) than the control………………………………………………………………….48 Table 8: Significant results comparing the two copper treatments and the two Dyneema treatments