00 Seagrass 23/7/99 10:15 AM Page i Seagrass in Australia STRATEGIC REVIEW AND DEVELOPMENT OF AN R & D PLAN Alan Butler Peter Jernakoff 00 Seagrass 23/7/99 10:15 AM Page ii CSIRO Cataloguing-in-Publication Entry Butler, Alan J., 1946– . Seagrass in Australia : strategic review and development of an R & D plan. ISBN 0 643 06442 7. ISBN 0 643 09168 8 (eBook). 1. Seagrasses – Government policy – Australia. 2. Seagrasses – Research – Australia. 3. Research – Australia – Evaluation. I. Jernakoff, Peter. II. Title. 584.740994 FRDC 1999 FRDC Project 98/223: Seagrass in Australia: strategic review and development of an R & D plan A.J. Butler Contact address: CSIRO Marine Research, GPO Box 1538, Hobart, Tas, 7001 Email:[email protected] P. Jernakoff Contact address: International Risk Consultants Environment Group (IRC Environment) 2 Emerald Tce, West Perth, WA, 6005 Email [email protected] Date: March 10, 1999 This book is available from: CSIRO Publishing PO Box 1139 (150 Oxford Street) Collingwood Vic 3006 Australia Tel: (03) 9662 7666 Int: +613 9662 7666 Fax: (03) 9662 7555 Int: +613 9662 7555 Email: [email protected] Web: www.publish.csiro.au 00 Seagrass 23/7/99 10:15 AM Page iii Disclaimer This report has been produced for the sole use of the Fisheries Research and Development Corporation (FRDC). The application or use of this report and or any data or information including recommendations contained within it shall be at the sole risk and responsibility of FRDC. CSIRO does not provide any warranty or assurance as to the accuracy or suitability of all or any section of the report, for any particular purpose or application. Neither CSIRO nor the personnel contracted to produce the report will be responsible to FRDC, or any person claiming through FRDC, for any consequences of its use or application (whether in whole or in part). 00 Seagrass 23/7/99 10:15 AM Page iv Contents Executive Summary vi Introduction xi 1. Status of Australian seagrass research and knowledge 1 1.1 Introduction 1 1.2 Seagrass plants 2 1.3 Habitat effects 8 1.4 Food webs 13 1.5 Gaps in seagrass knowledge and recommendations to address them 16 1.6 Acknowledgements 17 1.7 References 18 2. Seagrass dynamics and fisheries sustainability 25 2.1 Introduction 25 2.2 Importance of seagrass beds in fisheries production 26 2.3 Influence of seagrass status on fisheries sustainability 40 2.4 Gaps in understanding and future research needs 47 2.5 Recommendations for future research 49 2.6 Acknowledgements 50 2.7 References 51 3. Review of Australian rehabilitation and restoration programs 65 3.1 Introduction 65 3.2 Review of Australian projects 73 3.3 Recommendations for research 83 3.4 Acknowledgements 88 3.5 References 89 Appendix 3.1 Summary of seagrass rehabilitation and restoration projects in Australia 93 00 Seagrass 23/7/99 10:15 AM Page v Contents v 4. Monitoring and assessment of seagrass 116 4.1 Introduction 116 4.2 Critical review of existing literature 117 4.3 Gaps in understanding of monitoring issues 129 4.4 Recommendations for strategy and future research 131 4.5 References 133 5. Seagrasses and their management — implications for research 140 5.1 Introduction 140 5.2 Issues confronting seagrass managers 142 5.3 How is seagrass managed? 143 5.4 Information needs for better seagrass management 151 5.5 Assessing the effectiveness of seagrass management 156 5.6 Suggestions for improvement of seagrass management 157 5.7 Conclusions 162 5.8 References 163 Appendix 5.1 Questionnaire to seagrass managers 164 Appendix 5.2 Legislation and seagrass management 166 6. Research and Development plan 172 6.1 Roles of funding agencies and their R&D responsibilities 173 6.2 Suggested structure to maintain R&D links between organisations 178 6.3 Key issues and knowledge gaps 179 6.4 Goals of the R&D plan 181 6.5 Priorities for seagrass R&D 181 6.6 Strategies to implement, maintain and develop the R&D plan 187 6.7 Communication and coordination strategies 194 6.8 Summary 195 6.9 References 198 Appendix 6.1 Research needs identified by working groups 199 Appendix 6.2 Composition of steering committee and working groups 208 Appendix 6.3 Acronyms 210 00 Seagrass 23/7/99 10:15 AM Page vi Executive Summary The FRDC Seagrass Review follows the Corporation’s Fisheries Habitat Review. It reflects a shift from viewing fished species or even fisheries habitats as separate, unconnected entities to viewing them as components of larger ecosystems, and it seeks to develop a comprehensive, ecosystem-based management. The reviewers were asked to assess • Gaps in existing knowledge of seagrass ecosystems • Knowledge of links between seagrass and fisheries • The state of the art in rehabilitation and restoration of damaged seagrass beds • Monitoring and assessment of seagrass • Seagrass and fisheries management and to prepare a research and development plan to guide FRDC’s future invest- ment in the context of FRDC’s Ecosystem Protection Program. The review will also guide FRDC’s interaction with other agencies who have responsibilities in marine habitat management. Each of the five areas listed above was reviewed by a separate team of three experts, who co-opted other experts as necessary. The five reports were edited, and the R&D plan drafted, by the principal investigators. The whole report was dis- cussed with the steering committee and reviewed by four independent experts. Status of Australian seagrass research and knowledge The authors of this chapter examine the attributes of seagrass communities to determine whether seagrass form provides an indication of function, and hence the significance of particular seagrasses to fisheries. They examine habitat effects, relationships to water movement and nutrients, and mechanisms of seagrass decline, and discuss what is known about food webs associated with seagrasses, and of the transfer of biological productivity between seagrasses and other components of the marine ecosystem. The working group identified nine areas of knowledge gaps, and the authors suggest ways to address them. Some examples of gaps are: 1. Northern Australian, turbid-water seagrasses on remote, inaccessible coast- lines remain virtually unknown, 2. The importance, as habitat, of seagrasses in wave-exposed conditions and in deep water is not known, 00 Seagrass 23/7/99 10:15 AM Page vii Executive Summary vii 3. Understanding of the dispersal and recruitment characteristics of different seagrass species is inadequate, 4. Comparative studies are needed of the fates and influences of production from the seagrass system — seagrass detritus, plankton, epiphytic flora and fauna, benthic fauna and microphytobenthos. Seagrass dynamics and fisheries sustainability This chapter examines the evidence for links between seagrass and fisheries resources. It focuses on the reliability of that evidence, especially on the impor- tance of seagrass beds in fisheries production, and the influence of the extent of seagrass cover, type, or density on fisheries sustainability. The authors compare the relationships between fish and seagrasses to those of other estuarine and nearshore habitats. Then, more specifically, they explore the relationship of seagrass to fisheries; firstly, those species that are actually fished in seagrass areas, and secondly, those that are fished elsewhere but may have some link to seagrass. The next section examines the related, but distinct, question of the influence of seagrass status on fisheries sustainability. In conclusion, the working group identifies 17 major gaps in our under- standing and future research needs, and recommends specific research to address those gaps. Examples are: 1. Changes in juvenile fish and decapods before and after seagrass loss are poor- ly understood. Baseline studies of sufficient spatial and temporal intensity are needed to quantify natural variability in fish and decapods in seagrass beds, so useful comparisons can be made after seagrass loss. 2. The importance of exported seagrass detritus to commercially important fish in unvegetated habitats is poorly understood. What is the long-term effect of seagrass loss to these species? 3. The nature of the links with seagrass is still poorly known for many species. Those links might include feeding, protection from predators, or amelioration of physical disturbance. The role of small, non-commercial species in food chains for commercial species is only known in localised areas. Under- standing these links is important in predicting the effects of changes in sea- grass extent on commercial fish. 4. Research has hinted at the importance of many aspects of seagrass meadows relating to ‘landscape ecology’. It is critical to determine the importance of features such as size, shape, and spatial arrangement of meadows, the details of ocean currents over seagrass beds, and relations with other habitats (e.g. unvegetated areas, mangroves, deep water, sand bars). Review of Australian rehabilitation and restoration programs This chapter reviews international experience, then concentrates on Australian pro- jects in the restoration and rehabilitation of seagrasses. It identifies the factors that are important to success, although most of these have yet to be investigated for 00 Seagrass 23/7/99 10:15 AM Page viii viii Seagrass in Australia most seagrass species. Consequently, at this time, no projects in Australia can unequivocally demonstrate creation of a permanent, functional seagrass bed out of transplanting efforts. Nor have techniques been tested to the degree that par- ticular methods can be recommended for different seagrass species or habitats. Nonetheless, enough experience is available to enable the authors to review the issues important to successful seagrass rehabilitation and restoration. In making recommendations for future research the working group argues that restoration and rehabilitation depend on a thorough understanding of the sys- tem being restored, and therefore that it would be prudent to undertake restora- tion programs in combination with well constructed programs of research into the fundamental characteristics of seagrass.