UHI Thesis - pdf download summary Quantifying biotic interactions with inshore subtidal structures comparisons between artificial and natural reefs Beaumont, Jennifer C DOCTOR OF PHILOSOPHY (AWARDED BY OU/ABERDEEN) Award date: 2006 Awarding institution: The Open University Link URL to thesis in UHI Research Database General rights and useage policy Copyright,IP and moral rights for the publications made accessible in the UHI Research Database are retained by the author, users must recognise and abide by the legal requirements associated with these rights. This copy has been supplied on the understanding that it is copyright material and that no quotation from the thesis may be published without proper acknowledgement, or without prior permission from the author. Users may download and print one copy of any thesis from the UHI Research Database for the not-for-profit purpose of private study or research on the condition that: 1) The full text is not changed in any way 2) If citing, a bibliographic link is made to the metadata record on the the UHI Research Database 3) You may not further distribute the material or use it for any profit-making activity or commercial gain 4) You may freely distribute the URL identifying the publication in the UHI Research Database Take down policy If you believe that any data within this document represents a breach of copyright, confidence or data protection please contact us at [email protected] providing details; we will remove access to the work immediately and investigate your claim. Download date: 08. Oct. 2021 Quantifying biotic interactions with inshore subtidal structures: comparisons between artificial and natural reefs Jennifer Beaumont BSc. (hons.) A thesis submitted to the Open University in partial fulfilment of the requirements of the Degree of Doctor of Philosophy July 2006 Scottish Association for Marine Science UHI Millennium Institute ABSTRACT Artificial reefs have been deployed purposely worldwide to influence physical and biological processes around coastlines and in inshore waters; often to augment recreational diving and fishing, support environmental mitigation and habitat restoration and, more recently, for scientific research. The aims of this project were to develop standardised methods and protocols for use in artificial reef studies and to establish whether there were differences in the productivity and biotic interactions between artificial and nearby natural rocky reefs in Loch Linnhe, west coast of Scotland. A comparative study was carried out to evaluate methods used in the assessment of subtidal epibiotic assemblage structure followed by a detailed study to compare epibiotic recruitment to artificial and natural reefs using PVC plastic recruitment panels. Predator exclusion cages were used to assess the effects of predation on epifaunal recruitment at different locations. Epifaunal biomass on concrete reef blocks and infaunal biomass in soft sediments surrounding the artificial reef complex was determined and an estimate made of relative productivity between the Loch Linnhe artificial reef modules and their receiving environment. Finally, the trophic dynamics of artificial and natural reefs were investigated through the use of stable isotope ratios. These studies showed that post-settlement processes appear to be controlling differences in epifaunal recruitment to artificial and natural reefs in Loch Linnhe. Vertically orientated PVC recruitment panels, combined with galvanised wire mesh i predator exclusion cages, are recommended for use in comparative recruitment studies of subtidal artificial and natural reefs. It was also concluded that the Loch Linnhe artificial reef complex has increased the productivity to the local area and that the construction design of these artificial reefs would be a suitable option, with respect to the development of biological communities, for future artificial structures such as breakwaters. ii Acknowledgements I would like to thank all those who have made the past 3 years working at SAMS and living in Oban such an enjoyable experience. Firstly I would like to thank my supervisors, Martin Sayer, Craig Brown and Graham Shimmield, for giving me the opportunity to take on this project and for encouragement, help and support to complete it. I would also like to thank my thesis panel, Mike Burrows, Axel Miller and Kenny Black for their input and advice. This project would not have been possible without the help and support of the SAMS diving unit, the National Facility for Scientific Diving, and the crew of the SAMS research vessel, Seol Mara. To Dougie, Stephen, Hugh, Simon, Norman and Mickey – thank you very much. Also to my dive buddies Tim Comstock, Tom Wilding, Martin Sayer, Craig Brown and Dave Hughes – thanks for taking time out of your busy schedules to give me a hand. There are many others who have helped me along the way, but in particular I would like to thank the following: Mike Burrows for all his help with statistics – it would have taken me a long time to figure it all out by myself!; Shona Magill for showing me round the insides of a fish; Alex Keay for all his help in the aquarium; Duncan and Drew for many hours of PVC sheet and pipe cutting; Dave Hughes for pointing me in the right direction with Bryozoan taxonomy, Andy Davies for help with GIS, Adam Hughes and Heather Orr for advice on stable isotope and fatty acid sample preparation, Dave Bowden for convincing me that Master Document was the way forward, Suzie Cox and John Howe for advice on particle size analysis of sediments, and Jason Newton and Rona McGill for all their help and advice with stable isotope analysis. Finally I would like to thank my student year group – Sue, Des, Adam and Craig - for being there to bounce ideas off and to share the whole student experience with – I could not have wished for a better bunch to work alongside. Also to all the reprobates in the student office – it has been fun sharing an office with you all! My iii time as a PhD student at SAMS and in Oban would not have been the same without all those who have distracted me from my work, kept me sane(?), and made life so enjoyable. There are far too many of you to mention, but a few deserve special mention. Thanks to Finlo, Liz and Chris for so much fun both on the water and in the snow; to Mike, Mary, Tom, and Richard for some very memorable camping and walking trips, to all my friends from Murderball for encouraging me to get fit and providing so many opportunities for adventure, and to everyone at Oban Sailing Club – especially to Alison and the crew of Hot Toddy - I very much hope I can join you for more adventures afloat in the future. I would also like to thank my parents who have always helped and encouraged me to make the most of life’s opportunities. I would like to acknowledge and thank NERC for funding my PhD studentship (NER/S/A/2002/1055), and for providing a grant-in-kind (LSMSF 72-9/04) for stable isotope analysis with the NERC Life Sciences Mass Spectrometry Facility at East Kilbride. Also to the UHI Millenium Institute for providing postgraduate workshops and many training opportunities, and for part-funding my attendance to both the 39th European Marine Biology Symposium and the 8th Conference for Artificial Reefs and Artificial Habitats. And last, but by no means least, I would like to thank Foster Yeoman Ltd. for creating the Loch Linnhe artificial reef, in partnership with SAMS, and for providing extra reef blocks for use in experiments. iv Abstract I Acknowledgements III List of figures XI List of tables XX CHAPTER 1 General Introduction 1 1.1 Reefs 1 1.2 Artificial reefs 2 1.2.1 Artificial reef design and construction materials 3 1.2.2 Rigs to Reefs programme 5 1.3 Artificial reef research 7 1.3.1 Loch Linnhe artificial reef complex 8 1.4 Ecological functioning of artificial reefs 14 1.4.1 Fish and the attraction-production debate 14 1.4.2 Habitat complexity and attraction versus production 18 1.4.3 Crustacea 19 1.4.4 The attraction-production debate: current thinking 20 1.4.5 Epifaunal fouling: settlement and recruitment 21 1.4.6 Methods used in recruitment studies 26 1.4.7 Epifaunal recruitment and artificial reefs 28 1.5 Comparisons with natural reefs 29 1.6 Structure of thesis 30 1.7 Aims 31 v CHAPTER 2 Evaluation of techniques used in the assessment of subtidal epibiotic assemblage structure 32 2.1 Introduction 32 2.2 Materials and methods 34 2.2.1 Sampling site – “Methods” 37 2.2.2 Analysis – “Techniques” 37 2.2.3 Data analysis 40 2.3 Results 41 2.3.1 Biomass 41 2.3.2 Taxonomic data 42 2.3.3 Comparison between methods 46 2.4 Discussion 51 2.4.1 Biomass comparisons 51 2.4.2 Taxonomic comparisons 52 CHAPTER 3 Predation pressures on developing epifaunal assemblages at artificial and natural reefs 60 3.1 Introduction 60 3.1.1 Assessing predation pressures 61 3.1.2 This study 62 3.2 Materials and methods 65 3.2.1 Sites 65 3.2.2 Particle size analysis 68 3.2.3 Recruitment panels 68 3.2.4 Predator exclusion 70 3.2.5 Sampling protocol 74 3.2.6 Data analysis 75 vi 3.3 Results 76 3.3.1 Particle Size Analysis 76 3.3.2 Cage artefacts 79 3.3.3 Biomass 82 3.3.4 Multivariate analysis of taxonomic data 84 3.3.5 Univariate analysis of taxonomic data 87 3.4 Discussion 95 3.4.1 Site characteristics 96 3.4.2 Predation pressures at artificial and natural reefs 98 3.4.3 Proximity to reefs 100 3.4.4 Effects of predation on different taxa 101 3.4.5 Recruitment panel orientation 103 3.4.6 Predator exclusion cages 104 3.4.7 Conclusions 107 CHAPTER 4 Epifaunal recruitment at artificial and natural reefs in Loch Linnhe 109 4.1 Introduction 109 4.1.1 Supply-side ecology 109 4.1.2 Epifaunal assemblages on natural and artificial reefs 111 4.1.3 Epibiotic communities on artificial and natural reefs in Loch Linnhe 112 4.1.4 This study 115 4.2 Materials and methods 115 4.2.1 Seasonal predation study 115 4.2.2 Seasonal early epifaunal recruitment study 116 4.2.3 Epifaunal recruitment study 116 4.2.4 Data analysis 117 4.3 Results 118 vii 4.3.1 Effects of predation and cage artefacts on seasonal recruitment 118 4.3.2 Seasonal early recruitment to artificial and natural reefs in Loch Linnhe (caged data).