Aquaculture-derived terrestrial fatty acids in marine food webs

263 Pages·2017·10.83 MB·English

by  Camille White

Aquaculture-derived terrestrial fatty acids in
marine food webs

Camille A.White

Submitted in total fulfilment of requirements for the degree of
Doctor of Philosophy

2017

School of BioSciences, University of Melbourne
Declaration

This is to certify that:

The thesis comprises only my original work towards the degree of Doctorate of Philosophy
except where indicated in the Preface.

Due acknowledgement has been made in the text to all other material used.

This thesis is fewer than 100,000 words in length, exclusive of tables, maps, bibliographies
and appendices.

Camille Anna White

February 2017

Cover image: Aggregations of the white urchin, Echinus acutus, grazing beneath salmon
farms in Masfjord, Western Norway.
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Preface

I am the chief author and main contributor of all Chapters in this thesis. Chapters 2-6 were
co-authored by my supervisors Tim Dempster and Peter Nichols, who contributed to study
creation and design, as well as manuscript comments. Jeff Ross contributed to study design
as well as manuscript comments in Chapter 2 and Giovanni Turchini contributed to
experiment design in Chapter 3. Symon Dworjanyn, Raymond Bannister, Vivian Husa, Ben
Mos and Tina Kutti all contributed in varying degrees on design and technical aspects of
Chapters 4-6, as well as providing manuscript comments on Chapters 4 and 5. Chapters 2, 3
and 6 are manuscripts in preparation for submission to research journals. Chapters 4 and 5
have been submitted for publication and peer reviewed, with Chapter 4 accepted for
publication and Chapter 5 currently under review after being resubmitted with minor
revisions. I am the sole author of Chapters 1 and 7.

Authorship contributions

Chapter 2: White, C.A., Nichols, P.D., Ross, D.J. & Dempster, T. Dispersal of an
anthropogenic subsidy in a low productivity coastal environment. Manuscript.
Contributions: White (85%), Nichols (5%), Ross (5%), Dempster (5%).

Chapter 3: White, C.A., Nichols, P.D., Turchini, G. & Dempster, T. Maternal and multi-
generational effects of a high n-6 diet on marine invertebrates. Manuscript.
Contributions: White (80%), Nichols (5%), Turchini (5%), Dempster (10%)

Chapter 4: White, C.A., Dworjanyn, S.A., Nichols, P.D., Mos, B. & Dempster, T. , 2016.
Future aquafeeds may compromise reproductive fitness in a marine invertebrate. Marine
Environmental Research, 122:67-75
Contributions: White (80%), Dworjanyn (5%), Nichols (5%), Mos (2%), Dempster (8%)

Chapter 5: White, C.A., Bannister, R.J., Dworjanyn, S.A., Husa, V., Nichols, P.D., Kutti, T.
& Dempster, T. 2017. Consumption of aquaculture waste affects fatty acid metabolism of a
benthic invertebrate. Science of the Total Environment. Under revision – resubmitted with
minor revisions.
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Contributions: White (80%), Bannister (5%), Dworjanyn (5%), Husa (2%), Nichols (2%),
Kutti (1%), Dempster (5%)

Chapter 6: White, C.A., Bannister, R.J., Dworjanyn, S.A., Husa, V., Nichols, P.D. &
Dempster, T. An aquaculture derived trophic subsidy boosts populations of a keystone marine
invertebrate. Manuscript.
Contributions: White (80%), Bannister (5%), Dworjanyn, (5%), Husa, (3%), Nichols (2%),
Dempster (5%).

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Acknowledgements

I have been extremely fortunate in the team of support I have been surrounded with
throughout my PhD. First and foremost, thanks to Tim Dempster for the endless optimism
and encouragement, wealth of ideas and support in pursuing any number of opportunities
during my PhD, both personal and professional. I will miss our discussions! Thank you also
to Peter Nichols, for introducing me to the world of fatty acid analysis and lipid chemistry.
The time and patience you give your students is amazing and I am incredibly grateful for the
skill-set that you have imparted on me. Thanks to Giovanni Turchini, for the manufacture of
experimental diets, along with valuable conversations at the start of the project, and also to
Symon Dworjanyn, for all the lessons in sea urchin husbandry interjected with regular doses
of humour! Thank you to Raymond Bannister, for being so accommodating and willing to
support me in my urchin ideas and Norwegian endeavours, and to Jeff Ross, for facilitating
and supporting my Tasmanian work, and providing invaluable discussions as I developed my
skill sets.

A big shout-out all of my Dempster lab-mates at the University of Melbourne for their help
and support in both Norway and Australia. Particularly to Luke Barrett and Francisca
Samsing for never being too busy to lend me some statistical advice. Thank you also to
everyone who provided support and technical expertise across all the other places I was
fortunate enough to work out of along the way: CSIRO – Peter Mansour, Andy Revill; IMR -
Tina Kutti, Tore Strohmeier, Øivind Strand, Barbro Haugland Taraldset, Siri Aaserud Olsen,
Skye Woodcock, Nigel Keeley; VMSC – Rod Watson, Liz McGrath, Erin Cumming, Julia
Kent; NMSC – Alexia Graba-Landry, Ben Mos; IMAS – Andrew Pender, Adam Davey.
Particular thanks to Frode Oppedal (IMR) for your generosity and assistance during my
urchin collections and to Vivian Husa (IMR) for never being too busy to answer my algae
questions and being so supportive of my fieldwork in Norway.

Lastly, a particular thanks to my partner Brett, my family, the Forbes household and the
Cambridge-Best household. For endless support, hot dinners and a roof over my head
wherever I was, as I attempted to complete a PhD across three states and two countries on a
shoe-string budget. Thanks for making what could have been very difficult so much easier!

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Abstract

Aquaculture is an increasingly common trophic subsidy in coastal marine ecosystems, with
waste feed, faecal material and nitrogenous wastes potential food sources for marine
consumers. As modern aquafeeds are generally high in terrestrial lipids and oils, the
biochemical composition of the aquaculture-derived subsidy is relatively alien in the marine
environment. Using terrestrial fatty acids as a tool, I investigated dispersal and uptake of the
aquaculture subsidy, in both laboratory and field scenarios. I was able to demonstrate that
aquaculture outputs are widely dispersed in marine systems and assimilated by marine
consumers. Using marine amphipods and sea urchins as model species, I examined maternal
and multigenerational effects of increased terrestrial lipids in the diet of marine consumers. I
found that consuming waste could alter both biochemical composition and reproductive
outputs in invertebrate fauna. When applied to a field scenario, where aquaculture outputs
have been linked to increases in sea urchins, I found that population-scale effects will be a
trade-off between energetic benefits of consuming a lipid-rich subsidy, versus any negative
effects that a high terrestrial diet may have on reproductive outcomes.

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Table of Contents

Chapter 1: General Introduction ........................................................................................... 1
Trophic subsidies and the marine environment...................................................................... 1
Aquaculture outputs and environment interactions ................................................................ 7
Aims ..................................................................................................................................... 12
Chapter 2. Dispersal and assimilation of an anthropogenic subsidy in a low productivity
coastal environment ............................................................................................................... 24
Introduction .......................................................................................................................... 26
Materials and Methods ......................................................................................................... 29
Results .................................................................................................................................. 35
Discussion ............................................................................................................................ 48
Chapter 3. Maternal and multi-generational effects of a high n-6 diet on marine
invertebrates ........................................................................................................................... 64
Introduction .......................................................................................................................... 65
Methods ................................................................................................................................ 69
Results .................................................................................................................................. 77
Discussion ............................................................................................................................ 90
Chapter 4. Future aquafeeds may compromise reproductive fitness in a marine
invertebrate .......................................................................................................................... 106
Chapter 5. Consumption of aquaculture waste affects the fatty acid metabolism of a
benthic invertebrate ............................................................................................................. 116
Introduction ........................................................................................................................ 118
Materials and Methods ....................................................................................................... 122
Results ................................................................................................................................ 128
Discussion .......................................................................................................................... 139
Chapter 6. An aquaculture derived trophic subsidy boosts populations of a keystone
marine invertebrate ............................................................................................................. 155
Introduction ........................................................................................................................ 157
Materials and Methods ....................................................................................................... 160
Results ................................................................................................................................ 166
Discussion .......................................................................................................................... 173
Chapter 7: General Discussion ........................................................................................... 188
Tracing aquaculture-derived fatty acids in the marine environment.................................. 188
Biological effects of n-6 PUFA substitution in the diet of marine organisms ................... 199
Aquafeeds into the future ................................................................................................... 209
Consequences of an aquaculture-derived trophic subsidy in the marine environment ...... 211
From individuals to ecosystems ......................................................................................... 214
Concluding remarks ........................................................................................................... 217
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Appendix 1. Supplementary content for Chapter 2 .......................................................... 228
Appendix 2. Supplementary content for Chapter 3 .......................................................... 234
Appendix 3. Supplementary content for Chapter 4 .......................................................... 238
Appendix 4. Supplementary content for Chapter 5 .......................................................... 241
Appendix 5. Supplementary content for Chapter 6 .......................................................... 250

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List of Figures

Chapters 1-3 and 5-7

Figure 1.1. Calculated pelagic forage fish equivalent per unit of production of salmonids ... 9
Figure 1.2. Biochemical pathways leading to the synthesis of LC-PUFA ........................... 11
Figure 2.1. Principle coordinates analysis (PCO) on relative proportions of fatty acids in
farm and control sediments in Macquarie Harbour ............................................................... 38
Figure 2.2. Principle coordinates analysis (PCO) on relative proportions of fatty acids in
sediments 0–1000m from an active salmon cage .................................................................. 39
Figure 2.3. Concentration of key fatty acid biomarkers in sediments from 0-1000 m from
active salmon cage ................................................................................................................. 42
Figure 2.4. Principle coordinates analysis (PCO) on fatty acid composition of sediments,
benthic polychaetes and zooplankton .................................................................................... 44
Figure 2.5. Concentrations of key fatty acids in benthic polychaetes and zooplankton ....... 46
Figure 3.1. Principle Components Analysis on life history stages in Generation 1 of the
corophiid amphipod Jassa marmorata .................................................................................. 79
Figure 3.2. Principle Components Analysis comparing generational effects of dietary
treatment on corophiid adults and eggs ................................................................................. 80
Figure 3.3. Principle Components Analysis on life history stages in Generation 1 and
Generation 2 of the caprellid amphipod Caprella scaura ..................................................... 86
Figure 3.4. Principle Components Analysis comparing generational effects on caprellid
adults and eggs ....................................................................................................................... 88
Figure 5.1. Total fatty acid concentrations in feed, gonads and eggs of Echinus acutus from
the diet experiment ............................................................................................................... 128
Figure 5.2.Variation in standardised gonad indices for E. acutus from laboratory experiment
and field survey .................................................................................................................... 129
Figure 5.3. Principle components analysis (PCA) on relative proportions of fatty acids of
fatty acids in feed, gonad and eggs from the diet experiment ............................................. 130
Figure 5.4. Variation in concentrations of key fatty acids with dietary treatment from the diet
experiment............................................................................................................................ 133
Figure 5.5. Principle components analysis (PCA) on relative proportions of fatty acids in
feed, gonads and gut contents from the field survey ........................................................... 136
Figure 5.6. Variation in concentrations of key fatty acids in E. acutus gonads with distance
from a salmon farm .............................................................................................................. 128
Figure 6.1. Map of Masfjord, Hordaland, Norway, showing sites surveyed for urchin
abundance and size .............................................................................................................. 161
Figure 6.2. Results from the field survey of urchin abundance and average test size at farm
and control locations ............................................................................................................ 167
Figure 6.3. Mean effects of dietary treatment on urchin larval success and development . 169
Figure 6.4. Mean effects of diet on metabolism of urchins at Week 0 and Week 10 ......... 170
Figure 6.5. Mean effects of dietary treatment on lipid uptake in urchin gonads and eggs . 171
Figure 6.6. Histological examination of the gonads of urchins fed different diets ............. 172
Figure 6.7. Model output showing the number of 10-day urchin larvae present in the water
column from aquaculture and control locations................................................................... 173

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List of Tables

Chapters 1-3 and 5-7

Table 1.1. Anthropogenic subsidies in marine environments ........................................................ 4
Table 2.1. Fatty acid biomarkers for tracing dietary sources in the marine environment ....... 28
Table 2.2. Percent fatty acid composition of the aquafeed used in Macquarie Harbour ........ 35
Table 2.3. Fatty acid composition and key fatty acid biomarkers of sediments at farm and
control locations ....................................................................................................................... 37
Table 2.4: Fatty acid composition and key fatty acid biomarkers of sediments from 0-1000 m
from farms ................................................................................................................................ 41
Table 2.5: Fatty acid composition and key fatty acid biomarkers in benthic polychaetes and
zooplankton from 0–1000 m from farms ................................................................................. 45
Table 3.1. Percentage composition of major fatty acids in each diet treatment ...................... 71
Table 3.2. Fatty acid composition of Adults and Eggs from G0 and G1 of the corophiid
amphipod Jassa marmorata ..................................................................................................... 78
Table 3.3. Pair-wise P(MC) values determined by PERMANOVA and contribution of key
fatty acids by SIMPER for adults and eggs from corophiid amphipods.................................. 81
Table 3.4. Values for biological parameters of corophiid amphipods from G0 and G1 ......... 82
Table 3.5. Percentage fatty acid composition of adults from generations G0, G1, G2 & G3 of
the caprellid amphipod Caprella scaura.................................................................................. 84
Table 3.6. Percentage fatty acid composition of eggs from G0, G1 and G2 of the caprellid
amphipod Caprella scaura ...................................................................................................... 85
Table 3.7. Pair-wise P(MC) values determined by PERMANOVA and contribution of key
fatty acids by SIMPER for adults and eggs from caprellid amphipods ................................... 89
Table 3.8. Values for biological parameters of caprellid amphipods from G0, G1 and G2 ... 90
Table 5.1. Fatty acid profiles of experimental diets and Echinus acutus gonad and egg
samples ................................................................................................................................... 134
Table 5.2. Fatty acid profiles of feed from active salmon farms and wild Echinus acutus
gonads and gut contents ......................................................................................................... 137
Table 6.1. Carbon, nitrogen and total lipid values for experimental dietary treatments ....... 163
Table 7.1. Fatty acids as tracers of aquafeed waste in wild vertebrates, invertebrates and the
environment ........................................................................................................................... 191
Table 7.2. Reproductive outcomes of consuming elevated n-6 PUFA diet in marine
species .................................................................................................................................... 204

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