Auswirkung des Abfischens [Elektronische Ressource] : eine Fallstudie zur ökologischen Rolle der wirtschaftlich genutzten Seegurke Holothuria scabra (Echinodermata: Holothuroidea) in Moreton Bay, Australien / vorgelegt von: Svea-Mara Wolkenhauer
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Auswirkung des Abfischens [Elektronische Ressource] : eine Fallstudie zur ökologischen Rolle der wirtschaftlich genutzten Seegurke Holothuria scabra (Echinodermata: Holothuroidea) in Moreton Bay, Australien / vorgelegt von: Svea-Mara Wolkenhauer

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Auswirkung des Abfischens - Eine Fallstudie zur ökologischen Rolle der wirtschaftlich genutzten Seegurke Holothuria scabra (Echinodermata: Holothuroidea) in Moreton Bay, Australien Dissertation zur Erlangung des akademischen Grades doctor rerum naturalium (Dr. rer. nat.) der Mathematisch-Naturwissenschaftlichen Fakultät der Universität Rostock vorgelegt von: Svea-Mara Wolkenhauer, geb. am 5. November 1973 in Ottersberg aus Brisbane, Australien Brisbane, 3. Juli 2008 urn:nbn:de:gbv:28-diss2008-0101-2 Betreuung und Gutachtenerstellung durch: Prof. Dr. Ragnar Kinzelbach, Allgemeine und Spezielle Zoologie, Universität Rostock Prof. Dr. Gerhard Graf, Meeresbiologie, Universität Rostock ii Impact of removal - A case study on the ecological role of the commercially important sea cucumber Holothuria scabra (Echinodermata: Holothuroidea) in Moreton Bay, Australia To be submitted for the degree of Doctor of Philosophy to the University of Rostock July 2008 Svea Mara Wolkenhauer (Institute of Biosciences) iv Statement of Originality The work presented in this thesis is to the best of my knowledge original. It presents my own work except as acknowledged in the text. The material has not been submitted, either in whole or in part, for any degree at this or any other institution.

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Published 01 January 2008
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Auswirkung des Abfischens - Eine Fallstudie zur ökologischen Rolle der
wirtschaftlich genutzten Seegurke Holothuria scabra
(Echinodermata: Holothuroidea) in Moreton Bay, Australien



Dissertation
zur
Erlangung des akademischen Grades
doctor rerum naturalium (Dr. rer. nat.)
der Mathematisch-Naturwissenschaftlichen Fakultät
der Universität Rostock


vorgelegt von:
Svea-Mara Wolkenhauer, geb. am 5. November 1973 in Ottersberg
aus Brisbane, Australien


Brisbane, 3. Juli 2008
urn:nbn:de:gbv:28-diss2008-0101-2

Betreuung und Gutachtenerstellung durch:

Prof. Dr. Ragnar Kinzelbach, Allgemeine und Spezielle Zoologie, Universität Rostock
Prof. Dr. Gerhard Graf, Meeresbiologie, Universität Rostock

ii Impact of removal - A case study on the ecological role of the commercially
important sea cucumber Holothuria scabra (Echinodermata: Holothuroidea)
in Moreton Bay, Australia



To be submitted for the degree of Doctor of Philosophy to the
University of Rostock
July 2008



Svea Mara Wolkenhauer
(Institute of Biosciences)


iv
Statement of Originality
The work presented in this thesis is to the best of my knowledge original. It presents my
own work except as acknowledged in the text. The material has not been submitted,
either in whole or in part, for any degree at this or any other institution.


July 2008

v
Statement of Contributions of Others
Intellectual support for the research conducted in this thesis was provided by my PhD
advisors Tim Skewes, Dr. Sven Uthicke and Dr. Roland Pitcher. Editorial comments for
all thesis chapters were provided by Tim Skewes, Dr. Sven Uthicke, Dr. Roland Pitcher
and Prof. Ragnar Kinzelbach. Dr. Charis Burridge and Dr. Sven Uthicke provided
intellectual and editorial support for statistical methods for Chapter 2 and Matthew
Browne provided intellectual and editorial support for predictive models and graphs
presented in Chapter 3 and 4. Doug Chetwynd provided essential support to data
manipulation and extraction for the long-term study in Chapter 3.

Financial support for the research conducted in this thesis was provided by an Australia-
Europe Scholarship through the Department of Education, Science and Training,
Australia, the Daimler-Benz Foundation, Germany and by Dr. Roland Pitcher and Tim
Skewes, CSIRO Marine & Atmospheric Research, Brisbane.

Laboratory and field assistance was provided by A. Anas, D. Chetwynd, S. Corrie, D.
Dennis, M. Haywood, R. Kenyon, P. Kiehl, F. Manson, V. McClure, I. McLeod, T.
Skewes and R. Soares.



Candidate’s signature Date


Supervisor’s signature

vi
Acknowledgements
Independently pursuing a PhD abroad and creating the self-motivation to finalise this
manuscript was a magnificent as well as challenging experience for me. Many people
have been instrumental in shaping my work, my career and my personality during these
years in Australia. Without the support of those precious people I would not have been
able to thrive in my doctoral work and personal life. Here is a small tribute to some of
these very special people.
First and foremost, I would like to express my deepest gratitude to my co-supervisor
Tim Skewes whose dedicated and constant support has made him my primary advisor. He
taught me how to write academic papers, had confidence in me when I doubted myself.
More importantly, he taught me how to refocus on my work after my maternity leave. He
was always there to meet and talk about my ideas, always believing in my ability to
actually finish. Not only did his advice and ideas play a crucial role in the process of this
manuscript, but his constant trust, reassurance and encouragements during all stages,
made it possible for me to persevere and turn field work with vast data sets into this PhD.
Above all, he has been a trusted friend to me during all those years, both in work and
personal life, and I will truly miss him when I move further in my career.
Furthermore, I am deeply grateful to my co-supervisor Dr Sven Uthicke for his
essential contribution to the experimental design and for his patient feedback during the
early years of my PhD and again during the last year, when his constructive advice
greatly improved this manuscript and my publications.
I wish to express my sincere thanks to my main supervisors Prof Ragnar Kinzelbach in
Germany and Dr Roland Pitcher in Australia. They both provided excellent feedback and
vii
constructive criticism to experimental design and reviewing the final draft of this
manuscript. Especially Dr Pitcher’s “Popperian” ideals and concepts of a PhD had a
remarkable influence on how I approached my hypotheses and structured my research.
Special thanks go to Charis Burridge and Matthew Browne, my two most valuable
people in terms of mathematical and statistical advice to this manuscript. Without their
guidance and original contribution, my results would have had no substance to defend.
During my work at the Cleveland Labs I have collaborated with many colleagues for
whom I have great respect and I wish to extend my warmest thanks to all those who have
helped me with my work and kept me sane due to countless games of ‘Awesome Touch
Footy’. In particular, thanks are due to A. Anas, M. Barclay, A. Butler, R. Butler, J.
Carroll, D. Chetwynd, F. Coman, Q. Dell, D. Dennis, C. Dichmont, K. Forcey, G. Fry,
M. Haywood, R. Kenyon, I. McLeod, F. Manson, D. Milton, C. Moeseneder, F. Pantus,
N. Preston, S. Tabrett, T. Taranto and M. Tonks.
My warm thanks are due to the staff at the Moreton Bay Research Station on North
Stradbroke Island and the Centre for Microscopy and Microanalysis at the University of
Queensland for all their effort and help during my field studies and handling the endless
supply of sediment.
Victoria McClure, Petra Kiehl and Shaun Corrie were my most dedicated volunteers in
those long hours of field and laboratory work. I would like to express my warmest thanks
for their commitment, their patience and valuable ideas to this work; especially to
Victoria, whose cheerful nature kept me alive during the dark hours of sediment-sieving
and poo-collecting.
viii
I cannot leave out mentioning three of my closest and longest friends in science, Dr
Caroline Gaus, Dr Conny Guenter and Dr Fiona Manson who have provided me with
indispensable support during difficult times and celebrated with me during the height of
success.
I am forever indebted to the Daimler-Benz-Foundation, Germany, as well as the
Department of Education, Training and Youth Affairs of the Australian Government for
their financial support. Logistical support was provided by CSIRO Marine &
Atmospheric Research, Australia.
Last but not least I owe my loving thanks to Fabien, Yannick and Mamoune, who have
believed in me ever since, helped me to structure and focus my life (yes, sometimes
Frenchmen can help Germans in those regards) and brought incredible joy, respect and
warmth to my life outside of science. I would also like to thank my own mother, who has
raised me to be independent, self-sufficient and always aim high.
To conclude in the words of Wilhelm Bush: “Und die Moral von der Geschicht…”
…philosophical thinking makes all the difference when trying to balance social life,
working and writing a PhD. I wish you all happy reading!



ix
Abstract
The ecology of holothurians, their ecological role in marine ecosystems, and the
potential impacts of their removal (through over-fishing) was the subject of this study.
This was investigated by focusing on important aspects of holothurian behavioural
dynamics, such as burying and feeding, as well as assessing their impact on important
habitat variables such as sediment mixing, and seagrass and algae biomass and
productivity.
Certain species of holothurians have been harvested for the human food consumption
for centuries. The dry products of the body wall (also called ‘bêche-de-mer’ or ‘trepang’)
of these animals are considered as a delicacy to the Asian (particularly Chinese) food
industry. Currently, there are more than 20 holothurian species that are commercially
used around the world. Holothuria scabra is one of those most targeted species due to
their thick body wall and large size. Since most commercial species inhabit shallow
waters and are easily harvested by hand at low tide, high value species such as H. scabra
are easily over-exploited. H. scabra are already over-exploited or extinct in many
locations such as Solomon Islands, some places along the Indian coast and in many
places along the South-East Asian coastline.
The main objectives of this study were to: (a) document the difference in the
productivity and biomass of seagrass and benthic microalgae (BMA) with and without
H. scabra by means of in situ exclusion cages, (b) quantify the rate and extent of vertical
sediment transport associated with feeding and burying of H. scabra using luminophores
as tracers in aquaria, and (c) investigate the relationship between burying and feeding
x