Growth, Condition, and Survival of Larval Arctic Cod and Walleye Pollock in a Warming Ocean

152 Pages·2017·3.3 MB·English

AN ABSTRACT OF THE THESIS OF

Brittany L. Koenker for the degree of Master of Science in Marine Resource Management
presented on August 9, 2017

Title: Growth, Condition, and Survival of Larval Arctic Cod and Walleye Pollock in a Warming
Ocean

Abstract Approved:

Louise A. Copeman

Arctic cod (Boreogadus saida) is an ecologically significant species that plays a critical
role channeling energy throughout the Arctic marine food web. Arctic cod is uniquely adapted to
occupy ice edge habitats, however, a basic understanding of its larval physiology and habitat
requirements is lacking due to widespread sea ice cover which limits spring field sampling.
Forecasted shrinkage of sea ice habitat could facilitate invasions of non-ice-obligate North
Pacific gadids, such as walleye pollock (Gadus chalcogrammus). By assessing the sensitivity of
the early life stages of fish species to environmental conditions affecting growth (i.e.,
temperature and food availability), it is possible to better understand larval survival, and thus the
factors dictating success of the population in the face of climate change. To this aim, I conducted
laboratory experiments to directly examine the growth and survival of Arctic cod and walleye
pollock at two larval stages in response to forecasted changes in temperature and food
availability. Critical rates obtained from these experiments demonstrate that larval Arctic cod has
a competitive advantage over walleye pollock in terms of growth and survival at low
temperatures. However, rising temperatures and altered productivity regimes associated with
climate change have the potential to constrain the habitat that is available to Arctic cod.
Temperature-dependent growth models developed from this study emphasize the species-specific
and stage-specific differences in the growth of larval gadids and provide a baseline for
examining temperature-dependent growth in the field. Following laboratory experiments, I
examined the morphometric and lipid condition of each species under the same experimental
conditions, to investigate the effects of temperature and food availability on larval fish condition
and the suitability of different condition indices. Temperature and food availability impacted
larval condition and lipid storage in a species-dependent manner. Furthermore, later stage larval
condition was more sensitive to changes in prey availability at higher temperatures, indicating
that larval condition may be negatively impacted under a climate change scenario of combined
warming and reduced availability of lipid-rich prey. Collectively, the physiological rates
determined within my thesis will add to a better understanding of the mechanisms affecting
condition and survival of gadid larvae at the Arctic-boreal interface. Knowledge of the habitat
requirements of these ecological important species is essential for effective resource
management, and is key to understanding the broader implications of global change.
©Copyright by Brittany L. Koenker
August 9, 2017
All Rights Reserved
Growth, Condition, and Survival of Larval Arctic Cod and Walleye Pollock
in a Warming Ocean

by
Brittany L. Koenker

A THESIS

submitted to

Oregon State University

in partial fulfillment of
the requirements for the
degree of

Master of Science

Presented August 9, 2017
Commencement June 2018
Master of Science thesis of Brittany L. Koenker presented on August 9, 2017.

APPROVED:

Major Professor, representing Marine Resource Management

Dean of the College of Earth, Ocean, and Atmospheric Sciences

Dean of the Graduate School

I understand that my thesis will become part of the permanent collection of Oregon State
University libraries. My signature below authorizes release of my thesis to any reader upon
request.

Brittany L. Koenker
ACKNOWLEDGEMENTS

The work presented in this thesis would not have been possible with the guidance and
support of many people. I would like to express my sincere gratitude to all the people and
organizations that made my research possible and provided me with such a rich, interdisciplinary
experience at OSU.
First, I would like to thank my advisor, Louise Copeman, for taking a leap of faith on me
and for providing me with the laboratory and research experience that I hoped for. I am so
grateful for your patience and support while I learned experimental and laboratory protocols, and
the time you have put into answering my questions and providing insight into these experiments.
You provided me with the skills, materials, and guidance necessary for every stage of this project
and made me feel welcome in the Marine Lipids Laboratory.
I am also so grateful to my committee members, Ben Laurel and Lorenzo Ciannelli, for
contributing their expertise to this project. Ben, thank you for joining my committee from the
very beginning and being involved in every aspect of the project since. You have dedicated much
of your time and attention to guiding me through this project, and had an answer for each of my
endless questions. Lorenzo, thank you for joining this project and generously providing me with
hands-on help with statistical analyses and R programming, in addition to offering a fresh
perspective on the project design.
I would like to extend my sincere appreciation to the NOAA-AFSC staff at the Hatfield
Marine Science Center for the use of facilities, logistical support, and guidance. Paul Iseri, thank
you for your expertise in lab construction, tank design, and maintenance of the experimental
setup. Scott Haines, Michele Ottmar, and Eric Hanneman, thank you for your assistance in larval
husbandry and live food production, as well as, answering all my questions along the way. Thank
you to those who taught me or supported me through my work in the Marine Lipids Lab – Angie
Sremba, Michelle Stowell, Kalyn Hubbard. Your friendship and comradery during the many
hours of Chromarod development was invaluable.
I am also incredibly grateful for the overwhelming amount of work that takes place, often
behind-the-scenes, by everyone in the College of Earth, Ocean, and Atmospheric Sciences.
Robert Allan, Lori Hartline, and many others at CEOAS Admin – the educational experiences
offered by CEOAS programs would not be possible without you. Flaxen Conway, you have
given me an incredible introduction to Marine Resource Management and have helped me to
grow and succeed during my time at OSU. I am also thankful to my entire MRM cohort and
friends for all of the encouragement and laughter along the way.
Finally, an enormous thank you to my family and friends for supporting me during my
time at OSU, and long before that. Mom and dad, thank you for never doubting that I could
succeed in grad school or reach any of the goals that I set my mind to. Thank you, Allison, for
editing this document as I sit here writing this, and for setting the bar so high that I have no
choice but to continue growing and setting new goals if I want to keep up.
Cole, you have put up with the brunt of my stress and worry, with constant reassurance
and support. You now know more about larval fish than you ever hoped to, you’re welcome.
Lastly, my pup, Charlie. You have cuddled up with me for long nights of writing, listened to
every practice presentation, and forced me to get outside and take walks rain or shine. I couldn’t
have done it without any of you!
CONTRIBUTION OF AUTHORS

I am the first author on each of the manuscripts produced from this thesis (Chapters 2 and
3). With the assistance of my co-authors, I identified the research questions and performed
laboratory experiments for later stage larvae. I performed experimental sampling protocols and
data collection, in addition to, completing all data analyses and manuscript preparations.
Drs. Louise Copeman and Benjamin Laurel are co-authors on the manuscripts that were
produced from Chapters 2 and 3. They contributed to all stages of this research including
development of research questions, experimental design, material and facility use, data analysis,
interpretation of results, manuscript revisions and financial support. They also conducted the
laboratory experiments for first-feeding larvae and provided samples from these experiments for
lipid analyses.
Dr. Lorenzo Ciannelli is a co-author on the manuscript produced from Chapter 2. He
provided ample guidance on statistical analysis and development of growth models.
Additionally, he offered feedback on thesis design and aided in the revision of all chapters.
Funding for this research was provided by a North Pacific Research Board grant co-
authored by Drs. Copeman and Laurel. Additional support was provided in part by an Oregon
State University Provost’s Distinguished Graduate Fellowship and Frank M. & Gertrude R.
Doyle Foundation Scholarships.
TABLE OF CONTENTS
Page
1 General Introduction ................................................................................................................ 1
1.1 Thesis Overview ............................................................................................................. 1
1.2 Climate Change in the Arctic .......................................................................................... 3
1.3 Ecological Importance of Arctic Cod ............................................................................. 4
1.4 Early Life History ........................................................................................................... 5
1.5 Temperature Effects on Larvae ....................................................................................... 7
1.6 Lipid Metrics and Nutritional Condition ........................................................................ 7
1.7 Arctic Marine Management ............................................................................................ 9
1.8 Research Objectives ...................................................................................................... 11
1.9 References ..................................................................................................................... 13
1.10 Figures........................................................................................................................... 19
2 Effects of Temperature and Food Availability on the Survival and Growth of Larval Arctic
Cod and Walleye Pollock ...................................................................................................... 22
2.1 Introduction ................................................................................................................... 22
2.2 Methods......................................................................................................................... 26
2.2.1 Egg Sources .......................................................................................................... 26
2.2.2 Egg Incubation ...................................................................................................... 26
2.2.3 Experimental Design ............................................................................................. 27
2.2.4 General Husbandry ............................................................................................... 29
2.2.5 Live Food Preparation ........................................................................................... 29
2.2.6 Data Collection and Analysis ................................................................................ 31
2.3 Results ........................................................................................................................... 34
2.3.1 Temperature Effects on Survival and Growth ...................................................... 34
2.3.2 Interactive Effects of Temperature and Prey Availability .................................... 36
2.3.3 Temperature-Dependent Growth Models ............................................................. 39
2.4 Discussion ..................................................................................................................... 41
2.4.1 Temperature-Dependent Survival and Growth ..................................................... 42
2.4.2 Interaction of Temperature and Food Availability Impacts .................................. 46
2.4.3 Larval Gadid Growth Models in Relation to Climate Change ............................. 48
2.5 Conclusions ................................................................................................................... 50