University of New Mexico UNM Digital Repository Biology ETDs Electronic Theses and Dissertations Fall 12-6-2019 RECONSTRUCTING ENERGY FLOW THROUGH MODERN AND HISTORICAL MARINE COMMUNITIES: INSIGHTS FROM AMINO ACID ISOTOPE ANALYSIS Emma A. Elliott Smith University of New Mexico Follow this and additional works at: https://digitalrepository.unm.edu/biol_etds Part of the Biogeochemistry Commons, Biology Commons, and the Ecology and Evolutionary Biology Commons Recommended Citation Elliott Smith, Emma A.. "RECONSTRUCTING ENERGY FLOW THROUGH MODERN AND HISTORICAL MARINE COMMUNITIES: INSIGHTS FROM AMINO ACID ISOTOPE ANALYSIS." (2019). https://digitalrepository.unm.edu/biol_etds/341 This Dissertation is brought to you for free and open access by the Electronic Theses and Dissertations at UNM Digital Repository. It has been accepted for inclusion in Biology ETDs by an authorized administrator of UNM Digital Repository. For more information, please contact [email protected], [email protected], [email protected]. Emma A Elliott Smith Candidate Biology Department This dissertation is approved, and it is acceptable in quality and form for publication: Approved by the Dissertation Committee: Seth D Newsome , Chairperson Joseph Cook Thomas Turner James A Estes Torben C Rick i RECONSTRUCTING ENERGY FLOW THROUGH MODERN AND HISTORICAL MARINE COMMUNITIES: INSIGHTS FROM AMINO ACID ISOTOPE ANALYSIS by EMMA A ELLIOTT SMITH B.S., Biology, University of California Santa Cruz, 2013 M.S., Biology, University of New Mexico, 2018 DISSERTATION Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Biology The University of New Mexico Albuquerque, New Mexico May 2020 ii ACKNOWLEDGEMENTS I would like to extend my deepest appreciation to my advisor, Dr. Seth Newsome, whose mentorship and support has made this dissertation possible. I am also grateful to the members of my committee, Dr. Torben Rick, Dr. Jim Estes, Dr. Joe Cook and Dr. Tom Turner, for their feedback and guidance, and to Dr. Jim Norris, for help sampling historical kelps at the Smithsonian Institution. I would also like to thank Dr Marilyn Fogel, an amazing and inspiring researcher whose pioneering efforts have set a high bar for female isotope ecologists to strive towards. I would like to acknowledge my funding sources, which made much of this work possible. These include fellowships through the NSF Graduate Research Program (DGE-1418062) North Pacific Research Board, and American Association of University Women–Santa Fe Chapter. UNM sources of funding include the Latin American and Iberian Institute, Graduate and Professional Student Association, Biology Department, Biology Graduate Student Association, and the Center for Stable Isotopes. I also want to express my sincere gratitude to the many friends and colleagues who have made my time as a graduate student a joy. They are far too many to list, but include Sarah Foster, Alexi Besser, Dr. Cataline Tomé, Dr. Geraldine Busquets, all members of the Newsome Lab and UNM Center for Stable Isotopes. Special thanks also to Drs. Viorel Atudorei and Laura Burkemper for their help and expertise in the analytical portion of this project, as well as their boundless patience. Lastly, I want to thank my family for their unconditional love and support. In particular my mother, Felisa Smith, who instilled in me an appreciation for the natural world and showed by example that women do belong in science, my father, Scott Elliott who has always challenged me to go the extra mile, my sister, Rosemary Elliott Smith, and my talented and creative grandmother, Maria del Carmen Calvo, who is deeply missed. iii RECONSTRUCTING ENERGY FLOW THROUGH MODERN AND HISTORICAL MARINE COMMUNITIES: INSIGHTS FROM AMINO ACID ISOTOPE ANALYSIS by Emma A Elliott Smith B.S., Biology, University of California Santa Cruz M.S., Biology, University of New Mexico Ph.D., Biology, University of New Mexico ABSTRACT The fundamental currency of life is energy. Organisms need energy to grow, to survive and to reproduce. Understanding the acquisition of energy by consumers is thus a foundational aspect of biological research. This is especially important in the modern era, as impacts of ongoing anthropogenic effects will be mediated or amplified through food webs. Here, I explore how isotopic analysis of individual amino acids – a technique new to ecological studies – can be used to trace energy flow through animal communities in modern and ancient time periods. In particular, I focus on kelp forest food webs, which are nearshore marine ecosystems highly vulnerable to human impacts. I explore how important kelp (macroalgae in family Laminariales) are as an energy source to consumers from localities as diverse as Katmai National Park, Alaska, and Antofagasta, Chile. I also examine how iv the ecology of an important kelp forest species, the sea otter (Enhydra lutris) has changed over time in California. Finally, I employ a biochemical perspective to identify the mechanisms driving differences among producer isotopic values. My dissertation demonstrates that amino acid isotopic measurements can be used to confidently identify kelp-derived energy in consumers across space and time. Using this, I find that across different localities and oceanographic regions, kelp is vitally important to consumers as a source of energy. My work highlights the importance of understanding energy flow through food webs, and how this knowledge can help to better protect and manage biological systems. v TABLE OF CONTENTS List of Figures .................................................................................................................. vii List of Tables .................................................................................................................. viii Chapter 1: The importance of kelp to an intertidal ecosystem varies by trophic level: insights from amino acid d13C analysis ............................................................................1 Chapter 2: Reductions in the dietary niche of southern sea otters (Enhydra lutris nereis) from the Holocene to the Anthropocene ............................................................25 Chapter 3: Multichanneling in a Chilean kelp forest is facilitated by intraspecific specialization ....................................................................................................................48 Chapter 4: Biochemical mechanisms and environmental influences on the amino acid isotopic composition of marine primary producers ......................................................71 Appendix 1: Supplementary Materials for Chapter 1 ................................................101 Appendix 2: Supplementary Materials for Chapter 2 ................................................120 Appendix 3: Supplementary Materials for Chapter 3 ................................................146 Appendix 4: Supplementary Materials for Chapter 4 ................................................154 References ......................................................................................................................161 vi LIST OF FIGURES Figure 1.1 ..........................................................................................................................13 Figure 1.2 ..........................................................................................................................15 Figure 1.3 ..........................................................................................................................16 Figure 1.4 ..........................................................................................................................18 Figure 2.1 ..........................................................................................................................27 Figure 2.2 ..........................................................................................................................31 Figure 2.3 ..........................................................................................................................38 Figure 2.4 ..........................................................................................................................40 Figure 3.1 ..........................................................................................................................61 Figure 3.2 ..........................................................................................................................63 Figure 3.3 ..........................................................................................................................64 Figure 4.1 ..........................................................................................................................86 Figure 4.2 ..........................................................................................................................88 Figure 4.3 ..........................................................................................................................90 Figure 4.4 ..........................................................................................................................94 vii LIST OF TABLES Table 1.1 ............................................................................................................................17 Table 2.1 ............................................................................................................................32 Table 2.2 ............................................................................................................................39