Biology ETDs

Publication Date

Fall 12-6-2019


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 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.




stable isotopes, community ecology, compound specific stable isotope analysis, kelp forests, conservation biology, biogeochemistry

Document Type


Degree Name


Level of Degree


Department Name

UNM Biology Department

First Committee Member (Chair)

Seth Newsome

Second Committee Member

James Estes

Third Committee Member

Torben Rick

Fourth Committee Member

Thomas Turner

Fifth Committee Member

Joseph Cook