Dr. Kelton McMahon
Ocean Sciences Department
University of California, Santa Cruz

Research Interests

I am interested in building a quantitative, mechanistic understanding of how human-environment interactions affect the functioning and resilience of coastal ecosystems, both top down (e.g. overfishing, invasive species) and bottom up (e.g. habitat degradation, climate change). My research takes places in a variety of coastal ecosystems, from tropical coral reef seascapes to Arctic fjords and lagoons, which form critical interfaces between humans and the environment. My research uses a multidisciplinary approach that pushes analytical frontiers, particularly in compound-specific stable isotope analysis (CSIA), to examine resource acquisition and allocation though studies of trophic dynamics and population connectivity. My research program is firmly rooted in fundamental ecological theory, but extends beyond the ecological questions to the applied management and practical decision-making needed to resolve current and emerging coastal ocean challenges. I work with local/regional governances to enhance both our research capacity, through complimentary knowledge systems and approaches, and the effectiveness of coastal management, through community participation. This work sheds light on the reciprocal relationship between the modifying actions of humans on coastal ecosystems and the good and services provided to people by those systems. My research is aimed to provided critical scientific support for the design and effective implimentation of ecosystem-based management policies, such as networked marine protected areas, necessary for successful long-term management and conservation of coastal ecosystems.


Trophic dynamics and animal movements establish links among humans, animals, plants, microbes, and the environment through resource acquisition and allocation. These linkages, in turn, create a reciprocal relationship between ecosystem goods and services and the impacts of humans on ecosystem structure and function. My research combines advanced analytical tools, including compound-specific stable isotope analysis (CSIA), with traditional ecological knowledge to provide new levels of detail on these connections and the roles they play in ecosystem functioning and resilience. My talk will present three case studies around this theme: 1) developing CSIA tools to identify essential habitats and migration corridors for socio-ecologically important fishes, 2) examining coral reef productivity and diversity through carbon flow pathways in tropical seascapes, and 3) exploring terrestrial-marine coupling supporting a culturally important subsistence fishing system in the Arctic. This work draws upon multiple research fields with distinct knowledge systems and methods to develop a mechanistic understanding of how resource acquisition and allocation affect the functioning and resilience of human-inclusive ecosystems. Together, these projects illustrate my long-term research goals aimed at solving current and emerging challenges in the coastal ocean related to overfishing, invasive species, coastal development, and climate change. This research has and will continue to contribute directly to the kinds of knowledge to action policies necessary to exact real change in critical coastal ecosystem management.