By Isabella King. Mentor Prof Seth Newsome. Understanding the dietary habits of marine predators is crucial for conservation and ecosystem management. One such marine keystone species is the sea otter (Enhydra lutris), which plays a vital role in shaping nearshore ecosystems by regulating prey populations. Their influence on habitat structure and dynamics, particularly in kelp forests and eelgrass beds, makes them an important species for conservation efforts. However, variations in these habitats may contribute to a variation in prey resources, availability, and overall dietary differences. While existing research on sea otter populations in kelp forests show a diet mainly composed of sea urchins, crabs and snails, less is known about the diversity of prey and dietary habits of sea otters in estuarine habitats. Hence, I propose to use stable isotope analysis (SIA) to compare sea otter diet composition in kelp forests and estuaries, providing insight into the trophic variability of sea otters in each habitat. By analyzing δ13C and δ15N isotopic signatures in vibrissae (whiskers) collected from California sea otters in Big Sur (kelp forests) and Elkhorn Slough (estuary), I will examine food web dynamics, prey selection, and potential dietary specialization. Based on previous research, I anticipate that sea otters in kelp forests will primarily feed on invertebrates such as crabs or sea urchins, whereas those in estuaries may exhibit greater dietary specialization in response to limited prey availability. This study contributes to the growing body of research using SIA to track dietary trends in animals while providing new insights into estuarine sea otter diets in California.
