Mathias Symposium 2016

Bodega Marine Laboratory/Reserve

February 26-28, 2016
2016 Lecturers

Benjamin H. Becker
Deputy Associate Director, Natural Resource
Stewardship and Science, National Park Service
Associate Adjunct Professor, UC Berkeley
PhD University of California, Davis

Long-term Trophic Level Variation of California Current Seabirds from 1880 – 2005

Prey availability and quality can affect seabird reproductive success, survivorship, and long-term population persistence. A key question is to what degree dietary variation in seabirds is explained by top-down (human harvesting of prey) or bottom-up effects (natural variability, climate change) on prey availability. We sought to test the relative importance of these factors by examining variation in diet (trophic level) and niche width (dietary diversity) in five species of California Current seabirds from the 1880s – 2005 using stable carbon and nitrogen isotope ratios feathers of feathers from museum specimens. To ensure that isotope signatures represented the California Current, we chose seabird species that underwent both basic and alternate molt in or near central California: Common Murre (Uria aalge), Marbled Murrelet (Brachyramphus marmoratus), Tufted Puffin (Fratercula cirrhata), Pelagic Cormorant (Phalacrocorax pelagicus), and Cassin’s Auklet (Ptychoramphus aleuticus). Overall, trophic level declined for most species over the study period, suggesting less reliance on fish and more on invertebrates. Most of the decline in trophic level was explained simply by time, suggesting long-term monotonic changes. However, relationships to oceanic indices and prey harvest will also be discussed.

Bio: Ben Becker is the Chief Scientist and Marine Ecologist at Point Reyes National Seashore. He also manages the Pacific Coast Science and Learning Center, which facilitates external researchers working in the park and the dissemination of new findings to park managers and the public. This includes immersive science programs for Bay Area youth. 

Jessica L. Blois
Assistant Professor
School of Natural Sciences, UC Merced
PhD Stanford University

Ecological Processes in a Changing Environment: Perspectives from the Past

Understanding the patterns of and mechanisms underlying biodiversity change is important given the many factors that may influence future species and communities. To provide a long-term context for recent and future biodiversity changes, my research explores the influence of two potential primary drivers of biodiversity change: climate and associations between species. In this talk, I focus on several projects that use the Quaternary fossil record of the past 21000 years to disentangle these two potential drivers, and in the process, explore the robustness of models commonly used to project future biodiversity changes. Overall, Quaternary fossil assemblages show strong signals of environmental structuring which implies that, at least at broad scales, climate-based models are relatively good for predicting changes in species and communities. Interactions between species are likely influencing assemblage structure and diversity as well; incorporating associations between taxa into models could lead to relatively greater predictive ability, particularly across periods of substantial climate change. Despite improved understanding of the factors structuring Quaternary biodiversity, models perform poorly with increasing amounts of climate change and regardless of whether associations are included or not, so care needs to be taken when projecting biodiversity changes into potential no-analog climates of the future.

Bio: Dr. Jessica Blois is an Assistant Professor in Life and Environmental Sciences at UC Merced.  Dr. Blois received her undergraduate degree in Ecology, Behavior, and Evolution from the University of California, San Diego and then worked for a few years as a biological technician for the U.S. Forest Service in Oregon and California. She then went on for graduate work, first to earn her M.A. in Biological Sciences from Humboldt State University in 2005, then her PhD in Biology from Stanford University in 2009. She worked as a postdoctoral research associate at the University of Wisconsin, Madison before moving to a faculty position at UC Merced in January 2013. Dr. Blois is a paleoecologist interested in understanding the factors contributing to changes in genes, species, and communities across time and space. Her work combines field work aimed at broadening our samples of fossil and modern mammals, ancient and modern DNA to understand how genetic diversity is structured spatiotemporally, and paleobiogeographic modeling. Most of her work is on small mammals and vegetation over the last 21,000 years in North America. She has particular interests in teasing apart the roles of environmental versus biotic drivers of biodiversity change, in merging data from different kinds of fossil proxies such as mammal bones and plant macrofossils, and in merging perspectives from the past and present to help conserve future biodiversity.