Research Overview

I am interested in how climate change will affect organisms’ ecology and geographic distributions. My research focuses on a species of seaweed, Pelvetiopsis limitata, which is common in the rocky intertidal from Point Conception, on the coast of Central California, to Vancouver Island, British Columbia. I look at how the survival of both adult and embryo life history stages varies with climatic conditions. I also look at the biomechanical properties of this seaweed, to see how an individual’s size affects its likelihood of being ripped from the rocky shore by waves. And, I use GIS techniques and mathematical modeling to see how the distribution of P. limitata might change under different climate change scenarios.

Demographic Study of Adults

For three and a half years, I conducted a demographic study of P. limitata at the Bodega Marine Reserve. I tagged individuals at two tidal elevations at four sites, and I checked their growth and survival every 8 weeks. I had expected hot summer temperatures to have an adverse effect on adult survival, but I was wrong; adult mortality was highest in the winter, when they are ripped off of the rocks by big waves associated with strong storms.

Experiments on Embryo Survival

This summer, I’m conducting manipulative field experiments to look at the factors that impact embryo survival. I’m asking a number of questions. First, I want to know if the increase in temperature, predicted to occur as a result of global warming, will affect embryo survival. I seed ceramic plates with embryos and attach the plates to the rock in the intertidal. I use 2 plate colors. The dark plates get hotter than the white plates—instant climate change!  Second, I want to know whether embryo survival differs at different tidal elevations. And third, I’m examining whether embryos need to be under the shade of a canopy of adult algae in order to survive, or if they can survive alone. If this species is to endure rising sea levels, new generations must be able to survive at higher elevations, without the shade and protection provided by their parents.

Biomechanics of P. limitata

From the demography study, I know that adults are at risk of being dislodged by waves. And larger algae are more likely to be ripped off than smaller algae. This summer, I’m working with some friends at the Denny Lab at Stanford’s Hopkins Marine Station to figure out how the drag forces experienced by P. limitata scale with algae size.

Geographic Distribution

I’m using GIS techniques to see if the geographic distribution of this species is constrained by climate and topography. I will also see how its distribution may change under different climate change scenarios.

My research uses a variety of techniques to answer one of the most pressing questions of our time: how will the natural world respond to a changing climate?