The Effect of Temperature Change on the Relationship Between Tegula funebralis Grazing and Algal Growth Rates

The turban snail, Tegula funebralis, is an herbivore along the central California coastline that feeds on a variety of algae. It has an important role in the intertidal and shallow subtidal food webs because it links the primary producers to higher trophic levels. However, these food web dynamics are expected to be increasingly impacted by changes in temperature due to climate change. In the past few decades, the temperature around the world has risen significantly and is estimated to rise a maximum of 3°C over the next century. Although T. funebralis has a wide thermal tolerance, it has a limited ability to acclimate, thus it faces high risk in the event of sustained warming (Stenseng 2005). We are interested in the effects of climate change associated temperature shifts on marine environments, so we wanted to focus our studies on discovering the effects of temperature on kelp forests grazing organisms in our local ecosystems. Here we investigate the impact of temperature change on the relationship between T. funebralis grazing and growth rates (essentially a measure of how efficiently these snail convert food resources to body mass). Individual snails were placed in tea infusers with equal amounts of kelp in tanks of different environmentally relevant temperatures (8°C, 13°C, 18°C, and 24°C). Snail weight and kelp weight were measured 3 times a week over the course of 4 months. For each trial, we calculated the average snail growth rate and the average grazing rate. Data analysis was done using the R statistical programming language. We present a comparison of snail weight gain to kelp weight loss, finding the rate of snail grazing on kelp and how it is affected by changing temperatures.