Behavioral Response of Hermit Crabs (Clibanarius digueti) to Dissolved Carbon Dioxide

Abstract:

CO₂ induced ocean acidification is currently changing the population dynamics of marine organisms. As a result of ocean acidification, marine organisms expend extra energy on modifying behaviors. The current rate of ocean acidification will deplete the marine food chain that much of the world relies on as their major food supply.

The purpose of this study was to understand whether and how ocean acidification affects the behavior of hermit crabs Clibanarius digueti. We hypothesized that an increase in carbonic acid would modify grazing and individual movement, because an increase in acidification alters the normal chemical composition of the water and potentially the niche occupancy of C. digueti.

A model tidal pool experiment consisting of two tanks (control and treatment) inhabited with seven living C. digueti was set up in the Ocean Biome of Biosphere-2. Each tank was also provided with uninhabited shells: two Turbo fluctuosa and four Cerithium sp. Gaseous CO₂ was dissolved into a treatment tank and measured as dissolved CO₂ by using a sodium hydroxide titration method. Additionally, water conditions were characterized for UV- light and temperature. Two trials were run in this experiment with tanks and treatments interchanged in each trial. We assessed whether increased CO₂ affected hermit crab shell change rate.

We found that shell changes only happened among C. digueti placed under increased CO₂. The information from this analysis will allow us to assess whether ocean acidification affects basic behavior in hermit crabs, which could later affect population dynamics. Bringing together all of this information will allow us to measure the effects of climate change on the behavior of C.Digueti.

---

<< Previous Abstract | Next Abstract >>