Graduate Research Assistant - Rebecca Gooding
NOAA/Padilla Bay NERR Research Assistantship Recipient
Impacts of Climate Change on Mussel Bed Communities
Rebecca Gooding
PhD candidate, University of British Columbia
Department of Zoology
Vancouver, BC
Effects of temperature and mussel size on intertidal mussel bed infaunal communities: implications for climate change and biodiversity.
Background
Mussel beds are made up of more than just mussels (Fig. 1). These habitats are home to hundreds of epifaunal species. Organisms inhabiting the intertidal zone must withstand pounding waves, temperature extremes, and air exposure as the tides move in and out. Mussel shells and byssal threads (the filaments or “beards” which mussels use to attach themselves to their substrates) offer protection from the harsh conditions of the rocky intertidal environment (Fig. 1).
Fig. 1. A mussel bed in Padilla Bay. Close-up shows the byssus of a mussel.
While mussel beds can withstand the changing tides, global climate change may cause damage to these diverse ecosystems. As the amount of carbon dioxide in the air increases, so does the amount of carbon dioxide dissolved in seawater. The resulting acidification changes the basic chemistry of the oceans and decreases the growth rate of organisms which rely on dissolved calcium carbonate to build their shells. If current carbon dioxide emission trends continue, it is possible that mussels will remain smaller for longer periods of time and be less able to protect associated epifauna (organisms which live among the mussels) from temperature extremes, which may also increase due to global climate change. Rebecca Gooding, a graduate student working towards her PhD at the University of British Columbia in Vancouver and the recipient of a 2008 Padilla Bay Research Assistantship, is studying how mussel size and mussel bed temperature impact epifaunal communities. Her research is being conducted on the rocky shores of Saddlebag Island, located just east of Guemes Island in Padilla Bay.
Fig. 2. Rebecca Gooding adjusting the mesh cages surrounding mussel plots on Saddlebag Island.
Methods
Becca used two techniques to create mussel beds on the rocky shores of Saddlebag Island (Fig. 2, 4):
- Transplant Plots: Becca transplanted mussels of various sizes from dock pilings to the rocky shores of Saddlebag Island, enclosing the transplants in mesh cages to keep out predators, such as sea stars (Fig. 3). Mussels of small (10-30 mm) and large (35+ mm) shell lengths were painted black to increase their temperature or white to decrease their temperature. “Cool/large”, “cool/small”, “warm/large”, and “warm/small” plots were created using this technique.
After ten weeks, all contents of the transplant plots will be removed and examined in the lab to determine the populations and diversity of epifaunal organisms present among the mussels.
- 2. Recruit Plots: Becca cleared the algae from small plots and added mesh cages to keep out predators. Mussels were allowed to settle naturally on the exposed rock. Mesh shades attached to the cages were used to decrease the temperature in the “cool” plots. Because the intertidal shore of Saddlebag Island experiences unusually high temperatures, unshaded plots were considered to be “warm”.
Becca will survey the recruit plots without removing organisms for the first three months of the experiment. After that, a subset of the “warm” and “cool” plots will be removed entirely every few months and brought to the lab to determine the populations and diversity of mussel bed epifauna. This periodic sampling will also allow Becca to determine whether temperature affects the rate at which succession (changes in an ecological community’s species composition after the establishment of a new habitat) occurs in the mussel beds.
Fig. 3. Pisaster ochraceus, a mussel predator that prevents mussel beds from growing on Saddlebag Island.
Project Significance
By sampling the epifauna among the mussels to determine diversity and succession patterns, Becca will be able to observe how differences in mussel size and mussel bed temperature combine to impact the hundreds of other organisms that call mussel beds home. Becca’s research will provide insight into how intertidal communities in and around Padilla Bay might react to the warmer temperatures and ocean acidification that global climate change may cause. It will also provide a framework for future research into climate change’s impact on whole communities rather than just individual species.
Fig. 4. Rebecca Gooding working on experimental plots on Saddlebag Island.
Biographical Information
Rebecca Gooding is a PhD student in the Department of Zoology at the University of British Columbia in Vancouver. She received a 2008 Padilla Bay Research Assistantship to help fund her research project, “Effects of temperature and mussel size on intertidal mussel bed infaunal communities: implications for climate change and biodiversity.”