Outreach | 2016 International Coral Reef Symposium

The sea anemone Anthopleura elegantissima occurs in the intertidal zone from Mexico to Alaska. It is symbiotic with two genera of microalgae, the highly productive dinoflagellate Symbiodinium and the less productive chlorophyte Elliptochloris. The enzyme carbonic anhydrase (CA) catalyzes the interconversion of bicarbonate and CO2 and is known to play an important role in delivering CO2 to symbionts embedded deep in host tissues. Symbiont types in anemones are differentially distributed depending on latitude, tidal height, and light level. Anemones containing Symbiodinium are found at lower latitude, higher light environments compared to Elliptochloris-containing anemones that occur at higher latitude and lower light. Anemones in very low light lack symbionts. Previous research found aposymbiotic (without symbionts) and Elliptochloris-containing anemones to have similar and low CA activity compared to Symbiodinium-containing anemones. We predicted that anemones collected from lower latitudes would have greater CA activity than anemones of the same symbiotic state at higher latitudes. To test the effect of light on CA, A. elegantissima from the Oregon coast were collected and split into three 30-day treatments: dark, low light, and high light. To test the effects of latitude A. elegantissima were collected from several locations ranging from central Oregon to the Puget Sound. Symbiont density counts and CA assays were performed in triplicate on each anemone. Our results suggest that latitude, symbiont type and density, and light interact to influence CA in A. elegantissima.