Effects of increased pCO2 levels on the nematocyst densities in the symbiotic sea anemone Anthopleura elegantissima

Abstract

The temperate sea anemone Anthopleura elegantissima participates in a facultative symbiosis with two genera of unicellular photosynthetic algae. Under stressful conditions such as increased levels of pCO2, anemones expel their algal symbionts causing the anemones to rely more heavily upon heterotrophic feeding. A heavier reliance on heterotrophic feeding could be accomplished by increasing the density of nematocysts. Anthopleura elegantissima individuals were collected from the Friday Harbor Laboratories shoreline (48° 32.7646 N, 123° 00.5932 W), Washington in June 2014, and the number of nematocyst per μg of protein was measured to determine if increasing oceanic pCO2 levels will affect the density of nematocysts. The number of nematocyst per μg of protein was measured again after 7 days in higher (2200 μatm) or ambient (700 μatm) pCO2 conditions. There was no difference in the density of nematocysts between individuals kept in different pCO2 levels.