Decreasing pH affects Seagrass Epiphyte Communities

Increasing CO₂ in the atmosphere is affecting marine ecosystems, including seagrass beds. Epiphytes are a component of seagrass ecosystems. Epiphytes make a significant contribution as important primary producers in the food chain. Increasing atmospheric CO₂ leads to a decrease in oceanic pH that can result in an unfavorable environment for the epiphytic community. This study was conducted to determine the effect of increasing CO₂ on seagrass epiphytic communities and biomass. Using a field experiment, we manipulated dissolved carbon dioxide to 800 - 1000 ppm in line with the forecast increase in atmospheric CO₂ levels in the year 2100. In situ C0₂ manipulations were conducted using an open-top mesocosm. The CO₂ enrichment was conducted by adding CO₂ at a concentration around 800 - 1000 ppm. This CO₂ was injected directly using a pump and hose to the acrylic mesocosm chamber. Epiphyte community structure was affected, with an increase in the abundance of filamentous algae but a decrease in the coralline algae community in the CO2 enriched treatment units. Overall, CO₂ enrichment had no effect on epiphyte biomass.