10:45 AM - 12:15 PM
[AOS17-P13] Effect of Ocean Acidification on Community Photosynthesis in a Coastal Ecosystems; analysis based on movement of water mass
Keywords:Macroalgae, Photosynthesis, Water mass
Increase in anthropogenic CO2 emission and accompanying change in carbonate chemistry of seawater (Ocean acidification) are serious threat on marine ecosystems. Assessment at species level using aquarium showed inhibition of calcification and CO2 fertilization for primary producers, but the responses are species-specific. The areas around volcanic CO2 vents are assumed as natural analogues of ocean acidification. Surveys around CO2 vents would allow us to understand the effect of OA at ecosystem level.
We had discovered CO2 vents nearby the coast of Shikine Island, Izu Archipelago on 2014, and details of carbonate chemistry around this area had been well described. To evaluate the effect of ocean acidification on community photosynthesis. We set a plot of quadrat with 20 m × 20 m, and 4 loggers of dissolved oxygen were placed on its corners. At the center of the plot, loggers of pH, light and current were placed. Based on the direction and velocity of current, we estimated the duration of movement of water mass between the corners. Since benthic algal community produce oxygen under light condition, it is possible to estimate community photosynthesis using change in oxygen concentration and duration of water mass movement.
Community photosynthesis was significantly correlated with solar irradiance, showing direct relationship between light and photosynthesis. If high CO2 concentration fertilizes community photosynthesis, slope between light and community photosynthesis would increase. However, the slopes were not significantly different between two sites. CO2 fertilization could increase ecosystem function and services. Therefore, it is prospected positive effect of ocean acidification, but at community level in a coastal zone, benthic primary producers would be not fertilized by high CO2.
We had discovered CO2 vents nearby the coast of Shikine Island, Izu Archipelago on 2014, and details of carbonate chemistry around this area had been well described. To evaluate the effect of ocean acidification on community photosynthesis. We set a plot of quadrat with 20 m × 20 m, and 4 loggers of dissolved oxygen were placed on its corners. At the center of the plot, loggers of pH, light and current were placed. Based on the direction and velocity of current, we estimated the duration of movement of water mass between the corners. Since benthic algal community produce oxygen under light condition, it is possible to estimate community photosynthesis using change in oxygen concentration and duration of water mass movement.
Community photosynthesis was significantly correlated with solar irradiance, showing direct relationship between light and photosynthesis. If high CO2 concentration fertilizes community photosynthesis, slope between light and community photosynthesis would increase. However, the slopes were not significantly different between two sites. CO2 fertilization could increase ecosystem function and services. Therefore, it is prospected positive effect of ocean acidification, but at community level in a coastal zone, benthic primary producers would be not fertilized by high CO2.