Results

pCO2 in seawater is controlled by the pH. With low pH we have high pCO2 (Figure 1). The beach and the sea tables seem to follow a pattern, but the seawater from the sea tables is approximately 0.04 units more acidic.

Measurements of pCO2 at the beach showed high pCO2 during the morning (Figure 2). Accumulation of respiration from the night before is what we believe caused elevated pCO2 during the morning. Reduction of pCO2 by ~ 90 ppm during the afternoon is probably a result of photosynthesis. We did not take samples from the sea tables to see the diurnal variability of pCO2 there because the pH measured by the DataSonde was stable, meaning the concentration of CO2 was relatively constant.

In situ measurements of pH at the sea tables and the intake showed that the seawater from the intake is more acidic than water in the sea tables (tsea tables= 4710.79, tintake= 11,402.00, p<0.05) (Figure 3). Comparing the three study sites, we found that the sea water from the intake is more acidic than the sea tables, which are more acidic than the beach.

Figure 1. Comparison of pH and p CO2 from Shannon Point Beach and Shannon Point Marine Center sea tables. (A) Seawater from the sea tables is more acidic than the beach by 0.04 units. (B) The seawater from the sea tables has higher p CO2 than the beach. Data are means (±SD), n=3.

Figure 2. Diurnal variability of p CO2 at Shannon Point Beach. In the morning p CO2 is high because of respiration during the previous night. During the day, photosynthesis takes place making CO2 decrease. Data are means (±SD), n=3.

Figure 3. In situ pH measurements from the DataSonde at the sea tables and the intake. The seawater at the intake is more acidic than the sea tables.

Page Updated 06.12.2012