Table 1. Summary of experimental settings, carbonate system parameters, nutrient levels, photosynthesis parameters, and sponge bioerosion figures (all values are given as mean values ± standard deviation for 10 days of exposure).
| Variable with [unit] or (scale) | below present pCO2 | present-day pCO2 | elevated pCO2 | strongly elevated pCO2 |
| temperature [°C] | 25.27±0.51 | 25.27±0.51 | 25.27±0.51 | 25.27±0.51 |
| salinity (PSS) | 33.15±0.23 | 33.14±0.24 | 33.14±0.24 | 33.15±0.23 |
| pH (NBS scale) | 8.24±0.02 | 8.17±0.03 | 8.02±0.04 | 7.63±0.08 |
| pH (converted to total scale) | 8.11±0.02 | 8.04±0.03 | 7.90±0.03 | 7.55±0.07 |
| DIC [µmol/kg] | 1911.7±11.3 | 1945.4±19.7 | 2011.6±27.7 | 2153.3±55.7 |
| TA [µmol/kg] | 2226.1±16.6 | 2231.0±13.8 | 2225.7±17.6 | 2232.3±14.5 |
| pCO2 [µatm]* | 338.6±37.4 | 393.2±55.6 | 570.9±82.4 | 1409.5±369.6 |
| pH (total scale)* | 8.10±0.04 | 8.05±0.05 | 7.91±0.05 | 7.57±0.12 |
| HCO3 − [µmol/kg]* | 1679.6±26.3 | 1730.2±35.7 | 1836.8±39.2 | 2031.4±67.4 |
| CO3 2− [µmol/kg]* | 222.6±16.9 | 204.2±18.5 | 158.7±16.1 | 82.2±22.3 |
| ΩAr * | 3.59±0.27 | 3.29±0.29 | 2.56±0.26 | 1.32±0.36 |
| ΩCa * | 5.45±0.40 | 5.00±0.45 | 3.89±0.40 | 2.01±0.55 |
| nitrate NO3 [µmol/l] | 0.05±0.05 | 0.03±0.02 | 0.02±0.01 | 0.03±0.05 |
| nitrite NO2 [µmol/l] | 0.04±0.01 | 0.03±0.01 | 0.04±0.02 | 0.03±0.00 |
| ammonium NH4 [µmol/l] | 0.14±0.23 | 0.10±0.15 | 0.04±0.04** | 0.05±0.03 |
| phosphate PO4 [µmol/l] | 0.08±0.02 | 0.08±0.02 | 0.07±0.03 | 0.07±0.02 |
| silicate SiO2 [µmol/l] | 4.80±0.41 | 4.85±0.49 | 4.69±0.60 | 4.89±0.44 |
| luminous intensity at start [cd] | 7359.4±343.5 | 7078.0±752.8 | 6782.1±415.7 | 6898.5±422.6 |
| Fv/Fm before treatment | 0.68±0.01 | 0.68±0.01 | 0.68±0.00 | 0.68±0.00 |
| Fv/Fm after treatment | 0.60±0.01 | 0.59±0.01 | 0.61±0.01 | 0.61±0.01 |
| F0 before treatment | 0.22±0.01 | 0.22±0.01 | 0.22±0.01 | 0.22±0.01 |
| F0 after treatment | 0.13±0.02 | 0.14±0.01 | 0.13±0.01 | 0.14±0.01 |
| penetration depth [cm] | 1.25±0.13 | 1.30±0.20 | 1.37±0.12 | 1.34±0.09 |
| sponge biomass [g] | 1.49±0.16 | 1.50±0.07 | 1.54±0.08 | 1.48±0.06 |
| weight change per replicate [g] | −0.32±0.07 | −0.32±0.02 | −0.38±0.04 | −0.52±0.06 |
| change relative to present-day [%] | 99.76±19.98 | 116.91±11.04 | 161.11±18.11 | |
| weight change per control [g] | 0.08±0.02 | 0.05±0.00 | 0.05±0.02 | 0.04±0.01 |
| bioerosion rate [kg m−2 yr−1] | 2.22±0.45 | 2.23±0.15 | 2.60±0.25 | 3.59±0.40 |
*
Carbonate system parameters computed with the software CO2SYS.
**
One contaminated sample excluded from analysis.