Figure 1. Tide pool pH and pCO₂ values measured over time.

Over 6 hr following isolation of pools by the receding tide, (A) pH increased by an average of 0.4 units (total scale) and (B) pCO₂ declined by an average of ∼233 µatm. However, there were no differences in pH (P = 0.591) or pCO₂ (P = 0.777) between control pools (with no CO₂ added; red circles) and +CO₂ pools (blue triangles). Values are means ±s.e.