Why is measuring ocean pH so important?

Ocean acidification is the ongoing decrease in the pH of the Earth's oceans, caused by the uptake of atmospheric carbon dioxide (CO2) as water and air mix at the water’s surface. Oceans, rivers and lakes absorb roughly one third of human-created CO2 emissions (22 million tons) each day.

Before the industrial era began, the average pH at the ocean surface was about 8.2 (slightly basic; 7.0 is neutral). Current ocean pH is roughly 8.1. This drop of 0.1 pH units represents a 25% increase in acidity over the past 200 years. Stress on marine life due to acidification (lowering the pH) leads to dying or severely affected ecosystems.

pH Ocean Sensors

Sea-Bird Scientific manufactures the following pH sensors: 
pH and CTD plus Dissolved Oxygen, for Moored applications to 50 m — SeapHOxTM (ion selective field effect transistor type pH sensor)

pH and CTD plus Dissolved Oxygen, for Moored applications to 2000 m — Deep SeapHOxTM (ion selective field effect transistor type pH sensor)

pH for Moored applications to 50 m — SeaFETTM

pH for Autonomous profiling floats (Argo) — Float Deep SeaFETTM

pH and CTD plus Dissolved Oxygen, Chlorophyll, and Turbidity, for Moored applications to 350 m – HydroCAT-EP (pressure-balanced glass-electrode /AG/AGCl-reference pH probe)

pH only, for Profiling applications to 1200 m — SBE 18 (pressure-balanced glass-electrode /Ag/AgCl-reference pH probe)

pH and ORP, for Profiling applications to 1200 m — SBE 27 (pressure-balanced glass-electrode /Ag/AgCl-reference pH probe)