Measurements of the upper water column (to 30-m depth) of pH, temperature, conductivity, chlorophyll and dissolved oxygen at Santa Catalina Island were made from a fixed mooring and by profiling the water column from a boat and on SCUBA. The average pH (8.08 at 18 m) was found to be higher than that reported off the nearby mainland and the Northern Channel Islands. The higher value is thought to result from less upwelling at the island compared to other locations. Within the accuracy of the sensors there was no seasonal dependence detected at near-surface, nor a pH signal associated with the sub-surface chlorophyll
maximum. Variations in pH at depth corresponded to advection of gradients by internal waves. We conclude that marine life living at depths affected by internal waves experience significant variation in pH; and, the internal waves associated with the island’s slope increase the average pH found at depth relative to nominal values.
Gelpi C., in review. Dynamics of pH at Santa Catalina Island. Catalina Marine Society. Article.
