Meeting Abstract
Pseudoreplication and similar experimental design errors continue to be prevalent in ocean acidification (OA) research. One of the major impediments to creating properly replicated trials is the cost of purchasing enough control systems to independently regulate CO2 concentration in separate holding tanks. To bring down the cost of such replication we developed and tested a pH-stat system constructed largely with open hardware. This pH-stat controller was built around an Arduino Mega 2560 microcontroller board, using an Atlas Scientific EZO pH circuit to interface with the pH probe, an Adafruit MAX31865 to interface with a PT100 temperature sensor, and controlling pH by actuating a solenoid valve to deliver pure CO2 gas to a bubble stone immersed in the holding tank water. These systems were tested over a 3-week period with a single octopus occupying each controlled holding tank. Tank pH was periodically verified using the m-cresol purple photometric method. We found the control system performs comparably to similar units commercially available for a fraction of the price, possibly making appropriately replicated OA treatments available to many more institutions.
