Closed vs Flow-Through Respirometry
Closed Cell Respirometry
The closed cell method is generally more sensitive than the flow-through method to changes in respiration rate and has a faster response time. However, the main drawback of the closed-cell method is that as the experiment proceeds the organism will deplete the oxygen level inside the cell. If the oxygen concentration within the cell is allowed to drop below a certain threshold level then the organism’s behaviour and hence respiration rate may be affected.However, running shorter experiments and stopping to flush the cell out, before the critically low oxygen level is reached, then refilling with oxygen-saturated water could combat this.
Flow-Through Respirometry
Flow-through respirometry is slightly more complicated than closed-cell, as the researcher will have to establish the correct balance in the flow rate to detect and measure changes in respiration without forming a significant concentration gradient within the chamber.
However the flow-through method ensures that the oxygen concentration remains constant throughout the course of the experiment and negates the requirement to refill the chamber with fresh water. Therefore, once the researcher has established the correct flow-rate, the experiment can essentially proceed over a much greater timescale without the concern of the oxygen concentration, or indeed any waste products, affecting the organism's behaviour.