What are the typical challenges you meet when setting up a microsensor experiment?
It’s all about stability and ease of access! Stability – no unsteady tables or shaky tanks and containers – is the main thing in any microsensor set-up. I use a lot of time to ensure that the pots, the cores, or the trays where I have my specimens are well fixed, e.g. to the table or the bottom of the tank. Then, I fix all cables, and also the leaves if working with plants, to avoid that I break a sensor already in the process of mounting it in the micromanipulator… My laboratory set-ups look very “clean”.
What were your initial reasons for going into the field?
Curiosity! I started with laboratory measurements in seagrasses and got fantastic data. But the uncertainty of whether the observed phenomena also occurred in the field situation was there
– so I had to go and see.
What would you state as the greatest advantages of starting the experiment in the laboratory and then proceed into the field?
You know exactly what you are looking for! I strongly prefer to identify a mechanism in the lab where I can control all the environmental parameters such as temperature, light, flow – and
stability of the set-up. The interesting part for me and the readers of the scientific papers is then to go and show that this mechanism also operate in the field situation regardless of fluctuations
in all of the above environmental parameters.
Then, what is the greatest challenge you have experienced working in the field?
Working in a peat swamp in South West Australia was probably the greatest challenge! The water was shallow so I didn’t have to SCUBA dive but the peat swamp was incredibly unstable. Walking 5 m away from the set-up would cause the entire set-up with micromanipulators and sensors to move. I had to float around and never touch the bottom in order to get the sensors in place.
Could you give examples of when combining field and laboratory measurements were of a particular advantage?
Working with submerged rice – or seagrasses – in the field situation has provided new insight into internal aeration of plant tissues. Our previous laboratory measurements have not been
able to provide real knowledge of the importance of simultaneous changes in light, temperature and water flow and how these parameters all affected the oxygen status of the tissues.
The exciting data on the following pages of this flyer speaks for itself and I hope it will stimulate other research groups to try and combine laboratory and field measurements regardless of the
topic they are working on.
Why does in situ data impress reviewers? Why is it so persuading?
Field measurements are impressive to reviewers and readers because they already know how hard it is to do it in the controlled laboratory situation. Even in the laboratory it is difficult enough
to position a microsensor in the tissue right where it is needed. Research in the field is challenging but the reward is immense!
A standard question we get from new customers is how often sensors break during experiments. What is your experience?
I rarely break a sensor during measurements! Sensors break during handling i.e. when removing it from its protective casing, mounting it in the micromanipulator or inserting it into the tissue. Once the set-up is up and running, the microsensors rarely break – unless the set-up is unstable or macrofauna is attracted to the set-up and starts fiddling with it. The bull sharks in Florida Bay completely wrecked a set-up.
Any good advice to new microsensor users? Patience! It takes a while before you have achieved the necessary skills. But once you feel comfortable with the data you get, it is so rewarding to get insight into processes and mechanisms that
nobody has studied before.
Conclusion on lab and field data
Leaf gas films are hypothesized to improve internal aeration of the plant during the day, as leaf gas films enhance CO2 uptake and thereby promote photosynthesis. This is seen as higher root pO2 in plants with intact gas film compared to plants without. The two studies described investigate gas film based on laboratory experiments and experiments in the field.
In the laboratory, root pO2 increases in light periods in submerged plants, probably due to reduced outward diffusion of photosynthetically produced O2. Removal of gas film resulted in a decrease in root pO2 to just below the initial level (see fig 1A). This can be explained by decreased O2 production by photosynthesis as a result of impeded CO2 entry. In darkness, root pO2 rapidly decreased to 25% (see fig. 1B) when submerged in light and declined to close to zero when the gas film was removed.