Why we use microsensors
Dirk DeBeer, Ph.D.
Max Planck Institute for Marine Microbiology
Friday, August 3, 2001
12:00 Noon–Pacific Forum
Microsensors are needle type sensors with tips from 1 micron to 20
microns in diameter. With these devices a range of compounds can be
measured. Most relevant for microbial ecology are O2, pH, H2S,
Ca2+, CH4, CO2, NH4, NO3-,
and NO2-. Due to the small tips, disturbance is
minimal and spatial resolution is optimal. The response times are usually
in the order of seconds. We use microsensors to study (micro) biological
activities on and inside interfaces. Examples are marine and freshwater
sediments, biofilms covering solid surfaces, microbial mats, corals and
calcifying algae, and burrowing fauna. The processes we focus on are
photosynthesis, calcification, sulfate reduction, sulfide oxidation,
nitrification, and denitrification.
The microanalyses allow, in principle, two types of studies. First,
conversion rates can be measured, which allows budget studies in
ecosystems. Second, the fast response times and highly localized nature of
the measurements allow studies about the mechanisms of processes.
Two studies will be presented. A study on mineralization rates in
intertidal sediments shows that direct measurement with microsensors is a
unique and convincing method. Another study will be presented on the
mechanism of calcification in corals and calcifying algae.
Next: Long-term change and stability in the California Current System