Tiny dots engraved into green acrylic trace data from the FRRf (Fast Repetition Fluorometer). The length (x axis) of the green sheet represents a number of microsecond flashes of red light, cast from the FRRf into water. Graphs produced from data gathered by the FRRf represent light ‘soundings’ at certain depths. The depth recorded here is within the ‘sweet spot’ (at about 70 m), where most algae live. The height (y axis) of the acrylic sheet represents the levels of light (intensity) emitted from the algae in response to microsecond flashes from the FRRf. The higher the intensity of response from algae (indicated by dots higher on the y axis), the greater is their capacity to photosynthesize – or, as UTS scientist Jim Franklin says, the greater is their Happiness.
Below is the graph that was traced onto acrylic:
Jim explains how the light works to measure the happiness of algae.
The sweet spot is where you’ve got the light coming down from above, and nutrients coming up from the bottom, and you tend to get a layer where most of the photosynthesis actually occurs. And that’s where most of the algae actually live.The bulk of algae live at about 70 m because the surface waters are too bright.
Algae appear green because they don’t absorb green. They reflect it back. This one [FRRf instrument] is putting out a red light, optimised for the photosynthetic absorption by algae. So, when they get that light in, they can do several things. Now if everything is going well they can use some of that light to make sugars, basically, along the photosynthetic chain … If things are going badly they may not be able to use that light at all, in which case it all ends up as heat. If light is absorbed for photosynthesis, in that process of absorbing the light, some of the energy is re-emitted as fluorescence at fluorescences of longer wave lengths – photons – of deep red. Now how much fluorescence [fluorescent emittance] you get compared to what you put in is a good indication of how that photosynthetic chain is working.
A simple animation was made by ‘grabbing’ and then combining frames from the screen display of graphed data: