We have developed a unique silhouette (shadow) video photography (SVP) system for making behavioural observations of small aquatic organisms. SVP is superior to standard cinegraphic or video imaging techniques because it allows filming of events in a large depth of field (~15-30 cm), with a relatively large field of view [limited only by the size of the collimating lenses], magnification is independent of distance from the cameras, the resolution is very good (objects as small as 0.2 mm can be resolved), and image quality is unaffected by ambient light level. In addition, the system does not require intense light sources such that free-swimming lice can be observed under relatively natural conditions.
Analysis of the images obtained from the SVP system allows for detailed characterization of the reactions of aquatic organisms to different environmental conditions. This type of analysis provides us with information on overall activity, swimming patterns, foraging and prey search behaviours. All of these are directly relevant, and of great importance, in developing appropriate rearing environments. Such observations can be used very effectively in order to evaluate different combinations of rearing conditions.
Please click on the images to obtain further details about this equipment.
You can read all about our SVP system, and associated software, in the Methods section of the article locatedHERE.
All of these movies were generated using our unique silhouette imaging system which is presented and explained here.
The following book contains useful information on the imaging techniques that we use:
Settles, G.S. (2001). Schlieren and Shadowgraph Techniques. Visualizing Phenomena in Transparent Media. Springer-Verlag, Berlin, ISBN: 3-540-66155-7