August 22, 2006
Lashed to the deck next to the bongo nets was an intriguing piece of equipment that was being tested by Jon Hare. It had a yellow triangular-shaped surface and lots of electronic equipment on the underside. This object was called a video plankton recorder or VPR for short, and there were only five other similar ones currently in existence. It was designed and built by an engineering company who worked in close collaboration with scientists at Woods Hole and its purpose was to continuously take photographs of the zooplankton it encountered as it descended through increasing depths in the ocean. It had sophisticated strobe lighting and camera systems at the front that could record twenty images per second. The images were stored on a hard drive unit at the rear of the device that was removed once the VPR surfaced and downloaded to a computer on the ship. One dive with the VPR could yield as many as 25,000 images. Many of these images ultimately had to be discarded though because they were too blurred or had been captured at angles that were not useful for zooplankton identification purposes - one of the ultimate design goals of the VPR.
Jon had only had the chance to test out the VPR a few times and was still working on ironing out problems and developing techniques to optimize its capabilities. The best zooplankton images he had obtained so far were too crude for precise identification purposes, although they were of use in sorting the creatures into major groupings such as copepods, amphipods and fish larvae. He hoped that further trials with the VPR, coupled with the development of more sophisticated image analysis techniques, would eventually allow him to identify zooplankton at least down to the genus level.
One of the problems with conventional plankton tows using nets is that everything gets squashed together in the net and it is not possible to determine the depth at which different organisms were collected. For fragile organisms like jellyfish just being in the net is enough to turn them into mush. The VPR has the potential to solve these problems and to reveal information on the vertical distribution of species that will help scientists to develop a greater understanding of these creatures that constitute the base of the ocean food web.