Video Plankton Recorder (VPR)

Video Plankton Recorder

The Video Plankton Recorder attached to a winch cable on the deck of the R/V Atlantis at the WHOI dock. Credit: C. S. Davis ©Woods Hole Oceanographic Institution.

The Video Plankton Recorder (VPR) (Davis et al, 1992a, b) is an underwater video microscope that can be deployed in various ways to make observations of small organisms and other particles. In the newest VPR system, a high-resolution digital video camera is focused on a region 7-20 mm across (depending on magnification) at a working distance of 50 cm. Depth of field is determined via calibration and is typically 3-8 cm, yielding a sampling volume of 1-32 ml. Lighting is provided by a 20-W strobe, with a 1-µs pulse duration, aimed obliquely to provide dark-field illumination.

Calanus with oil sac
Calanus with oil sac. Credit: C. S. Davis ©Woods Hole Oceanographic Institution

Plankton, such as mesozooplankton in the size range 0.2 – 20 mm, can beimaged. These include such groups as copepods (which are among the most numerous animals on earth), jellyfish, worms, and larval forms of many species including starfish, barnacles, and crabs. The quality of images is sufficient to distinguish among these major taxonomic groups, and in some cases, distinct species can be identified. The images can be classified automatically, using a trained neural network, even at a video-image acquisition rate of 30 frames per second (30 Hz). Such automated classification effects a rapid reduction of a vast quantity of data to figures describing patterns of concentration.

Video Plankton Recorder
In early 2002, Fred Thwaites, left, and Steve Faluotico conducted sea trials for a second generation VPR, shown here without its front cowling. Credit: T. Kleindinst ©Woods Hole Oceanographic Institution.

The current VPR model is designed to be towed at speeds up to 10 knots and has recently been towed at 12 knots across the Atlantic. Its on-board flight control computer coupled with horizontal and vertical tail fins allow it to be towed in auto-pilot mode such that it automatically undulates between commanded depths and moves out to the side of the vessel when near the surface, thus avoiding the vessel wake.

The VPR was developed during the U.S. GLOBEC Georges Bank Regional Program, to which it contributed unique and valuable data about mesozooplankton (Davis et al. 1996, Gallager et al. 1996, Ashjian et al. 2001). Its capabilities are being steadily expanded, while it is also being adapted for more routine surveying operations.


Pseudocalanus with eggsHydroidsDiatom coilpolychaete

JellyfishJellyfishJellyfish
A gallery of plankton imaged by the Video Plankton Recorder. Top row, L to R: Pseudocalanus with eggs, hydroids, diatom coil, and a polychaete. Bottom row: Three jellyfish. Credit: C. S. Davis ©Woods Hole Oceanographic Institution.

Related Links

http://science.whoi.edu/users/cdavis/vprimages2/FrameSet.htm

References
Ashjian, C. J., C. S. Davis, S. M. Gallagher, and P. Alatalo. 2001. Distribution of plankton, particles, and hydrographic features across Georges Bank described using the Video Plankton Recorder. Deep-Sea Res. II 48: 245-282.
 
Davis, C. S., S. M. Gallager, M. Marra, and W. K. Stewart. 1996. Rapid visualization of plankton abundance and taxonomic composition using the Video Plankton Recorder. Deep-Sea Res. II 43: 1947-1970.
 
Gallagher, S. M., C. S. Davis, A. W. Epstein, A. R. Solow, and R. C. Beardsley. 1996. High-resolution observations of plankton spatial distributions correlated with hydrography in the Great South Channel, Georges Bank. Deep-Sea Res. II 43: 1627-1663.
 
Davis, C. S., S. M. Gallager, M. S. Berman, L. R. Haury, and J. R. Strickler. 1992a. The Video Plankton Recorder (VPR): design and initial results. Arch. Hydrobiol. Beiheft Ergeb. Limnol. 36: 67-81.
 
Davis, C. S., S. M. Gallager, and A. Solow. 1992b. Microaggregations of oceanic plankton observed by towed video microscopy. Science, 257, 230-232.