It's hard to believe a tiny animal like krill could exist in large enough numbers to feed an animal as massive as a whale, let alone the world's population of whales (even if we did do our best to hunt whales to extinction in the 1800s). Likewise, it's hard to fathom that a modest little organism like a copepod could kick up enough wake to churn the ocean's deep waters to the surface as effectively as more traditionally studied processes such as wind/wave action and tides. But this is exactly what one post-doctoral scholar at the Woods Hole Oceanographic Institute is showing, and visually.
Dr. Kakani Katija and her colleagues published a paper this week in JOVE that shows off a cool new device they've developed to record fluid motion caused by the movements of animals in their native habitats using a laser and a hand held video recording device they've dubbed SCUVA (self-contained underwater velocimetry apparatus). The device illuminates particles in the water and records their motion as an animal moves through the field of view. The video footage can then be plugged into software that tracks each particle's movement, creating a neat diagram of vectors around the traveling organism. The device is particularly significant because it allows data to be collected in situ rather than in a lab where native conditions and behavior are difficult if not impossible to recreate. The resulting stills are visually intriguing, but the video clips contained in the author interview are even better.
We know that ocean currents play a major role in climate regulation. If, as Dr. Katija suspects, the daily vertical migrations of tiny but abundant organisms like krill and copepods can have as much of an effect on ocean mixing and currents as wind and tides, one can only imagine the impact rising ocean temperatures, collapsing fisheries, and ocean acidification could have on these important populations. I can see the bumper stickers now: Krill for a Comfy Climate, and Copepods Combat Climate Change! Get ready to heart copepods. I do.
Katija, K., Colin, S. P., Costello, J. H., Dabiri, J. O. (2011). Quantitatively Measuring In situ Flows using a Self-Contained Underwater Velocimetry Apparatus (SCUVA) Journal of Visualized Experiments (56), e2615, DOI: 10.3791/2615 (2011)