Plankton and People in the Western South Atlantic

Dark Water Plume off of Brazil

The MODIS image below shows a long plume of dark water extending some 800 kilometers to the south by southwest of Rio de Janeiro, Brazil -- first crossing and then roughly following the outer edge of the continental shelf. Recent surface samples indicate that this is a bloom of the fast-swimming ciliate, Myrionecta rubra, which is known to form recurring large blooms in some parts of the world and has an interesting life style. The above Aqua-MODIS image was collected on January 19, 2014.

natural-color MODIS image of dark bloom off of Brazil

Waiting for Their Turn

While looking at the full-resolution (i.e. formed from bands having 250- and 500-meter wide pixels) version of the above image, my eye was attracted to a cluster of light spots just offshore of the Brazilian port city of Paranaguá, and I wondered what those could be. Small islands in the region look that way, but islands are not usually arranged in such a regular pattern, and there are no islands in that particular patch of ocean. A quick internet search revealed the answer.

The regular spots on the image below are ships waiting to use the port facilities at Paranaguá. The ships all have lengths of 200 meters give or take a few tens of meters, and they are relatively bright with respect to the surrounding ocean, so they reflect enough photons back to the MODIS sensor to significantly increase the signal for even a detector in one of the 500-meter bands of the instrument.

The next image down the page is a screenshot of the fleet-monitoring web site referenced above and it shows a similar distribution of ships a few days after the MODIS image was collected.

full-res MODIS view of Brazil near port of Paranagua screen shot of port traffic on an arbitrary day in January 2014