Stirring Up a Bloom off Patagonia

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Stirring Up a Bloom off Patagonia

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Cocco-lithophores

<<The most interesting art often arises from the convergence of different ideas and influences. And so it is with nature sometimes. Off the coast of Argentina, two strong ocean currents recently stirred up a colorful brew of floating nutrients and microscopic plant life just in time for the summer solstice.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this image of a massive phytoplankton bloom off of the Atlantic coast of Patagonia on December 21, 2010. Scientists used seven separate different spectral bands to highlight the differences in the plankton communities across this swath of ocean.

The milky green and blue bloom developed in an area known as the Brazil-Falklands Confluence. It's where the warm salty waters of the subtropical Brazil Current flow south and meet the colder, fresher waters brought north from the Southern Ocean by the Falklands (Malvinas) Current. Where these currents collide along the continental shelf—known to oceanographers as a shelf-break front—turbulent eddies form and pull nutrients up from the deep ocean. Also, the Rio de la Plata runs off the land and deposits nitrogen and iron-laden sediment into the ocean just north of the area shown in the image.

Add in some strong summer sun, and you have a bountiful feast for the microscopic, floating plants—phytoplankton—that form the center of the ocean food web. Those plants become food for everything from microscopic animals (zooplankton) to fish to whales.

Though it is impossible to say for sure without direct sampling of the water, most of the phytoplankton blooming in this photo are likely coccolithophores, single-celled plants that form calcite scales. (Calcite is a carbonate mineral often found in limestone chalk.) Blooms of coccolithophores are common in those waters in southern hemisphere's spring and summer. Diatoms might also be in the mix.>>