The changing ocean
The ocean has been in the news quite a bit lately. On the west coast of the United States, water temperatures have been higher than normal; catches of fish have been smaller; and the number of phytoplankton has dropped. Whether or not this is due to global warming, no one knows for sure, and no one knows if the trend will continue next year, either.
But this year, the winds have been unusually weak, failing to generate much upwelling and reducing the amount of phytoplankton.
Off Oregon, for example, the waters near the shore are 5 to 7 degrees warmer than normal and have yielded about one-fourth the usual amount of phytoplankton, said Bill Peterson, an oceanographer with the National Oceanic and Atmospheric Administration in Newport, Oregon.
Why the concern over phytoplankton? Well, the phytoplankton in the ocean accounts for the majority of carbon dioxide metabolism in the atmosphere. Phytoplankton take carbon dioxide up, and when they die (or are eaten), they “pump” the CO2 into the bowels of the ocean in the form of calcium carbonate (limestone). Consider that if all of the calcium carbonate were broken down into calcium ions and carbon dioxide, that the atmosphere would weigh 40 times what it does today, and the planet would look a lot more like Venus than the Earth we know today.
But on the other side of the world, phytoplanton have bloomed. (Larger image) All is not well, however, as too much phytoplankton can de-oxygenate huge swaths of the ocean and stifle normal marine life. Scientists, again, aren’t sure what’s causing the abnormalities in the Baltic Sea, and they’re not sure if it will happen again next year.
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Algal blooms and the lack thereof disrupt normal ocean life quite a bit — it’s not a good balancing act to bloom too much on one side of the world and not the other, because both disrupt normal ocean processes.
Algae that die and sink to the bottom stimulate growth of decomposers, especially bacteria. Decomposition can result in the depletion of oxygen in the deeper water layers, and these conditions may result in fish kills or replacement with less valuable species more tolerant of higher phosphorus and lower oxygen levels. Deoxygenation also may cause chemical changes in the mud on the bottom, lowering the redox value of the sediment, releasing chemicals and toxic gases.
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