Why Lake Erie is Under Attack from Algae Blooms
NASA Earth Observatory
An image of the Lake Erie algae bloom acquired by NASA's Aqua satellite on October 9, 2011.
Among the most beautiful, mysterious and downright regular events on planet Earth are the colossal blooms of plankton in oceans, seas and lakes. As you'll see in this slideshow, with the specially-designed satellite eyes, like that of SeaWiFS and others, we can see these blooms in more detail than ever before possible. Still, the whys and wheres of these blooms remain largely mysterious. New research is starting to tease out what triggers these blooms, including the toxic "red tides" that make the news. Scientists have also discovered signs that these gigantic expanses of single-celled organisms might behave like a single massive beast. If so, these are superorganisms -- the largest on the planet. Seen just by its chlorophyll -- the stuff that makes plants green -- the Gulf Stream seems to pour like dragon fire from the Carolinas in this image. The Gulf Stream is not just a warm current, it's also a cozy place to grow. This false color image shows more detail than possible in a visible light view. The chlorophyll concentration is lowest in the blue areas and grades higher through aqua, green, yellow, orange and red. Credit: NASA/GeoEye
World of Chlorophyll
Global chlorophyll portraits of the Earth's oceans are showing them to be as changeable and seasonal as plants on land -- even more so because vast colonies of microscopic phytoplankton in the seas can be carried far and wide by currents. As you'll see in the coming images, the combinations of currents, water temperatures and nutrient levels can make for some startling and complex images. Credit: NASA/GeoEye
River of Heat
A true river within the Atlantic Ocean, the Gulf Stream current can be seen clearly meandering off Cape Cod (upper left) in this sea surface temperature image. Get ready: The next image shows the same scene at the same time, but strictly in terms of where the chlorophyll is growing strong. Credit: NASA/GeoEye
River of Green
Warm waters moving north by way of eddies pinched off in the Gulf Stream meanders help feed productive seas there. The waters to the south are mixing with cooler water and less productive. The stark differences create a feast for the eyes. Credit: NASA/GeoEye
Chlorophyll-rich eddies like this one in the southwest Indian Ocean are one of the ways warmer and colder waters are able to mix. This MODIS image shows a 200-kilometer-wide eddy south of Madagascar. Eddies like this one have been known to persist for years. Credit: NASA/GeoEye
Pea Soup on Ice
Even in natural colors, blooms can be striking -- and in surprising places. This pea-soup-green bloom was captured in the act in Antarctica's Ross Sea on Dec. 6. 2004. The phytoplankton-thick waters were found just north of the Ross Ice Shelf. Credit: NASA/GeoEye
Another enhanced natural color image shows where waters of the South Atlantic Ocean encounter the nutrient-rich polar waters which surround Antarctica. The coiled eddy in the lower left of this picture falls within this clashing of waters. The winners in this clash of waters are the green phytoplankton that benefit from both waters and can thrive in the collision zone. Credit: NASA/GeoEye
This July 25, 2007, chlorophyll view of the Mozambique Channel, between the island of Madagascar and Mozambique reveals a unsuspected system of interconnected, phytoplankton-rich eddies. In natural light none of the connections are readily apparent. They look, instead like a patchwork of unconnected blooms. Credit: NASA/GeoEye
Dust blowing off the land and into the sea serves as fertilizer to phytoplankton. Here the dust comes from the dry central Baja California Peninsula, carried west over the Pacific Ocean. This bloom was caught in the act on Nov. 2, 2004. Credit: NASA/GeoEye
Tasmania Meets Jupiter
The ocean east of Tasmania here is shown using satellite data, false colors and a bit of artistic license. The image enhances the subtle color differences in the water caused by not only phytoplankton but by dissolved organic matter, sediment, bubbles and what not. Even the Earth's atmosphere and the MODIS instrument itself might be contributing to these colors, which is why such things are normally filtered out for scientific purposes. The result is a sea that resembled the turbulent atmosphere of Jupiter. Just goes to show that every now and then aesthetic considerations can and should prevail. Credit: NASA/GeoEye
Lake Erie is under attack from noxious algae blooms, and the problem only looks likely to get worse if something isn't done to reverse the trend, new research suggests.
In the summer of 2011, western Lake Erie turned a noxious green, as a massive algae bloom coated the surface and lapped up in mats along the shore. At its peak, the bloom covered an area 2.5 times larger than that of any Erie bloom on record, according to a study published yesterday (April 1) in the Proceedings of the National Academy of Sciences.
Several factors converged to cause the bloom and may increasingly do so in the future, said Anna Michalak, a study co-author and researcher at the Carnegie Institution for Science at Stanford University.
Fertilizing the algae
First, agricultural practices have changed in the past few years, allowing for more fertilizer to run off from fields in the surrounding region and end up in the lake, Michalak said. There, the fertilizer feeds the growth of algal blooms. The practices include increased use of fertilizer, earlier application of the nutrients on bare ground and less use of tillage, in which fertilizer or manure is worked into the soil.
The first technique was intended to deliver fertilizer before spring storms, so farmers would not have to pick a time to apply fertilizer between rains, Michalak told OurAmazingPlanet. However, the method hasn't worked as intended, due in part to larger than expected storms. The second practice, avoiding tillage of the soil, helps preserve nutrients in the earth, but may increase the amount of fertilizer lost in large spring rains, she said.
Perhaps more importantly, runoff was made worse by explosive spring storms in 2011, which dropped a lot of rain in a very short period of time and washed the fertilizer away, Michalak said. In the lake, above-average temperatures also nourished the algae. Furthermore, a lack of strong winds prevented the lake from being mixed up, which normally makes algae sink to the bottom and brings low-lying water up to the surface, she said.
Unfortunately for Lake Erie, climate change is expected to lead to larger spring storms, warmer temperatures and fewer strong winds in the future, Michalak said. Dealing with climate change on a global level, then, could have an important local effect, she said.
But agricultural practices are more easily changed. Methods that lead to less fertilizer loss would help farmers, who must pay for the nutrients, as well as the lake environment, she said.
Ugly and harmful
"We need management policies that are good for agriculture as well as the lake ecology," Michalak said. "It doesn't do anybody any good to have these nutrients flowing into the lake. It's money being wasted by the farmers, and you are essentially fertilizing the algae instead of fertilizing the crops."
The nutrients in the fertilizer runoff, particularly phosphorous, feed the growth of a type of algae called cyanobacteria. Besides being unsightly, the blooms hurt fish in the lake by decaying and consuming massive amounts of oxygen, creating dead zones. But the cyanobacteria also pose a health hazard to people; the predominant type of cyanobacteria present in the 2011 bloom, called Microcystis, produce a potent liver toxin. The study found that levels of this toxin in the surface of Lake Erie were up to 200 times above the limit deemed suitable by the World Health Organization.
Invasive zebra mussels and quagga mussels have added to Lake Erie's problems, as these organisms preferentially eat phytoplankton that live in the lake and that normally compete with cyanobacteria, Michalak said.
The 2011 bloom "was a significant one in Lake Erie and I agree that it is unlikely to be unique," said Jan Ciborowski, a researcher at the University of Windsor, Ontario, who wasn't involved in the study.
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