GLIN==> U-Michigan: Record-breaking 2011 Lake Erie algae bloom may be sign of things to come

 April 1, 2013
Contact: Jim Erickson, (734) 647-1842, ericksn at umich.edu

*EDITORS*: High-resolution photos and map available at
http://www.ns.umich.edu/Releases/2013/Mar13/algae.html

*Record-breaking 2011 Lake Erie algae bloom may be sign of things to come*

ANN ARBOR—The largest harmful algae bloom in Lake Erie's recorded history
was likely caused by the confluence of changing farming practices and
weather conditions that are expected to become more common in the future
due to climate change.

Rather than an isolated, one-time occurrence, Lake Erie's monumental 2011
algae bloom was more likely a harbinger of things to come, according to
University of Michigan researchers and colleagues from eight other
institutions.

The interdisciplinary team explored factors that may have contributed to
the event and analyzed the likelihood of future massive blooms in the lake.

"Intense spring rainstorms were a major contributing factor, and such
storms are part of a long-term trend for this region that is projected to
get worse in the future due to climate change," said aquatic ecologist
Donald Scavia, director of U-M's Graham Sustainability Institute. "On top
of that we have agricultural practices that provide the key nutrients that
fuel large-scale blooms."

A paper summarizing the team's findings was published online April 1 in the
journal Proceedings of the National Academy of Sciences.

The first author of the paper is former U-M researcher Anna Michalak, now
at the Carnegie Institution for Science. Eighteen U-M co-authors from
various departments and schools contributed to the study, which looked at
land use, agricultural practices, precipitation, temperature, wind, lake
circulation and surface runoff.

"This event was caused by a complex combination of factors, and I think
this paper really puts all the pieces together in a very clear and
systematic way," said U-M atmospheric scientist Allison Steiner, one of the
co-authors. "We tried to think about this problem in a much more
cross-disciplinary way than I think other people have thought about it
before."

The researchers found that a series of intense spring rainstorms and runoff
events resulted in record-breaking levels of phosphorus, a nutrient in crop
fertilizers that also fuels rampant algae growth, washing into western Lake
Erie.

That set the stage for an algae bloom that covered about 2,000 square miles
by the time it peaked in early October 2011. That's more than three times
larger than any previously observed Lake Erie algae bloom, including blooms
that occurred in the 1960s and 1970s, when the lake was famously declared
dead.

The 2011 spring storms included one that dumped 2 inches of rain over
Ohio's Maumee River basin in 24 hours on May 26 and 6.8 inches total for
the month of May 2011—more than 20 percent above the long-term monthly
average. The Maumee is a primary tributary to western Lake Erie, and it
drains an agricultural watershed where corn, soybeans and wheat are grown.

In their study, the researchers used 12 computerized climate models to
determine if rainstorms like the May 2011 events are more likely to occur
in the future. The models, which incorporate the anticipated effects of
human-caused climate change due to the buildup of heat-trapping greenhouse
gases, showed that the frequency of spring rainstorms that drop more than
1.2 inches is likely to double in this region by the end of the century.

"The models do predict an increase in extreme springtime precipitation
events, and that's driven by an increase in greenhouse gases," said
Steiner, an associate professor in the Department of Atmospheric, Oceanic
and Space Sciences.

Once the 2011 Lake Erie bloom formed, unusually warm water temperatures and
calm winds created ideal conditions to promote summer algae growth. "All of
these factors are consistent with expected future conditions," the 29
authors of the PNAS paper wrote.

An algae bloom is a rapid buildup of algae in a body of water, and harmful
blooms are those that damage other organisms—including humans—through the
production of toxins or by other means. Algae blooms can foul harbors, clog
boat motors, reduce fish populations and sometimes lead to the formation of
low-oxygen "dead zones" where most aquatic organisms cannot survive.

The 2011 Lake Erie bloom was composed almost entirely of toxic blue-green
Microcystis algae. Concentrations of mycrocystin, a liver toxin produced by
the algae, peaked at about 224 times World Health Organization guidelines,
according to the researchers.

In addition to meteorological conditions, other factors contributed to the
2011 Lake Erie algae bloom. Chief among them is the widespread adoption,
since the mid-1990s, of no-till farming and other agricultural practices
that have increased the availability of a type of phosphorous, known as
dissolved reactive phosphorous or DRP, that promotes algae growth.

In no-till farming, crops are planted without plowing by inserting seeds
into small holes. The technique reduces erosion but leaves high levels of
phosphorous-bearing fertilizer in the upper surface soil, where heavy
rainstorms can wash it away. Trends toward autumn fertilizer application
and surface broadcasting of fertilizers also create conditions for enhanced
phosphorous runoff.

Unless there's a significant shift away from these practices, runoff from
farmland in the Maumee River watershed and other Western Basin watersheds
will likely continue to provide the nutrients needed to trigger massive
Lake Erie algae blooms.

In addition, the current emphasis on producing corn for ethanol production,
as well as a trend in the Midwest toward declining acreage reserved for
conservation purposes, is likely to exacerbate the problem, said Michael
Moore, a professor of environmental economics at U-M's School of Natural
Resources and Environment and one of the paper's co-authors.

"Corn is the crop on which phosphate-based fertilizer is most heavily
applied," Moore said. "So the intensification of corn production is a
problem, and part of the solution would be to rethink this emphasis on corn
production for biofuels."

In addition to Michalak, Steiner, Moore and Scavia, authors of the PNAS
paper are Eric Anderson, Dmitry Beletsky, Steven Boland, Nathan Bosch,
Thomas Bridgeman, Justin Chaffin, Kyunghwa Cho, Rem Confesor, Irem Dalo?lu,
Joseph DePinto, Mary Anne Evans, Gary Fahnenstiel, Lingli He, Jeff Ho, Liza
Jenkins, Thomas Johengen, Kevin Kuo, Elizabeth LaPorte, Xiaojian Liu,
Michael McWilliams, Derek Posselt, R. Peter Richards, Ed Verhamme, David
Wright and Melissa Zagorski.

In addition to the Department of Atmospheric, Oceanic and Space Sciences,
the School of Natural Resources and Environment, and the Graham
Sustainability Institute, U-M units that participated in the research are
the Cooperative Institute for Limnology and Ecosystems Research, the
Department of Civil and Environmental Engineering, the Ford School of
Public Policy, Michigan Sea Grant, and the Department of Economics.

The research was supported by grants from the National Science Foundation,
the National Oceanic and Atmospheric Administration and the Lake Erie
Protection Fund.

More information about NSF Grant No. 1039043, "Extreme events impacts on
water quality in the Great Lakes: Prediction and management of nutrient
loading in a changing climate," is available at
http://www.miseagrant.umich.edu/nsfclimate.


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