Quantcast

How Your Diet Contributes to Nutrient Pollution and Dead Zones in Lakes and Bays

Insights + Opinion
iStockr / iStock / Getty Images Plus

By Donald Scavia

Every year in early summer, scientists at universities, research institutions and federal agencies release forecasts for the formation of "dead zones" and harmful algal blooms in the Gulf of Mexico, the Chesapeake Bay and Lake Erie. This year the outlook is not good.


The dead zone that forms annually in the Gulf of Mexico is likely to approach, if not surpass, record size at roughly 7,250 square miles. Another dead zone in the Chesapeake Bay is projected to be within the top 20% recorded over the past 20 years — about 2.1 cubic miles, equivalent to over 3.5 million Olympic-size swimming pools. And Lake Erie is also projected to set records, with almost 50,000 tons of potentially toxic algae.

The key factor driving these forecasts is winter and spring rainfall considerably above normal across the central U.S. The winter of 2018-2019 was the wettest on record across the nation, and May was the second-wettest month on record.

Predicting the results isn't rocket science. More rain means more flooding and more runoff from farmlands. These waters carry heavy loads of nutrients, mainly from fertilizer, that fuel algal blooms. The end results include fish kills, closed beaches, possible drinking water alerts and loss of coastal property value.

Treading Water

Algal blooms occur when water bodies become overloaded with nitrogen and phosphorus from farms, water treatment plants and other sources. Warm water and nutrients promote rapid growth of algae. Some strains can be toxic or even fatal to aquatic life and humans.

Eventually algae settle to the bottom and decay. This process depletes dissolved oxygen in the water, creating "dead zones" where oxygen levels are low enough to kill fish.

Scientists and public officials have understood this problem for decades, but progress toward addressing it has been painfully slow. Nutrient loads, dead zones and harmful algal blooms in these systems dominated by agriculture have increased or held grudgingly steady for decades.

Dead zone and harmful algal bloom trends with 2019 forecasts in red.


From http://scavia.seas.umich.edu/hypoxia-forecasts/

The main policy tool available now to combat nutrient losses from agricultural lands is the Farm Bill, enacted about every five years, which provides funds for voluntary conservation efforts. Between 1995 and 2015, the U.S. Department of Agriculture provided almost $32 billion in conservation incentive payments. U.S. water quality would be much worse without these programs, but they simply have not been sufficient to reduce nutrient loads over time.

Nutrient load trends; 2019 loads in red.

From: http://scavia.seas.umich.edu/hypoxia-forecasts/

Warmer and Wetter

Scientists predict that as the climate warms, this problem is likely to get worse.

Most climate models forecast increased precipitation, especially intense spring rains, for most of the Midwest, the Great Lakes basin and the mid-Atlantic. As air warms, it can hold increasing amounts of water vapor, which contributes to more precipitation during extreme weather events. In turn, heavier rainfall will impact nutrient runoff and dead zone formation.

Under a worst-case climate change scenario, in which global temperatures rise nearly 5 degrees Celsius above preindustrial levels by 2100, very heavy precipitation events in the Midwest, Great Plains and Southeast regions would increase sharply.

NOAA

A Dietary Strategy

Farm-based conservation programs are important, and some new practices could improve nutrient management. For example, farmers can widen drainage ditches to create two-stage ditches, which allow water to flow onto vegetated side "benches" that capture nutrients during periods of heavy rainfall.

A two-stage ditch has a low-flow channel and a vegetated side 'benches' that are flooded during higher flows. The grass slows water flow and allows nutrients to settle out.

Ohio State University Extension, CC BY

But even these measures would have to be implemented at unprecedented scales to be effective. The challenge is even more daunting when recognizing that, for example, while the annual total phosphorus load to Lake Erie is large, it is only 10% of the amount applied in fertilizer each year. In addition, as with the Chesapeake and Mississippi watersheds, soils around Lake Erie are already laden with nitrogen and phosphorus.

In my view, part of the solution could be using markets to drive a shift away from industrial-scale corn production, which is a major source of nutrient pollution. One major step would be eliminating the federal mandate requiring oil companies to blend corn-based ethanol into gasoline, which consumes 40% of U.S. corn production.

This will be politically difficult as long as presidential primaries start in Iowa. But other strategies may be more feasible, such as encouraging private-sector companies to demand corn raised through more sustainable practices.

Reducing meat consumption, which consumes another 36% of U.S. corn production for animal feed, could also have a significant impact. Studies have shown that reducing this demand for row crops reduces nutrient pollution.

This idea has gained momentum with the growth of the alternative meat industry. The success of startups like Beyond Meat and Impossible Foods is luring giants like Tyson and Perdue into the game. Some are even struggling to keep up with demand for plant-based meat alternatives, particularly in China. One recent market analysis suggests that plant-based "meat" will surpass animal sources globally by 2040.

AT Kearney, CC BY-ND

Shrinking Agriculture's Footprint

Scientists have understood for decades that excess nitrogen and phosphorus degrade Lake Erie, the Chesapeake Bay and the Gulf of Mexico. Nutrient inputs from sewage treatment plants and other discreet, easily identifiable sources have declined because they are regulated under the Clean Water Act.

But the nutrients fouling these water bodies now come mostly from diffuse sources, particularly industrial-scale row crop agriculture. Those operations are not subject to the Clean Water Act, and voluntary conservation programs seem to have at best kept pace with the expansion of large-scale farming.

After analyzing these issues and providing policy advice on them for much of my 45-year career, it's frustrating to see so little change. But I am hopeful that current work that addresses agricultural pollution in broader contexts may have an impact.

For example, recent reports connecting reduced meat consumption to both positive environmental effects and improved health should provide additional incentives for change. Research institutes and scholars are laying out comprehensive global pathways to more sustainable agriculture that are designed to feed the world and protect and restore natural ecosystems.

My hope lies in the combination of health- and market-driven movement toward plant-based meat substitutes and enlightened policies that support more sustainable practices in agriculture's critical role of providing food and fiber to the world.

Donald Scavia is professor emeritus at the School for Environment and Sustainability, University of Michigan.
Disclosure statement: Donald Scavia has received funding from the National Science Foundation, the Environmental Protection Agency, the National Oceanic and Atmospheric Administration, Environment and Climate Change Canada, the Erb Family Foundation, the Joyce Foundation, and the C.S. Mott Foundation.

Reposted with permission from our media associate The Conversation.

EcoWatch Daily Newsletter

Farms with just one or a handful of different crops encourage fewer species of pollinating and pest-controlling insects to linger, ultimately winnowing away crop yields, according to a new study.

Up to half of the detrimental impacts of the "landscape simplification" that monocropping entails come as a result of a diminished mix of ecosystem service-providing insects, a team of scientists reported Oct. 16 in the journal Science Advances.

Monocrop palm oil plantation Honduras.

SHARE Foundation / Flickr / CC BY-NC 2.0​

"Our study shows that biodiversity is essential to ensure the provision of ecosystem services and to maintain a high and stable agricultural production," Matteo Dainese, the study's lead author and a biologist at Eurac Research in Bolzano, Italy, said in a statement.

It stands to reason that, with declines in the sheer numbers of insects that ferry pollen from plant to plant and keep crop-eating pests under control, these services will wane as well. But until now, it hasn't been clear how monocultures affect the number and mix of these species or how crop yields might change as a result.

Aiming to solve these questions, Dainese and his colleagues pulled together data from 89 studies cutting across a variety of landscapes, from the tropics of Asia and Africa to the higher latitudes of northern Europe. They tabulated the number of pollinating and pest-controlling insects at these sites — both the absolute number of individuals and the number of species — along with an assessment of the ecosystem services the insects provided.

In almost all of the studies they looked at, the team found that a more diverse pool of these species translated into more pollination and greater pest control. They also showed that simplified landscapes supported fewer species of service-providing insects, which ultimately led to lower crop yields.

The researchers also looked at a third measure of the makeup of insect populations — what they called "evenness." In natural ecosystems, a handful of dominant species with many more individuals typically live alongside a higher number of rarer species. The team found as landscapes became less diverse, dominant species numbers dwindled and rare species gained ground. This resulting, more equitable mix led to less pollination (though it didn't end up affecting pest control).

"Our study provides strong empirical support for the potential benefits of new pathways to sustainable agriculture that aim to reconcile the protection of biodiversity and the production of food for increasing human populations," Ingolf Steffan-Dewenter, one of the study's authors and an animal ecologist at the University of Würzburg in Germany, said in the statement.

The scientists figure that the richness of pollinator species explains around a third of the harmful impacts of less diverse landscapes, while the richness of pest-controlling species accounts for about half of the same measure. In their view, the results of their research point to the need to protect biodiversity on and around crops in an uncertain future.

"Under future conditions with ongoing global change and more frequent extreme climate events, the value of farmland biodiversity ensuring resilience against environmental disturbances will become even more important," Steffan-Dewenter said.

Reposted with permission from our media associate Mongabay.

View of an Ivorian cleared forest at the edge of the 35.000 hectares Peko Mont National Park on Oct. 8, 2016. The Mont Péko National Park is located in the west of Ivory Coast where the forest officers fight with illegal immigrants to protect an exceptional flora and fauna, espacially dwarf elephants. SIA KAMBOU / AFP / Getty Images

Ivory Coast's rainforests have been decimated by cocoa production and what is left is put in peril by a new law that will remove legal protections for thousands of square miles of forests, according to The Guardian.

Read More Show Less
Sponsored
The Apusiaajik Glacier, as seen from Kulusuk village in East Greenland. Like most glaciers in Greenland, it's retreating rapidly, changing the local landscape year by year. Photo credit: Karin Kirk

By Karin Kirk

Greenland had quite the summer. It rose from peaceful obscurity to global headliner as ice melted so swiftly and massively that many were left grasping for adjectives. Then, Greenland's profile was further boosted, albeit not to its delight, when President Trump expressed interest in buying it, only to be summarily dismissed by the Danish prime minister.

During that time I happened to be in East Greenland, both as an observer of the stark effects of climate change and as a witness to local dialogue about presidential real estate aspirations, polar bear migrations and Greenland's sudden emergence as a trending topic.

Read More Show Less

Heavy metals that may damage a developing brain are present in 95 percent of baby foods on the market. Cirou Frederic / PhotoAlto Agency RF Collections / Getty Images

Heavy metals that may damage a developing brain are present in 95 percent of baby foods on the market, according to new research from the advocacy organization Healthy Babies Bright Futures (HBBF), which bills itself as an alliance of scientists, nonprofit organizations and donors trying to reduce exposures to neurotoxic chemicals during the first three years of development.

Read More Show Less
Chicago skyline on July 22 as high winds continue to push the waters of Lake Michigan over the top of the pedestrian and bike trail along the lakefront in Chicago. Raymond Boyd / Michael Ochs Archives / Getty Images

By Daniel Macfarlane

Every fall, I take my environmental studies class camping at Sleeping Bear Dunes National Lakeshore on Lake Michigan. Some years the beach extends more than three meters to the water. This year, in many spots, there was no beach at all.

Read More Show Less
Sponsored
Insects like bees, butterflies and even certain species of beetle and ant incidentally pollinate our crops when they collect protein-rich pollen and sugary nectar. Rolf Dietrich Brecher / CC BY 2.0

By Kerstin Palme

Creepy-crawlies are among the oldest life forms on this planet. Before dinosaurs ever walked the earth, insects were certainly already there. Some estimates date their origins to 400 million years ago. They're also extremely successful. Of the 7 to 8 million species documented on Earth, around three quarters are likely bugs.

But several insect species could disappear for good in the next few decades and that would have serious consequences for humans.

Read More Show Less
Swedish automaker Volvo unveils its first electric vehicle the XC40 Recgarge EV, during an event in Los Angeles on Oct. 16. Frederic J. BROWN / AFP / Getty Images

Volvo introduced its first-ever all-electric vehicle this week, kicking off an ambitious plan to slash emissions and phase out solely gas-powered vehicles starting this year.

Read More Show Less
Cars are queued in Turin, Italy in August. Particulate matter levels were the highest in Italy, Poland and the Balkans countries. Nicolò Campo / LightRocket / Getty Images

Air pollution in Europe led to more than 400,000 early deaths in 2016, according to the most recent air quality report published by the European Environment Agency (EEA).

The report, released Wednesday, found that almost every European who lives in a city is exposed to unhealthy air, Reuters reported.

Read More Show Less