nutrient

The Gulf Of Mexico Dead Zone | Earth Wise

July 19, 2021 By EarthWise Leave a Comment

Every summer, a so-called dead zone forms in the Gulf of Mexico. It is primarily caused by excess nutrient pollution from human activities in urban and agricultural areas throughout the Mississippi River watershed.

When these excess nutrients reach the Gulf, they stimulate excess growth of algae, which eventually die and decompose, depleting oxygen as they sink to the bottom. These low oxygen levels near the Gulf bottom cannot support most marine life. Animals that are sufficiently mobile – such as fish, shrimp, and crabs – generally swim out of the area. Those that can’t move away are stressed or killed by the low oxygen.

A team of scientists funded by the National Oceanic and Atmospheric Administration issues an annual forecast for the dead zone based upon a suite of models that incorporate river flow and nutrient data.

The 2021 forecasted area is somewhat smaller than, but close to, the five-year measured average for the dead zone, which is 5,400 square miles, roughly the size of the state of Connecticut. Each year, these forecasts are reported as comparisons to long-term averages, but the problem is that the long-term average is unacceptable.

The Interagency Mississippi River and Gulf of Mexico Hypoxia Task Force has set a goal of reducing the size of the dead zone to a five-year average of 1,900 square miles – about a third of the current average.

Large reductions in nutrient loads have been called for in federal and state action plans for nearly 20 years, but clearly these reductions have not yet been sufficient. The Interagency Task Force continues to provide information for managing nutrient loads in the Mississippi River Basin.

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Average-sized ‘dead zone’ forecast for Gulf of Mexico

Photo, posted October 6, 2020, courtesy of Christine Warner via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Tracking Down Gluten Sensitivity | Earth Wise

October 6, 2020 By EarthWise Leave a Comment

Celiac disease is a well-documented autoimmune disease triggered by exposure to the dietary proteins found in wheat, rye, and barley. Celiac disease affects less than 1% of Americans yet many more people claim to be sensitive to gluten.

When people with celiac disease eat gluten, their body mounts an immune response that attacks the small intestine. These attacks lead to damage on the villi, the small projections that line the small intestine that promote nutrient absorption. Symptoms range from various digestive problems to fatigue, weight loss, bloating, and anemia. Ultimately, it can lead to a variety of serious health complications.

Until recently, there was a tendency by doctors to dismiss the complaints of people who claimed to be sensitive to gluten but do not have celiac disease. That is starting to change, in part as a result of studies conducted at Columbia University that looked at the biological basis for non-celiac gluten sensitivity.

The new study shows that people with non-celiac gluten sensitivity produce a high level of anti-gluten antibodies but that these antibodies are different from the ones triggered by celiac disease and that the inflammatory responses they instigate are also different. The more restrained inflammatory response is much less likely to be associated with autoimmune activity and intestinal cell damage. In addition, the immune system of people with non-celiac gluten sensitivity appears to be able to gradually reduce its inflammatory response over time.

Discovery of these antibodies could be used in the future to help doctors more readily identify people with non-celiac gluten sensitivity, which now is difficult to diagnose. The researchers also believe that their work could lead to potential new therapies for celiac disease, which is currently treated only with dietary restrictions.

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Unique Antibody Profile Sets Gluten Sensitivity Apart from Celiac Disease

Photo, posted November 27, 2010, courtesy of Francis Storr via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Shrinking Alaskan Salmon | Earth Wise

September 24, 2020 By EarthWise Leave a Comment

According to a new study published in the journal Nature Communications, salmon returning to Alaskan rivers have become significantly smaller over the past 60 years. As a result of climate change and competition from hatchery fish, wild salmon are spending less time at sea and are returning to spawning grounds at younger ages.

The study, by scientists at the University of Alaska at Fairbanks and the University of California Santa Cruz, examined measurements of over 12 million fish collected by the Alaska Department of Fish and Game from 1957 through 2018. Over that time period, four out of Alaska’s five wild salmon species – Chinook, chum, coho, and sockeye – have shrunk in size. Chinook salmon is the official state fish of Alaska and they used to stay out at sea for seven years before returning to spawn. Many are now returning to rivers at just four years old and are on average 8% smaller than they were 30 years ago.

The shrinking size of Alaskan salmon has consequences for people, the economy, and ecosystems in Alaska. Wild salmon is a staple food for many residents of the state, particularly among indigenous groups. More generally, Alaska produces nearly all of the wild salmon in the U.S. Commercial fishing of over 200 million wild salmon in 2019 resulted in $657 million in income. The fish are also an important food source for bears and other wildlife and the spawning migration of salmon plays an important role in nutrient transportation in Alaskan river ecosystems.

Multiple factors are driving the changes in the salmon population, but the largest effects are the changing climate and the abundance of salmon in the ocean due in part to hatchery production that results in competition for the salmon’s food.

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Alaska’s Salmon Are Significantly Smaller Than They Were 60 Years Ago

Photo, posted September 5, 2019, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Dead Zone In The Gulf Of Mexico | Earth Wise

July 6, 2020 By EarthWise Leave a Comment

The Gulf of Mexico has an area of low to no oxygen in the water that can kill fish and other marine life. It is an annual event that is primarily caused by excess nutrient pollution from human activities in urban and agricultural areas throughout the Mississippi River watershed. When these excess nutrients reach the Gulf, they stimulate the overgrowth of algae, which eventually die and decompose, depleting the oxygen in the water as the algae sink to the bottom.

These low oxygen levels near the bottom of the Gulf cannot support most marine life. Some species – among them many fish, shrimp, and crabs – swim out of the area, but animals that can’t swim or move away are stressed or killed by the low oxygen. The dead zone in the Gulf occurs every summer.

A recent forecast for this summer’s dead zone predicts that the area of low or no oxygen will be approximate 6,700 square miles, which is roughly the size of Connecticut and Delaware combined. This is about 1,100 square miles smaller than last year’s dead zone and much less than the record of 8,776 square miles set in 2017. But it is still larger than the long-term average size of 5,387 square miles.

Making comparisons to the long-term average ignores the fact that the long-term average itself is unacceptable. The dead zone not only hurts marine life, but it also harms commercial and recreational fisheries and the communities they support. The actions that have been taken so far to reduce pollution in the Mississippi watershed are clearly not sufficient to drastically reduce the dead zone in the Gulf.

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Large ‘dead zone’ expected for Gulf of Mexico

Photo, posted October 17, 2017, courtesy of NOAA’s National Ocean Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Disappearing Kelp Forests

January 9, 2018 By EarthWise Leave a Comment

In recent decades, ocean temperatures in many places have warmed by nearly 3 degrees Fahrenheit. An effect of this warmer water is the decimation of what were once luxuriant giant kelp forests in eastern Australia and Tasmania. There used to be thick canopies covering much of the region’s coastal sea surface, but they have wilted in the intolerably warm and nutrient-poor water.