The art and science of cultivating marine or freshwater life for food and industry. Aquatic ecosystem that exhibits effects of eutrophication, such as elevated nutrient levels, harmful algal blooms, and negative changes in the benthic community.
Layers of gases surrounding a planet or other celestial body. (singular: bacterium) single-celled organisms found in every ecosystem on Earth.
Type of aquatic bacteria (not algae) that can photosynthesize light to create energy. Also called cyanobacteria and (in freshwater habitats) pond scum.
Greenhouse gas produced by animals during respiration and used by plants during photosynthesis. Carbon dioxide is also the byproduct of burning fossil fuels.
Popular food fish native to the North Atlantic Ocean. Tiny ocean animal, some of which secrete calcium carbonate to form reefs.
Type of aquatic bacteria that can photosynthesize light to create energy. A nation that has high levels of economic activity, health care, and education.
Nations with low per-capita income, little infrastructure, and a small middle class. Community and interactions of living and nonliving things in an area.
Association of European nations promoting free trade, ease of transportation, and cultural and political links. Build-up of sediment and organic matter in bodies of water, which may cause a change in the productivity of the ecosystem.
Nutrient-rich chemical substance (natural or man made) applied to soil to encourage plant growth. Art and science of raising and harvesting fish and other seafood, such as shrimp or crabs.
Fossil fuels formed from the remains of ancient plants and animals. Part of a body of water deep enough for ships to dock.
Rapid growth of algae, bacteria, or other plankton that can threaten an aquatic environment by reducing the amount of oxygen in the water, blocking sunlight, or releasing toxic chemicals. Watering land, usually for agriculture, by artificial means.
Animal excrement or waste used to fertilize soil. Chemical element with the symbol N, whose gas form is 78% of the Earth's atmosphere.
Substance an organism needs for energy, growth, and life. To harvest aquatic life to the point where species become rare in the area.
Chemical element with the symbol O, whose gas form is 21% of the Earth's atmosphere. Piece of land jutting into a body of water.
The rapid, dense accumulation of algae or other plankton that contain red or brown pigments; also called algal bloom. Overflow of fluid from a farm or industrial factory.
Liquid and solid waste material from homes and businesses. Aquatic ecosystem that once exhibited low oxygen levels, but is now improving.
Rise and fall of the ocean's waters, caused by the gravitational pull of the moon and sun. Bird with long, thin legs adapted for walking and feeding in shallow water.
Dead zones are caused by excessive nitrogen and phosphorous pollution from human activities, including: Agricultural runoff from farmland that carries nutrients from fertilizers and animal manure into rivers and streams, eventually flowing into the Chesapeake Bay.
Dead zones form in both the Bay’s main stem and its tidal rivers, typically in deeper water near the bottom. The location, extent, and severity of the dead zones can change throughout the year, usually peaking during the summer months.
For example, more rain during the spring months can wash more pollution into rivers like the Susquehanna, the Bay’s largest tributary, leading to a bigger dead zone. On average, the Chesapeake Bay dead zone covers between 0.7 and 1.6 cubic miles during the summer months, when the water is warmest and oxygen levels are historically lowest.
For example, researchers at the Virginia Institute of Marine Science (AIMS) have hypothesized that the Bay’s dead zone contributes to stress and disease in striped bass, loss of animals from the bottom of the Bay’s food chain, and a reduction in nutrition for predators, as bottom dwellers’ growth is stunted by lack of oxygen. Shrinking the dead zone is one of the primary goals of the Chesapeake Clean Water Blueprint, the science-based plan to reduce pollution and restore the Bay to health.
The best way we can reduce algal blooms and dead zones is to implement the Blueprint by putting in place the best management practices that control pollution from urban and agricultural lands, as well as wastewater treatment plants and septic systems. Together, and only together, can we prevent dead zones and ensure vibrant habitats for aquatic life in the Chesapeake Bay.
Make a donation to help CBF continue the fight to stop the pollution that causes dead zones. “More than 212,000 metric tons of food is lost to hypoxia in the Gulf of Mexico,” says marine biologist Robert Diaz of The College of William & Mary in Williamsburg, Va., who surveyed the dead zones along with marine ecologist Rutgers Rosenberg of the University of Gothenburg in Sweden.
Only a few dead zones have ever recovered, such as the Black Sea, which rebounded quickly in the 1990s with the collapse of the Soviet Union and a massive reduction in fertilizer runoff from fields in Russia and Ukraine. Fertilizer contains large amounts of nitrogen, and it runs off of agricultural fields in water and into rivers, and eventually into oceans.
This fertilizer runoff, instead of contributing to more corn or wheat, feeds massive algae blooms in the coastal oceans. More algae mean more oxygen-burning, and thereby less oxygen in the water, resulting in a massive flight by those fish, crustaceans and other ocean-dwellers able to relocate as well as the mass death of immobile creatures, such as clams or other bottom-dwellers.
And that's when the microbes that thrive in oxygen-free environments take over, forming vast bacterial mats that produce hydrogen sulfide, a toxic gas. Technological improvements, such as electric or hydrogen cars, could solve that problem, but the agricultural question is trickier.
Although field trials over the last four years have proved the genetic changes' effectiveness, further testing and government approval means that such crops will not be grown before 2012. “It's a big economic benefit for farmers if they use only half as much nitrogen as well a big beneficial impact on nitrogen runoff into waterways,” says Rey, who hopes that this product will be adopted as quickly as herbicide-resistant crops, which only took five years from introduction in 1998 to become nearly 70 percent of the corn grown in the U.S., and is now nearly 90 percent.
That inability to recover is driven not only by the nitrogen buried in the sediment but also by water layers that don't mix with one another, despite the massive flow of rivers like the Mississippi. For example, as Hurricane Katrina bore down on the Louisiana coast with its powerful winds blowing faster than 130 miles (210 kilometers) per hour, the monstrous tropical storm delivered a benefit: it mixed the warm, oxygen-rich surface waters with the colder, almost oxygen-free waters beneath, dispelling the largest dead zone in the U.S. for a time.
Hoping for hurricanes is neither popular nor sensible, so scientists in the Baltic Sea nations, desperate for solutions, are considering so-called geoengineering options: large-scale human interventions into natural systems. Ultimately, it may take revolutions in agriculture and transportation, along with the energy of hurricanes to bring life back to dead zones.
Dead zones in the oceans and seas, which are referred to as “hypoxia,” are caused because there are low oxygen levels in the water. One of the largest dead zones in the world today is in the Gulf of Mexico, sitting off of the coasts of Texas and Louisiana.
There are ways that we all can provide solutions to dead zones, so they are not as large or prevalent. Urban homes can reduce runoff issues that contribute to dead zones by starting their own compost pile.
As an added benefit, this can often reduce the amount of waste that must enter the garbage cycle. Not every chemical is removed, even when treated, which means the waters that come back may still have those cleaning supplies present.
No till farming can conserve up to 2 inches of water in cropland soil, which reduces the need for irrigation and the runoff that is produced from those efforts. It also helps to conserve the topsoil so that the nitrogen and phosphorus do not enter the marine life arena.