Farming and the Fight Against Hypoxia in the Gulf
Hypoxia occurs naturally in bodies of water worldwide. Excessive nutrient loads cause low oxygen levels in waterways, leading to algal overgrowth. As these algae decompose, they consume oxygen, creating dead zones void of marine life.
The largest hypoxic zone in U.S. coastal waters is in the northern Gulf of America. It is caused primarily by nutrients from the Mississippi River watershed, which drains a vast area of agricultural land and urban centers, carrying a significant nutrient load into the Gulf. The hypoxic zone has covered more than 8,500 square miles at its largest1. A similar dead zone forms in the Chesapeake Bay each summer.
Causes of the Northern Gulf of America Hypoxic Zone
Nutrient runoff from agriculture is a primary driver of hypoxia. Excess nitrogen and phosphorus from fertilizers and livestock waste enter the Mississippi River and flow into the northern Gulf, fueling algal blooms. As these die and decompose, bacteria consume oxygen, creating dead zones.
Urban wastewater and industrial discharge also contribute to nutrient pollution. Many cities along the Mississippi River release wastewater containing high levels of phosphorus and nitrogen. Industrial facilities may discharge nutrient-rich waste, worsening hypoxia, while stormwater runoff carries additional pollutants that feed algal growth.
Once in the Gulf, these excess nutrients trigger a destructive cycle. The algal blooms thrive, then die off and fall to the ocean floor, where bacteria break them down, consuming oxygen. This depletes water oxygen levels, forcing sealife to move on, leaving behind a devastated ecosystem.
The effects of hypoxia on the Gulf ecosystem
The Northern Gulf of America Hypoxic Zone disrupts the marine ecosystem by creating large areas of low-oxygen water, forcing many fish, shrimp and crabs to move to oxygen-rich areas. This migration reduces biodiversity in the affected region and increases competition for food and space in nearby waters.
Another significant consequence is the damage to marine food chains. Many small organisms that are food for larger predators die in hypoxic conditions, reducing the available prey for aquatic life and birds. This disruption can cause declines in key commercial species, such as shrimp and red snapper, which may struggle to find food and suitable spawning grounds.
How hypoxia impacts the economy
The hypoxic zone has significant economic consequences, particularly for the commercial fishing industry. Shrimp, crab and fish populations migrate away from low-oxygen waters, reducing catches and increasing fuel costs for fishermen traveling farther to find viable areas. This leads to lower profits, higher seafood prices and potential job losses for those dependent on Gulf fisheries — an industry that generates $1 billion a year2.
As the Gulf ecosystem degrades, the appeal of coastal destinations declines, negatively impacting property values and local economies. Charter boats and bait shops lose revenue as fish populations decline. Associated algal blooms can lead to beach closures and health warnings, deterring tourists and affecting local businesses such as hotels, restaurants and water sports providers.
How agriculture and other stakeholders are mitigating the hypoxia problem
Agriculture is adopting best management practices to reduce nutrient runoff and mitigate the Northern Gulf Hypoxic Zone. Many farmers are implementing cover crops, buffer strips and conservation tillage to prevent soil erosion and keep excess nitrogen and phosphorus from reaching waterways. These methods help retain nutrients in the soil, reducing their transport into the Mississippi River system. Precision agriculture technologies, such as soil testing and GPS-guided fertilizer application, allow farmers to apply only the necessary nutrients, minimizing waste and runoff.
Efforts to improve nutrient management plans are also gaining traction. Many farmers are shifting to slow-release fertilizers and optimizing the timing of fertilizer application to align with crop needs, reducing excess nutrients washing into rivers. Some agricultural operations adopt wetland and bioreactor practices, which act as natural filters by capturing and breaking down nutrients before reaching larger water systems.
The Northern Gulf of America Hypoxic Zone presents a complex challenge with far-reaching environmental and economic consequences. Addressing this issue demands sustained research and collaborative action among stakeholders. By working together, we can minimize hypoxia's impacts and safeguard the Gulf's valuable ecosystem and economy for future generations.
Brought to you by America’s soybean farmers.
1National Oceanic and Atmospheric Administration. (2023, August 2). Larger-than-average Gulf of Mexico ‘dead zone’ measured. NOAA. https://www.noaa.gov/news-release/larger-than-average-gulf-of-mexico-dead-zone-measured
2National Centers for Coastal Ocean Science. (n.d.). Northern Gulf of Mexico Hypoxia Program (NGOMEX). NOAA. https://coastalscience.noaa.gov/science-areas/habs/habhrca/ngomex/