Nitrogen pollution is a recurring theme among scientists studying Tampa Bay. It is the primary threat to Tampa Bay's continued recovery, yet it is often difficult for people to understand how a substance essential to life on earth may actually endanger that life.
The answer lies in the familiar adage that too much of a good thing can be harmful. Just like people, estuaries require a balanced diet of nutrients to remain healthy. In Tampa Bay, nitrogen is the most critical nutrient.
Nitrogen is the basic fuel of the Tampa Bay system, producing a steady supply of phytoplankton- tiny one-celled plants such as algae that are a critical element of the bay's food web - and supporting other plants such as seagrasses.
Left alone, Tampa Bay would weather natural fluctuations in nitrogen concentrations without long-term consequences. But adding nitrogen to the system, through sewage, stormwater runoff and air pollution, can tip the scales that keep the bay's overall nitrogen regime in balance. An overdose of nitrogen sends the algae in the bay on a feeding binge. They multiply rapidly, clouding the water and preventing sunlight from reaching seagrasses and other plants.
As the algae die and decay, they consume precious oxygen in the water, killing fish and other aquatic animals.
In the 1970s, TBEP researchers estimate that the bay was receiving 10 times the amount of nitrogen that was present in 1938 - before people began to flock to the bay's borders. The result was murky water, lifeless sediments and pervasive algae blooms.
Today, nitrogen loadings to the bay have been dramatically reduced, thanks to improvements in technologies to cleanse wastewater and stormwater. The bay is clearer than it has been in decades, its sediments are again teeming with life, and seagrasses are rebounding in many areas where they had nearly disappeared.
But nitrogen levels remain about four times higher than they were 50 years ago, and holding onto the gains already achieved will be an even greater challenge as the region continues to grow. That is why keeping a tight rein on nitrogen sources is a key element of the TBEP's blueprint for the bay's future.
