Ecologists often refer to “nutrient loading” as an adverse environmental condition. It can be confusing, because nutrients are supposed to be good, right? But as in the case of some vitamin supplements, too much of a good nutrient can create problems.
Let’s look at nitrogen and phosphorus, two elements that are essential to plant growth. They occur naturally and move through ecosystems in cycles driven by plant uptake, death, and decomposition.
When these nutrients get into water, they fertilize aquatic plants, like the seagrasses that provide habitat for fish and crustaceans. So far, so good. But the process can get out of control when too many of these nutrients get into the water.
In particular, algae can grow rapidly. Massive amounts of algae, called an algae bloom, block the light needed by other organisms. And when the tiny plants die, their decomposition depletes oxygen from the water. This makes the water body inhospitable for fish, clams, crabs, and other underwater organisms.
Nutrient loading comes from a variety of sources: fertilizer for lawns and gardens, manure from farm animals that washes into waterways, and human waste that escapes treatment plants. Car exhaust and power plant emissions also contain nitrogen compounds.
Just as in our bodies, the key is to keep nutrients in balance to help avoid health problems. Right now, the nutrient load delivered to many ecosystems is out of balance, and these systems are not healthy.
Photo, taken on September 12, 2010, courtesy of Derek Hatfield via Flickr.