[audio:http://wamcradio.org/EarthWise/wp-content/uploads/2012/03/EW-05-02-12-Fertilizer-II.mp3|titles=EW 05-02-12 Fertilizer II]
Fertilizer makes our crops grow bigger and our grass greener. But nutrients from fertilizer end up in our waterways, where they may fertilize microscopic plants called phytoplankton.
These tiny plants grow rapidly. When they die, their remains feed bacteria that consume oxygen that is needed by other organisms. The same thing can happen when untreated sewage ends up in waterways. This process is called Eutrophication.
You may notice it when ponds turn green with algae in the summer. This can happen naturally, but when an aquatic ecosystem absorbs excess nutrients, adverse consequences can ensue.
“Too much plant growth is a bad thing.”
Jon Cole is a senior scientist at the Cary Institute…
“In the case of the algae, too much plant growth has a number of effects. One of them is that you get this unsightly bloom. When that bloom sinks to the bottom and starts to decay, its microbial respiration sucks the oxygen out of bottom water, and that can cause it to be a really hostile environment for fish and other things we tend to care about.”
“Another effect is that the algal species that tend to grow under enriched conditions are often ones that aren’t great for the environment that was there before. For example, we tend to get large colonial or filamentous forms that aren’t good food for this plankton – so they’re not helping the food web. And some of the forms are toxic, both to the organisms in the lake, to humans, and to wildlife. This is particularly true for the so-called blue green algae, sometimes called the Cyanobacteria.”
We all like green grass, and we certainly want healthy and plentiful crops. But we have to balance these positives with the health of our lakes and rivers and the organisms they support.
Web Extra
Jon Cole, a senior scientist at the Cary Institute, discusses some ways that too much plant growth, like that of Cyanobacteria, can be controlled…
[audio:http://wamcradio.org/EarthWise/wp-content/uploads/2012/03/Cole_web_extra.mp3|titles=Cole_web_extra]Links
Dr. Jonathan J. Cole
http://www.caryinstitute.org/people_sci_cole.html
Wastewater and the Hudson River
http://www.ecostudies.org/chp_waste_river.html
Photo, taken on June 20, 2010 using a Canon PowerShot A570 IS, courtesy of Lake Improvement Association via Flickr.