Eutrophication & Management 5.4.1-5.4.3, 5.3.1-5.3.2

Eutrophication The addition of excess nutrients (phosphates and nitrates) to a body of water…..can be natural, but is usually accelerated by humans.

Anthropogenic phosphates & nitrates Agriculture sources: Fertilizer Animal Waste/Manure Non-agriculture sources: Detergents Industrial effluent Sewage Are most of these point source or non-point source pollutants?

Process of Eutrophication Run-off including phosphates and nitrates enter body of water. Algae begin to quickly grow. Algal bloom forms (mats of algae) What does this cause? Reduces? Because there are now less plants, there is going to be less___________. What 2 things will this cause?

What increases when aquatic plants decrease? This increased turbidity decreases light penetration and therefore causes less photosynthesis, so more plants die! (Aquatic plants are also called macrophytes) As the animals, plants, and algae die, BOD goes up….Why? So what is happening to even more of the oxygen in the water? Therefore you have multiple _______ feedbacks!

Turbid Water Dead Fish!

Macrophytes decrease

Death of the lake or “Dead Zones” At some point all of the available oxygen is going to be used up and everything dies….including the algae….total collapse of the food chain and decreased diversity. This increases the sediments in the bottom of the lake as it settles. The lake ends up a very clear blue…no life (oligotrophic)

Accumulation of Sediments

Local Example… The Chesapeake Bay

The Watershed Over 64,000 square miles Incorporates 6 states: DE, MD, NY, PA, WV, VA, and Washington D.C. ~16 million people live in the watershed Over 100,000 streams, creeks, and rivers flow into the bay

A Quick History of the Bay The first explorers reached the Bay in the 1500s By 1650, land around the watershed was being cleared for agriculture and timber production. As early as 1750, some ports became unnavigable due to increased sediment By the end of the nineteenth century, 60% of watershed forests had been cleared. It took 300 years to develop the first 2 million acres of watershed land and only 50 years to develop an additional 3 million acres.

State of the Bay Half of the forested lands surrounding the bay have been cleared. Over half of the wetlands are gone. 90% of underwater grasses are gone. 98% of the Bay’s oyster population is gone. They used to filter entire volume of the Bay in 3 to 6 days….now it takes about a year! In 2006, the Chesapeake Bay Foundation gave the Bay a ranking of 29 out of 100

Eutrophication Pollution Management – “Replace” Using alternative detergents with no phosphates Using crops that need less fertilizer or rotational planting/grazing. Use of cover crops in off season. What will this do? Planting riparian buffers Education through PSA’s

Eutrophication Pollution Management – “Regulate” Controlling amount of development Legislation: Oyster Disease Research Program MD and VA have harvesting regulations Clean Water Funding Improving sewage treatment facilities and septic systems to better remove phosphates and nitrates

Eutrophication Pollution Management – “Restore” Dredging sediments and algae out Pumping oxygen into body of water Construction of oyster reefs Since 1997, CBF has transplanted 7 million oysters; plan to produce 31 million in the next 10 years.

Of Replacing, Regulating and Restoring…which the best strategy for the environment? What is usually necessary in order to effectively manage pollution?