OR… The role of nutrients in the cultural eutrophication of Lake Erie Northwest Regional Office Office of the Great Lakes 18 April 2016

You’re glumping the pond where the Humming-Fish hummed! No more can they hum, for their gills are all gummed. So I’m sending them off. Oh, their future is dreary. They’ll walk on their fins and get woefully weary. In search of some water that isn’t so smeary. I hear things are just as bad up in Lake Erie.

Fertilized v. Unfertilized Fertilized Unfertilized (Jim’s lawn) Fertilized (Bob’s lawn) Unfertilized Fertilized

Compost. Piled Higher and Deeper.

P in lakes. Of the 3 major nutrients (N-P- K), phosphorus in the primary fertilizer for aquatic plants. Sources – Chemical fertilizer – Detergents – Manure – Sewage Nitrate and Sucrose fertilizers only phosphorus added Schindler DW Eutrophication and recovery in experimental lakes: Implications for lake management. Science 184:897–899

Too much P in lakes Harmful Algal Blooms (HABs) – See Nate Irwin Cladophora Dead Zones

What is The Dead Zone? A clever term for an area of very low dissolved oxygen at the bottom of Lake Erie. Sounds better than seasonal hypoxia/anoxia Fish need O 2. No O 2 = No fish

Making a Dead Zone(s) Stratified Lake Put P in lake Aquatic plants and algae grow Plants and algae die, sink, rot

3 Lakes Eries 3 Basins Western- Zmax- 62 feet Central Zmax- 82 feet Eastern Z max 210 feet

The 3 Basins

Anti-cyclonic Circulation of Central Basin Journal of Geophysical Research: Oceans Volume 118, Issue 11, pages , 22 NOV 2013 DOI: /2013JC Volume 118, Issue 11,

Epilimnion (warmer, mixed by wind, plenty of O2) Hypolimnion

Why does it matter? Managing central basin hypoxia is a specific objective of the GLWQA. Phosphorus reduction targets are based on computer models that don’t consider Eckman pumping and may over-estimate the volume of the hypolimnion Better understanding of hypolimion is needed for accurate models and effective management.

What are we doing Adding additional Water Quality Network monitoring sites Working with Ohio EPA to better define the thermocline Data may lead to better management decisions.

PA Transects

Contact: Jim Grazio Office of the Great Lakes