Assessing and Addressing the re-Eutrophication of Lake Erie Don - PowerPoint PPT Presentation

Assessing and Addressing the re-Eutrophication of Lake Erie Don Scavia

The Team Donald Scavia, J. David Allan, Kristin K. Arend, Steven Bartell, Dmitry Beletsky, Nate S. Bosch, Stephen B. Brandt, Ruth D. Briland, Irem Daloğlu, Joseph V. DePinto, David M. Dolan, Mary Anne Evans, Troy M. Farmer, Daisuke Goto, Haejin Han, Tomas O. Höök, Roger Knight, Stuart A. Ludsin, Doran Mason, Anna M. Michalak, J.I. Nassauer, R. Peter Richards, James J. Roberts, Daniel K. Rucinski, Edward Rutherford, David J. Schwab, Timothy Sesterhenn, Hongyan Zhang, Yuntao Zhou University of Michigan, Purdue University, Grace College, Ohio State University, Heidelberg University, University of Wisconsin-Green Bay, University of Wisconsin-Madison, LimnoTech, Oregon State University, Korea Environment Institute, Carnegie Institute for Science, Ohio Department of Natural Resources, USGS, NOAA Physical Scientists, Ecologists and Chemists, Physical and Ecological Modellers, Engineers, Social Scientists, Practitioners

What is hypoxia? (aka the Dead Zone)

Radiant energy W ind Tem perature Upper w arm , w ell Oxygen m ixed epilim nion Stratified Flux therm ocline Low er colder, poorly m ixed hypolim nion W ell Sedim entation of Mixed Organic Matter Hypoxia = “Dead Zones” Decom posing organic m atter consum es O 2

Lake Erie: Length: 241 miles Southern most, warmest, and Breadth: 57 miles Average Depth: 19 m most productive Great Lake M aximum Depth: 64 m Volume: 116 cubic miles Shoreline Length: 871 miles Water Surface Area: 9,910 square miles Watershed: 30,140 square miles Flushing Time: 2.6 years Population: 10.5 million U.S. 1.9 million Canada “Walleye Capital of the World”

Special Physical Characteristics

Central Basin Anoxia (no oxygen ) Increased through 1970s (phosphorus pollution) Decreased following GL WQA-based clean-up Central Basin anoxia over time Classic Success Story 80 70 60 50 % Anoxia 40 30 20 10 0 1955 1960 1965 1970 1975 1980 1985

Central Basin Hypoxia (DO< 2 mg/ l) Downward trend continued through the mid-1990s Then a resurgence Zhou et al. 2012

Western Basin Algal Booms Similar trend through the mid-1990s Then a resurgence Scavia et al. (in review)

M assive 2011 Toxic Bloom

What M atters to Hypoxia? Thickness of Central Basin Bottom Layer Air temperature, winds, length of season Organic M atter Flux to the Bottom Algal production and settling – P supply – Length of season

What M atters to Algal Blooms? Air temperature, winds, length of season Algal production and settling – P supply – Length of season

What M atters? Thickness of Central Basin Bottom Layer Air temperature, winds, length of season Organic M atter Flux to the Bottom Algal production and settling – P supply – Length of season

Thinner Bottom Layer? => Less O 2 Available

Thermocline Depth and Stratification Strength 3 D. Beletsky et al -2 -7 y = -0.0109x + 16.977 R² = 0.0363 -12 y = 0.0264x - 71.129 R² = 0.1223 -17 -22 1970 1975 1980 1985 1990 1995 2000 2005 2010 No clear evidence through 2005 Rucinski et al. 2010

Water Column Oxygen Depletion Rate Rucinski, et al 2010

What M atters? Thickness of Central Basin Bottom Layer Air temperature, winds, length of season Organic M atter Flux to the Bottom Algal production and settling – P supply – Length of season

GL WQA led to successful reduction in P loads Reached the 11,000 M T target quickly M ostly point source reductions Remaining loads dominated by non-point sources Dolan and Chapra 2012

D. Baker, Heidelberg

The Trends Particulate Phosphorus Particulate Phosphorus, Maum ee M aumee River 0.6 Flow -w eighted Mean Concentration ( m g/ L) 0.5 0.4 0.3 0.2 Particulate Phosphorus, Sandusky Sandusky River 0.1 0.6 Flow -w eighted Mean Concentration ( m g/ L) 0 0.5 1970 1975 1980 1985 1990 1995 2000 2005 2010 0.4 0.3 0.2 0.1 P . Richards, Heidelberg 0 1970 1975 1980 1985 1990 1995 2000 2005 2010

The Trends in Dissolved Reactive P M aumee River Dissolved Reactive Phosphorus, Maum ee 0.12 Flow - w eighted Mean Concentration ( m g/ L) 0.1 SRP 0.08 0.06 0.04 Sandusky River Dissolved Reactive Phosphorus, Sandusky 0.14 0.02 Flow - w eighted Mean Concentration ( m g/ L) 0.12 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 0.1 0.08 0.06 0.04 0.02 P . Richards, Heidelberg 0 1970 1975 1980 1985 1990 1995 2000 2005 2010

Water Column Oxygen Depletion Rate DRP Load O 2 depletion rate Rucinski et al 2010

Richards 2012

High-resolution SWAT model the Sandusky Watershed I. Daloglu

Observed DRP Load 4-year M oving Average 600 500 400 SRP (kg/ year) 300 200 100 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 P . Richards

Calibrated and validated with observed Sandusky DRP loads 600 500 Observed Baseline 400 300 Baseline Representative : - Tillage practices 200 - Fertilizer inputs - Crop choices - Fertilizer timing 100 - Soil P accumulation in topsoil 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 4 per. M ov. Avg. (Baseline-KD8) 4 per. M ov. Avg. (Observed)

How about fertilizer use trends? 350.0 300.0 250.0 Fertilizer inputs kg/ ha 200.0 150.0 100.0 50.0 0.0 1974-1981 1982-1986 1987-1991 1992-1996 1997-2001 2002-2006 2007-2010 11-52-00 11-52-00 00-15-00 Han and Allan 2010

Fertilizer application rate scenario: Little impact on trend 600 500 Constant fertilizer 400 Baseline 300 200 100 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 4 per. M ov. Avg. (Baseline-KD8) 4 per. M ov. Avg. (constantfertKD8)

Tillage practices scenario: Increased conservation tillage Sandusky County Conservation Tillage 100000 MTWH 80000 NTWH Acres 60000 MTSB 40000 NTSB MTCN 20000 NTCN 0 1989 1991 1993 1995 1997 1999 2001 2003 2005

Tillage practices scenario: Appears to have some impact 600 500 100% notill 400 Baseline 300 200 100 100% conventional 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 4 per. M ov. Avg. (Baseline-KD8) 4 per. M ov. Avg. (convKD8) 4 per. M ov. Avg. (notillKD8)

Is this because of the P accumulation at topsoil? 600 500 Observed 400 300 Baseline 200 100 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 4 per. M ov. Avg. (Baseline-KD8) 4 per. M ov. Avg. (Observed)

Is this because of the P accumulation at topsoil? Surface application of P fertilizer and manure Fertilizer application exceeding crop needs Adoption of conservation tillage Soil stratification

M odified topsoil SRP: runoff concentration ratio in the SWAT model 600 500 400 Introduce No-Till 300 200 100 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 Higher values allow phosphorus to accumulate at topsoil Lower values allow more P runoff/ vulnerability

Simulated SRP Load Appears to be a significant factor 600 500 400 But … 300 Constant PHOSKD 200 100 Baseline 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 4 per. M ov. Avg. (Baseline-KD8) 4 per. M ov. Avg. (baseline)

Lake Erie Extreme Precipitation Sandusky Watershed 12 10 Number of storm events 8 6 4 2 0 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015

Random weather scenario 500 450 Actual Weather 400 350 Random Weather 300 250 200 150 100 50 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015

Reversed weather scenario 600 500 Actual Weather 400 300 200 100 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 4 per. M ov. Avg. (Baseline-KD8)

Reversed weather scenario Weather matters, but interacts 600 with land-based conditions 500 Actual Weather 400 Reversed Weather 300 200 100 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 4 per. M ov. Avg. (Reversed weather) 4 per. M ov. Avg. (Baseline-KD8)

Simulated SRP Load Watershed appears more vulnerable to 600 weather impacts in recent years. 500 Observed Soil P accumulation 400 and tillage and fertilizing practices appear to underlie the 300 weather driver. Baseline 200 Change in overall fertilizer rates shift 100 load but do not seem to drive the pattern. 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 4 per. M ov. Avg. (Baseline-KD8) 4 per. M ov. Avg. (Observed)

But, if weather matters … … where are we heading?

Predicted Storm Intensity Hayhoe et al. 2010

Do Phosphorus Loads Matter?

3.5 Smelt relative abundance 3.0 1987-2005 (number / trawl min) Smelt: Commercial Fisheries R 2 = 0.46 2.5 Hypoxia: Water Quality M odel 2.0 1.5 1.0 0.5 0.0 40 50 60 70 80 90 100 Hypoxia duration (days) 10000 Smelt commercial harvest 1987-2005 8000 R 2 = 0.64 (metic tonnes) 6000 4000 2000 0 40 50 60 70 80 90 100 Ludsin, Pangle et al. Hypoxia duration (days)

Vertical Distributions under Strong Hypoxia Y ellow Perch Rainbow Smelt 0 0 Daily 5 M ax. Density Hypoxia 10 OFF 75% 15 20 50% 25% 0% Höök et al Depth (m) M ulti-species, 1-D individual-based model