Lake Erie “re-Eutrophication” Don Scavia Graham Sustainability Institute University of Michigan
Lake Erie Eutrophication Serious Toxic and Noxious Algal Blooms Annual Hypoxia
History: Increased with increasing TP load Decreased with decreasing load ������������������������������ Central Basin Anoxia �� �� �� �� �������� �� �� �� �� � ���� ���� ���� ���� ���� ���� ����
Central Basin Anoxia ������������������������������ �� �� �� Y. Zhou �� �������� �� Central Basin Hypoxia �� �� �� � ? ���� ���� ���� ���� ���� ���� ����
Water Column Oxygen Depletion Rate Rucinski, et al 2010
Similar Trends in Algal Biomass - plus return of cyanobacteria Conroy & Culver 2005
Microcystis in Lake Erie The Microcystis- Anabaena bloom of 2009 was the • largest in recent years in our sampling region …until 2011 • 2011 T. Bridgeman
Extent of 2011 Bloom WLE Bloom driven by concentration Note apparent diluting effect of Detroit River
What Matters to Hypoxia? Thickness of Central Basin Bottom Layer Air temperature, winds, length of season Organic Matter Flux to the Bottom Algal production and settling – P supply – Length of season
What Matters to Algal Blooms? Air temperature, winds, length of season Algal production – P supply – Length of season
So What’s Been Going On?
Mussel Impact on Hypoxia Not Obvious ��� ��������������������������� ��� Pre-ZM: 1969-1989 Pre-ZM: 1969-1989 ��� ��� p=0.72 ��� Post-ZM: 1990-2002 Post-ZM: 1990-2002 ��� ��� ����� ������ ������ ������ ������ ������ �����������������������������������
What Matters to Hypoxia? Thickness of Central Basin Bottom Layer Air temperature, winds, length of season Organic Matter 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 yet Rucinski et al. 2010
What Matters to HAB and Hypoxia? Thickness of Central Basin Bottom Layer Air temperature, winds, length of season Organic Matter Flux to the Bottom Algal production and settling – P supply – Length of season
What accounts for the large interannual variation in Microcystis blooms? -What is the effect of Maumee River P loading? The best predictor of Microcystis annual crop is the cumulative TP load from the Maumee River from January to August.
SRP Load O 2 depletion rate Rucinski et al 2010
WHY? Rucinski et al 2010
D. Baker
Phosphorus Loads to Western Basin - 2005 5,697 Metric Tonnes/year Data compiled by Dave Dolan, UW-Green Bay Maumee data from Heidelberg University
The Trends Particulate Phosphorus ���������������������� �!����� Maumee River ��� "��#$#��������!����%������������������� ��� ��� ��� ��� ���������������������� �&�����'( Sandusky River ��� ��� "��#$#��������!����%������������������� � ��� ���� ���� ���� ���� ���� ���� ���� ���� ���� ��� ��� ��� ��� P. Richards, Heidelberg � ���� ���� ���� ���� ���� ���� ���� ���� ����
The Trends in Dissolved Reactive P Maumee River ����������������������������� �!����� ���� "��#$#��������!����%������������������� ��� SRP ���� ���� ���� Sandusky River ����������������������������� �&�����'( ���� ���� "��#$#��������!����%������������������� ���� � ���� ���� ���� ���� ���� ���� ���� ���� ���� ��� ���� ���� ���� ���� P. Richards, Heidelberg � ���� ���� ���� ���� ���� ���� ���� ���� ����
)��������������������������* Grand Thames Buffalo-Eighteenmile Big Creek St. Clair Cattaraugus Sydenham Lake Clinton St. Clair Rondeau Rondeau Watersheds Chautauqua-Conneaut Detroit Huron Ashtabula- Cedar Creek Ashtabula-Chagrin Chagrin ! Ottawa-Stony Ottawa-Stony Raisin Grand ! ! Black-Rocky Cedar- Cuyahoga Portage Huron- Vermilion Sandusky Maumee �������������
Relative importance of individual P sources �������������� ���������������������������������������������������������������� ����������� ������������������������������������������������������������������������ �������������� ����������������������������������������������� �������������
Calibrated Soil & Water Assessment Tool (SWAT) models for Major Watersheds Higher resolution exploration in the Sandusky I. Daloglu
Simulated DRP Load 600 SWAT model calibrated to 500 observed Sandusky loads. 400 300 Model 200 Observation (4 year moving average) 100 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 Observed (4 yr average) 4 per. Mov. Avg. (Baseline)
Simulated DRP Load 600 Something else is happening – 500 perhaps tillage Constant High Fertilizer practices? 400 Actual Fertilizer Trend 300 Constant Low Fertilizer 200 100 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 4 per. Mov. Avg. (BaselineKD15) 4 per. Mov. Avg. (Low2) 4 per. Mov. Avg. (High2)
Perhaps a “no-till impact”? Mean Annual TP in Runoff as a Function of Tillage Management Paired treatment begins 7.00 6.00 Total P (mg/L) 5.00 No-till decreases TP Conv. 4.00 3.00 in runoff … No-till 2.00 1.00 0.00 Mean Annual DP in Runoff as a Function of Tillage Management …but increases 0.90 0.80 DP in runoff. Dissolved P (mg/L) 0.70 0.60 Conv. 0.50 0.40 No-till 0.30 0.20 0.10 0.00 Sims and Kleinman. 2006. Phosphorus
Enriched soil P near surface Phosphorus Stratification After 20 Years of No-till on a Blount silt loam, Seneca County, OH lbs/ac Bray P1 0 50 100 Depth Below Soil Surface - 0 -1 -2 Inches South Part Field -3 -4 North Part Field -5 -6 -7 Bill McKibben, CCA Logan Labs
Simulated DRP Load 600 500 No-till 400 Actual Tillage Trend 300 Conventional tillage 200 100 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 4 per. Mov. Avg. (BaselineKD15) 4 per. Mov. Avg. (Conventional) 4 per. Mov. Avg. (Notill)
Bary P1 (lbs/acre) 100 120 20 40 60 80 0 1962 Long-Term Soil P for NW Ohio 1973 1976 1979 1980 1983 1984 1985 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 From A&L Laboratory, Ohio 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
PHOSKD values (Soil P/Runoff P) 350 300 250 Introduce No-Till PHOSKD (m3/Mg) 200 150 100 50 0 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015
Simulated DRP Load 600 500 400 ? 300 Variable PHOSKD 200 Constant PHOSKD 100 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 4 per. Mov. Avg. (BaselineKD15) 4 per. Mov. Avg. (Baseline-KDConstant)
Lake Erie Extreme Precipitation Sandusky Watershed 12 Number of storm events 10 8 6 4 2 I. Daloglu 0 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015
Simulated DRP Load 600 Actual Weather 500 400 300 200 100 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 4 per. Mov. Avg. (BaselineKD15)
Recommend
More recommend