Upload
ohio-environmental-council
View
1.682
Download
7
Embed Size (px)
DESCRIPTION
DISSOLVED OXYGEN IN LAKE ERIE: TEMPORAL, SPATIAL,AND WEATHER- INFLUENCED TRENDS IN THE CENTRAL BASIN, SANDUSKY SUBBASIN, AND WESTERN BASIN Presented at Ohio Academy of Sciences, April 2012
Citation preview
Maya Hughes
Maya Hughes
DISSOLVED OXYGEN IN LAKE ERIE: TEMPORAL, SPATIAL,AND WEATHER-
INFLUENCED TRENDS IN THE CENTRAL BASIN, SANDUSKY SUBBASIN, AND WESTERN BASIN
Maya C. Hughes1, Phoenix Golnick1,2, and Douglas D. Kane1,2
1F.T. Stone Laboratory, Put-In-Bay OH 43456 and
2Natural Science and Mathematics Division, Defiance College, Defiance OH 43512
Outline
• Background of Hypoxia, Lake Erie, and Stratification
• Purpose and Objectives • Weather (2010 and 2011) • Methods • Results • Why Important?
Overview
Hypoxia
• Less than 2.0 mg/L of dissolved oxygen • World-wide problem • Changed drastically in short period of
time • Increasing problem in estuarine
water and shallow coasts • Accelerated by human activities
• Historically, problem in the central basin
• Nutrient loading • Summer stratification
Hypoxia: Lake Erie
Stratification
Stratification
Objectives
1.Compare relationships between temperature, dissolved oxygen concentration, chlorophyll a concentration, and depth.
2.Compare oxygen dynamics between western basin, Sandusky subbasin, and the central basin of Lake Erie.
3.Compare oxygen dynamics and stratification of the three basins to observed rates in summer of 2010 in order to understand effects of weather.
Weather Comparison of 2010 and 2011
March April May June
Weather Comparison of 2010 and 2011
Number of storm events
(defined as three or more hours of continuous wind speed greater than 7 m/s)
Weather Comparison of 2010 and 2011
(Steinhart et al. 2005)
Methods
• Sampled six sites in the Central basin, Sandusky subbasin, and western basin
• Secchi Disk • Multiparameter sonde (every 0.5 m) :
» Temperature (°C) » Dissolved Oxygen (mg/L) » Chlorophyll a (ug/L)
Methods
Six Sites Sites
Results: Hypoxia found earlier this year- by a week
Results: Hypoxia in Western Basin (Kelleys Island Deep) and Sandusky Subbasin (Offshore)
Results: Stratification
Central Basin
Sandusky Subbasin
Western Basin
Results: Comparing 2010 to 2011
Depth of hypolimnion (m)Site (Month) 2010 2011AP (June) 14.0 12.0AP (July) 15.0 16.5LO (June) 12.5 13.0LO (July) 13.5 16.0EAST (June) 10.0 14.0EAST (July) 11.0 13.0EAST (July) 12.0 13.0SOFF (June) 10.0 13.5SOFF (July) 10.0 13.0SOFF (July) 11.0 12.5KID (June) 12.0 13.0KID (July) 12.0 11.0KID (July) 12.0 13.0
Sites where start of hypolimnion was deeper in 2011 than 2010
Results:
• Significant difference in hypolimnion thickness
~0.73 m
Hypolimnion thickness
Hypolimnion depth
• Significant difference in hypolimnion depth
~1.42 m
• ANOVA:General Linear Model: Mean DO (mg/L) versus basin, year, month
• Significant difference in dissolved oxygen between basins and months, but not between years
Results
P Compared to α = 0.05Basin 0.000 < 0.050Month 0.000 < 0.050Year 0.553 > 0.050Basin*Year 0.020 <0.050Year*Month 0.517 >0.050
Conclusions
• Hypoxia was found earlier this year than last summer (1 week)
• Significant difference in stratification -Hypolimnion thinner -Hypolimnion deeper • Relationship between year and basin and
dissolved oxygen • Central basin increased in dissolved
oxygen • Sandusky Subbasin and western basin
decreased
Hypoxia: Effect on Fish
• Effect habitat quality • Influence metabolism, growth, reproduction,
and behavior • Vertical and horizontal migration • Increase spatial overlap- predation and
competition
Round Goby Smallmouth Bass Yellow Perch Steelhead (Rainbow) Trout Walleye
(Vanderploeg et al. 2009, Brandt et al. 2011, Arend et al. 2011)
Friends of Stone Laboratory Dr. Jeff Reutter
Captains Russ Brohl and Matt Thomas
Thank You
Acknowledgments
Hypoxia: Effect on Fish
Results: Interactions