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