1 / 15

Lake Erie Hypoxia: Comparison of Oxygen Dynamics in the Western Basin with the Sandusky Subbasin

Brie Elking Supervisor: Dr. Doug Kane. Lake Erie Hypoxia: Comparison of Oxygen Dynamics in the Western Basin with the Sandusky Subbasin. Why do we care about Dissolved Oxygen?. Dissolved Oxygen (DO) is essential for most aquatic life Hypoxia occurs when the DO concentration drops below 2 mg/L

iokina
Download Presentation

Lake Erie Hypoxia: Comparison of Oxygen Dynamics in the Western Basin with the Sandusky Subbasin

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Brie Elking Supervisor: Dr. Doug Kane Lake Erie Hypoxia: Comparison of Oxygen Dynamics in the Western Basin with the Sandusky Subbasin

  2. Why do we care about Dissolved Oxygen? • Dissolved Oxygen (DO) is essential for most aquatic life • Hypoxia occurs when the DO concentration drops below 2 mg/L • Hypoxia can kill fish if it is prolonged • Also it can become anoxic, or have no DO left

  3. How does DO become depleted? • Through respiration of organisms • Through abiotic processes • Through decomposition of organic matter http://www.epa.gov/lakeerie/eriedeadzone.html

  4. Why is there no replenishment? • Thermal Stratification • Separates the lake into three layers: epilimnion, metalimnion, hypolimnion • Epilimnion- oxygen due to photosynthesis and diffusion • Metalimnion separates the epilimnion and hypolimnion • Hypolimniongets oxygen from a subsurface chlorophyll maximum • once the algae die they add to the depletion http://www.pearl.maine.edu/windows/community/Water_Ed/Dissolved%20Oxygen/DO_whatisit.htm

  5. Hypoxia and Anoxia • Central Basin may have large areas of hypoxia/anoxia • The Sandusky Subbasin typically goes hypoxic and anoxic • The Western Basin will go anoxic though it is not as common Burns et al. 2005 Conroy et al. unpublished

  6. Goal To compare the oxygen dynamics of the Western Basin and the Sandusky Subbasin and to see how closely their DO concentrations relate to each other

  7. Where were samples taken?

  8. How was this done? • Four sampling dates between June 26th and July 15th • DO and temperature profiles were taken every half meter until the bottom • The mean DO (mg/L) for the water column, epilimnion, and hypolimnion were compared • If no stratification had occurred only water column means were looked at • Compared using a Mann-Whitney test between WB and SSB, p < 0.05

  9. What did we find? That all four dates had data that were not statistically significant However, on July 15th there was stratification for two sites in the Sandusky Subbasin (SSB) and no sites for the Western Basin (WB) Even though the difference between mean DO is not significant this observation is noteworthy It appears that on the last sampling date WB and SSB were starting to deviate from each other

  10. What was happening on the sampling dates? • June 26th - all sites stratified, WB and SSB • July 3rd- all sites isothermal, WB and SSB • July 10th- all sites stratified, WB and SSB • July 15th - SSB- 1 site isothermal • 2 sites stratified • WB all sites isothermal

  11. Did any sites have hypoxia? • Only one site, E, experienced hypoxia over the sampling period • Hypoxia was found on July 15th • Hypoxia is typically found by July 4th, with stable stratification happening in early June • The stratification that occurred during the sampling period was not stable as it fluctuated • We looked at possible reasons for this and compared them to data from the past 5 years • Wind speed, wind direction, and water level

  12. What makes this year different? Wind data- 45005 - W ERIE 28NM Northwest of Cleveland, OH Buoy Station- Marblehead OH, #9063079 All data from June 1st to July 15th

  13. What does this mean? Stratification started later than in other years due to a higher water level thus stable stratification was not observed until the end of the sampling period. Hypoxia was only seen at one location in the Sandusky Subbasin, when in recent years it would be observed earlier and at more stations in the subbasin.

  14. Thanks to everyone who helped • Dr. Joe Conroy Dr. Doug Kane Capt. Matt Thomas Amy Miller http://stonelab.osu.edu/_media/stonelab/fosl/membership.pdf http://www.ael.osu.edu/ael-JoeConroy.html

  15. Questions?

More Related