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Boundary dynamics of the hypoxic hypolimnion of Lake Erie's central basin

"The distributions and productivity of benthic inverterbrates (quality  and availability of fish food) in Lake Erie's central basin may be  highly influenced by summer hypoxia.  Data on dissolved oxygen (DO)  depletion in shallow hours-long) intrusions of hypoxic (<2 mg/L)  hypolimnion water into nearshore areas.  We recorded DO concentrations  once or twice a day during intervals of 3 to 4 days in July and August  2  6 along depth gradients (7.4 m-16.9 m) near Lorain, Ohio.  The  region of hypoxia followed the contour of the lake bottom, being  shallower in nearshore waters and deeper further offshore.  At a given  site, the thickness of hypoxic water varied by 1.5 m over a few hours.   DO concentrations <1 mg/l were found briefly as shallow as 1  m in  July.  DO <1 mg/L was generally restricted to depths >16m during our  July sampling interval and >14.5 m during the August interval.    The project concluded that: 1) hypoxic events of sufficient duration  to impact invertebrate and fish communities probably occur frequently  in nearshore wates of the central basin, and 2) elevated oxygen demand  of sediments beneath shallow inshore waters in sufficiently great to  result in hypoxia or anoxia near the sediment-water interface even at  depths above the hypolimnion.    The above findings should correlate with the structure of the benthic  invertebrate communities both within and beyond the observed lateral  excursions of the hypolimnion and should help to explain the  distributions of oxygen-sensitive taxa such as Hexagenia spp.  (burrowing mayflies) and Dreeissena spp. (zebra and quagga mussels)."

Status
In progress
Type
Project
Start Date
End Date
Scope of Study
Field Investigation
Scale of Phenomena
Ecosystem
Impact of Pollutants
Nutrients, Including Phosphorus
Resource Management
Wildlife
Lake Basin Connecting Channels
Lake Erie
State Province
Ohio
Annex Numbers
Surveillance and Monitoring

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