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Impacts of the Zebra Mussel (Dreissena Polymorpha) on Large Lakes: Influence of Vertical Turbulent Mixing

Edwards, William J.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1392139735

Abstract Details

2002, Doctor of Philosophy, Ohio State University, Evolution, Ecology and Organismal Biology.
Hydrodynamics strongly influences the role of benthic filter feeders in benthic- pelagic trophic coupling in large lakes. In this dissertation I investigate the interactions of vertical turbulent mixing, light and particulate and dissolved constituents in a large lake, Lake Erie. An Acoustic Doppler Profiler was used to investigate the hydrodynamics of a near shore region of the Lake Erie western basin and then incorporated the measured parameters in a numerical simulation to estimate the amount of phytoplankton biomass consumed by zebra mussel grazing in the benthos. The modeled results were then compared with vertical profiles of algal abundance. Diel average eddy diffusivity estimates varied from 10-5 to 10-4 m2s-1 at the sample site location. The simulations indicate that eddy diffusivities of this order of magnitude can result in extremely low algal biomass near the benthos, while the upper water column remains relatively unaffected. Discounting inputs from algal reproduction, I estimate that between 8 and 67% of the algal biomass is consumed each day at the sample site, depending on the shape and magnitude of the diffusivity profile. Measured vertical biomass profiles have a zone of algal depletion near the benthos, but little evidence of depletion near the surface. I found the daily flow of algal biomass into the benthos was strongly coupled with the magnitude of turbulent mixing, suggesting the flux of algal biomass into the benthos was small compared with previously published estimates that ignored the paucity of turbulent mixing occurring. Vertical mixing can also cause changes in exposure to incident radiation. The depth of the wind-mixed layer and diel thermoclines often determine the light climate of individual plankters, which, due to the random nature of turbulence can be different for plankters at the same depth. Time scales associated with photoresponse are often similar to various mixing time scales, on time scales of minutes to hours. I develop a method to estimate primary productivity, considering the effects of vertical turbulent mixing. The indirect temperature gradient microstructure method was used for calculating energy dissipation, from which I obtain Lagrangian diffusivity estimates. I then apply literature values of photosynthetic parameters (the slope and shape of the photosynthesis-irradiance curve) and a random walk simulation, using the diffusivity estimates, to predict the light climate of the phytoplankton and thus the primary productivity. I find that at some points in time and space, notably in early morning convective mixing, that photosynthesis may be underestimated by as much as 45%. However, diel thermocline formation reduces this effect, trapping algae near the surface and causing near surface declines in production. Separated from the source of mixing, the surface wind-shear, the lower water column primary production is still increased by more than 15% relative to the static model. Patterson et al. (1985) found that six factors influence the vertical oxygen budget in the central basin: 1) Vertical mixing; 2) exchange across the air-water interface; 3) photosynthesis; 4) community respiration; 5) sediment oxygen demand (benthic respiration); and 6) horizontal transport. However, since that time, the trophic status of the lake has undergone profound changes due to the changing phosphorus loading and introduction of the exotic zebra mussel into the lake. Zebra mussels may introduce a large sink for oxygen within the hypolimnion as they spread across the fine sediment (Haltuch et al. 2000). I therefore test the importance of hypolimnion thickness on oxygen depletion, a measure of the total loss of oxygen in the hypolimnion over time (expressed per unit area). I found that hypolimnion thickness is a major factor in hypolimnion oxygen depletion. Entrainment events, which reduced the thickness of the hypolimnion, can increase the oxygen depletion rather than alleviate it. I also test the role of transport processes, across variation in time and depth, in oxygen transport in the central basin using an oxygen budget at differing times of day and quantify the relative importance of four different transport processes. I found that the only significant process in oxygen depletion is bottom shear, caused by hypolimnetic current and influenced by bottom roughness (including biotic roughness caused by zebra mussels) and current speed, which prevents or allows the limitation of the delivery of oxygen to the benthos. Decreases in bottom shear, lead to decoupling of the hypolimnion thickness-oxygen depletion relationship and control by the intensity of the mixing.
David A. Culver (Advisor)
Diane Foster (Committee Member)
Chris Rehmann (Committee Member)
Peter Curtis (Committee Member)
111 p.
Organismal Biology; Zoology

Recommended Citations

Citations

  • Edwards, W. J. (2002). Impacts of the Zebra Mussel (Dreissena Polymorpha) on Large Lakes: Influence of Vertical Turbulent Mixing [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392139735

    APA Style (7th edition)

  • Edwards, William. Impacts of the Zebra Mussel (Dreissena Polymorpha) on Large Lakes: Influence of Vertical Turbulent Mixing. 2002. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1392139735.

    MLA Style (8th edition)

  • Edwards, William. "Impacts of the Zebra Mussel (Dreissena Polymorpha) on Large Lakes: Influence of Vertical Turbulent Mixing." Doctoral dissertation, Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392139735

    Chicago Manual of Style (17th edition)

osu1392139735
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© 2002, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.