The effects of water turbulence on the limnology of a shallow prairie wetland

Abstract

In the first year of this study a field survey was conducted in the Blind Channel of the Delta Marsh, Canada to determine the influence of wind-induced water turbulence on the limnology of a shallow, prairie wetland. Hourly and seasonal changes in wind stress had a marked effect on suspended particulate concentration in the water column while phytoplankton biomass was affected by wind stress on a short-term (hourly) basis only. Research in the second field season involved a manipulative experiment. Small-diameter littoral enclosures incorporating pumps which permitted in situ control of turbulence were utilized to examine the effects of controlled water turbulence on the limnology of the marsh. Because small enclosures lack turbulence, and are therefore plagued to some extent by enclosure effects, the use of artificially-generated turbulence within enclosures was evaluated as a posible means of alleviating enclosure effects. Turbulence within enclosures influenced all limnological parameters examined (suspended particulate concentration, water clarity, oxygen and nutrient levels, phytoplankton and periphyton biomass and productivity) except water temperature. Enclsoure effects on many of these parameters were evident and turbulence within the enclosures greatly alleviated these enclosure effects. The use of small-diameter turbulent enclosures appears to provide realistic data when compared to the adjacent marsh.