Nutrient status of wetlands in the Interlake Region of Manitoba, Canada

Preliminary observations indicated that the productivity of wetlands in the Interlake region of Manitoba, Canada is low, resulting in limited use by waterfowl and other wildlife species. This study compared nutrient availability, algal biomass, and invertebrate abundance and biomass between two Interlake wetlands. The Narcisse site was a typical Interlake wetland with no known source of external nutrient input. The Cruise Marsh site was a wetland similar to the Narcisse site except for the operation of a cattle feedlot on its shore. Total dissolved and suspended N and P levels were higher at the Cruise Marsh site throughout much of the year. Phytoplankton and epiphytic periphyton biomass were also much higher at Cruise Marsh. Epipelon biomass in unvegetated Narcisse sites was higher than found in vegetated Narcisse sites or at Cruise Marsh. Invertebrate abundance and biomass were lower at Narcisse. The Narcisse wetlands do appear to be nutrient limited, which in turn affects the algae and higher order consumers like invertebrates. These low invertebrate levels likely play a role in the low use by waterfowl and other marsh birds in these wetlands.