Northern prairie marshes (Delta Marsh, Manitoba) : I. Macroinvertebrate responses to a simulated wet/dry cycle / Henry R. Murkin and Lisette C.M. Ross.

Includes bibliographical references (pages 565-569)

The Marsh Ecology Research Program (MERP) was a long-term
experiment (0 track the response of the marsh ecosystem to a simulated
wet/dry cycle in the Delta Marsh. The Delta Marsh is a
large lacustrine marsh on the south shore of Lake Manitoba in
south-central Manitoba. The objective of this chapter is to review the
changes in aquatic invertebrate distribution and abundance during the various
stages of this experimental wet/dry cycle. During the dry stage aquatic
invertebrates within the MERP experimental cells were dormant life stages
and flying adult insects from the adjacent main marsh. Available habitat
structure and food resources changed significantly following reflooding as
the cells moved from the regenerating to the degenerating stages of the
cycle. Invertebrate densities increased quickly following reflooding and
remained fairlv constant over the five years of flooding; however. there
appeared to be a succession of taxa. with those groups responding to the
conditions associated with early flooding giving way to those associated
with the more open conditions characteristic of prolonged flooding. Habitat
complexity and available food resources are important factors in determining
the benthic and epiphytic invertebrate abundance and distribution during
the wet/dry cycle in prairie wetlands. Habitat structure provided by
marsh vegetation and associated litter combined with algal food resources
contributed to the high invertebrate standing crops in these systems.