SURVEY OF THE ECOLOGY OF SUBMERGED AQUATIC MACROPHYTES IN CENTRAL CANADA

A total of 305 sites were examined in southern Manitoba and adjacent regions for submerged macrophytes in relation to water body and substrate type, and eight water chemistry parameters. Decreasing numbers of macrophyte taxa showed significant t-test results for the hydrochemical parameters in the following order: total alkalinity, total filtrable residue, pH, dissolved organic matter, combined nitrate and nitrite, molybdenum blue phosphorus, chloride, and sulphate. Most macrophytes tended to occur at sites where certain other species were also present. χ2 tests revealed 287 significant correlations between pairs of plants, of which 278 were positive and nine were negative. Net hydrochemical preferences were assessed for each plant pair by comparing the significant positive and negative affinities for the eight parameters; one-third of the significant χ2 correlations did not coincide with the apparent net preferences of the respective plants. The most common species did not form the greatest number nor the most highly significant positive correlations with other plants. The similarities between pairs of plants were compared in terms of the significant positive correlations shown by each plant for other species. The major plant groupings that emerged appeared to reflect the habitats in which they most often occurred. © 1979.