Oxygen dynamics and plant-sediment interactions in isoetid ...

Paper 3In sediments enriched with 0.4 or 1.6%organic matter, anoxia in the dark was markedlyprolonged in Lobelia’s leaf lacunae compared toplants on un-enriched control sediments (Fig. 2).In contrast, anoxia never developed inLittorella’s leaf lacunae and the diurnal coursehere typically varied between 25-30 kPa in thelight and 5-15 kPa in the dark with no differencebetween control and enriched sediments.Plant performance and critical leaf nutrientsBoth Lobelia and Littorella reduced thedevelopment of roots relative to leaves withincreasing sediment enrichment (Fig. 3). Lengthof leaves relative to roots increased significantlyas a function of sediment organic matter andsignificantly more for Lobelia than Littorella(Linear regression, slope difference, p