The effect of sediment characteristics on the distribution of aquatic macrophytes

Two transplant studies and a correlation study were used to investigate the effects of sediment characteristics on the distribution of three aquatic macrophytes; Stuckenia pectinata, Elodea canadensis, and Myriophyllum sibiricum. In an enclosure transplant study, Elodea canadensis outgrew all competitors in its own sediment. Furthermore, small vegetative portions of Elodea canadensis that remained in the sediment after it was screened actually displaced mature transplants from other sediment types. An in-situ full-factorial reciprocal transplant study using the three plants was also conducted. Parameters including shoot length, shoot weight, root length, root weight, the presence of fruiting bodies and survival were measured on macrophytes grown in four different sediment types, each autoclaved and non-autoclaved. Sediments were characterized for grain size, pH, cation exchange capacity, carbonate content, and elutriate nutrient content. Most plant growth parameters differed significantly with type and autoclave status of sediments. In Elodea canadensis and Myriophyllum sibiricum, but not Stuckenia pectinata, highly significant statistical differences were found in most plant traits between autoclaved and non-autoclaved treatments, as well as between the different sediment types. In the correlation study quadrats were sampled along transect lines run through naturally occurring beds of the three plants. Percent cover and above ground biomass of the macrophytes were correlated to the sediment characteristics in the reciprocal transplant experiment, as well as total carbon, total nitrogen, and elemental concentrations in both the sediments and plants. Seventy elements and ten major oxides were analyzed by aqua regia acid digestion, neutron activation, and lithium metaborate/tetraborate fusion in the sediments and sixty-four elements were determined by total acid digestion in the plants. A number of sediment characteristics showed significant positive or negative correlations with sediment type, with Elodea and Myriophyllum sediments being similar and Stuckenia sediment being dissimilar. Elodea canadensis growth parameters were most positively correlated, and Stuckenia pectinata growth parameters were most negatively correlated with, ammonia concentration. These findings indicate that macrophyte beds are highly stable community components, and are relevant to studies involving wetland construction, aquatic restoration, or the appearance and success of invading species.