Mobilization of sediment phosphorus by submersed freshwater macrophytes

Abstract

The mobilization of sediment phosphorus (P) by three submersed freshwater macrophyte species was investigated on five different sediments. The study was conducted under controlled environmental conditions in lucite columns that enabled the separation of" sediment and plant roots from the overlying P-free 'complete* nutrient solution. The species investigated (Egeria densa. Hydrilla verticillata, and Myriophyllum spicatum) had minor root systems (on a biomass basis), but were demonstrated to be fully capable of deriving their P nutrition exclusively from the sediments. Phosphorus absorption and transloeation Into shoots (i.e., mobilization) was substantial, and in some cases suggested a greater than 1000-fold turnover of interstitial water PO4-P over a 3-month period. Sediment P mobilization, a function of both plant growth and tissue P concentration, differed considerably among plant species and sediments. Phosphorus release from the species investigated appears to be primarily dependent upon tissue decay rather than excretory processes. The mobilization of sediment P by submersed macrophytes represents an important aspect of the P cycle, and may affect the overall metabolism of lacustrine systems.

Biotic, chemical, and morphometric factors contributing to winter anoxia in prairie lakes

“…Clear lakes had much lower water column TP concentrations, implying they might be less productive; however, the mean macrophyte biomass per unit area was ϳ2.5ϫ higher than in turbid lakes (Table 5). Water column TP concentrations do not necessarily indicate the concentration of phosphorus available to rooted macrophytes because they acquire phosphorus primarily from the sediments (Barko and Smart 1980;Cariganan and Kalff 1980). We did not measure sediment phosphorus, but it is unlikely that sediment phosphorus limits macrophyte growth because nutrient loading from the watershed is high in these shallow prairie lakes (Allan et al 1980).…”

Wetland nutrient removal: a review of the evidence

“…Vegetation is also important in encouraging sedimentation (Uusi-Kamppa et al, 1997), providing a carbon source for denitrification (Haycock and Burt, 1993) and controlling sediment oxygen and water content via respiration, transpiration and influencing humic content. A number of wetland species and aquatic macrophytes within wetlands can stimulate denitrification and nitrification (Hill, 1997), but can enrich the P content of the water column during senescence (Barko and Smart, 1980;Carpenter, 1980) and enhance P release from sediments (Stephen et al, 1997). Despite this, a smaller proportion of the swamps and marshes increased P loading than did riparian areas.…”

Linking phosphorus pools of water, sediment and macrophytes in running waters

“…The vast majority of work has been done in lentic alkaline waters, and a considerable amount of information has been accumulated. The conclusion of these extensive studies is that lacustrine sediments generally are a more important source of phosphorus than is lake water (Barko & Smart 1980, Rattray et al 1991. Most studies on lacustrine macrophytes have been conducted in chambers in laboratory (Denny 1972, DeMarte & Hartman 1974, Bole & Allan 1978, Best & Mantai 1979, Barko & Smart 1980, Gabrielson et al 1984, Smart & Barko 1985, Best et al 1996.…”