Aquatic Plant-Mediated Phosphorus Migration in Lake Agmon-Hula, Israel

The drainage of the Hula wetlands and old “Lake Hula” was completed in the late 1950s. A significant area of land use was converted from its natural habitat to agricultural cultivation. Nevertheless, soil properties deteriorated; consequently, 40 years later, a land reclamation project was completed. A significant part of the reclamation project was the creation of a new shallow Lake Agmon-Hula (LAH). This shallow lake was a key component of the reclamation project, aimed at boosting tourism in the valley. Immediately after water filled the LAH, the adjacent land was invaded by both natural and reintroduced plant species. A follow-up program to monitor individual species and total biomass distribution of submerged, emerged, and floating plants, along with their TP and TN content, was carried out routinely, accompanied by assessments of inflow and outflow (effluent) phosphorus and nitrogen sources in the LAH. The overwhelming presence of nitrogen and the limited availability of phosphorus for rooted plant uptake were concluded. Considering Liebig’s law, which states that plant growth is dictated by the scarcest resource, a contrasting result was found. The uptake of phosphorus, as the limiting factor, is preferred during biomass onset development, whereas it is transferred into LAH waters (measured as effluent at Station 49) later on during the degradation of biomass. The limited nutrient is the most influential factor in enhancing its concentration in lake water through involvement in vegetation biomass dynamics.