ASSESSING THE TROPHIC STATUS OF LAKES WITH AQUATIC MACROPHYTES

We propose that as a first approach the trophic status of natural and artificial lakes having growths of aquatic macrophytes may be assessed by using the total nutrient concentration in the water column (nutrients contained in the macrophytes plus those in the water) in conjunction with existing classification systems. We developed our approach because current approaches for assessing the trophic status of lakes do not adequately classify lakes dominated by aquatic macrophytes. This occurs because conventional sampling and trophic state assessment emphasize conditions in the water and do not consider the nutrients, plant biomass, or organic production associated with macrophytes. Relationships between aquatic macrophytes and other trophic indicators are discussed because changes in macrophyte abundance influence the structural and functional characteristics of lakes. These changes alter perceptions of water quality and overall lake quality.