Influence of Potamogeton crispus harvesting on phosphorus composition of Lake Yimeng

Abstract

Harvesting is an important method used to control the overproduction of Potamogeton crispus in lakes. A three-year comparative field study was performed in a eutrophic lake (harvested area) and its connected lake (non-harvested area) to determine the effects of harvesting on the phosphorus (P) composition and environmental factors in the water and sediment. Results revealed that harvesting significantly reduced the dissolved total P and dissolved organic P (DOP) and increased the alkaline phosphatase activity and particulate P (PP) in the water. No significant differences were detected in the water total P (TP), soluble reactive P, chlorophyll-a, pH, and dissolved oxygen between the harvested and non-harvested areas. Sediment TP and organic P (OP) were significantly reduced in the harvested area. Harvesting changed the P composition in the water. In the non-harvested area, P was mainly formed by DOP (40%) in the water body, while in the harvested area, PP was the main water component (47%). Harvesting increased the proportion of inorganic P (IP) in the sediment and decreased the proportion of OP. In the water, the IP to TP ratio in the non-harvested and harvested areas were 58.26% and 63.51%, respectively. Our results showed that harvesting changed the P composition in the water and sediment. In the harvesting of submerged vegetation, our results can serve as a reference for the management of vegetation-rich lakes.

Interspecific Differences in the Effects of Calcium and Phosphorus Coprecipitation Induced by Submerged Plants on the Water-to-Phosphorus Cycle

“…After the death of submerged plants, as a result of reversible adsorption reactions, H 2 O-P re-enters a water body in the form of soluble phosphorus and is directly utilized by other aquatic organisms [12,13], while NaOH-P becomes soluble inorganic phosphorus through microbial decomposition [37,38]. This could explain the sharp increase in water phosphorus content after a decline in submerged vegetation [6,8]. Compared with H 2 O-P and NaOH-P, HCl-P is not easily dissolved or adsorbed under normal circumstances, and phosphorus is difficult for organisms to dissolve and adsorb.…”

“…Similarly, the variation in OP with P. crispus over time suggested that the mineralization rate differed because of differences in the rhizosphere oxygen secretion capacity of the two species, as discussed above. For the sixth week, the increase in OP might be ascribed to the abscission of linear leaves of C. demersum as the decomposition of plant residues increases the proportion of OP [6].…”

“…In shallow lakes, submerged plants can effectively reduce the phosphorus levels in overlying water during the growing season [6] and affect the movement and transformation of phosphorus at the sediment-water interface [7][8][9]. Submerged plants remove phosphorus from water in three main ways: surface adsorption to form adsorbed phosphorus (H 2 O-P), plant absorption to form sodium hydroxide-extractable phosphorus (NaOH-P), and coprecipitation with supersaturated CaCO 3 to form calcium phosphorus (CaCO 3 -P) [10][11][12][13].…”

Nutrients and Environmental Factors Cross Wavelet Analysis of River Yi in East China: A Multi-Scale Approach

“…The DO in the research region increases in the spring owing to P. crispus reproduction and decreases in the summer due to P. crispus decline in the water body. P. crispus growth may also absorb N and P from the River Yi, resulting in a decrease of N and P in the water [44]. N and P are released into the water during the decomposition of P. crispus, which is a major reason influencing the periodic variation in N and P concentration in the water.…”