Nutrient accumulation potential and nutritional value of some emergent macrophytes for restoration of eutrophic water bodies in Greater Cairo, Egypt

The current work evaluates the sequestration efficiency of five aquatic macrophytes for inorganic and organic nutrients in their biomass to restore eutrophic wetlands, besides their nutritive quality as animal fodder. Plant, water, and sediment samples were collected from two watercourses (Ismailia canal and Nahia drain) supporting the growth of each of five aquatic plants (Cyperus articulatus, Cyperus alopecuroides, Mentha longifolia, Typha domingensis, and Vossia cuspidata) for chemical analysis. Cyperus articulatus produced the highest biomass (1727.7 g m−2), while M. longifolia had the lowest (115.3 g m−2). The highest levels of N and P (19.20 and 13.20 mg g−1, respectively) were recorded in T. domingensis shoots, while the highest Mg and Na (14.30 and 0.19 mg g−1) were in its belowground tissues. Additionally, M. longifolia shoots had the highest concentrations of K and Ca (0.29 and 17.40 mg g−1). Cyperus articulatus had the highest carbohydrate content, but the lowest crude fiber (CF) and total protein (TP) in its belowground and aboveground tissues, respectively. Menth longifolia's shoot had the highest TP and lowest ash content, while its root had the highest ether extract (EE) concentration. Moreover, the root of T. domingensis had the highest ash content, while its shoot had the highest CF and the lowest nitrogen-free extract (NFE). The five aquatic plants can sequester large amounts of nutrients compared with other similar species. However, T. domingensis is the best plant for extracting most nutrients to restore eutrophic watercourses because it has the highest potential to store nutrients in its aboveground tissues per unit area. Moreover, the nutritional value of the aboveground parts of the five studied species lies within the range of sheep, goat, dairy cattle, and beef cattle forage quality.