Factors affecting community structure, distribution pattern and chemical composition of aquatic macrophytes in El-Rayah El-Nasery and El-Noubaria Canal of Nile River, Egypt

Abstract

This paper provided an ecological and phytochemical evaluation of the aquatic macrophytes at El-Rayah El-Nasery and El-Noubaria Canal of the Nile River, Egypt. Throughout the study period from spring 2015 to winter 2016, 12 macrophyte species related to 6 families and 8 genera were recorded, one floating species, three submerged and eight emergent. Myriophyllum spicatum L., Echinochloa stagnina (Retz.) P. Beauv, Potamogeton perfoliatus L. and Cyperus articulatus L. were found as the most frequent species. In comparison, autumn, spring and the sites (N7, N8) at the end of El-Noubaria Canal were recorded as the richest seasons and sites in species numbers. The analysis of the macrophyte biochemical composition revealed the presence of species specificity as well as temporal and spatial variations. In the two studied areas, nitrogen-free extracts constitute the major part of the macrophyte organic matter content, while total lipid constitutes the minor one. Among all the analyzed macrophyte samples, the highest values of protein, digestible crude protein and nitrogen were found in autumn samples of P. perfoliatus from site N5 (after the confluence of El-Rayah with El-Noubaria Canal), while the highest energy value and metabolized energy were obtained from the winter samples of M. spicatum from site N4 (the beginning of El-Noubaria Canal). There were different relationships between the different macrophyte species, their chemical composition and the ambient water variables. Therefore, it is difficult to detect a main single factor affecting their pattern of variation. However, in general, the analyzed macrophytes could be considered a good economic natural food resource for animals and fishes.