Nutrient enrichment, especially by nitrogen and phosphorus, can have a significant effect on watercourses, resulting in changes in aquatic communities,vegetation and invertebrate assemblages, including large increases in the biomass of filamentous algae, cyanobacteria and macrophytes [1–3]. Dissolved oxygen (DO) may be enhanced during the day due to photosynthesis but it declines at night with respiratory oxygen demand and may fail to recover the next day [4,3]. Species of invertebrates and fish adapted to low Dissolved oxygen concentrations may become more abundant while more sensitive species decline.