Shallow open waters are small bodies of standing or gently flowing water that represent a transitional stage between lakes and marshes. They vary greatly in physical and chemical composition. Their mid-summer depth is less than 2 m and open expanses of water comprise at least 75% of their area. Ponds, pools, oxbows and channels are all different types of shallow open water. Their surface is free of vegetation except for aquatic macrophytes. Unlike lakes, the water temperature in shallow open waters is uniform, lacking any stratification.