Submerged Stage - Hydrarch
This habitat which is now shallower and is richer in nutrients and where light is available up to a certain depth, becomes suitable for the growth of rooted, submerged hydrophytes like Myriophyllum, Elodea, Hydrilla, Potamogeton Vallisneria, Utricularia and Ceratophyllum. These grow at various depths, mostly rooted in the muddy or sandy bottom depending on the species, and also on the clearness or turbidity of water.
Year after year, this vegetation expands and covers large areas, and brings about marked changes in the habitat. Materials eroded by streams, rainwater or surface runoff are brought to the pond, and some of it are deposited on the plants because they form a direct obstacle in its advance, and especially because they slow down the currents, when the plants and the associated animals die, they sink to the bottom, where because of the insufficient oxidation, this organic matter is partially decomposed. Thus humus is formed which cements the mucky soil together making it firmer. The result of these reactions is the building up of substratum and shallowing of lake. Obviously, this process is disadvantageous to the present occupants and these are eventually replaced by another type of plants, which are of floating type.