Effects of Aquatic Herbivorous (Snails) on Submerged Macrophytes in Rivers

Aquatic ecosystems are one of the most important ecosystems. They contain algae, bacteria, fungi, higher plants and animal. The men life strongly tied to aquatic ecosystem, for example a large amount food and oxygen men requirement provides by aquatic ecosystem. Therefore, appraising of aquatic ecosystems in order to sustainable exploration them is necessary. The aims of this study was evaluation the roles of aquatic herbivorous on various aspects of aquatic plants. Fresh water ecosystems (rivers), because aquatic plants have vital roles in aquatic ecosystems. This experiment was conducted in artificial streams (a small model of river or stream). The effects of herbivorous snails on freshwater macrophytes was conducted during 11 days in artificial streams. We studied the effects of different densities of snail on four freshwater macrophytes productivity (Ceratophyllum demersum, Potamogeton gramineus, Chara braunii and Lemna minor ). Results revealed that herbivorous snail decreased wet mass, dry mass and primary growth rate (PGR) of the freshwater macrophytes. These results suggest that herbivorous snails have a major role in freshwater macrophytes communities.The greatest primary growth rate (PGR) was observed in Ceratophyllum and Chara had the lowest primary growth rate compare to the other macrophytes.

Keywords:

macrophytes , snail , primary growth rate