Aquatic Weed Biodiversity And Its Impact On Fish Productivity Of Pisciculture Ponds In Some Specific Sitesof South Bengal
Creators: name: Tanmay Sanyal, Prof. Anilava Kaviraj
Publisher: name: Zenodo
Year: 2017

description: Aquatic weeds are more scientifically termed as aquatic macrophytes.  They have a great role on aquatic ecosystem as because they are the secondary producer on ponds, lake, river, ditches or any other aquatic ecosystem.  Some of them have a great importance on mineral recycling by their several enzymatic metabolic action.  Macrophytes are essentially a part of an ecosystem which can assimilate some essential nutrients such as – carbon, nitrogen, phosphate – they are not only the uptaker of nutrient, but also the source of nutrient bank to the higher organisms, i.e. consumer.  Some macrophytes are good pollutant remover such as (heavy metals), so they are the major part for waste water purification system in aquaculture practice.  Many species population density in directly or indirectly related with respect to the scale of pollution owing to their pollution indicating capability.  The macrophytes when grow enormously and can chock the water body so that it has no such environment for good and hyginic pisciculture practice.  Then they are transformed “macrophyte to “unwanted or undesirable weed”.  It has been proved that some macrophytes are essential for growing some species of fish directly by consuming macrophytes (<em>Ctenophrayngodon idella</em>) or can be indirectly beneficial for nutrition or food chain.  Macrophytes are the flowers, bushes and trees of the under water wetland valued, they provide cover and spawning ground for fish, habitat for both invertebrate epiphytic community and food and habitat for the moose, muskrats and other animal. It can release O<sub>2</sub> to the fresh water animal.  They are the vital component of all fresh water thats why must be preserved in moderate abundance for a healthy productive lake.  The physical factor of sediment, texture, wave action, water depth and light have the key role for macrophytes growth.  Water depth restricts immergent vegetation to a maximum depth of a about 1.5m and wave action abroads immergent, free flowting and flowting leaved vegetation. Disturb the bottom sediment can pull up the rooted vegetation which can increase the turbidity and reduce the light availability to the submerged plants. Aquatic macrophytes generally collonies to depth receiving 1% - 4% of surface light intensity.  The mean summer Sacchidepth is about 1.3 m and macrophytes might be expected down to a depth of 3.3 m.  A complex interaction between the physical and chemical parameters with respect to water is well established.  In general oligotropic pond has low abundance of aquatic macrophytes in relation to mesotrophic pond.  Macrophytes are restricted to a fringe on the shoreline because light levels under water are low as a result of planktonic algal concentration in hyper eutrophic lake.  <em>Myriophyllum </em>sp., <em>Ceratophyllum </em>sp. and <em>Potamogeton </em>sp. are the indicator of nutrient rich condition of pond.  Plant growth has additional effect on the formation and distribution of aquatic bed form.  Because stem and leaf obstruct the flow (Hickin, 1984).  The ecological and economic impact with invessive species are of critical concern to land manager.