A beel thicky infested with water hyacinth

Important rolc in determining the chemical quality of water. The chemical and physical
load brought tn by rain water or surface runsff gets concentrated by evaporation and
altcred by chemical and biological interaction within the system. causing seasonal
variat~ons of various parameters.
Biological characteristics
The ltvtng parl of the ecosystem or the biotic communities in water is governed
by thc vanations of physical and chemical features of the wata body and trophic
interactions associated with it. Biottc communities of the ecosystem can be categorized
broadly as ( I) aurorrophs and (2) hererorrophs. The autotrophs include photosynthetic
ptgmenl bring microscopic plants, plankton and macrophytes. Heterotrophs categov
tncludcs consumers and decomposers The pr~mary organic productivity and the fish
ylcld polcntlal of a water body thus dcpnds largely on the relat~ve abundance of
various communit~cs and the~r associations. Beels are generally cons~dered as h~ghly
cutroph~catcd system with h~gh rate of primary product~vity. The energy produced at the
prlnlary stagc r e.. phytoplankton and macrophytes are transformcd into h~ghcr troph~c
levels through food chams. It IS the eficiency at which this energy 1s transfomrrtd Into
fish lcvcl that detcrmtnes the effccttveness of management In beels. tao maln
path\vays.~,r:. the grci:tng choir1 and the cit7rrrrw clrrrin are found. In the grarlng chaln.
prlmaq productlv~ty IS done by phytoplankton whlch IS grazed by zooplankton. 111 case
of dctr~tus cham, the macrophytes produce the pnrnary energy. In the absence ot' fish
feeding on tnacrophytes, these plants die and settle at the bottom adding to detrltus In
such cases, detritivorous fish flourish and contribute to fishery.
SAI.IENT ECOL.OGICA1, FEATURES OF BEELS IN ASSAM
Soil quality
Soil is vital in maintaining the productivity of any water body. It is one of the
main interfaces through which nummt is released to the water medium. Apart from
helping mineralization of the organic deposits at the bonom, soil provides shelter and
food to the benthic fauna and flora, which play a significant role in maintaining the
nutnent status of overlying water. Dishibution of soil types in Assam is illustrated in
Fig. 3. Soils of the floodplain wetlands receive additional input in terms of organic
matter. inorganic minerals. silt and clay. Since most of the floodplain wetlands are