A beel thicky infested with water hyacinth
A beel thicky infested with water hyacinth
A beel thicky infested with water hyacinth
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
dominant position aAa Chlmuphywe in the cc~lhrl Auram zom. The order of<br />
domination of various cltsaes of phytoplrnktas in central Assun ame is M follows :<br />
Chlorophyceae > Dinophyme > BaciIlariophycene > Myrophymre ><br />
Euglenophyceae.<br />
Phytoplankton diversity in the Iowa Aasam zone of the Brahmaputre valley was<br />
richer. A total of 6 classes represent the phytoplankton group including Chrysophyceae.<br />
AAa Chlorophyceae, Myxophyceae was tbc most dominant group in the lower Assam<br />
zone. Low altitude, higher tcrnpmture and gradual slop provided conducive<br />
conditions for richer plankton growth. Greater amount of nutrient availability favoured<br />
the blooming of the blue green algae (Myxophyceae). The order of domination of<br />
phytoplankton in lower Assam becls was as follows: Chlorophycrae > Myxophyceae ><br />
Dinophyceae > Euglenophyceae > Bacillanophyceae > Chrysophyceae. Another<br />
notable feature in the becls in lower Assam was the high rate abundance of<br />
Euglenophyceae.<br />
Phytoplanktem in the &Is of Barak valley represented by the same four classes<br />
as was observed in the upper Assam <strong>beel</strong>s. The order of domination was Chlorophyceae<br />
> Bac~llanophyceae 1 Myxophyceae> Dinophyceae.<br />
Five groups of zooplankters were present in the <strong>beel</strong>s of Assam viz. Rorifera.<br />
Copepoda. Cladocera, Osfracoda and Protozw. There were 8 genera of Rotifera. 4<br />
genera of Copepoda, 3 genera of Cladocera and 1 each of Osrracoda and Proiozou.<br />
Generally, Copepoda dominated the zooplankton communities in the &Is surveyed,<br />
followed by either Cladocera or Rotifera. Members of Ostracoda were recorded only<br />
from the <strong>beel</strong>s of upper Assam.<br />
Benthos<br />
Benthic communities varied widely in the <strong>beel</strong>s in the range of 0 to 1763<br />
organisms/ml (Table 11). Of the three <strong>beel</strong>s of Tinsukia district, Mota and Rampur<br />
bals arc devoid of any benthic community. Mobpang in the same district has a thin<br />
population of 32 units/m2. Most of the <strong>beel</strong>s of Barak valley districts were poor in<br />
bmthic community while <strong>beel</strong>s of Marigaon and Kamrup districts were rich in bottom<br />
macrofauna. Beels of Golaghat, Nagaon, Darrang and Sonitpur had moderate population<br />
of benthos. The becle of Tinsukia, Dibrugrih and Sibaagnr hod scanty or nq population<br />
of benthos. (hbqods dominated the benUu$ orgnnim followad by bivalves,