cifri annual report 2007- 2008 - Central Institute of Brackishwater ...

and Eichhornia. Macrobenthlc abundancc in the
wetland was recorded 258 and 692 nos.m3 (average
475 nos.m") durtny monsoon and winter,
respcctively.
Fishegv . Thc wetland harbours rich fish dtversity,
besides, stockcd IMC and cxotics, a lolal of 23 fish
species were recorded during the period. Total fish
production from the wetland durtng past 3 ycars has
bcen reponed from 9.0 1012.0 L'ycar (225.0-300.0 kg
hayr'). Ptsh catch composltlon of the jheel
reponcdly dominated by IMC. foliowed by exotics.
catfiuhes, murrcls and wccd fisher. Thc jhccl holds
sizeable population of some highly prized murrcls
(Ophioccphulur marulius and Ophiop,cnrs, Cirundo nonro
1,~pldocephaius Kuniea, ctc. In addit~on, thc Indm
majorcarps (C,'. curia. L. rohilu, C, mrigu1a)and exotic
carps (C idelia. H mol!lrrx and C ~arpirr) wcrc
stocked In the clcnrcd ponlon ofthc bccl durlng Junc-
July. 2007. A tentatlvc statirt~cal dcstgn oi
experiments (randomlrcd block destgn) lias been
prepared for carryinn out in ~ilu cxpcrlmcnts on I
pen enclosures of npprox. 500 5q.m. sac) rrn
stnndardizat~onof'lish srock cnhanctmientprotocols.
Slandardizingfish slnckenhuncernen~pro~ocol,~
Dorakohora ,an, u closcd serpcntlnc shilllow bccl
(waler-sprcad area 7.71 ha; avcrage depth 1.2 m)
locatcd at Kalnrup dtstrict of Assam, was
~nvcstryated. 'l'hc beel was lheavtly infested wtth frccfloating
macrophytes (mamly C'!('hhorniu c'rusr~pcs)
foiiowcd by rubmcrgcd (Hydnlla sp.. Vulirncriu sp.1
andmarglnal macrophytcs(~phasp.).
Wuirr qualriy . Chardcterlscd by alkaltnc pH (7.4),
moderatc temperaturc (32C1, ion dissolvcd uxygen
(4 mgl") and moderatc free CO, (6 rngl ')
conccntrdttons, moderatc total alkaltnity (64 rngl I),
low hardness (32 mgl I , moderatc spccific
cunductivity (95.6 pScml) and torsi dissolved solids
(46.3 ppm), low calclum (16.03 mgl") and
magnes1um(h.5 mgl ).
Fi,rhery: Ftsh fauna of the bccl comprlacd 45% alrbreathing
fishcs (Anubas lesludineus, Cnliro
Microcosm expcrinlcnt US 35 days duration uuh
performed to smdy lhe cffcct of five diffcrcn~
macrophytcs vtz. Ekhhnrirm tusiipc,. So/,r,81i~
nioi~~s~o, ilvdrillu ~ ~~n~~illota, VUJI~OIC~U .spir~,li~ otid
Cemrophyllum dcmcrrum using one contuner
without ntacrophytr ai control Thc cxperlmvn:
rrvealcd thi~t Eichhornia cru~s!p~i ~nllucnccd
negatively on water temperaturc, watef-pH, dissolved
oxygen and spcctfc conductlvlty and posltlbc Illl~dCt
on free C:O, and total alkdiintty as compared to othcl.
typcs of macrophytcs. Vullisneria rp. showed strong
negative influcncc on total alkalinity sign~fylng Its
capacity toutiltzc HCO, ion forphotuayntlicsis.
Vallirneria sp, and water hyacinth were the
most elliclcnt in utlltzing avaiisbic ions pnrcnt In
sedlment as revealed hy low sp conductiv~ly of
sediment as compared lo other typcs of niacrophytea.
Sedimcnt enzymc profiles showed decrcascd
phosphorus solubtlizauon in terms of alkaline
phosphatasc activity whcrcas that in tcrms US acid
jarciafur, Clarias balmchus, Hetempncwr~sfo~~sil~~,
Channo srrtatus, C punclanis, C onenlulis, ctc. phosphatase activity increascd due to float~ng