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alkalinity, hardness, ammonia and nitrite were 598 RAHMATULLAH, S.M.; RAHMAN,
recorded in favorable condition, which basically
influenced the abundance and seasonal distribution
of phytoplanktons.
597 RAHMAN, M.M.; BEGUM, A. (Caritas
Fisheries Program, Dhaka); ALI, M.S. & ALI,
M.S. (Dept. of Zoology, Dhaka University,
Dhaka). Abundance and Seasonal Variation of
Zooplankton in Relation to Some Physicochemical
Factors in the Hamil Beel of Bangladesh. Bang. J.
Zool., 2006, 34(1), 7-12.
Zooplankton abundance in the Hamil beel
fluctuated distinctly and their populations varied
from 460 to 2353 ind./l. The highest number was
recorded in April followediIn May. In November,
the populations dropped to a minimum
concentration (460 individual/1). In the
zooplankton community, the leading group was
rotifers (43.47%) followed by cladocerans
(22.59%). naupli (10.71%), protozoans (9.19%),
copepods (8.35%) and ostracods (7.16%). A total
of 23 zooplankton genera was identified which
composed of nine Rotifera, three Copepoda, three
Cladocera, one Ostracoda and seven Protozoa.
Water temperature, transparency, water depth, pH.
dissolved oxygen (DO), free carbondiox de (CO 2),
alkalinity, hardness, ammonia and nitrite were
recorded in pertinent condition. The zooplankton
abundance was significantly affected by the
interaction with the physicochemical parameters.
The rotifers correlated positively with DO and
inversely correlated with the combined effects of
free CO 2, alkalinity, ammonia, water depth and
transparency. The copepod abundance decreased
with the increase in transparency and water depth.
The cladoceran showed a significant positive
correlation with DO and inverse correlation with
free CO 2 ammonia and hardness, respectively. The
ostracods showed a significant positive correlation
with pH and inverse correlation with ammonia.
215
M.M. & AHMED, G.U. (Dept. of Aquaculture,
Bangladesh Agricultural University, Mymensingh).
Reproductive biology, artificial propagation and
larval rearing of two freshwater eels, Monopterus
cuchia and Mastacembelus Armatus. Bang. J. Fish
Res., 2005, 9(1), 13-14.
Studies on reproductive biology and artificial
propagation including larval rearing of freshwater
mud eel, Monopterus cuchia and spiny eel,
Mastacembelus armatus were attempted. The
gonadosomatic index (GSI) of mud eel ranged
from 0.41 (August) to 5.52 (June) in males and
0.53 (August) to 7.61(June) in females. In both
cases the GSI showed a peak in June. Fecundity
ranged from 228 (TL - 396 mm; W - 78g) to 5510
(TL - 865 mm; W - 630 g). In case of spiny eel, the
GSI varied from 0.65 (August) to 8.30 (July) in
males and 0.70 (August) to 10.46 (July) in females.
GSI showed single peak in July. Fecundity ranged
from 570 (TL - 240 mm, W - 30 g) to 10870 (TL -
601; W - 350g). Histology of the testes and ovaries
of the eels were carried out to investigate the
gonadal development stages during the
reproductive months (August to November 2003).
In case of male M. cuchia, the secondary
primordial germ cells, primary spermatogonium,
some spermatogonia A and clone of
spermatogonium B in testis were observed in
September. In October-males different sized
lobules having spermatogonia, spermatocytes and
spermatids were observed. In the ovary of M.
cuchia, polygonal shaped oocytes were seen during
September. The oogonia were reduced with dense
and irregular shaped during October. Numerous
pycnotic cells were visible during November. In
male M. armatus numerous broken lobule walls
were found in testes during September. In October,
abundant primary germ cells, pycnotic nests of
degenerating cells, spermatogonia and spermatids
were observed. In females, ovaries had distinct