316
Aquaculture of Cypr‘inia‘s
adjusted between 1 and 60 minutes. The recording capacity is 1 month with ]
measurement
per hour and parameter. Each week the operator cleans and checks
the
captors, visualizes, and collects the recorded data with a portable micro
computer
(144 K octet). If necessary new parameters of interval recording
are
programmed. In the laboratory data are transfered on a computer in order
to
determine the most important parameters of pond dynamics and their action
mechanism. Associated with the necessary biological control of nutrients,
plankton and fish, this measurement system will constitute a useful research
tool
in studying environmental response to all technical events such as
fertilization.
’
STUDIES ON AQUATIC WEED ASSOCIATED FAUNA IN POND ECOSYSTEM. K. JANAKI PAM,
Dcpa/utmcwt 05 Zoo£ogy, Nagajum
Nagajum NagM—522570, INDIA.
A general survey of aquatic weed associated faunal communities was made in
15 ponds in the Guntur District, Andhra Pradesh, India. Of these, one tempo—
rary pond, one semi—perennial pond and two perennial ponds were selected for
detailed investigations on hydrochemical parameters, aquatic flora and asso—
ciated fauna. The flora and fauna were quantitatively sampled employing a
modified Wisconsin trap. The ponds were classified as medium hard, hard and
very hard based on hydrochemical characteristics. The macrovegetation was
represented by 13 species and the weed associated fauna belonged to 28 fa—
milies. In certain water bodies the periphytic fauna was dominated by non—
molluscan component, particularly insect larvae, while in others molluscs
were
present significantly. The ponds of the District can be divised into
élig0trophic, mesotrophic and eutrophic based on their productivity. It was
observed that ponds rich in calcium salts supported greater diversity of
flora and higher density of associated fauna (4,884 individual/sq m).
ORGANIC FERTILIZATION IN FRY REARING.
B.
LANOISELEE, R. BILLARD and G. de
MONTALEMBERT,
de UL€£cäLn La Roche en
27530, FRANCE.
Several experiments on organic fertilization in carp and pike breeding ponds
were
carried out in a fish farm in Morvan. Repeated dumping of pig manure
(0.5, 1.5 and 3.0 t/ha/wk, or an equivalent of 2.5, 7.5 and 15 Kg DM ha/d),
as
the
sole outside source of organic matter, improved pond yield in all cases.
The biomass increase between ponds given 0.5 t/ha/wk and 3.0 t/ha/wk was
about 70% for 5—week old pike and 90,60 and 352 for carp alevins et 15,30
and 80 days of age, respectively. Weekly fertilization with 1.5 t/ha/wk over
a
3—month period increased carp larvae yield to almost twofold that of an
unfertilized pond. Maximal yield of young carp of 1 g was obtained by weekly
fertilization with 4 t/ha (20 Kg DM/ha/d); increasing the manure supply cau—
sed fish growth to slow down. The young fish got a good start with organic
fertilization but after 3 to 4 weeks, the amount of available food decreased
greatly and so did fish growth, indicating that organic fertilization, as it
was
practised, was not high enough to maintain a high biomass of young CHYPIn ponds given a large amount of aerated manure, the zooplankton populations
developed rapidly and the phytoplanckton populations declined (increased
water transpareney); the effect of this was to limit the daily amplitude of
phy31cal—Chemical factors such as dissolved oxygen and pH. On the other hand;
the utilization
of non—aerated manure caused the original phytoplanckton
population to increase and thus the amplitude of these parameters to augment;
manure
oxygen consumption (BDD = 15—23 g/l) only slightly affected the
amounts
of
dissolved 02. Although there was a great deal of ammoniacal nitrogen
the manure
(0-7‘3-5 8/1), its high concentrations in the water were
restricted to
the areas where
the manure was
dumped and these concentrations
-
were
of short duration (2 to 3 h after spreading).
Aquaculture of Cypr‘inia‘s
adjusted between 1 and 60 minutes. The recording capacity is 1 month with ]
measurement
per hour and parameter. Each week the operator cleans and checks
the
captors, visualizes, and collects the recorded data with a portable micro
computer
(144 K octet). If necessary new parameters of interval recording
are
programmed. In the laboratory data are transfered on a computer in order
to
determine the most important parameters of pond dynamics and their action
mechanism. Associated with the necessary biological control of nutrients,
plankton and fish, this measurement system will constitute a useful research
tool
in studying environmental response to all technical events such as
fertilization.
’
STUDIES ON AQUATIC WEED ASSOCIATED FAUNA IN POND ECOSYSTEM. K. JANAKI PAM,
Dcpa/utmcwt 05 Zoo£ogy, Nagajum
Nagajum NagM—522570, INDIA.
A general survey of aquatic weed associated faunal communities was made in
15 ponds in the Guntur District, Andhra Pradesh, India. Of these, one tempo—
rary pond, one semi—perennial pond and two perennial ponds were selected for
detailed investigations on hydrochemical parameters, aquatic flora and asso—
ciated fauna. The flora and fauna were quantitatively sampled employing a
modified Wisconsin trap. The ponds were classified as medium hard, hard and
very hard based on hydrochemical characteristics. The macrovegetation was
represented by 13 species and the weed associated fauna belonged to 28 fa—
milies. In certain water bodies the periphytic fauna was dominated by non—
molluscan component, particularly insect larvae, while in others molluscs
were
present significantly. The ponds of the District can be divised into
élig0trophic, mesotrophic and eutrophic based on their productivity. It was
observed that ponds rich in calcium salts supported greater diversity of
flora and higher density of associated fauna (4,884 individual/sq m).
ORGANIC FERTILIZATION IN FRY REARING.
B.
LANOISELEE, R. BILLARD and G. de
MONTALEMBERT,
de UL€£cäLn La Roche en
27530, FRANCE.
Several experiments on organic fertilization in carp and pike breeding ponds
were
carried out in a fish farm in Morvan. Repeated dumping of pig manure
(0.5, 1.5 and 3.0 t/ha/wk, or an equivalent of 2.5, 7.5 and 15 Kg DM ha/d),
as
the
sole outside source of organic matter, improved pond yield in all cases.
The biomass increase between ponds given 0.5 t/ha/wk and 3.0 t/ha/wk was
about 70% for 5—week old pike and 90,60 and 352 for carp alevins et 15,30
and 80 days of age, respectively. Weekly fertilization with 1.5 t/ha/wk over
a
3—month period increased carp larvae yield to almost twofold that of an
unfertilized pond. Maximal yield of young carp of 1 g was obtained by weekly
fertilization with 4 t/ha (20 Kg DM/ha/d); increasing the manure supply cau—
sed fish growth to slow down. The young fish got a good start with organic
fertilization but after 3 to 4 weeks, the amount of available food decreased
greatly and so did fish growth, indicating that organic fertilization, as it
was
practised, was not high enough to maintain a high biomass of young CHYPIn ponds given a large amount of aerated manure, the zooplankton populations
developed rapidly and the phytoplanckton populations declined (increased
water transpareney); the effect of this was to limit the daily amplitude of
phy31cal—Chemical factors such as dissolved oxygen and pH. On the other hand;
the utilization
of non—aerated manure caused the original phytoplanckton
population to increase and thus the amplitude of these parameters to augment;
manure
oxygen consumption (BDD = 15—23 g/l) only slightly affected the
amounts
of
dissolved 02. Although there was a great deal of ammoniacal nitrogen
the manure
(0-7‘3-5 8/1), its high concentrations in the water were
restricted to
the areas where
the manure was
dumped and these concentrations
-
were
of short duration (2 to 3 h after spreading).