| Author | Pham Anh Tuan |
| Call Number | AIT Thesis no. AE-92-29 |
| Subject(s) | Fish ponds
Biotic communities
|
| Note | A thesis submitted in partial fulfillment of the requirements
for the degree of Master of Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | A series of short term toxicity tests of an organophosphate
insecticide dipterex (2,2,2- trichloro-1-hydroxylthylphosphate) on
Nile tilapia (Oreochromis niloticus), Hoina, Chlorella were
carried out under laboratory conditions. 24-h , 48-h, 72-h and 96-
h LC50 for tilapia averaging 0.6 g at 24 - 29oC, pH: 7.5 - 7.8
were 3.98 ppm, 2.09 ppm, 1.57 pmm and 1.43 ppm, respectively.
While 12- h, 24-h LC50 values for Hoina were 2.09 ppm and 0.64
ppm . The safe concentration of dipterex for 0. nilotious was
estimated as 0.173 ppm. A reduction in net primary productivity
of pure cultured Chlorella in 3 .5 ppm and 5 ppm dipterex were
investigated; in these two concentrations, net productivities of
the algae were 80.2% and 62 .5% as compared to that of the
control .
A long- term test of 10 weeks with tilapia cultured in tanks,
including 6 treatments with three replicates each, was conducted
in order to investigate long term effects of dipterex application
on a fish pond ecosystem. The highest values of dissolved oxygen
and the lowest N02 - N concentrations were recorded from 3.5 ppm
and 5 ppm dipterex treatment (P<0.05). However , there was no
direct effect of dipterex on water quality . Chlorophyll-a
concentrations were not decreased after al l dipterex
administrations, although a reduction in n et primary productivity
was observed in 3.5 ppm and 5 ppm treatments at the second and
the third administration. The number of total zooplankton, as
well as copepod nauplii, was decreased after each dipterex
treatment in all concentrations. In contrast, there was no
evidence of a reduction in number of Brachionus. Fish mortality
was recorded in all dipterex treatments fol lowing the first
administration. Lower mortality was observed after the later
dipterex administrations. The re was a highly significant
difference (P <0.01) in fish biomass, after the first dipterex
administration through to the e nd of test. The lowest fish
biomass was in 3.5 ppm and 5 ppm dipterex treatments.
An additional experiment was carried out to investigate the
direct effects of clipterex administration on dissolved oxygen
concentration, however, no conclusion concerned with this matter
could be reached.
Based on the present study ,
ppm or below was recommended as
containing Nile tilapia. |
| Year | 1992 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Phillips, Michael J. |
| Examination Committee(s) | Lin, Chang Kwei ;Knud-Hansen, Christopher F.
|
| Scholarship Donor(s) | The Government of New Zealand; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1992 |
