Muhammad Sohail

Variation Of The Primary And Secondary Productivity In Monoculture And Polyculture System Of Fish Pond - 2010

The present study was planned to check the primary and secondary productivity of fish
ponds. The primary productivity was checked by the estimation of chlorophyll-a and
abundance and diversity of phytoplankton in fish pond, the secondary productivity was
studied by identifying and counting the species of zooplankton. Sample were obtained
from treated and controlled ponds; in treated ponds in addition to periodic fertilization of
ponds, supplementary experimental fish feed was provided but in controlled ponds only
fertilizers (organic and inorganic) was applied to enrich the productivity. This study
provides a comparison of the effect of fish feed on plankton productivity. Data were
obtained on weekly basis during l " September to 31 November and on daily basis from
I st November to is" November. The data were collected weekly for chlorophyll
concentrations in fish ponds and fortnightly for phytoplankton and zooplankton
abundance and diversity and were related with the physico-chemical parameter. The
amount of chlorophyll a pigment and plankton abundance in treated and control pond of
Catla catla, Cirrhinus mrigala and Labeo rohita was observed. It was high in pond
containing Cirrhinus mrigala ranging from 2.056-4.421 IJ.g/L in pond containing Catla
catla it was low (ranging from 0.313-0.768 IJ.g/L). It was observed those ponds that were
treated although showed significantly higher chlorophyll-a, phytoplankton and
zooplanktons but fish was keeping the biomass grazed and there were no blooms of
phytoplankton were observed after the application of fertilizer. Data obtained weekly as well as every day showed a decrease in the level of chlorophyll
with the time. It was high in the treated ponds compared to control pond however the decreasing trend remained same. Primary productivity as studied from chlorophyll was
significantly difference in the ponds with Cirrhinus mrigala (F = 40.14**) and was non
significant in ponds with Labeo rohita ( F = 2.9SNS) and Catla catla (0.75NS) when
studied weekly and chlorophyll concentration values when observed daily showed
Cirrhinus mrigala (F = 52.91 **) Labeo rohita ( F = 20.00**) and Catla catla (11.73*)
all were significantly different and were higher in treated ponds in comparison to control
ponds. The diversity indices for phytoplankton and zooplankton distribution abundance
were estimated for treated and control ponds with different species of fish (Cirrhinus
mrigala, Labeo rohita and Cirrhinus mrigala). Higher values of diversity (H' =),
equitability (E =) and Simpson index (D= ) was observed in treated pond of Cirrhinus
mrigala.



Department of Fisheries & Aquaculture

1337,T


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