Abstract:
Macrophytes are very important component in lentic as well as lotic systems.
Macro-invertebrates are directly influenced by macrophytes as they provide refuge
and food for macro-invertebrates directly or indirectly. Macro-invertebrates
macrophyte relationship has been studied extensively in terrestrial ecosystem, but
for aquatic system it is much less. The study was based on the preference of macro invertebrates for different macrophytes in two fresh water bodies in southern
province of Sri Lanka.
Physico-chemical and Biological parameters were observed in three sites in each
tank. Study was carried out for 6 months of period. As physico-chemical
parameters Temperature, Depth, Light penetration. Conductivity, Dissolved
Oxygen, Biological Oxygen Demand, Primary productivity, Salinity, Alkalinity,
Nitrate concentration and Phosphate concentration were observed data was
collected for each parameter. As biological parameters data on aquatic plant
associated macro-invertebrates per unit area from different sections of particular
aquatic macrophyte were collected. Mean comparison of physico-chemical
parameters and Biological parameters were carried out by one-way ANOVA to
compare each site and different aquatic plants. Abundances of macro-invertebrates
of each site were determined by graphically.
In Godapitiya tank dominantly found Olu and Kumudu. But in Kadawara tank,
found Nelum, Hydrilla, Salvinia as well as Olu and Kumudu. Physico-chemical
parameters proved that the Godapitiya tank was in a moderately polluted state. The
“I
graphical inspection of data was revealed that P0 4 concentration of Godapitiya
tank was higher because the farmers use phosphate fertilizers into the surrounding
paddy cultivation and eventually drain these substances into the tank by rain.
Graphical investigation also revealed that the abundance of Chironomidae is much
high in each sites in two tanks which alarming the pollution state of the Godapitiya
tank. It was observed that family Chironomidae, Pyralidae and Baetidae mostly
prefer leaves, while Dytiscidae prefer roots. Biological parameters indicated that
aquatic macro-invertebrates were directly affected by the macrophytes. It can be
concluded that different aquatic macro-invertebrates colonize in the unique
sections in order to their needs.
