Abstract:
The present study focused on the ecological role of aquatic macrophytes on micro ecosystem diversity of pondweed beds in Embillakala lagoon of Bundala National Park.
The taxonomic investigation indicates that pondweed beds of Embillakala lagoon may
comprise of a hybrid of Potamogeton crispus (Linnaeus, 1753) and Potamogeton
nodosus (Poiret, 1788). The study compared the physico-chemical parameters and
biological parameters between the pondweed beds and non-weedy localities of the
lagoon. Mean dissolved oxygen level and the BOD5 were respectively significantly
higher in pondweed beds (8.92±0.1mg/l; 1.7±0.3mg/l) in contrast to non-weedy localities
(5.35±0.3mg/l; 1.3±0.1mg/l) and the mean nitrate concentration was also significantly
higher in pondweed beds (1671.16±606.2pg/l) when compared with non-weedy localities
(133.14±22.5pg/l). Mean suspended solids were comparatively lower in pondweed beds
(193.24±116.4mg/l) than in non-weedy localities (222.6±156.5mg/l). Means of dissolved
phosphate level (78.1±35.0pg/l), gross primary productivity (0.56±0.1mg/l/h), salinity
(2.57±0.28ppt), alkalinity (3.5±1.2mmol/l) and suspended solids were not significantly
different between pondweed beds and non-weedy localities. Results showed a
significantly (p<0.01) higher abundance of microcrustaceans (Phyllodiapotomus
annendalai, Cyclops minutus, Cypridiopsis sp), prawn larvae and insect larvae in
pondweed beds in contrast with non-weedy localities indicating the value of the
pondweed beds as a larval feeding ground. Benthic mollusc species Phos senticosus and
Bithynia tentaculata were also abundant in pondweed beds. As shown by the present
study, pondweed beds exhibit a specific ecological identity. Further studies on pondweed
beds and non-weedy localities are encouraged as a useful indicator to understand the
micro-ecosystem dynamics and diversity in Bundala water bodies. Regulation of the
growth of pondweed beds in Embillakala lagoon may be a useful management tool
