A STUDY OF SELECTED ECOLOGICAL ASPECTS OF THE AQUATIC ENVIRONMENT AND SOME SOCIOLOGICAL ASPECTS IN BUND ALA NATIONAL PARK - A RAMSAR WETLAND IN SRI LANKA

Abstract

Bundala National Park (BNP) is the first Ramsar wetland in Sri Lanka. Present study aimed to investigate ecological aspects o f Malala lagoon, Embillakala lagoon and Bundala Lewaya in BNP. This study also focused on some sociological aspects in BNP. Physico-chemical parameters and biological parameters o f selected lagoons were probed in random, spatial and temporal scale. Diversity and feeding preferences o f fish fauna inhabiting these lagoons were examined. Birds associated with lagoons were investigated with a special reference to their habitat preferences and abundance. Ecological importance o f pondweed beds o f Embillakala lagoon was analyzed. The association between neighboring human community and BNP was also investigated. Morphological features and hydrological characters o f each lagoon differed. Present study identified important phytoplankton, zooplankton and benthic assemblages in each lagoon. Seasonal variation o f physicochemical parameters and biological parameters o f three lagoons were described. Data indicated the spatial and temporal changes o f physico-chemical parameters and key zooplankton species in Malala lagoon. Salinity fluctuations accompanied with changing nutrient levels seemed to play a key role in designing the biological environment o f the lagoons. Thirty-two fish species were recorded from three lagoons. They were categorized into dermersal, pelagic, bentho-pelagic and reef associated guilds. Fish stomach content analysis highlighted the important food items in lagoons. Fishes were classified as piscivorous, zooplanktonivorous and omnivorous depending on their feeding preferences. Analysis o f bird communities revealed that each lagoon performed as a specific habitat for birds. Lagoon area and salinity strongly correlated with bird abundance. The reduction o f abundance o f migratory waterfowls and resident water birds taxa were noted. The difference o f physico-chemical parameters and biological parameters between pond weed beds and adjacent weed free localities revealed that they perform as an important micro-ecosystem. A significant density o f phytoplankton, zooplankton, and benthos inhabited the pondweed beds in contrast to the non-weedy localities. Overall data indicated that studied lagoons are delicate and extremely dynamic ecosystems. Poor education level associated with underprivileged living condition was common in the studied human community. Occupational practices such as fishing, land use practices, utilization o f other park resources have profound effects on the health o f the Park environment. Freshwater discharge into lagoons and anthropogenic desiccation o f lagoons were identified as key factors affecting lagoon hydrology and biology. This study stresses the importance o f long term monitoring programs in Bundala lagoons. Action plans and management plans should be designed in accordance with the dynamic nature o f lagoons and stakeholder perceptions. Investigation o f ecological characteristics more precisely can strengthen sustainable utilization o f resources and conservation efforts.