Human impacts and the status of water quality in the Bundala RAMSAR wetland lagoon system in Southern Sri Lanka

Abstract

The brackish coastal wetlands in the Bundala National Park, the only RAMSAR site of southern Sri Lanka, are an important waterfowl habitat and economic zone. Bundala Lagoon, one of the three key lagoons of the Bundala wetlands, remains largely intact and relatively pristine, but the other two interconnected lagoons, namely, Embilikala and Malala, are impacted by drainage from 25.6 km 2 of upstream agricultural lands. Seasonal variations of water quality of the three lagoons and the key processes affecting water quality and quantity in these lagoons were studied during three agricultural seasons, to better understand the characteristics of the system. Bundala Lagoon, which was not affected by agriculture, recorded the highest ammonia and total nitrogen concentrations and the lowest phosphorus levels. Higher phosphorus levels in Embilikala Lagoon were related to the upstream agricultural activities with 65% of its total phosphorus measured being reactive phosphorous. Phosphorus additions occurred during the early months of the paddy cultivating seasons. Processes affecting the water quality of the Embilikala-Malala lagoon system included agricultural drainage, livestock additions, and breaching of the sand bar between Malala Lagoon and the sea. The salinity level of the Bundala Lagoon was higher than the others due to the connection to the sea, salt farms in the western part, and less dilution of salt from relatively low surface runoff and rainwater. All three lagoons reported pH levels conducive to most aquatic species. The primary production by phytoplankton in the lagoons of the Bundala wetland was phosphorus limited regarding their ratios of nitrogen to phosphorus. This study provides an overview of the present status of the lagoons of the wetland. Further work is needed to evaluate the impact of the external nutrient and water inputs on the flora and fauna of the lagoon environments. Suitable management practices to ensure the sustainability of the lagoon ecosystem can be derived through this increased understanding.

Influence of Limiting Factors on Phytoplankton and Coliform Population in an Inundated, Isolated Wetland

“…The addition of nutrients and changes in water and land use due to agriculture, human settlements, and small industries may induce reversible or irreversible ecological changes in wetlands (Piyankarage et al 2004). Diversity of plankton population is fairly dependent on quality of water and climatic factors.…”

Seasonal and Spatial Variations in Water Physicochemical Quality of Coastal Potou Lagoon (Côte d’Ivoire, Western Africa)

“…Better understanding of coastal lagoons characteristics and potential impacts allows policy makers and lagoons users to derive and implement policies, legislation and management practices leading to suitable use of coastal lagoons resources for economic gains while preserving their biodiversity. Such interventions require improved knowledge on the processes influencing the physical, chemical and biological characteristics of the lagoons and ongoing changes due to land use practices in the proximity of sensitive lagoons [10].…”

Anthropogenic impact on water quality of Chilika lagoon RAMSAR site: a statistical approach

“…Such interventions require improved knowledge on the processes influencing the physical, chemical and biological characteristics of the wetlands and ongoing changes due to land use practices in the proximity of sensitive wetlands and lagoons (Piyankarage et al 2004).…”