Retrospective study on changes in Dondra lagoon (2006–2017) resulting from tsunami impact and post-tsunami development

Abstract

Spatio-temporal changes during the last twelve year period (2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017) and their impacts on ecological and socio-economic status of Dondra lagoon, southern coast of Sri Lanka were studied as many lagoons in southern Sri Lanka are being seriously affected due to anthropogenic pressure in the recent past. The changes of Dondra lagoon and its immediate surroundings were studied in conjunction with a GIS-coupled ecological survey and a questionnaire survey. The lagoon water surface area has decreased by about 0.92 ha (~8%) and the mangrove cover has increased by about 1.38 ha (~11%) over this period. The salinity of the lagoon has also reduced, forming a 'low saline' (3 psu) regime. About 40% of the lost water surface has scarified for a newly formed land mass (~0.4 ha) within the proximal part of the lagoon. The bridge, broken by the tsunami of 2004, has newly been constructed twice during the reporting period. The construction most likely led to impair the inflow and outflow through the lagoon mouth. Several development projects were launched in the immediate periphery of the lagoon stimulated soil erosion causing heavy siltation in the lagoon. The above changes in the morphometry of the lagoon is a cumulative effect of two factors; impaired inflow and outflow through the lagoon mouth, and the increase of the sediment input to the lagoon. If the ongoing processes are sustained, the lagoon will change into a different landscape. Therefore, early intervention to restore the lagoon hydrology is highly recommended if the lagoon ecosystem is to be protected.

Assessing the Influence of Anthropogenic Land-Use Changes on Bird Diversity and Feeding Guilds—A Case Study of Kalametiya Lagoon (Southern Sri Lanka)

“…Indeed, even though the reedbeds resulted from a recent invasion of the lagoon, they now sustain an important part of Kalametiya's avifaunal diversity. This confirms that, as mentioned by [12], a management plan with the objective of returning the entire lagoon to its past state could disturb this community and lead to significant changes in bird species composition. The removal of vegetated areas to retrieve past water surfaces could be expected to negatively impact bird species relying on the new habitats while benefiting species relying on water resources, leading to a shift in the community composition.…”

“…Despite these ecological services and economic benefits, overexploitation of the resources, urbanization, eutrophication, pollution, and modification in their watersheds have been threatening coastal lagoons around the world [3]. Coastal ecosystems in Sri Lanka have not escaped from this pressure, as many lagoons have been subject to anthropogenic-driven changes in recent times [1,[9][10][11][12]. Among the human activities that have been affecting coastal lagoons, inland irrigation projects are prominent in Sri Lanka [11,13].…”

A Concise Study on Essential Parameters for the Sustainability of Lagoon Waters in Terms of Scientific Literature

“…These ions do not exist in higher amounts, but their presence would cause long-term effects. Most urban lagoons are contaminated due to urban runoff, pesticides, fertilizers, and construction debris, which lead to rise TDS in lagoons (Madarasinghe et al, 2020). Therefore, a comprehensive understanding of TDS using authentic past study results is compulsory to evaluate the undergoing sequences and to formulate effective solutions.…”

Human health risk attributed to consumption of seafood and recreation swimming in Negombo Lagoon, Sri Lanka: An assessment on lagoon water and inhabitant oysters (Crassostrea cucullata Born, 1778)

“…Lagoon ecosystems, which comprise approximately 13 % of coastlines globally, play a pivotal role in sustaining biodiversity and the livelihoods of coastal communities by serving vital sources of dietary protein and economic opportunities (Newton et al, 2018;Derolez et al, 2023;Rodrigues-Filho et al, 2023). Nonetheless, the invaluable economic and ecological functions of coastal lagoons are susceptible to anthropogenic disruptions (Derolez et al, 2020;Madarasinghe et al, 2020aMadarasinghe et al, , 2020bLacoste et al, 2023), especially the introduction of fecal contaminants originating from human and livestock waste. Anthropogenic activities, such as seepage from sewer systems, direct discharge of untreated sewage, and mismanagement of livestock waste can introduce a spectrum of pathogens and pollutants that critically compromise the overall quality of lagoon water.…”