Browsing by Author "Subasinghe, K."

Now showing 1 - 4 of 4

Abundance and distribution of microplastics in Muthurajawela wildlife sanctuary and Pamunugama beach, Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Sandaruwan, U. A. C.; Vithana, P. V. A. S.; Sithumini, W. E. B. K.; Samaraweera, B. G. K. N. D. B.; Tharani, T.; Gallage, C.V.; Subasinghe, K.; Vidanage., S. P.
Microplastics (MPs), defined as plastic particles less than 5 mm, are increasingly recognized as a global environmental threat impacting marine and terrestrial ecosystems. This study investigates the prevalence, distribution and characteristics of MPs in the lagoon and coastal sediments of Muthurajawela Wildlife Sanctuary and Pamunugama Beach in Sri Lanka, areas interconnected through the Negombo Lagoon. Sediment samples were collected from 14 locations (06 from the Muthurajawela lagoon and 08 from the Pamunugama beach) distributed in both in low-tide line and mid-tide line identified through systematic sampling method. From each location, three replicate samples were collected to form a composite sediment sample and 20g of oven-dried sediment was used for analysis of MPs after performing a density separation on the sieved sample. The abundance, size, and shapes of MPs were examined using a stereomicroscope using “Optica TCB5.0” software. Observed MPs were divided into two size ranges: 5 mm – 1.1 mm and 1 mm – 0.5 mm and defined as “large MPs” and “small MPs” respectively. MPs were divided into five categories of shapes: fragments, filaments, films, foams and pellets. Findings indicated a higher abundance of MPs in Pamunugama Beach sediments (79.3 ± 10.3 MPs/Kg) compared to Muthurajawela lagoon (58.0 ± 10.8 MPs/Kg). In Muthurajawela, smaller MPs were more prevalent (79.87%) than larger MPs (20.12%), with a statistically significant difference (p<0.05; Two-sample T test) while Pamunugama Beach showed no significant difference in the abundance of large and small MPs. The abundance of total MPs was not significantly different between low and mid-tide lines at both study sites suggesting a low spatial variability in abundance (p>0.05; Two-sample T test). The most common MP shape in Muthurajawela was filaments (78.8%), while fragments (61.53%) dominated Pamunugama Beach. The study also underscores the impact of the MV X-Press Pearl ship disaster on Pamunugama Beach, contributing to the higher MP levels observed. MPs in Muthurajawela were primarily filament-shaped, likely sourced from urban wastewater and industrial activities, whereas Pamunugama Beach exhibited more fragment-shaped MPs due to recreational activities and natural fragmentation processes driven by coastal dynamics. These findings provide critical baseline data for long-term monitoring and highlight the need for targeted mitigation strategies. Future research should focus on the ecological impacts of MP pollution, particularly on wetland birds and other wildlife in these regions. Comprehensive studies examining the sources, pathways, and ecological consequences of MPs will further inform conservation efforts and policy decisions, ultimately contributing to the protection of Sri Lanka's unique coastal and wetland ecosystems.
The impact of forest conversion to the avifaunal diversity in Northern Flank of Knuckles mountain forest range
(University of Sri Jayawardhanapura, 2013) Subasinghe, K.; Weerawardhena, S.R.
Influence of vegetation attributes on bird functional traits in a Pinus mixed forest at Yagirala forest reserve, Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Gallage, C. V.; Perera, W. W. A. M. R.; Subasinghe, K.
Although many studies have examined changes to overall species composition and diversity of birds following the conversion of natural forests into forest plantations, only a few have examined changes to functional trait compositions. The present study investigated the functional trait responses to the conversion of natural forests to forest plantations by comparing the richness and abundance of functional categories of three traits: i) feeding guild (categories: carnivores, insectivores, frugivores, nectarivores, omnivores and granivores), ii) nesting habit (categories: non-cavity tree dependence nesting, tree cavity nesting, ground nesting and parasitic nesting), and iii) foraging stratum (categories: ground foraging, mid-high foraging, and canopy foraging) of a bird community in pinus mixed forest and adjacent natural forest at Yagirala Forest Reserve located in the Southern part of Kalutara district, Sri Lanka. Further, the study examined the relationships between the functional categories and vegetation attributes to explore the factors that drive functional trait responses to conversions. The richness and abundance of functional categories were estimated using the data of point count surveys conducted at pinus mixed forest, which encompasses areas undergoing natural regeneration and enrichment planting, and in the natural forest. At each point count station within the pinus mixed forest, vegetation surveys were conducted to determine the number of standing dead trees, native tree species density, number of woody debris, percentage of canopy cover, percentage of herbaceous cover and the heterogeneity of tree height and tree dbh. The functional categories in pinus mixed forest areas and the natural forest were compared using One-way ANOVA followed by Tukey’s pairwise comparison. The relationships between bird functional categories and vegetation attributes were analyzed using linear mixed models (LMMs). According to the findings of this study, the abundance of six functional categories and the richness of three functional categories per point count station were significantly differed between the pinus mixed forest areas and natural forest (p < 0.05; one-way ANOVA, Tukey’s post hoc test). The findings further revealed significant relationships between the richness and abundance of functional categories including tree cavity dependents, frugivores, insectivores and canopy foragers with vegetation attributes such as number of standing dead trees, native tree species density, number of woody debris and percentage of canopy cover (p < 0.05; LMMs). This study emphasizes the potential of exotic forest plantations to support local bird communities by managing vegetation composition and structure effectively.
Spatial and temporal variations of Pavo cristatus (Indian Peafowl) density in Southern Province of Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Kodithuwakku, K. C.; Subasinghe, K.
The Indian peafowl (Pavo cristatus), traditionally native to arid regions of Sri Lanka, has recently been observed migrating to wetter areas, raising concerns about potential crop damage in the Southern Province. This study investigates the spatial variation in Indian peafowl density across the croplands of the Galle, Matara, and Hambantota districts in the Southern Province and the trends related to changes in peafowl abundance and their predators based on community feedback. Density measurements of Indian peafowl were conducted using fixed-width strip-transect (1×0.08 km) surveys in 25 sampling plots from September 2023 to February 2024. The same transects were utilized to determine the density of specific predator species, including jackals, diurnal raptors, and stray dogs. Structured interviews were conducted with 10 households near each transect to gather information regarding noticeable changes in Indian peafowl and predator populations over recent years. A One-way ANOVA, followed by Tukey's test, was used to compare the peafowl densities among the three districts after testing for normality using the Anderson-Darling test in Minitab version 20.2. The association of Indian peafowl density with predator abundance was assessed using Generalized Linear Mixed Models (glmmTMB package in R version 4.3.2). Information gathered through structured interviews was used to confirm the presence of predators within the study plots when predators were not reported during transect surveys. The study results indicated the presence of Indian peafowl across all three administrative districts of the Southern Province, which encompass dry, intermediate, and wet climatic zones, and revealed significant differences in peafowl densities per transect among these districts. Hambantota exhibited a significantly higher peafowl density (7.92 ± 2.43) compared to Matara (5.33 ± 1.03) and Galle (3.71 ± 1.11), while no significant difference was observed between Galle and Matara. The analysis revealed that peafowl density was not significantly associated with the densities of stray dogs and raptors or the presence/ absence of jackals (p > 0.05; GLMM). According to the survey responses (n = 500), 76% of residents from Hambantota district had observed a decrease in peafowl abundance over the past decade, whereas 94% and 98% of respondents from Matara and Galle, respectively, reported an increase e in the Indian peafowl density. A majority of respondents (89%) from the Galle and Matara districts reported a noticeable decline in natural predator populations over the past decade, identifying this decline as a major factor contributing to the increased abundance of Indian peafowl in the area. A significant proportion of residents (82%) from the Hambantota district attributed the observed decrease in Indian peafowl density to habitat degradation, particularly the reduction of suitable environments for feeding and reproduction, due to urbanization and construction activities. These findings underscore the need for long-term studies to monitor peafowl densities and address underlying causes to mitigate human-wildlife conflicts.