Browsing by Author "Gunaratne, A.M."

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Allochthonus inputs into seasonal reservoirs: "Ornithological eutrophication" as a source of nutrient enrichment
(Sri Lanka Association for Fisheries and Aquatic Resources, 2010) Gunaratne, A.M.; Jayakody, S.; Amarasinghe, U.S.
The current study evaluates a lesser known allochthonus nutrient input into water sources, i.e. accumulation of bird faecal matter. Asian Open bill (An8stomus oscit8ns) population is increasing in Sri Lanka and due to mass breeding within reservoirs and higher population densities. Faecal matter could be a potential input of nutrients. Field investigations were carried out in Anavilundawa Ramsar sanctuary during 2007/08, where the reservoir was divided into four strata; inlet, breeding ground, centre and outlet. Surface and bottom water samples were analyzed for NO;, NH:, PO.... K+, hardness and dissolved oxygen (DO). Total depth, Secchi depth, temperature, turbidity and water pH were also recorded. In surface layers, the highest amount of NO; was recorded for breeding ground (0.55 mgr') followed by reservoir centre. The highest levels of PO... (0.93 mgr'), alkalinity (142 mgr') and NH: (1.9 mgr') were also recorded in breeding grounds. In the bottom layers. the highest level of NO; was recorded in breeding ground (0.49 m r') followed by reservoir centre. Similarly, the highest levels of PO."- (0.83 mgr ), alkalinity (147 mgr') and NH: (2.16 mgr') were recorded from the breeding ground. The lowest level of DO was recorded for breeding grounds 'both in surface layers (2.03 mgr') and bottom layers (0.84 mgr'). The lowest levels of pH were recorded for breeding grounds in surface layers (5.90) and bottom layers (5.93). The highest level of turbidity was recorded at the centre of reservoir for both surface water (30.95 NTU) and bottom water (2.76 NTU). Canonical variate analysis indicated the influence of ornithological eutrophication in water with four strata being significantly distinct for surface layer whilst, similarities in water quality in inlet and outlet for bottom layer. Hence bird faecal matter could be a constraint for maintaining water quality; however the results also suggest evidence for self regulation of water quality within the system. a character which needs to be retained.
Fluctuations in Avian Distribution and Diversity in Anavilundawa Ramsar Sanctuary
(Department of Wildlife Conservation, 2014) Gunaratne, A.M.; Jayakody, S.; Amarasinghe, U.S.
Many of the seasonal water bodies in Sri Lanka harbour substantial numbers of aquatic birds. Local aggregation of water fowl during communal roosting and colonial breeding results in substantial inputs of nutrients into aquatic systems and can alter fresh water aquatic systems. The present study calculated the density and species richness of true aquatic bird and aquatic associated bird species in Anavilundawa Sanctuary (Ramsar Site) from July 2007 to July 2008 using the point count method. In Anavilundawa reservoir, the number of true aquatic bird species was higher (40.49 ± 1.251 birds ha-1) than the number of aquatic associated bird species (3.40 ± 0.437 birds ha-1). Amongst true aquatic birds recorded in the study area, Anastomus oscitans (Asian openbill) was the most abundant species (137.43 ± 7.246 birds ha-1). Further, Asian openbill inhabited only the Anavilundawa reservoir for nesting and breeding. Density and species richness of birds were the highest during rainy season when migratory species also arrived at the site. During the rainy season; the highest bird density was recorded in tree-covered habitats (11.72 ± 1.683 birds ha-1) followed by shallow open water habitats (2.05 ± 0.724 birds ha-1) and grass covered habitats (1.84 ± 0.579 birds ha-1). The lowest bird density was recorded in deep open water habitats (0.40 ± 0.263 birds ha-1). During the dry season when the migratory species left the area a few resident species have engaged in nesting activities. During the dry season too, the highest bird density was recorded in tree covered habitats (1.57 ± 0.497 birds ha-1) followed by grass covered habitats (0.99 ± 0.317 birds ha-1) and shallow open water habitats (0.63 ± 0.374 birds ha-1). Red-wattled Lapwing was the most abundant aquatic associated species recorded (2.05 ± 1.137 birds ha-1). The result also showed that true aquatic birds have the highest species diversity i.e., Shannon’s index (N1 = 2.233), species richness i.e., Margalf’s index (R1 = 2.015), Menhinick’s index (R2 = 0.782) and species evenness (E = 0.899) which were much higher compared to aquatic associated birds. It is concluded that Anawilundawa Sanctuary has retained its potential as an important ecosystem for avifauna despite human mediated disturbances.
Impact of bird faecal matter mediated nutrients on water quality in Anavilundawa reservoir and habitat occupancy and behaviour of selected bird species in two reservoirs of Anavilundawa ramsar sanctuary, Sri Lanka
(2014) Gunaratne, A.M.
“Ornithological eutrophication” as a source of allochthonous nutrient enrichment in Anavilundawa reservoir, Sri Lanka
(2015) Gunaratne, A.M.; Jayakody, S.; Amarasinghe, U.S.
Mass aggregation of waterfowls for breeding, results in allochthonous nutrient inputs intoaquatic systems. This study evaluated accumulation of bird droppings as allochthonusnutrient input and its ﬂuctuations in Anavilundawa International Ramsar Sanctuary in SriLanka where Asian openbill (Anastomus oscitans) mass breeding occurs annually. Reservoirwas divided into four strata: Inlet, breeding ground, reservoir centre and outlet. The highestnutrients levels (NO3,PO43,NH4þ, alkalinity) and the lowest dissolved oxygen and pHlevels were recorded in breeding grounds for both surface and bottom water. The highestturbidity was recorded in inlet surface and centre bottom water. Canonical Variate Analysis ofwater quality parameters indicated the signiﬁcantly distinct inﬂuence of ornithologicaleutrophication on surface water of four strata whilst, showing similarities in water quality ofbottom layers in inlet and outlet. In the breeding ground, surface water was covered with thickmats of aquatic ﬂora consisting of Water hyacinth, Salvinia, duckweed and Polygonum.Therefore, it is concluded that in addition to dilution, amelioration of water quality could alsobe happening due to absorption by plants. Due to interactions between invasive plants andwaterfowls, restoration with native aquatic ﬂora is needed to be considered to regain reservoirresilience and self-sustenance.