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Item Allelopathic effects of the invasive plant Wedelia (Sphagneticola trilobata L.) aqueous extract on common beans (Phaseolus vulgaris L.)(Horizon publishers India, 2023) Perera, K.R.S.; Ratnayake, R.M.C.S.; Epa, U.P.K.Sphagneticola trilobata (L.) Pruski is an alien invasive weed with aggressive growth habits, environmental stress tolerance, and the ability to synthesize allelochemicals. However, in many parts of the world, this plant is still recommended for use in composting, phytoremediation, and as an ornamental ground cover in gardens. The present study investigated the allelopathic effect of S. trilobata on the seed germination, growth and yield of Phaseolus vulgaris L. To analyze the allelopathic effects of S. trilobata on P. vulgaris seed germination, hundred seeds of P. vulgaris were exposed to different concentrations of the aqueous extracts of fresh and dry S. trilobata (2.5×102, 5.0×102 and 7.5×102 g/L) in Petri dishes for five days. The impact of S. trilobata aqueous extract on the growth and yield of P. vulgaris was also studied with seedlings planted in a compost soil mixture. Results of the study suggested negative impacts of S. trilobata extracts on P. vulgaris seed germination, growth and yield. P. vulgaris seed germination was significantly lower in the treatments than in the control (p<0.05). Further, P. vulgaris plants treated with fresh plant extracts at 5.0×102 and 7.5×102 g/L concentrations had significantly lower shoot height, growth rate, leaf area, fresh shoot weight, dry shoot weight, root length, pod length and yield (p<0.05) than controls. From the results of the study, it can be concluded that S. trilobata aqueous extracts have a dose-dependent allelopathic effect on P. vulgaris seed germination, growth, and yield and among the dry and fresh plant extracts, fresh plant aqueous extracts have a more significant allelopathic impact. As S. trilobata contains water-soluble allelochemical, it should not be used in biofertilizer production, phytoremediation, or as live mulch.Item The ontogenetic dietary shift of blue stripped hermit crab Clibanarius longitarsus (Decapoda, Diogenidae) in the Negombo estuary, Sri Lanka(Sri Lanka Association for Fisheries and Aquatic Resources, 2012) Ranaweera, B.D.P.S.; Epa, U.P.K.Hermit crabs represent an important portion of many intertidal and moderately deep benthic marine communities worldwide, where they play an important role in the food chain. Present study was conducted to determine the ontogenetic dietary shift of a tropical hermit crab, C. longitarsus inhabiting in the Negombo estuary. About sixty specimens of different sized hermit crabs were collected from intertidal and supra tidal areas of the estuary and they were preserved in 5% formalin. Hermit crabs were carefully removed from occupying shell in the laboratory and their body lengths and weights were measured. According to the measurements they were grouped in to five length classes (LC). The length and weight ranges were, LC 1 (3.0 - 5.0 mm, 0.10 - 1.90 g), LC 2 (5.07.0mm, 0.32 - 2.11 g), LC 3 (7.0 - 9.0 mm, 1.04 - 2.57 g), LC 4 (9.0 - 11.0 mm, 1.36 - 2.93 g) and LC 5 (11.0 - 13.0 mm, 2.48 - 4.10 g), respectively. Gut analysis was conducted to find out the major food items available in their diet. C. langitarsus inhabiting in Negombo estuary showed omnivorous feeding habits. The major food items found in the gut content of C. longitarsus were diatoms, green algae, blue green algae, animal parts, detritus and higher plant parts. The highest relative abundance was recorded for detritus while the lowest was recorded for animal parts. Comparatively higher amount of green algae (19 %), blue green algae (3%) and diatom (23 %) were recorded in length class 2 than that of other length classes. The highest relative abundance of plant parts (34%) were recorded in length class 4 and the lowest in length class 5. Detritus (56%) and animal parts (1%) were highly abundant in gut content of length class 5. Diatoms (9%) and blue green algae (1%) were least abundant in length class 1. The lowest relative abundance of green algae (9%) was recorded in length class 4. Animal parts were not recorded in the gut content of C. longitarsus in length classes 2 and 4. Detritus was the lowest (28%) food item found in the gut content of length class 2. The highest trophic niche breadth was observed in length class 2 (1.45) while the lowest value was recorded in length class 5 (1.22). The cluster analysis and Multidimensional scaling (MD5) based on different length classes and the % relative abundance of different food categories of C. longitarsus, produced two clusters at 90.5% similarity level. But these two clusters were not significantly different (p>0.05; one-way ANOSIM). Therefore, it is concluded that no ontogenetic dietary shift in C. longitarsus inhabiting in the Negombo estuary.Item Effects of shrimp farming practices on water quality of northern part of the Dutch canal(Sri Lanka Association for Fisheries and Aquatic Resources, 2010) Gunawardana, P.V.S.L.; Epa, U.P.K.; Hettiarachchi, M.Most of the shrimp farms in Sri Lanka are concentrated over a distance of about 120 km around Chllaw Lagoon, Dutch Canal, Mundal Lake and Puttalam Lagoon, with 70% of farms depending on the Dutch Canal for water. Farms take water in from the canal and discharge their effluent into the same water sources without proper treatments. Discharge of pond effluent has led to deterioration of water quality in the main water sources. Present study was carried out to investigate the changes of water quality parameters in Northem part of Dutch canal (7"63'N 79 _D80'E to 7 D85'N 79 D80'E) in relation to different shrimp farming practices in selected five sampling sites at Karukkupane, Nalladarankattuwa, Muthupanthiya, Udappuwa and Madurankuliya_ Water samples were collected biweekly from September 2008 to January 2010 from both surface and bottom layers at the pre-selected sampling points. Temperature, turbidity, conductivity, saliliity, BOO, DO, TDS, flow rate, pH, NH3, PO."' and chlorophyll- a in the collected water samples were analyzed. In addition, shrimp farming activities adjacent to five sampling points were recorded. Surface water samples did not show significant inter-site differences for the parameters determined except for temperature, DO and pH which are subjected to diumal variations too. Bottom water samples of Udappuwa and Madurankuliya had significantly higher levels (P< 0.05) of turbidity (24.25 :I: 8.4 NTU and 32.4 :I: 9.3 NTUj. pH (9.1:1: 2.3 and 10.2:1: 1.6), NH3(0.22:1: 0.006 mgll and 0.32:1: 0.012 mgll PO. (0.046 :1:0.007 mgll and 0.079 :I: 0.011 mgll) , chlorophyll-a (27.2 :I: 8.3 mg m and 32.8 :I: 6.1 mg m-3) and BOO (2.42 :I: 0.60 mgJI and 3.40 :I: 0.8mg1l) compared to other sampling sites. Flow rates of water at five sampling points didn't show significant differences ( P>0.05) and had an average value of 1.3 :I: 0.36 m3/s. Sub optimal levels for DO, BOO, pH, NH3, PO."' and chlorophyll-a were recorded at Udappuwa, Madurankuliya and Muthupanthiya areas of the Dutch canal, where shrimp farm density is moderately higher. Results of the study exemplify that higher levels of shrimp farming activities can alter quality of water in the Dutch Canal, making it less suitable for shrimp culture. Therefore it is suggested to have treatment facilities especially at the areas like Udappuwa, Madurankuliya and Muthupanthiya, to improve the quality of receiving water from shrimp farms in order to minimize the environmental impacts of shrimp culture industry and to assure the sustain ability of future shrimp cultivation.Item A study on increasing larval survival of sea horse (Hippocampus kuda) under culture conditions(Sri Lanka Association for Fisheries and Aquatic Resources, 2010) Ranasinghe, R.A.P.G.; Epa, U.P.K.; Chandraratne, N.; Mallawaarachchi, M.A.J.C.Sea horse (Hippocampus kuda), one of the most heavily exploited species in both traditional medicines and marine aquarium trade were reared for their marketable size at the hatchery of National Aquaculture Development Authority (NAQDA), Pitipana, Negombo. Some aspects of biology (growth parameters, survival rates) and pathology (recurrent outbreaks of disease conditions leading to mass mortalities of larvae) of the H. kuda were studied under the hatchery condilions. Average height of the adult male H. kuda used in the study was 10,65 cm:t: 0.15 while female was 11.10 cm:t: 0.21. Average weight of the adult male was 9.10 g :t: 0.55 and female was 7.82 g :t: 0.34 respectively. Average number of larvae released by a male at releasing time was 250 :t: 30 individuals. The length of new born larvae was 0.98 cm :!: 0.02. Growth was characterized by three inflexion points at the 2nd, 10th and 16'" weeks, during their growth cycle up to marketable size, The mean growth rates at three inflexion points were 1.66, 1.06 and 1.028 cm week" respectively. The highest growth rate was observed in the second week. Highest condition factor (1.03 :t: 0.371) was observed in the first week. Specific growth rates (SGR) showed great variability while the highest SGR was observed within first week (5.15 :t: 0.95) and the lowest in the 8th week (0.72 :t: 0,13). Survival rates of larvae within first five weeks ranged from 40 - 50% while it was 3,25% at marketable size under present hatchery conditions. Vibrio species and fungi were identified in moribund individuals and three antibiotics (Tetracycline, Oxi-tetracycline and Erythromycin) were tested as remedial measures for Vibrio infections. Tetracycline as a bath treatment (30 mgl L) was the most effective antibiotic to control Vibrio outbreaks. The effective dosage of CuSO. was 0.25 ppm for control tungal infections. According to the trials conducted survival rates of larvae could be increased up to 80 % within first fIVe weeks using above mentioned treatments.Item Invasive potential of exotic ornamental fish species in Sri Lanka(Department of Zoology and Environmental Management, University of Kelaniya, Sri Lanka, 2017) Piyathissa, M.G.M.U.; Ranasinghe, S.D.A.E.; Ranasinghe, Y.G.; Rathnayaka, R.M.K.H.; Epa, U.P.K.The accidental releases of fish species from ornamental fish industry have become one of the top five pathways for the introduction of invasive species in the world. These accidental releases of species in to new environments are more environmentally damaging in most instances compared to intentional introductions. Seven out of 12 invasive alien animal species found in Sri Lanka are fish species and majority of them have been introduced by ornamental fish trade. This study was conducted to assess the invasive potential of exotic aquarium fish species in Gampaha, Kandy and Polonnaruwa districts in Sri Lanka. Twenty aquarium hobbyists, three pet shops and three fish breeders in each district were randomly selected and fish species present in their captivity were identified. The invasion potential of species present was evaluated using their thermal tolerance, history of invasion elsewhere, and potential propagule pressure calculated by frequency of occurrence in homes, pet shops and breeding centers. Reasons for fish releases and biosecurity measures adopted by the industry were also recorded using a questionnaire survey. Overall 51 exotic ornamental fish species belong to 14 families Poeciliidae, Loricariidae, Characidae, Osteoglossidae, Cyprinidae, Osphronemidae, Helostomatidae, Cichlidae, Acanthuridae, Callichthyidae, Characidae, Cichlidae, Salmonidae, Scombridae were recorded during the study. Xiphophorus maculatus, Pterygoplichthys pardalis, Poecilia reticulate, Cyprinus carpio, Osphronemus goramy, Trichogaster trichopterus, Clarias batrachus, Pterophyllum scalare, Carrasius auratus, Danio rerio and X. helleri had high invasive potential while Osteoglossum bicirrhosum, Astronotus ocellatus, Astronotus sp., Puntius tetrazona and Betta splendens have moderate invasive potential in the country. Colossoma macropomum, Salmo trutta, Pethia conchonius, Gymnocorymbus ternetzi, Hemichromis bimaculatus and Acanthurus dussumieri showed low invasive potential. The reasons for releasing fish into natural environments were increasing body size, aggressive behavior, diseases, high reproduction rate, difficulty to maintain and due to unexpected floods. Fish breeders cover the ponds by a net to prevent fish escapes and to prevent predators as a biosecurity measure. Education, training and extension be used to inform general public and aquarium industrialist of invasiveness of fish species and their environmental impacts. Laws and regulations to prevent fish releases to natural environment should be introduced and implemented through intervention of the government.Item Feeding Ecology and Length-weight Relationship of Indian Glass Barb, Laubuka laubuca (Hamilton 1822) at Maguru Oya Stream (Deduru Oya River Tributary), Sri Lanka.(Asian Fisheries Society, 2016) Epa, U.P.K.; Narayana, N.M.A.J.Laubuka laubuca (Hamilton 1822) is a poorly studied freshwater fish found in South and Southeast Asia. This study was conducted to investigate the feeding habit and length-weight relationship of L. laubuca at Maguru Oya Stream, Sri Lanka. Gut contents of 180 fish were analysed, and food particles identified were categorised into 15 broad taxonomic groups. Relative abundance of each food category was calculated for 1-3, 3-5 and >5 cm length classes. Trophic niche breadth, food electivity index and Fulton’s condition factor of L. laubuca were calculated. Length-weight relationship was determined using the expression, W = aLb. Laubuka laubuca was a euryphagous-planktivorous fish and it showed a size dependent feeding pattern. Young fish had significantly broader (P<0.05) trophic niche breadth than that of adults. According to food electivity indices L. laubuca preferred euglenoids, rotifers, insect larvae, crustacean larvae, arachnid larvae and macrozoobenthos which were highly abundant in stream habitat. Laubuka laubuca showed a positive allometric growth pattern with length-weight relationship of log W = -2.3684 + 3.3528 log TL. Due to high availability of preferred food items in its habitat and positive allometiric growth L. laubuca could be categorised under least concern category in the IUCN Red List.Item Fatting of Mud- carb Scylla serrata in Cages using Locally Available Animal by – Products in a Brackish Water Pond(Rajarata University of Sri Lanka., 2009) Fernando, K.S.G.S.; Epa, U.P.K.; Sundarabarathy, T.V.Item Impact of fishing by white hoary pea Tephrosia candida (Fabales, Fabaceae) on diversity and abundance of fish in the streams at the boundary of Sinharaja Man and Biosphere forest reserve, Sri Lanka(Revista de Biologia Tropical/ International Journal of Tropical Biology and Conservation, 2016) Epa, U.P.K.; Mohotti, C.R.W.C.Local communities in some Asian, African and American countries, use plant toxins in fish poisoning for fishing activities; however, the effects of this practice on the particular wild fish assemblages is unknown. This study was conducted with the aim to investigate the effects of fish poisoning using Tephrosia candida, on freshwater fish diversity and abundance in streams at the boundary of the World Natural Heritage site, Sinharaja Forest Reserve, Sri Lanka. A total of seven field trips were undertaken on a bimonthly basis, from May 2013 to June 2014. We surveyed five streams with similar environmental and climatological conditions at the boundary of Sinharaja forest. We selected three streams with active fish poisoning practices as treatments, and two streams with no fish poisoning as controls. Physico-chemical parameters and flow rate of water in selected streams were also measured at bimonthly intervals. Fish were sampled by electrofishing and nets in three randomly selected confined locations (6 x 2 m stretch) along every stream. Fish species were identified, their abundances were recorded, and Shannon-Weiner diversity index was calculated for each stream. Streams were clustered based on the Bray-Curtis similarity matrix for fish composition and abundance. Physico-chemical parameters of water were not significantly different among streams (P > 0.05). A total of 15 fish species belonging to four different orders Cypriniformes, Cyprinodontiformes, Perciformes and Siluriformes were collected; nine species (60 %) were endemic, and six (40 %) were native species. From these, 13 fish species were recorded in streams with no poisoning, while five species were recorded in streams where poisoning was practiced. Four endemic and one native fish species were locally extinct in streams where fish poisoning was active. Fish abundance was significantly higher in control streams (32-39/m2) when compared to treatment streams (5-9/m2) (P < 0.05). We concluded that fish poisoning with T. candida may have resulted in a significant reduction in species richness, total abundance and Shannon-Weiner diversity index of fish species in the studied streams at the boundary of Sinharaja forest. We recommend that this fishing practice should be strictly regulated, and to inform local communities about the legal status of fish poisoning, its consequences and the importance of fish diversity for local livelihoods and conservation purposes.Item Toxicity of aqueous extract of white hoary pea, Tephrosia candida (Papilionoideae) on Nile tilapia, Oreochromis niloticus (Cichlidae) fingerlings(Sri Lanka Association for Fisheries and Aquatic Resources, 2016) Mohotti, C.R.W.C.; Epa, U.P.K.Fish poisoning using Tephrosia candida, which is an exotic plant to Sri Lanka is taking place in streams in the boundary of the Sinharaja forest, a tropical forest range, designated as a world heritage site by UNESCO in 1988. T. candida is a source of flavonoids and rotenoids including rotenone, tephrosin, and deguelin. Fishermen add large amounts of grounded plant matter to kill almost all the fishes in the stream within a short period of time. This method of unregulated fishing may have a long term negative effect on fish diversity and abundance in the area. A 96 h static renewal toxicity bioassay was carried out in the laboratory to determine the median lethal concentration (LC50) of aqueous extract of T. candida leaves on Oreochromis niloticus fingerlings. Experimental fish were exposed to test water in 20 L glass aquaria with concentrations of plant extract of 5, 7.5, 10, 15 and 20 mg L-1. All five treatments aquaria and the control aquaria without plant extract were triplicated. Fish exposed to plant extract showed symptoms of toxicity including, initial inactivation, agitated swimming, turning movement, air gulping, increased opercular movement followed by erratic swimming, loss of reflex, slow opercular movement, setting at the bottom motionless and knockdown before death. The gills of the dead fishes were damaged, swollen and external bleeding were observed. Lower concentrations of the extracts had sub lethal effects which manifested as zigzag movement, air gulping, increased opercular movement and some fish gathered near the air stones. The LC50 values at various exposure periods were 10.83 mg L-1 for 24 h; 8.61 mg L-1 for 48 h; 7.26 mg L-1 for 72 h and 6.43 mg L-1 for 96 h. It could be concluded that the application of T. candida extract causes lethal toxic effects on fish even at very low concentrations.Item Lesson 30: Identification and culture of ornamental aquatic plants(Research Services Centre, Faculty of Science, University of Kelaniya, 2015) Epa, U.P.K.