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  Subjects -> WATER RESOURCES (Total: 160 journals)
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Sri Lanka Journal of Aquatic Sciences
Number of Followers: 1  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1391-2038
Published by Sri Lanka Journals Online Homepage  [71 journals]
  • Water quality, microcystin-LR, and Cylindrospermopsin contamination status
           of spring and dug well water in CKDu high, low, and non-prevalent areas of
           Sri Lanka

    • Abstract: Cyanotoxins, Microcystin LR (MC-LR) and Cylindrospermopsin (CYN) are hepato and nephro toxins and considered as one of the hypotheses for Chronic Kidney Disease of Unknown Etiology (CKDu) in Sri Lanka. Recent studies have revealed that significant number of dug wells in the North Central and Uva provinces where CKDu is prevalent are contaminated with cyanotoxins MC-LR and CYN. In the present study, cyanotoxin; MC-LR, CYN, and potential toxin-producing cyanobacteria were studied in 330 dug wells and 9 spring water samples collected from CKDu high prevalent areas in several Divisional Secretariats (DS) and Grama Niladhari (GN) divisions of Anuradhapura (Padaviya DS, Medawachchiya DS, Kebithigollewa DS), Polonnaruwa (Medirigiriya DS), Badulla (Girandurukotte GN) and Ampara (Dehiaththakandiya DS) districts, low prevalent areas in Anuradhapura district (Galnewa DS, Rajanganaya DS), non-prevalent areas in Angunakolapelessa DS of the Hambanthota district. General water quality parameters: temperature, pH, conductivity, Dissolved Oxygen (DO), Nitrate (N-NO3-), Nitrite (N-NO2-), Ammonia (N-NH3), Total Phosphorus (TP), and Total Hardness (TH) were determined using standard spectrophotometric and titrimetric methods. BACON test kits were used following manufactures instructions to quantify the CYN, and MC-LR concentrations by using the ELISA plate reader. Cyanobacteria density and species composition were determined under light microscopy following the standard algae and cyanobacteria keys. With the exception of Electrical Conductivity, all of the water quality parameters tested remained within the SLSI drinking water quality standard range. Microcystis spp. cell densities ranged from 14±3 to 1590±256 cells mL-1, where MC-LR concentration ranging from 0.04±0.01 to 3.89±0.02 µg L-1. At different CYN concentrations (0.04±0.01 to 3.59±0.05 µg L-1), Cylindrospermopsis spp. cell densities varied from 15 ±4 to 615±112 cells mL-1. Well water collected from Hambanthota district and spring water was collected Kebithigollewa DS, in Anuradhapura did not record cyanotoxins and cyanobacteria. The factor analysis classified well waters into three clusters of high, low, and non-prevalence areas with presence and absence of cyanobacteria and cyanotoxins. In contrast, springs were classified to a separate cluster. High concentrations of MC-LR and CYN were found in wells where CKDu high prevalent 85% of Padaviya DS and 80% of Medirigiriya DS, respectively. High Nitrate-N (3.01±0.56 mg L-1) and Nitrite-N (0.69±0.09 mg L-1) concentrations were recorded in well water collected from high CKDu prevalence areas. Thus, the results of the present study showed a relationship between cyanobacteria, cyanotoxins and CKDu records in the study area. Accordingly, further comprehensive studies are needed to be carried out to confirm the relationship between cyanotoxins and CKDu in Sri Lanka as cyanotoxin were listed in the WHO report as one of the possible reasons for CKDu. Published on 2022-10-05 00:00:00
  • A field guide to the fishes in freshwaters of Sri Lanka

    • Abstract: No abstract available Published on 2022-10-05 00:00:00
  • Microcystin-LR contamination in Nile tilapia (Oreochromis niloticus) in
           some water bodies in Sri Lanka

    • Abstract: Microcystin-LR (MC-LR) is a cyanotoxin produced by certain cyanobacteria species. It is toxic to humans and animals. Several studies have demonstrated that cyanotoxins accumulate throughout the food chain, eventually reaching high levels in freshwater fish. The Nile tilapia (Oreochromis niloticus) is the most popular freshwater fish in Sri Lanka and in most Asian countries. The current study sought to determine MC-LR concentration in Nile tilapia collected from thirteen freshwater reservoirs; Nallachchiya, Galkulama, Anakattiya, Padaviya, Nachchaduwa and Kalawewa in Anuradhapura District, Parakrama Samudraya, Halmilla, Kaudulla and Ambagaswewa in Polonnaruwa District, Muwapatigewela in Ampara District, and Ulhitiya and Rathkinda in Badulla District. The fish and water samples were collected, transported, and analyzed following standard procedures, and MC-LR was determined using a BEACON ELISA kit. To determine the MC-LR and Tolerable Daily Intake (TDI) levels in fish, samples of the fish skin, flesh, and head were collected and analyzed according to World Health Organization (WHO) guidelines. A comparison was made between the MC-LR levels of fish in different reservoirs and the WHO TDI standards (0.04 μgkg-1day-1). From the Padaviya, the highest mean concentrations of MC-LR were found in fish skin (3004.25 ± 30 μg kg-1), following head (836.25±18 μg kg-1) and flesh (41.67±8 μg kg-1). The average daily intake of MC-LR in the skin and head of all samples exceeded the WHO's TDI (0.04 μg kg-1 day-1). According to the findings of this study, consumption of fish heads and skin increases the risk of MC-LR accumulation in the human body by a significant amount. Published on 2022-10-05 00:00:00
  • Physico-chemical properties of chitosan extracted from Whiteleg shrimp
           (Litopenaeus vannamei) processing shell waste in Sri Lanka

    • Abstract: The present study investigated the potential of whiteleg shrimp shell waste to use as a source of chitosan which has a limited focus on previous Sri Lankan studies. Comparatively higher amount of chitosan yield (33.53%) was obtained in the study with 91.78 ± 0.66 (%) of dry matter content, 8.22 ± 0.66 (%) of moisture content, 1.08 ± 0.24 (%) of ash content, 80.43% of the degree of deacetylation, 435.87 ± 1.03 cP dynamic viscosity and a good thermal stability up to 312 °C. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the structure of chitin and chitosan by the presence of their characteristic IR bands and X-ray diffraction analysis further verified the crystalline structure of the extracted chitin and chitosan. Scanning electron microscopic (SEM) images of the extracted chitosan recognized the layers of flakes with porous and fibril structures. According to the energy-dispersive X-ray spectroscopy image, carbon, oxygen and nitrogen were observed as the major elements in the extracted chitosan and no calcium peaks were detected confirming effective demineralization in the extraction process. Further, DPPH (2,2-diphenyl-1-picryl hydrazy) assay revealed that the chitosan solution with the concentration of 10 mg/mL was having 66.45% of free radical scavenging activity. Thus, the present study reveals that the chitosan with high quantity and quality can be extracted from whiteleg shrimp (Litopenaeus vannamei) processing shell waste in Sri Lanka suggesting a solution to the waste accumulation in processing factories while proposing an alternative income generation strategy from waste.  Published on 2022-10-05 00:00:00
  • Spatial distribution and dynamics of selected mangrove forests on the east
           and west coasts of Sri Lanka

    • Abstract: The climate and edaphic characteristics primarily determine the spatial distribution and dynamics of mangrove forests. The present study was initiated to determine how species composition and structural characteristics vary along with climate and substrate salinity of six mangrove forests located on the west coast, i.e., Negombo estuary, Chilaw lagoon, and Malwathu oya estuary, and east coast, i.e., Batticaloa lagoon, Uppar lagoon, and Urani lagoon. The structural parameters in terms of tree height, basal area, biomass, and density were obtained to determine the vegetation structure of mangrove forests. The current study found that although the structure of mangrove communities of the two coasts does not differ significantly (P<0.05), plant diversity in mangrove areas on the west coast is significantly higher than that of the east coast mangroves. In contrast, the biomass accumulation in west coast mangroves is relatively lower than that of east coast. Tree height was found to influence the productivity in terms of biomass increment of mangrove forests under investigation. As such, our study suggests that regional variations in salinity, temperature, and rainfall primarily serve as drivers of variation in mangrove species composition and vegetation structure of mangrove forests along the coasts of Sri Lanka. Published on 2022-10-05 00:00:00
  • Knowledge and prospects of Sri Lankan aquatic science research: A
           bibliometric analyses

    • Abstract: The present study summarizes the research productivity and international collaboration in aquatic studies conducted by Sri Lankan scholars during 2000-2019. The study was based on the SCOPUS® database. R programming language, package bibliometrix and Vosviewer software were employed in the analysis. Results of the present study indicate that increasing growth trend in the annual number of publications. A significant correlation (p<0.05) between the number of articles and per capita GDP (Gross Domestic Production) was also observed. Senior authors dominated in terms of the article count, citation count, h index, and other author productivity indices. Journal of the National Science Foundation of Sri Lanka had the highest article count (n=33). Aquatic studies in Sri Lanka were more locally funded. Sri Lanka had strong research collaborations with Japan, South Korea and Australia. During 2000-2019, the transition of aquatic studies from lacustrine field studies to molecular lab-based studies were observed. The findings of the present study may provide a comprehensive understanding on the current context and future directions of aquatic studies in Sri Lanka. Published on 2022-03-21 00:00:00
  • Present status of smoked fish processing at Mahakanadarawa reservoir in
           Mihintale, Sri Lanka.

    • Abstract: Fish smoking has become a popular processing method in Mahakanadarawa reservoir, with the potential for substantial demand among frequent visitors to Anuradhapura. This industry generates considerable income for the local livelihoods and reduces the post-harvesting losses. Government and Non-government Organizations have recognized the necessity of expanding the smoked fish industry in this area. However, there is a scarcity of scientific information on this vital industry. This study focuses on the current state of smoked fish production in the Mahakanadarawa reservoir. A field survey was conducted to determine the types of fish and fuel wood used, the type of technology they apply, and the challenges they encounter in both storage and in the supply chain to the consumer. The majority of smoked fish processors were found to be directly connected with fishing in the Mahakanadarawa reservoir and when there is a surplus catch, fishers produce smoked fish. Although tilapia is the most abundant smoked fish in the study area, snakehead is the most popular fish with a higher commercial value. Hence, breeding strategies should be used for such commercially important species. Smoking technologies in the study area are still at an extremely rudimentary level, leading to substantial processing losses due to uneven exposure to heat and smoke. Different types of fuelwoods are used by the processors to enhance the characteristic colour and smoky aroma that enticed their buyers. These types of woods may have essential anti-oxidant and bactericidal properties in addition to their distinctive flavour, colour, and aroma, and as such, further studies are recommended. Most of the smoked fish producers do not have adequate technologies for packaging and storage their products. Majority uses paper-based cartons and discarded Styrofoam boxes. Such paper-based materials generally absorb the valuable fish oil while poorly sealed Styrofoam containers are attributed to rancidity and growth of molds. Thus, empowering them with sufficient technologies and resources may reduce postharvest losses and lead to ensuring the catering of growing consumer demand throughout the year. Published on 2022-03-21 00:00:00
  • Dried fish production and trade in Negombo, Sri Lanka

    • Abstract: A well-established year-around dried fish production process is practiced at Negombo, the west coast of Sri Lanka, and this study evaluates the present status of this industry using the data collected from February to December 2017. There are forty-two dried fish processing centres at Negombo sea street area, providing livelihood opportunities for ~320 employees. Eighteen fish species belonging to 9 families are used in dried fish production and species belonging to the family Carangidae made the highest percentage contribution (21.6%), followed by the Clupeidae (21.4%), and Scombridae (21.4%). The results of the Quality Index (QI)Method revealed that both high-quality and very low-quality fish are used in dried fish production, and the overall QI of Katsuwonus pelamis, Euthynnus affinis, Decapterus macarellus, and Elagatis bipinnulata ranged from 15–16. Effects of drying on proximate composition were assessed, and significantly higher crude protein, content was recorded in dried fish than in fresh fish (p<0.05, t-test). Drying has also resulted in a significant increase in crude fat content in all these species except for Canthidermis maculatus (p<0.05; t test). De-heading and gutting, washing, salting, rewashing, drying, and packing were the major steps in the dried fish production process. Although the total coliform was reported in water samples used in the dried fish processing centres, it was not encountered in any of the dried fish samples. The dried fish value chain mainly consisted of fishermen, buyers, processors, sellers, and consumers, and upgrading of products, processes, and functions along the value chain was suggested to produce better quality dried fish and increase the profit margins of value chain actors. Published on 2022-03-21 00:00:00
  • Effect of autoclaving as a pre-treatment in the wet reduction process for
           extracting fish oil from yellowfin tuna heads

    • Abstract: Various studies have focused on extracting fish oil using a variety of methods, yet, the wet reduction process is the common industrial method as it is environmentally friendly. However, the use of autoclaving in extracting oils from fish or fish by-products are comparatively less. Therefore, this study was conducted to extract crude oils from the yellowfin tuna (Thunnus albacares) head, the lipids richest body part compared to processing offcuts like skin, viscera etc., by a simple wet reduction process using an autoclave at 121°C as the pre-treatment with different holding times (15, 30, and 45 min). The maximum extraction yield of 5.37±0.22 % was recorded at 30 min holding time of autoclave. No significant changes in peroxide value, moisture content and colour values were observed for the different autoclaving durations (P > 0.05). Conversely, acid value, p-anisidine value and total oxidation value (TOTOX) were increased significantly with a longer autoclaving duration of 45 min (P < 0.05). However, all peroxide values, p-anisidine value, TOTOX value were below the standard values stated by the World Health Organization (WHO) except the acid values which shows the need for refinery before any applications. Based on the spectra of Attenuated total reflectance - Fourier transform infrared (ATR-FTIR), autoclaving for a longer time resulted in lower intensity at wavenumbers around 3,012 - 3,013 and 1,741 - 1,744 cm−1 and shifting of bands to lower wavenumbers showing its effect on the structural changes of molecules in the oil. All extracted oils resulted in a high PUFA content than MUFA and SFA contents based on the fatty acid composition. The DHA (C22:6, n3) was the most prominent fatty acid in all the oil samples. However, PUFA content was reduced slightly by increasing the autoclaving duration at 45 min. Therefore, this study concludes autoclaving at 121°C for 30 minutes as the optimum pre-treatment conditions to extract fish oil from yellowfin tuna heads using the wet reduction process. Published on 2022-03-21 00:00:00
  • Length weight relationships of fish species collected after impoundment of
           the Three Gorges Reservoir (TGR) in China; a study carried out in the
           upper Yangtze River

    • Abstract: The Three Gorges Dam in the upper Yangtze River in China is the largest hydropower project in the world. Length- weight relationships (LWRs) are reported for fish species collected from three locations of the reservoir from November 2010 to October 2011. Fish were collected from the local fishing boats using 1.5 cm nylon mesh trap nets or 4, 5 and 6 cm nylon mesh gillnets (100- 120 m long × 1.4-1.5 m high). A total of 7,311 fish representing 49 species of 11 families were collected during the study period. There were 2,680 fish belonging to 32 species of 8 families sampled in Zigui (near the dam) reach, 2,845 fish representing 46 species of 8 families in Wanzhou (middle of the reservoir) reach and 1,786 fishes representing 38 species of 8 families in Fuling (upper reservoir) reach. The family with the highest number of species was Xenocyprididae. The intercept (a) and slope (b) of LWRs are useful in fisheries science in many ways. Therefore, the present study provides baseline data on LWRs of the economically valuable and most abundant fish species in the recently commissioned Three Gorges Reservoir. Published on 2022-03-21 00:00:00
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