Sri Lanka Journal of Aquatic Sciences最新文献

{"title":"Solutions to an alien species invasion from aquarium aquaculture: Isolation and characterization of acid soluble collagen from sailfin catfish, Pterygoplichthys disjuctivus (Weber, 1991) in Sri Lanka","authors":"H. Herath, N. Kalutharage, P. Cumaranatunga","doi":"10.4038/sljas.v25i1.7573","DOIUrl":"https://doi.org/10.4038/sljas.v25i1.7573","url":null,"abstract":"Sailfin catfish (Pterygoplichthys disjunctivus) has become an invasive species within inland water bodies in Sri Lanka but there are no controlling methods presently. Present study investigates the suitability potential of acid soluble collagen/ gelatin from P. disjuctivus, to establish commercial demands for this invasive fish. Samples were collected from Udawalawa Reservoir, Sri Lanka and categorized into two lengths groups according to the length; L1 (30.6 ± 2 cm) and L2 (25.1 ± 3 cm). Acid soluble collagen was extracted from skin, flesh, bone and fin of P. disjuctivus using established acid soluble methods. The average yield of collagen (w/w%) on wet weight basis from skin, flesh, bone and fin for L1 were 26.20 ± 3.32%, 10.66 ± 2.01%, 3.40 ± 0.73%, 3.19 ± 1.79% and for L2 were 22.96 ± 2.16%, 9.19 ± 0.72%, 3.01 ± 0.63%, 2.84 ± 1.06%, respectively. There were significant differences in average yield of collagen among different tissues of fish within the same length group but there were not among the two length groups (p ≥0.05). The moisture content in the collagen extracted from, skin, flesh, bone and fin of L1 were 78.30 ± 0.1% , 84.0 ± 0.1%, 75.18 ± 1.02%,  and 75.45 ± 0.95% and for L2 were 80.07 ± 0.15%, 83.86 ± 1.05%, 78.19 ± 0.95%, 77.12 ± 1.06% respectively; Similarly, protein contents were 48.14 ± 1.05%, 54.43 ± 2.99%, 48.14 ± 0.95%, and 48.56 ± 0.90% for L2  49.29 ± 1.03, 49.13 ± 0.95%,  47.26 ± 0.95% and 47.73 ± 0.95%; lipid content of skin, flesh, bone and fin of L1 were 0.9 ± 0.1%, 0.97 ± 0.06%, 1.08±0.15%, and 0.89±0.09% and for L2 were 0.96 ± 0.03%, and 0.99 ± 0.03%, and 1.20 ± 0.11%, and 1.03 ± 0.06% respectively; and ash content of skin, flesh, bone and fin of L1 were 25.76 ± 0.95%, 22.16±1.11%, 32.16±0.91%, and 29.18±0.95% and for L2 were 34.10 ± 0.95, 22.29 ± 0.95%, 28.166 ± 0.9 and 41.17 ± 1.00% respectively. In collagen extracted, % protein, %lipid and %ash were significantly different among flesh, skin, bone and fin within the same length group (p ≤ 0.05) but not among length groups (p ≥0.05). UV spectrum and FTIR spectrum of extracted four types of collagen indicated high percentage of collagen. Flesh and skin of P. disjuctivus can be recommended as a good source of collagen for potential industrial applications.","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"49 1","pages":"19"},"PeriodicalIF":0.0,"publicationDate":"2020-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74326386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Availability of animal food organisms and their utilization by cyprinids in Sri Lankan hill-stream pools","authors":"J. Vijverberg, M. Land, A. Vreeke, B. Amarasinghe, K. Kortmulder","doi":"10.4038/SLJAS.V24I2.7567","DOIUrl":"https://doi.org/10.4038/SLJAS.V24I2.7567","url":null,"abstract":"The food and feeding of cyprinid fishes in three stream pools in South West Sri Lanka, was investigated from 29 June 1984 to 25 February 1986. S.W. Sri Lanka was chosen as a study site because the rainforest and its fish fauna are here severely threatened. Feeding ecology was studied by gut contents analysis. The availability of prey organisms in the environment was quantified and food utilization in each pool was estimated by comparing diet compositions of the fish species with the food availability. Seven cyprinid species represented more than 98% of the fish numbers caught. These were Pethia cumingii (PC), Puntius dorsalis (PD), Dawkinsia singhala (DS), Pethia nigrofasciata (PN), Systomus pleurotaenia (SP), Devario malabaricus (DM) and Rasbora daniconius (RD). Three of these species: the two surface feeders DM and RD and the generalist SP fed > 33 % (biovolume) on terrestrial arthropods. Since we were not able to quantify the availability of terrestrial arthropods - mainly ants falling from the trees into the stream - these three species were not included in part of the analysis. Chironomid larvae were most abundant and, on basis of biovolume, the most important animal food items of the remaining four cyprinid species (PC, PD, DS, PN). PD and PN strongly positively selected chironomid larvae, but DS and PC only weakly negatively. Although coleopterans and ephemeropterans were after chironomid larvae the most abundant food items in the environment the former were often negatively selected and ephemeropterans positively, so that the latter were generally after chironomid larvae the most frequently eaten food items.","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"210 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73056980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combining insights into reproduction and gear selectivity to enhance management advice for Encrasicholina heteroloba (Engraulidae) in the west coast of Sri Lanka","authors":"N. Navarathne, D. Dissanayake","doi":"10.4038/SLJAS.V24I2.7569","DOIUrl":"https://doi.org/10.4038/SLJAS.V24I2.7569","url":null,"abstract":"Encrasicholina heteroloba belonging to the family Engraulidae is a commercially important fish species in the small-scale artisanal fisheries in Sri Lanka. Fishery, reproductive biology and gillnet selectivity pattern of E. heteroloba were assessed using the data collected from the Negombo fish landing site on the west coast of Sri Lanka from January to December 2015 in order to provide baseline information such as catch rate, total production, reproductive seasonality, size at first sexual maturity (L50) and gear selectivity pattern of this data poor fishery. E. heteroloba are mainly exploited using drift gillnets of 1.1 cm, 1.2 cm and 1.8 cm stretched mesh sizes. Females spawn throughout the year reporting a peak spawning in July. The sizes at first sexual maturity of E. heteroloba male and female are 7.40 cm and 7.45 cm, respectively. The gillnet selectivity study revealed that the optimum length (Lopt) and selection range of E. heteroloba varied with mesh sizes and estimated Lopt for 1.0 cm, 1.2 cm and 1.8 cm mesh sizes were 5.6 cm, 6.4 cm and 9.2 cm, respectively. We suggest to promote use of 1.8 cm mesh gill nets as a higher percentages of immature individuals are landed when smaller mesh (","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87959078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of gonads and evidence of protogyny in Spangled emperor (Lethrinus nebulosus) from the coastal waters off Negombo, Sri Lanka.","authors":"R. Ranatunga, S. Rathnayaka","doi":"10.4038/SLJAS.V24I2.7570","DOIUrl":"https://doi.org/10.4038/SLJAS.V24I2.7570","url":null,"abstract":"Gonad development and maturation of the spangled emperor Lethrinus nebulosus (Forsskal, 1775) inhabiting coastal waters off Negombo, Sri Lanka was investigated to understand the reproductive strategies. Sexual ontogeny was investigated using histological examinations of the gonads and changes in sex ratio with body size. Cellular characteristics and the most advanced germ cells presented in the gonads were considered for determining the sex and maturity stages. The transitional gonads were characterized by changes in internal gonad structure such as the appearance of spermatocyte and degenerated oocytes in the same developmental stage. Thick strands of stromal tissue within the lamellae and branched secondary strands were observed in transitional individuals. Increased blood vessels and sperm sinuses within the gonad wall were also an indications of sex transition. Therefore, L. nebulosus living in coastal waters off Negombo exhibited an early indication of protogynous hermaphroditism among adults. The sizes at 50% sexual maturity of males and females were estimated to be 29.5 cm and 39.5 cm respectively. A dramatic change in the sex ratio of the adult size classes suggested that female to male sex transition observed between 28.5- 40.4 cm body sizes. Sex ratios were 1.23: 0.46: 1 for female: transitional: males indicating slightly female-biased overall sex ratios. Female dominance in smaller size classes and male dominance in larger size classes were also evident Mean size at first capture recorded for L. nebulosus (19.6 cm) was well below the mean sizes of maturity for both male and female. Size-specific differences in sex ratios and reproductive potential indicate that conventional regulations that impose size limits for capture would not be very effective for the management of L. nebulosus.","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81033855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Natural leaf packs and invertebrates in a tropical stream: Is there a functional relationship?","authors":"H. Walpola, M. Leichtfried, L. Füreder","doi":"10.4038/SLJAS.V24I2.7568","DOIUrl":"https://doi.org/10.4038/SLJAS.V24I2.7568","url":null,"abstract":"Naturally occurring leaf packs in five sites along the elevation gradient in Eswathu Oya stream in Sri Lanka were sampled and analysed for species composition of leaves and benthic macroinvertebrates. Eswathu Oya is a perennial, low order, mountain stream in the wet climatic zone of Sri Lanka. Leaves of only five species of plants were found in all sites – Hevea brasiliensis, Ochlandra stridula, Alstonia macrophylla, Terminalia arjuna and Melia azedarach. In each sampling site Hevea brasiliensis and Ochlandra stridula leaves were found in higher abundance. The contribution of other leaves varied with the site. Diptera larvae of the family Chironomidae, were the dominant group of leaf colonizing animals. The relative abundance of Chironomidae decreased along the elevation gradient in the down-stream. Gathering Collectors (GC) were the dominant functional feeding group (FFG) found in all leaf packs, but their abundance decreased along the downstream elevation gradient. Shredders were not present, as reported from some other tropical streams. Predators and Scrapers were increased along the downstream gradient. Filtering Collectors and Pierce-Herbivores did not show a clear pattern. The study documents that macro invertebrate communities responded to change in water quality, availability of leaves and their nutritional quality along the elevation gradient in Eswathu Oya, Sri Lanka.","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80712866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Whale watching in Sri Lanka: Understanding the metadata of crowd-sourced photographs on FlickrTM social media platform","authors":"Tharindu Bandara, T. Bandara","doi":"10.4038/SLJAS.V24I2.7566","DOIUrl":"https://doi.org/10.4038/SLJAS.V24I2.7566","url":null,"abstract":"Data mining on social media platforms (Instagram™, Flickr™, and Twitter™) is rapidly increasing and application of data mining techniques has contributed to significant findings in various fields such as tourism, ecology, and politics etc. In the face of globalization and nature-based tourism is thriving in many countries, social media activity on tourism is increasing despite the socio-economical barriers. In this context, this paper attempts to understand the metadata of photographs related to whale watching in Sri Lanka in Flickr social media platform. Photographs related to whale watching was extracted and analyzed for i) photographic content ii) Geo-tags iii) Social-tags and iv) Photographers’ nationalities by using Flickr API (Application Programming Interface) and self-written python program script. Content analysis of the photographs has identified five major categories (human activity, accommodation, natural phenomena, animals and other) of photographs based on the major element present in each photograph. Mapping of geo-tagged photographs indicated that Mirissa was the hotspot for whale watching in Sri Lanka. Moreover, the present study suggests that mapping of geo-tagged photographs can be used as proxy data for whale distribution in Sri Lanka.  Analysis of social tags indicated that tags indicating whale (156), Sri Lanka (144) and Mirissa (133) were popular among the photographers. The demographic profile of the photographers indicated that the highest number of photographers (25%) from the United Kingdom followed by Sri Lanka (18.69%) and China (12.94%) interested in whale watching. Despite some of the weaknesses, this study has demonstrated that metadata of Flickr photographs can effectively be used for understanding the basic information related to whale-watching tourism in Sri Lanka.","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82420276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ecology and Diversity of Plankton in Kotmale Reservoir, Sri Lanka","authors":"A. Warusawithana, S. Yatigammana","doi":"10.4038/SLJAS.V24I1.7565","DOIUrl":"https://doi.org/10.4038/SLJAS.V24I1.7565","url":null,"abstract":"Present study investigated the relationship between plankton communities and environmental variables in five different locations of the Kotmale Reservoir during the period of June 2008 to May 2011. A total of 123 plankton species were recorded with 85 species of phytoplankton and 38 species of zooplankton. The relative abundance data indicate that Aulacoseira granulata (31.06%), Botryococcus braunii (12.34%) and Microcystis sp. (11.93%) were the dominant phytoplankton species while Acanthocystis turfacea (52.22%) was the dominant zooplankton species. Staurastrum cingulum was the dominant species in sites where the immediate catchment is covered with reservation forest with no significant inflow streams. Aulacoseira granulata, Fragellaria capucina and Navicula sp. were abundant in locations where the highest total phosphorus (TP) values were recorded. The main inflow streams, Puna Oya and Pundalu Oya appear to bring nutrient rich waters from its catchment with dense tea estates, agricultural lands, industries and villages. Microcystis sp. was abundant in locations where the highest values for TP, dissolved phosphorus (DP), ammonia, conductivity and turbidity were recorded. Botryococcus braunii was dominant in the location where Puna Oya reaches the reservoir. Staurastrumlepta canthum was abundant in the location located closer to the dam where the water body mostly contains limnetic characteristics. Among the zooplankton, cladocera species were abundant in sites where Staurastrum cingulum was identified. Rotifers and ciliate protozoans were identified closer to the dam and at the sites with high dominance of Microcystis sp. Accordingly, it was apparent that the distribution and abundance of these plankton species depend on the prevailing environmental conditions which ultimately show their ability to use as environmental indicators.","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"100 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76064164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cyanotoxins: A hidden cause of Chronic Kidney Disease of unknown etiology (CKDu) in Sri Lanka - A review","authors":"P. Manage","doi":"10.4038/SLJAS.V24I1.7562","DOIUrl":"https://doi.org/10.4038/SLJAS.V24I1.7562","url":null,"abstract":"CKDu has been identified as a major public health issue in countries such as Sri Lanka, India and Nicaragua, which causes significant deaths per year. Significant similarities have been observed among these endemic nephropathies regardless of their geographical separation. Existing evidence favors a multi-factorial etiology, but research over the last few decades has failed to recognize the specific risk factors. Based on the geographical distribution that is unique and evidence of histopathological nature, it is speculated that CKDu is environmentally induced health problem. Hypothesis linking acetylcholinesterase (AChE) inhibiting organophosphate pesticides, metal-chelating glyophosate, agrochemicals, cadmium, arsenic, fluoride, hardness, and algae/cyanobacteria are considered as important factors in the etiology of CKDu. However, to date, no single geochemical parameter is shown to be directly related to the CKD etiology on the basis of the elements determined during research studies, and it is very likely that the unique hydrogeochemistry and microbiology of the drinking water is closely associated with the incidence of the disease in the endemic areas. The paper discuss understudied area of research is whether cyanotoxin formation from algal blooms may be a risk factor that contributes to CKDu in Sri Lanka as cyanotoxins in CKDu has been considered but not investigated.","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91118319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of sub-lethal gamma irradiation on antibiotic susceptibility profile and population dynamics of Enterococcus faecalis and Escherichia coli in water","authors":"A. O. Ogunniran, O. M. David, M. O. Isinkaye, A. K. Olawale","doi":"10.4038/SLJAS.V24I1.7563","DOIUrl":"https://doi.org/10.4038/SLJAS.V24I1.7563","url":null,"abstract":"Disinfection of water is important in the control of waterborne diseases. It is used to kill or inactivate microorganisms in a gradual process that involves a number of physical–chemical and biochemical processes. The effects of sub-lethal gamma irradiation on survival and resistant pattern of two indicator organisms used in assessing water quality: Enterococcus faecalis and Escherichia coli were investigated in this study. Plate count agar and disc diffusion methods were used to determine the load and antibiotics susceptibility pattern of the test organisms respectively before and after exposure to different doses of gamma irradiation in sachet water samples. Survival pattern of the two indicator organisms to gamma- ray showed a decline in the populations of the organisms with time compared to the controls (non-radiated). The effect of the irradiation on the E. coli was dose dependent, it initially responded to the effects of the irradiation in the first 4 days of exposure compared to the control. On exposure to 4 and 5 gy gamma rays a minimum population was reached on the 7th day. At p","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89229661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Validation of microwave-assisted sample extraction-high performance liquid chromatography (HPLC) method for quantitative analysis of hydrolysed amino acids in aquatic biological samples","authors":"G. Jayasinghe, B. Jinadasa","doi":"10.4038/SLJAS.V24I1.7564","DOIUrl":"https://doi.org/10.4038/SLJAS.V24I1.7564","url":null,"abstract":"A sensitive and widely applicable High-Performance Liquid Chromatography (HPLC) with fluorescence detector (FLD) method for determination hydrolysed amino acids in fish and aquatic products was developed and validated through study. The method involved a microwave-assisted sample extraction and protein hydrolysed with the hydrochloric acid and propionic acid. The separation was performed by Shim-pack HR-ODS column with a gradient mobile phase. The total separation time was 25 min per run. The method showed satisfactory linearity, repeatability, accuracy, and limit of detection for 21 amino acids with the 1-100 mg/L calibration range based on 10 µL injection. The fish, fish feed, canned fish and seaweeds samples were analysed successfully by using this developed method.","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"51 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87576295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}