Zoology

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Habitat related variations and comparison of fatty acid composition of muscle and stomach contents of secondarily colonized Malabar Sprat (Ehirava fluviatilis) in Sri Lanka
(NeBIO, An International Journal of Environment and Biodiversity, Vol.10(3), pp.152-163, 2019) de Zoysa, H.K.S.; Amarasinghe, U.S.; Edirisinghe, E.M.R.K.B.; Sundarabarathy, T.V.
Ehirava fluviatilis is a marine origin clupeid found in Southern India and Sri Lanka, also found in two freshwater lakes, namely Parakarama Samudraya and Rajanaganaya reservoir, and that places are identified as secondarily colonizedhabitats. The objectives of this study were carried toinvestigate the fatty acid (FA) profile in the flesh of E.fluviatilis, to investigate the FA profile in the food of E. fluviatilis, and identify the impactof the FA profiles for colonisation. The Bligh and Dyer extracting method was used to lipids extraction of flesh and stomach contents of E. fluviatilis and Gas Chromatography (GC) was used to identify the different types of FAs. Data were statistically analyzed to examine the differences in the quantities of different FAs using ANOVA and principal component analysis (PCA). The predominant FAs were recorded in two different habitats ofE. fluviatilis in both flesh) and stomach contents. The only recorded difference between FAs profile was the presence of C 18:2 (n-4) in the Rajanganaya reservoir. The difference in the FA profile may lead to colonization of marine origin E. fluviatilis in Rajanganaya reservoir as a freshwater lacustrine habitat due to the ability of modification of FAs. Further, this study also indicates that the presence of specific FAs could be used as biomarkers to identify species.
Application of pollution indices to quantify the pollution status of shallow sediments of the Bolgoda Lake, Sri Lanka
(National Science Foundation of Sri Lanka, 2016) Wijeyaratne, W.M.D.N.
The present study was conducted to assess the pollution status of the shallow sediments of the Bolgoda Lake in Sri Lanka using sediment pollution indices. Shallow sediment samples were collected as replicates from five sites with different land uses in the monsoonal and nonmonsoonal seasons in 2013. The samples were acid digested and analysed for Cd, Cr, Cu, Ni, Fe and Zn. The heavy metal concentrations were used to calculate: (1) contamination factor (Ci f ); (2) degree of contamination (Cd); (3) pollution loading index (PLI); (4) enrichment ratio (ER); (5) geoaccumulation index (Igeo) and (6) ecological risk factor (Eri ) of the shallow sediment samples. In addition, the quality of the sediments were also assessed by comparing with the numerical sediment quality guidelines (SQGs) and consensus-based sediment quality guidelines (CBSQGs). Significant spatial variations of element concentrations and sediment quality indices were identified in the study area. The pollution level of the study sites ranged from unpolluted to heavily polluted due to heavy metals. The contamination factors for all the heavy metals except Zn indicated moderate, considerable or very high level of pollution in both sampling sessions. The potential ecological risk factor for the heavy metals ranked as Cd > Ni > Cr > Cu > Zn for both sampling sessions indicating the highest potential ecological risk from Cd. The pollution load index for all the study sites except site E in both sampling sessions showed human associated pollution with a PLI higher than 1. All the samples were categorised into class 1 (unpolluted to moderately polluted status) with respect to Cr, Ni, Cu and Zn and to class 0 (unpolluted status) with respect to Cd. The concentrations of Zn and Cd in the present study were lower than the threshold effect concentration (TEC) level of CBSQGs and therefore, was indicated as unlikely to be causing toxicity to benthic organisms. The concentrations of Cr and Ni were higher than the probable effect concentration (PEC) level of CBSQGs and indicated a probable toxicity to benthic organisms.
Feasibility Study for the Estimation of the Chlrophyll-a Using ASTER Data in an Eutrophic Lake, Sri Lanka
(Japan Geoscience Union, Japan., 2014) Dahanayaka, D.D.G.L.; Tonooka, H.; Wijeyaratne, M.J.S.; Minato, A.; Ozawa, S.
The objective of this study is to evaluate the performance of the previously proposed band ratio approach in estimating Chl-a in Bolgoda Lake, Sri Lanka as a representative example of Case II waters. Lake is located at western province in an area with lot of industries and also with some agricultural activities. Considerable amount of industrial effluents are discharged into it. Illegal filling and also encroachment has occurred in the recent past. This study focused on to determine the trends in eutrophication via Chl-a changes during the recent past, make predictions and recommend mitigatory measures and suggest precautionary measures to restore the environment. From March to December 2013, water samples at 5 points of Lake were collected once per month parallel to ASTER overpass and Chl-a of each sample was measured using a laboratory spectrophotometer. Cloud-free ASTER scenes acquired over Lake under clear sky conditions were selected during 2000 to 2013 for Chl-a estimation and trend analysis. All the ASTER images were atmospherically corrected using FLAASH and in-situ Chl-a data on Lake were regressively analyzed with atmospherically corrected three ASTER VNIR band ratios such as B1/B2 of the same date. Finally, the regression equation of the band ratio with highest correlation (B1/B2; R2 = 0.78) was used to develop algorithm for generation of 15-m resolution Chl-a distribution maps using atmospherically corrected time series satellite imageries in day by day basis. This method applied for ASTER band 1/2 ratio due to Chl-a is positively correlated with the green band reflectance and negatively correlated with the red band reflectance. Therefore, the reflectance ratio of green and red bands becomes a robust parameter to estimate the Chl-a content. According to the ASTER based Chl-a distribution maps it is clearly evident that eutrophication of the Bolgoda Lake has been gradually increased from 2005-2011. Further, results showed that there were significant eutrophic conditions throughout the year 2013 in several parts of the Lake and considerable spatial heterogeneity with higher concentrations being recorded water stagnant areas and in water adjacent to freshwater outlets. It is clear that Bolgoda Lake is apparently a disposal site of various discharges of factories in addition to poor drainage and sewage systems present in this area. Highly unplanned urbanization and absolutely lack of adequate waste disposal management facilities in industries close to Lake have resulted in pollution of water. If the present trend of waste disposal and unplanned urbanization continue, they would create enormous environmental problems in future. Results of the present study showed that information from satellite remote sensing can play a useful role in determining the changes in Chl-a related to eutrophication in Bolgoda Lake and in the development of time series Chl-a distribution maps. Such information is important for the future predictions, development and management of this area as well as in the conservation of biodiversity. Therefore we recommend incorporation with this technique for routine monitoring of water quality using multi satellite data such as ASTER in inland water bodies like Bolgoda Lake in the future.

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