International Letters of Natural Sciences Vol. 62

Abstract: Species composition, seasonal dynamics and distribution of phytoplankton were researched to characterize temporal dynamics and horizontal distribution of phytoplankton and to indicate the ecological status of the sites in the Zaporizke reservoir. During 2015 - 2016 a seasonal dynamics of species composition and quantitative characteristics of phytoplankton have been studied near Monastyrsky island in upper part of the reservoir both in surface and bottom layers in conjunction with water temperature measurement. At early September 2016 phytoplankton sampling was performed at different sites of the Zaporizke reservoir including the sites undergone to sewage impact. During phytoplankton seasonal dynamics diatom bloom was reported in March and early April and algae biomass was higher in the bottom layer with a gradual decrease in the direction of the surface layer. From July to October the apparent dominance of blue-green algae took place with a clear concentration in the surface layer. Domination of the species Microcystis aeruginosa determined phytoplankton distribution along the reservoir at the beginning of September. Despite the high resistance to the effects of toxic substances the level of Microcystis aeruginosa (Kützing) Kützing 1846 development decreased at the sites of direct sewage impact. At 100m below the sewages sites degree of phytoplankton development increased mainly due to increase of blue-green algae abundance. Indexes of phytoplankton showed the best ecological state at the site «near Kodaki water draw-off» and the worst ecological state at the sites of direct sewage impact. The results obtained are important to indicate ecological state of the sites in the Zaporizke reservoir.

Abstract: Spiders represent one of the most abundant components of the predatory arthropods in terrestrial ecosystem. Their effectiveness at restricting pest populations, both alone and as part of natural enemy complex has well demonstrated in many countries. The web, web-site attributes and predatory efficiency of Dark Tetragnathid Spider Tetragnatha mandibulata were assessed in Point Calimere Wildlife and Bird Sanctuary between August 2015 and March 2016. In the present study, the spiders used limited number of plants species. The relationship between web architecture and web-site attributes was estimated using Pearson’s correlation. Number of spiders recorded in the web showed the positive correlation with web horizontal and vertical length of the capture areas (p<0.05). Similarly, the web circumference showed the positive interaction with plant height and canopy width (p<0.05), which clearly indicated the importance of vegetations across the webs of Dark Tetragnathid Spider. Further, the microhabitat selection and utilization could also be impacted by non-trophic factors like structural features of plants that provide architectural supports to spiders. A total of 4620 insect pests comprising seven orders were entangled by the webs of dark tetragnathid spiders. Number of spiders in the web were positively correlated with number of insect pests (p<0.05), which clearly explained that the Dark Tetragnathid spiders restricting pest populations and therefore they are considered as useful organism in biological control.

Abstract: Habitat fragmentation results to displacement of inhabiting floral and faunal species. The resulting geographic isolation of various species affect regeneration, genetic flows and recruitment. Hence, a study was conducted in a forested area of Mt. Malindawag in Naawan, Misamis Oriental. Sampling stations were designated at the agro-forest, mid-forest and upper-forest habitat types. Species characterizations were based on DAO 2007-01 and IUCN Red List for conservation status. Results showed highest diversity index of flora at mid-forest while lowest diversity was observed in the agro-forest area. A tree species Canarium racemosum obtained highest Species Importance Value (SIV) at 38.6%, 42% and 30.8%, respectively in the three habitat types. The highest endemicity of flora was at mid-forest with 24% per DAO 2007-01 and 26% per IUCN conservation status. Majority of faunal species were birds that were mostly resident and common and were usually observed at upper-forest habitat. The relatively low diversity and endemicity of flora and fauna species could be due to the influx of human population. Various activities undertaken were threatening the inhabiting biodiversity, and therefore, demand immediate protection and conservation measures from formulating policies to increasing awareness of various stakeholders. Future related studies were recommended to increase scientific understanding on the interrelationships of socio-economic and ecological interactions of biodiversity to the inhabiting human population.

Abstract: The paper describes results of vegetative tests of active coal as a detoxiсant of herbicide remains in soil on eight varieties of summer rapeseed. The tests were performed with the purpose to align soil fertility on different breeding and test sites. The research is based on attempts to apply coal absorbent as a means of soil detoxication to neutralize herbicides remains in the process of oilseed brassica crops breeding. Several summer rapeseed varieties originated by All-Russian Rapeseed Institute were used as research objects [2,3,5-11]. Similar approaches have not been encountered in literature references available.

Abstract: This study assessed the quality of palm oil and soil quality from Ihube community, Okigwe L.G.A of Imo state in October 2015. The soil samples were collected from the top soil and the palm oil were collected immediately after extraction. The soil and palm oil were analyzed using standard analytical methods and the results obtained were compared to standards. The physicochemical analysis of the soil samples showed that ranges of EC (323.33±0.57-480.33±1.53 us/cm); Temperature (28.0±0.26 29.1±0.20 °C); %MC (20.9±0.80-40.8±0.10); %SOM (1.92±0.61-4.85±0.01) which were within the acceptable limits while CEC (5.471-8.1063 mg/kg); iron (0.311-0.731 mg/kg) and lead (0.004-0.054 mg/kg) were is not appreciable. The palm oil result showed that MC (0.32±0.09 %) which is above the acceptable limit, pH (4.71±0.01-4.74±0.01) and viscosity (23.41±0.44-106.23±0.55 mPas) obtained at temperature range 20 °C-50 °C. The FFA result for 10days showed ranges from (2.15±0.01-6.07±0.05 mgNaOH/g) with Fe, (2.00±0.01-5.43±0.51 mgNaOH/g) with Pb and (1.27±0.03-5.04±0.03 mgNaOH/g) without contamination. This was tested using anova at p = 0.05 respectively and showed significant difference between the results. However, the result obtained from these areas shows good quality soil for palm tree cultivation.

Abstract: The present study larvicidal activities of hexane, chloroform, ethyl acetate, acetone and methanol extracts of Halimeda macroloba, Decsne, Caulerpa racemosa (Frosk) Weber-Van-Bosses and Ulva lactuca Lin, (Chlorophyceae) against Aedes aegypti. The marine macro green algae extracts were tested against early 4^th instar larvae of A. aegypti using WHO protocol and concentrations of 200, 400, 600, 800 and 1000 ppm. The observed mortality was made 24 and 48 h after treatment, data was subjected to probit analysis to determine the lethal concentration (LC₅₀ and LC₉₀) of the treated larvae of the tested species. Among the tested extracts the maximum efficicacy was observed in the ethyl acetate extracts. The ethyl acetate extracts of the seaweeds showed the presence of terpenoids, tannins and phenolic compounds stronger than the other extracts. The results revealed that all the extracts showed varied levels of larvicidal activity against A. aegypti tested. However, the ethyl acetate extract of C. racemosa showed remarkable larvicidal activity against A. aegypti (LC₅₀=579.9 and LC₉₀=1255.4 ppm values at 24 h and LC₅₀ =495.4 and LC₉₀ =1073.9 ppm at 48 h) followed by U. lactuca (LC₅₀=588.1 and LC₉₀=1290.7 ppm values at 24 h, and LC₅₀₌ 530.8 and LC₉₀= 1160.0 ppm at 48 h), respectively. The lowest larval mortality was observed with hexane extract of H. macroloba against A. aegypti with values of LC₅₀=1116.8 and LC₉₀= 1824.5 ppm (after 24 h) and LC₅₀=1059.9 and LC₉₀=1768.3 ppm (after 24 h). The present studies indicate that the larvicidal activity and phytochemicals derived from the ethyl acetate extract of C. racemosa have the potential to be used as an ideal eco-friendly approach and effective mosquito vector control agent.

Abstract: Stratigraphic play based exploration approach facilitates the development of reservoir prediction models and prospect generation. The present study is carried out along the southern margin of the Loppa High within Hammerfest Basin, Barents Sea, Norway in order to identify the reservoir quality sand in Early Cretaceous age formations along the slope of the high. In this study 2D seismic lines; in which 8 lines are dip and 1 line is strike, and well logs data are interpreted. Outcome is a low-risk exploration technique that is capable of correctly predicting reservoir zones. The stratigraphic trap is identified in the Knurr and Kolje Formations of Adventdalen group, which act as source and seal rock for reservoir respectively. Three stratigraphic surfaces including base of Knurr Formation (sequence boundary), top of Knurr Formation, and Kolje Formation (maximum flooding surface) make a perfect trap for hydrocarbon accumulation. By utilizing the common risk segment analyses, it was identified that the maximum chances of hydrocarbon accumulation are in reservoir zone A and B which lies in up-dip direction.