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Öğe Assessing short-term effects of magnetite ferrite nanoparticles on Daphnia magna(Springer Heidelberg, 2020) Gokce, Didem; Koytepe, Suleyman; Ozcan, ImrenMagnetic nanoparticles (MNPs) are used in a wide range of sectors ranging from electronics to biomedicine, as well as in eutrophicated lake restoration due to their high P, N, and heavy metal adsorption capacity. This study assessed the effects of MNPs on mortality and morphometric changes of D. magna. According to the SEM, the synthesised MNPs were found to have spherical nanoparticles, be uniformly distributed, and have a homolithic size distribution of 50-110 nm. The EDX spectra confirmed the elemental structure and purities of these MNPs. A total of 396 neonates were used for short-term bioassays (96 h) through the MNPs in the laboratory (16:8 photoperiod). Experiments were applied in triplicate for each concentration of CuFe2O4, CoFe2O4, and NiFe2O4 MNPs and their respective control groups. Mortality and morphological measurements of each individual were recorded every 24 h. In the probit analysis, the 96-h LC50 (p < 0.05) for CuFe2O4, CoFe2O4, and NiFe2O4 MNPs was calculated to be 1.455 mg L-1, 39.834 mg L-1, and 21.730 mg L-1, respectively. CuFe2O4 MNPs were found to be more toxic than the other two MNPs. The concentrations of CuFe2O4, CoFe2O4, and NiFe2O4 MNPs drastically affected life span and morphologic growth of D. magna as a result of a short time exposure. The results of this study are useful for assessing what risks they pose to freshwater ecosystems.Öğe ASSESSMENT OF WATER QUALITY AND EPILITHIC ALGAE COMMUNITY STRUCTURE OF TOHMA RIVER, TURKEY(Parlar Scientific Publications (P S P), 2019) Gokce, Didem; Gulbenk, HandeThe Tohma Stream is among the most important tributaries of the transboundary Euphrates River. The aim of this work is to evaluate which are the most important environmental variables that might affect epilithic communities in Tohma Streams and species composition in microhabitats. A total of 89 taxa belonging to 4 phyla were identified in the study area (Bacillariophyta, Chlorophyta, Cyanobacteria and Charophyta). According to temporal and spatial heterogeneity of Tohma Stream, ecological indices of epilithic algal composition demonstrated significant differences at the 95% confidence level. Mean DIN: SRP< 10 ratio was recorded at sts 4, 5, 8 and 9 in dry and wet seasons. Mean DIN: SRP was detected 80.028 ratio due to excessive pollution runoff. There was a correlation between community diversity and Bacillariophyta which is the most abundance group. According to changes in the species level of community composition, stations have been separated into 2 main groups in UPGMA cluster analysis. Stl l was placed 2nd main group and this situation has also been confirmed in the RDA analysis due to Tohma Stream derived mainly from agricultural, domestic and organic runoffs from industrial zone were mostly higher than the other stations.Öğe Chronic and Acute Water-Soluble Microplastics Uptake and Effects on Growth and Reproduction of Daphnia magna(Springer Int Publ Ag, 2022) Gokce, Didem; Seftalicioglu, Merve Duygu; Erden, Busra Aksoy; Koytepe, SuleymanThis study focuses on the evaluation of chronic and acute effects of the water-soluble microplastics polyvinyl alcohol (PVA) and polymethacrylic acid (PMA) on the growth and reproduction of Daphnia magna. Within the scope of this study, first of all, PVA and PMA microplastics structures were structurally, thermally, and morphologically characterized. The size distributions and dimensional stability of these structures were determined. Then, the microplastics structures, whose structural and dimensional properties were determined, were applied to the growth and reproduction environments of D. magna at different concentrations. The effects of these microplastics on survival parameters, population growth, morphometric data, and lethal concentration were evaluated through short (96-h) and long (21-day) term analyses. In the long-term study, reproductive strategies affecting population density were examined. Acute and chronic experiments were performed in parthenogenetic females. In chronic triplicate experiments evaluating the population structure from which the reproductive data were obtained, the male neonate was recorded only at a concentration of 5 mgL(-1) MP-PVA. Decreased lifespan, ephippium production, embryo development, immature eggs, sexual differentiation, and morphologic deformations have been observed in D. magna due to different concentrations of microplastics polymers exposures.Öğe Effects of nanoparticles on Daphnia magna population dynamics(Taylor & Francis Ltd, 2018) Gokce, Didem; Koytepe, Suleyman; Ozcan, ImrenSpherical TiO2 nanoparticles (npTiO(2)) were prepared by controlled hydrolysis of tetraethoxy orthotitanate under a nitrogen atmosphere. ZnO nanoparticles (npZnO) were prepared using hydrothermal methods. The crystal structure, chemical, thermal and morphological properties of npZnO and npTiO(2) were characterised using Fourier Transform Infrared Spectrometer, enery-dispersive X-ray spectroscopy, X-ray diffraction, and scanning electron microscope techniques. The short- and long-term experiments were started with neonates taken from the same culture and laboratory condition. In the acute experiments, npTiO(2), npZnO, and cocktail concentrations were applied. 96h-LC50 values were 1.8, 0.7, and 0.1mgL(-1), respectively (p<.05). For the chronic experiments, different npTiO(2) concentrations were performed. 21d-LC50 value was 1.0mgL(-1) (p<.05). Morphometry became progressively worse in concentrations of more than 1mgL(-1) npTiO(2). Neonate and young individuals were more sensitive to death because of their low tolerance. This result was affected by population progeny and growth rates (p<.05). While control and 0.5mgL(-1) npTiO(2) groups were determined as growing population, 1.5 and 2mgL(-1) npTiO(2) groups had decreased population size as R-0 values. Consequently, the relationships between nanoparticle accumulation within Daphnia magna and its population structure and body morphometry for each concentration were important indicators. Its tolerance level to nanoparticles under laboratory conditions reflected its replacement and behaviour in the ecosystem.Öğe Effects of salinity tolerances on survival and life history of 2 cladocerans(Tubitak Scientific & Technological Research Council Turkey, 2014) Gokce, Didem; Ozhan Turhan, DuyguSalinity alterations in freshwater ecosystems greatly affect the survival and life history of zooplankton and, therefore, have an effect on higher trophic levels. Salinity is an essential and critical factor in determining the presence, dominance, and succession of organisms. After being collected in the field, Scapholeberis mucronata and Simocephalus vetulus were brought to the laboratory in water. Under laboratory conditions (24 +/- 1 degrees C; 16:8 h photoperiod), we evaluated the effect of different salt concentrations on the neonates. The LC50 values were determined at different halotolerance levels for S. mucronata (0.375 g L-1) and S. vetulus (0.250 g L-1). Results of experiments demonstrated that S. vetulus was more sensitive than S. mucronata, which has hyponeustonic behavior. Morphometrics of the body in salinity stress were measured for S. mucronata. In the measurements of body length, body width, and spine lengths, there were significant differences determined by post hoc analysis between the control, 0.250, and 0.375 g L-1 dose groups and the 0.500 and 0.625 g L-1 dose groups. However, no clear relation between ovum size and salinity concentration was found. This study demonstrated how an increase in salinity significantly affects survival and life history properties, which can cause changes in the zooplankton community structure.Öğe Growth and reproduction of Cyprinion macrostomus (Heckel, 1843) and Cyprinion kais (Heckel, 1843) populations in Karakaya Dam Lake (Euphrates River), Turkey(TUBITAK SCIENTIFIC & TECHNICAL RESEARCH COUNCIL TURKEY,, 2015) Alkan Uckun, Aysel; Gokce, DidemThis study investigated the age-length relationship, length-weight relationship, somatic condition, gonadosomatic index, and reproduction properties of Cyprinion macrostomus and Cyprinion kais. C. kais is an endemic species included on the IUCN Red List of Threatened Species in the Tigris-Euphrates Basin. A total of 153 C. macrostomus and 114 C. kais were collected. The estimated length-weight relationships were W = 0.725 x FL2.92 (r(2) = 0.87) for C. macrostomus and W = 0.417 x FL3.02 (r(2) = 0.93) for C. kais. The age-length relationships were L-t = 15.0 [1 - e(-0.212) ((t + 0.407))] and L-t = 15.4 [1 - e(-0.205 (t + 0.503))] for C. macrostomus and C. kais, respectively. Mean fecundity ranged from 313 to 1647.08 eggs/fish for C. macrostomus and from 295.1 to 1255.2 eggs/fish for C. kais. Mean oocyte diameter ranged between 0.13 and 1.34 mm for C. macrostomus and between 0.14 and 0.86 mm for C. kais. Based on gonadosomatic index, the spawning periods of C. macrostomus and C. kais were determined to be between June and August in the area of the study.Öğe Limno-Ecological Properties of Deep Reservoir, Karakaya HEPP, Turkey(Gazi Univ, 2011) Gokce, Didem; Ozhan, DuyguKarakaya Dam is the third largest dam lake and the second biggest electric generation plant in Turkey. CCA, UPGMA were explained that the effects of selected environmental factors on the composition and structure of macroinvertebrate communities in ecosystem. While the concentrations of nitrite and ammonium were high, the level of orthophosphate phosphorus was low in lake. Amounts of Zn, Cu, Pb, Fe, Cd, Cr were analyzed from sediment samples and monitor organism in the ecosystem. Consequently, there was a high level of metal pollution in the ecosystem and the organisms living in the sediment were directly affected by this pollution.Öğe RELATIONSHIPS BETWEEN ENVIRONMENTAL FACTORS AND PHYTOPLANKTON COMMUNITY IN TWO DAM LAKES(Parlar Scientific Publications (P S P), 2019) Gokce, Didem; Ercan-Altindag, SengulPopulation dynamics, diversity of phytoplankton and their combination with different environmental factors in Sultansuyu (SsDL) and Surgu Dam Lake (SrgDL) were investigated. While water samples were taken from water surface and Secchi depth for pigment analysis (Chl-a, Chl-b, carotene, pheophytin), they were taken vertically from surface to bottom of lakes for physico-chemical analysis. Diversity, evenness, richness, and dominancy indices were performed for the structure of phytoplankton population due to water quality of the dam lakes. A total of 114 taxa were identified in SsDL and 96 taxa were identified in SrgDL. While Cyanobacteria population changes and abundance were strongly correlated with SiO2 concentration (r= 0.915, p< 0.01), phytoplankton were not significantly correlated with NO3-N and SRP concentrations in SsDL. Total phytoplankton abundance was correlated with pH (r= 0.809); Euglenozoa was strongly correlated with temperature (r= 0.995) in SrgDL. In the assessment of Pearson's correlation analysis and RDA analysis, the interaction among community structure, temporal dynamics, and environmental variables was clearly seen. The present study provides a valuable baseline data on ecosystem quality of two dam lakes towards semi-arid condition.Öğe VARIATIONS OF PHYTOPLANKTON COMMUNITY STRUCTURE RELATED TO WATER QUALITY IN A DEEP DAM LAKE(Parlar Scientific Publications (P S P), 2014) Gokce, DidemNutrient concentrations and phytoplankton biomass were monitored in the upper Euphrates River. The purpose of this study was to obtain detailed information about the composition variations in the phytoplankton community, and to determine the driving force for the succession of the dominant genera. Cyanobacteria were predominant with 76.88 % of the total abundance in the Karakaya Dam Lake. Chlorophyta (7.81 % of the total abundance) was the most abundant group, followed by Bacillariophyta (7.72 %), Dinophyta (7.56 %), and Euglenophyta (0.03 %). The phytoplankton seasonal sequence was mainly correlated with environmental factors. Unimodal species distribution was shown in UPGMA cluster analysis, classified into the two cluster groups. RDA was used to examine relationships between measured environmental variables and phytoplankton populations of the study area. Eigenvalues of axes explained 100 % of the cumulative variance in species data and 99.6 % of the relationship between species and environmental data. According to water quality, DIN: SRP ratio was >16:1. Water temperature and conductivity were main driving forces for the seasonal succession of the abundance. Based on RDA-Pearson correlation analysis, the results showed that the phytoplankton abundance and biomass were positively correlated with the changes of environmental factors (p<0.01, p<0.05). Except for DO, Secchi, SRP, nitrogen, and pH, there were no correlations with the phytoplankton abundance and biomass. It is important to control the exogenous nutrient in order to maintain ecosystem healthiness of Karakaya Dam Lake.
