scholarly journals Seasonal Response of Daphnia pulex to Cyanobacterial Extracts at Different Temperatures in Valle de Bravo Reservoir (Mexico)

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 526
Author(s):  
S. Nandini ◽  
Carlos Sánchez-Zamora ◽  
S. S. S. Sarma
Keyword(s):  
Population Growth ◽  
Life Table ◽  
Mexico City ◽  
Population Growth Rate ◽  
Daphnia Pulex ◽  
Toxicity Tests ◽  
Different Temperatures ◽  
Acute Toxicity Tests ◽  
Higher Temperature ◽  
Set Up

Valle de Bravo reservoir supplies drinking water to 40% of Mexico City. Here we present data on the population growth and life-table demography of the cladoceran Daphnia pulex, cultured at temperatures of 20 °C and 25 °C and with different concentrations of the crude extracts from blooms of Microcystis aeruginosa, collected in January, and Woronichinia naegeliana, collected in September. We hypothesized that Daphnia pulex would be more sensitive at the higher temperature and to toxins from W. naegeliana as these blooms have been shown to be more toxic to rotifers. We extracted the toxins and conducted acute toxicity tests at eight concentrations of microcystins at 20 °C. The LC50 was 26.8 µg/L and 11.5 µg/L, respectively, for Microcystis and Woronichinia samples. The chronic toxicity tests included population growth and life-table demography studies at 5 and 10% of the LC50 concentration, at 20 °C and 25 °C. Four replicates for each of the three treatments, which consisted of treatments with low and high cyanotoxin levels and a control without cyanotoxins, were set up. The population growth rate ranged from 0.18 to 0.42 d−1 on the extracts from M. aeruginosa (January) and from 0.2 to 0.31 on extracts from W. naegeliana. Daphnia, being better adapted to cooler temperatures, was more adversely affected at 25 °C than 20 °C. The adverse effect of cyanobacterial extracts was greater from Microcystis than Woronichinia blooms. The tolerance of Daphnia pulex to cyanotoxins depends on the bloom-forming species and the temperature.

The effects of contaminated sediments of the Blesbok Spruit near Witbank on water quality and the toxicity thereof to Daphnia pulex

1999 ◽  
Vol 39 (10-11) ◽  
pp. 173-176 ◽  
Author(s):  
Liesl Hill ◽  
Sebastian Jooste
Keyword(s):  
Surface Water ◽  
Mine Drainage ◽  
Interstitial Water ◽  
Stream Water ◽  
Daphnia Pulex ◽  
Contaminated Sediments ◽  
Toxicity Tests ◽  
Major Route ◽  
Acute Toxicity Tests ◽  
Route Of Exposure

With the increasing focus on environmental issues, the objective of this study is to evaluate the potential impact of contaminated sediments of the Blesbok Spruit near Witbank - which receives acid mine drainage (AMD) inter alia - on biota. Direct transfer of chemicals from sediments to organisms is considered to be a major route of exposure for many species, and therefore focusing attention on sediment contamination and highlighting the fact that sediments are an important resource. Acute toxicity tests were performed on Daphnia pulex using both extracted sediment interstitial water and surface water. Chemical analyses were also performed on the sediment, interstitial water and surface water samples. The toxicity results suggest that metal toxicity adds significantly to the toxicity of the stream water which is enhanced by the effect of pH. The pH of the stream and interstitial water was consistently below 4.5.

scholarly journals THE IMPACT OF HUMAN FACTORS ON THE CHANGE IN VEGETATION COVER OF THE BE RIVER BASIN IN THE PERIOD FROM 2000 TO 2015

2020 ◽  
Vol 15 (9) ◽  
pp. 53
Author(s):  
Phan Văn Trung ◽  
Nguyễn Thám
Keyword(s):  
Growth Rate ◽  
Human Factors ◽  
Population Growth ◽  
River Basin ◽  
Vegetation Cover ◽  
Population Growth Rate ◽  
Mapping Method ◽  
Rapid Urbanization ◽  
Set Up ◽  
The Impact

 The Be river basin is located in the area with a rapid urbanization rate and a large immigrants proportion annually. Therefore, the population growth rate for the period from 2000 to 2015 in the river basin is up 3,53% which is 3,27 times as high as the population growth rate of Vietnam. These are the major causes leading to the fluctuation in vegetation cover of the Be river basin during over time. This research used methodologies including data collection, statistical analysis, mapping method and geographic information system to evaluate the impact of human factors to the vegetation cover fluctuation of the Be river basin in the period from 2000 to 2015. Based on the results of change map in the vegetation cover, a research group set up fluctuating matrix, analyze to clarify the vegetation coverfluctuation situation due to human’s impacts in the Be river basin in the period from 2000 to 2015. 

Effects of salinty and temperature on the acute toxicity of cadmium to the estuarine crab Paragrapsus gaimardii (Milne Edwards)

1977 ◽  
Vol 28 (6) ◽  
pp. 739 ◽  
Author(s):  
JK Sullivan
Keyword(s):  
Acute Toxicity ◽  
Cadmium Chloride ◽  
Toxicity Tests ◽  
Acute Toxicity Tests ◽  
Higher Temperature ◽  
Chloride Concentrations

In static acute toxicity tests on the crab P. gaimardii the cadmium chloride concentrations fatal to 50% of the test animals over 96 h were determined for temperatures of 5 and 19�C and salinities of 8.6,17.5,26.3 and 34.6‰. The LC50 values ranged from 15.7 to 101.9 mg Cd2+/1. The mortality was greater at the higher temperature but at both temperatures a decrease in salinity caused an increase in the lethality of cadmium for the crabs.

scholarly journals The Influence of Available Cu and Au Nanoparticles (NPs) on the Survival of Water Fleas (Daphnia pulex)

2019 ◽  
Vol 16 (19) ◽  
pp. 3617 ◽  
Author(s):  
Garncarek ◽  
Kowalska-Góralska ◽  
Senze ◽  
Czyż
Keyword(s):  
Gold Nanoparticles ◽  
Au Nanoparticles ◽  
Daphnia Pulex ◽  
Toxicity Tests ◽  
Median Lethal Concentration ◽  
Au Nps ◽  
Lc50 Value ◽  
Nano Gold ◽  
Acute Toxicity Tests

Applications of nanotechnologies in different sectors and everyday items are very promising and their popularity continues to grow. The number of products containing nanoparticles makes environmental exposure to nanoparticles inevitable. The current understanding of the relationships between nanoparticles and the environment is inadequate despite the fast growth of nanotechnologies. The aim of the study was to investigate the influence of copper and gold nanoparticles on Daphnia pulex survival. Our study included 48-hour acute toxicity tests and determination of median lethal concentration values (LC50s) for Cu-NPs and Au-NPs. For nano-copper, 24 h LC50 was assumed > 1 mg/L, and 48 h LC50 = 0.5117 mg/L. For nano-gold the LC50 value after 24 h was 0.4027 mg/L, and after 48 h 0.1007 mg/L. The toxicity of nano -gold solutions was thus found to be higher than that of nano-copper. The addition of Cu-NPs at 0.0625 mg/L and 0.125 mg/L caused an increased multiplication of daphnia, while Au-NPs at 1 mg/L was an inhibitor of reproduction.

scholarly journals Evaluation of toxicity from leachate lagoons sediments, using the toxicity leaching procedure - TCLP and acute toxicity tests

DYNA ◽  
2019 ◽  
Vol 86 (208) ◽  
pp. 192-198
Author(s):  
Patricia Torres Lozada ◽  
Yazmin Carabalí Rivera ◽  
Luz Edith Barba Ho
Keyword(s):  
Acute Toxicity ◽  
Poecilia Reticulata ◽  
Daphnia Pulex ◽  
Acid Soils ◽  
Biological Indicators ◽  
Toxicity Tests ◽  
Municipal Solid Wastes ◽  
Inorganic Matter ◽  
Acute Toxicity Tests ◽  
Agricultural Use

Landfills have been the most used alternative for final municipal solid wastes disposal, however, this system is the responsible of contamination problems associated with the generation of leachates, sediments and toxic gasses emissions. The sediments occur by the organic and inorganic matter precipitation from leachates dumped in retention lagoons, which can present toxic characteristics than affect the environment. The aim of this work was to evaluate the potential toxicity of leachates from a municipal landfill, using the TCLP procedure and acute toxicity assays with Daphnia pulex and Poecilia reticulata as biological indicators. The results showed that the sediment evaluated, did not exceed the stablished levels suggested by the EPA for the TCLP test, nor were they toxic to the organisms used. This results, suggests a potential agricultural use of this material in acid soils, since the nature of leachate sediments are pH alkaline and rich in nutrients and organic matter.

Alterations in Population Growth Rate of Caenorhabditis elegans Exposed to Dichlorvos

2014 ◽  
Vol 1073-1076 ◽  
pp. 101-105
Author(s):  
Chun Hua Wang ◽  
Chao Pin Li
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Life Table ◽  
Population Growth Rate ◽  
Culture Medium ◽  
Reproductive Rate ◽  
Net Reproductive Rate ◽  
C Elegans ◽  
Hanging Drop Method ◽  
Fluid Culture

Dichlorvos is an environmental hormone insecticide, and several studies have demonstrated its toxic effects on C. elegans. However, little is known about its effect on the population growth rate of nematode cohort. After exposing worms to dichlorvos (1, 10 and 50 μmol/L) for 4h, a life table experiment was conducted by a hanging-drop method with a semi-fluid culture medium. Results showed that the survival rate and fecundity of worms decreased significantly, and concentration-dependent inhibitions were also observed in net reproductive rate, total fertility rate, average lifespan and population growth rate, so these parameters were approved to be sensitive to dichlorvos, and could be used as monitors of dichlorvos pollutant. The life table experiment measured several life-cyle traits simultaneously, and integrated them into population growth rate, which reflects a population’s response to a specific pollutant. The experimental results proved that life table experiment was important for assessment of pollutants.

Life Table Evaluation of Chronic Exposure to a Pesticide

1981 ◽  
Vol 38 (5) ◽  
pp. 485-494 ◽  
Author(s):  
Richard E. Daniels ◽  
J. David Allan
Keyword(s):  
Population Growth ◽  
Life Table ◽  
Daphnia Pulex ◽  
Sublethal Effect ◽  
Intrinsic Rate ◽  
Growth Potential ◽  
Population Increase ◽  
Toxic Substances ◽  
Eurytemora Affinis

The copepod Eurytemora affinis and the cladoceran Daphnia pulex were cultured at sublethal concentrations of dieldrin to test the usefulness of the intrinsic rate of population increase, r, as a bioassay statistic. The 48-h LC50 for E. affinis was 23 μg/L, but population growth rate measured by the life table method was only 12% of its control value at 5 μg/L and was zero at 10 μg/L, indicating a substantial sublethal effect. In contrast, D. pulex had a higher EC50 (251 μg/L) and showed little impairment of population growth potential below 220 μg/L. We suggest that the cladoceran was less sensitive than the copepod in both short- and long-term tests because of its simpler life cycle and larger size at hatching. The life table estimate of r appears to be an ecologically realistic measure of sublethal stress and requires an equivalent or shorter time to conduct than conventional long-term tests.Key words: acute toxicity, chronic toxicity, life table, r, toxic substances, Daphnia pulex, Eurytemora affinis, pesticide, dieldrin

İstanbul İlçelerinin Nüfus Değişimi ve Kütük Bilgilerinin Analizi

2019 ◽  
Vol 6 (1) ◽  
pp. 37-72
Author(s):  
Ulaş Sunata ◽  
Dila Ergül
Keyword(s):  
Population Growth ◽  
Population Growth Rate ◽  
Population Change ◽  
Urban Migration ◽  
Specific Population ◽  
Related Factors ◽  
Internal Migrant ◽  
Level Analysis ◽  
Study District ◽  
Demographic Features

39 ilçesiyle Türkiye’nin en büyük nüfusuna sahip ili İstanbul aynı zamanda Türkiye’nin en çok iç göç alan şehridir. Özellikle kırdan kente göç bağlamında sosyo-ekonomik ve demografik özellikleriyle birçok araştırmaya konu olmuştur. Fakat İstanbul yerleşik nüfusunun Türkiye’nin diğer şehirlerine kayıtlı olma yoğunluğu da önemlidir. Bu çalışmanın amacı 2012 ve 2017 yıllarındaki nüfus değişimini göz önünde bulundurarak İstanbul ilçelerinin ayrıntılı nüfus yoğunluğu ve büyüme analizini yapmak, ilgili faktörleri değerlendirmek, hemşehri ağlarını okumak adına yerleşik nüfus kütük bilgileri bakımından inceleyerek elde edilen örüntüler doğrultusunda ilçe tipolojileri oluşturmaktır. Çalışmanın birinci bölümünde ilgili beş yıllık nüfus değişimlerine göre İstanbul ilçe nüfusları analiz edilmiştir. Ardından her bir ilçe için nüfusa kayıtlı olunan kente göre nüfus büyüme hızlarına bakılarak ilçelerin ağırlıklı olarak barındırdığı hemşehri ağları belirlenmiştir. İkinci bölümde ise ilçeler nüfus değişim özelliklerine göre belirli kategorilere ayrılmış ve bu kategoriler doğrultusunda ilçe tipolojileri oluşturulmuştur..ABSTRACT IN ENGLISHA District Level Analysis of Istanbul’s Population Change (2012-2017)Istanbul having the largest population of Turkey with its 39 districts is the most internal-migrant-receiving city in Turkey. Particularly in the context of rural-to-urban migration, Istanbul has been became a subject of various researches with its socio-economic and demographic features. However, the density of Istanbul’s settled population who registered other cities of Turkey is important. The main aim of this study is to analyse population growth of all districts considering the population change between 2012 and 2017, to evaluate the related factors and to develop a district typology by using the data of settled population according to their family registration in the name of reading the current countryman networks. In the first section of the study, district populations of Istanbul are examined regarding the related five-year change. Afterwards, most repeated countryman networks of all Istanbul’s districts are specified regarding the population growth rate of the registered cities. In the latter section of the study, districts were divided into categories regarding the specific population change features which help to create district typology.

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