scholarly journals Combined Effects of the Pesticide Spinetoram and the Cyanobacterium Microcystis on the Water Flea Daphnia Pulex

2021 ◽  
Author(s):  
Qiutong Shen ◽  
Yihe Zhan ◽  
Xuanhe Jia ◽  
Bangping Li ◽  
Xuexia Zhu ◽  
...  
Keyword(s):  
Aquatic Ecosystems ◽  
Daphnia Pulex ◽  
Population Level ◽  
Environmental Risks ◽  
Combined Effects ◽  
Negative Effects ◽  
Water Flea ◽  
Insecticidal Efficacy ◽  
Long Time ◽  
Survival And Reproduction

Abstract Spinetoram is one of the most worldwidely used pesticides for its high insecticidal efficacy and low human toxicity Following the large usage of spinetoram, the ecotoxicity and environmental risks to aquatic ecosystems have call for urgent study In the present study, we investigated the combined effects of spinetoram and the harmful alga Microcystis aeruginosa in freshwater, on survival and reproduction of Daphnia pulex Acute toxicity test of spinetoram resulted in negative effects on survival, with a 48h-LC50 value of 3771 µg L–1 Under the long-time exposure to environmentally relevant concentrations (018 and 035 µg L–1) of spinetoram and a low composition of Microcystis (30%) in the diet, D pulex showed both shorter longevity and lower fecundity, the time to first brood was also increased At population level, carrying capacity was highly decreased by spinetoram and Microcystis, whereas a significant decrease of intrinsic growth rate was observed at 035 µg L–1 spinetoram with 30% Microcystis as food The present study highlighted that pesticide spinetoram had highly toxic effects on D pulex and could reduce the tolerance of D pulex to M aeruginosa, causing great effects on D pulex population in natural waterbodies

scholarly journals Growth of duckweed upon exposure to aluminum and atrazine in the laboratory conditions

2018 ◽  
Vol 9 (2) ◽  
pp. 106-111
Author(s):  
Thi My Chi Vo ◽  
Minh Phap Dao ◽  
Thanh Son Dao
Keyword(s):  
Growth Rate ◽  
Aquatic Ecosystems ◽  
Natural Waters ◽  
Lemna Minor ◽  
Viet Nam ◽  
Combined Effects ◽  
Ecological Health ◽  
Negative Effects ◽  
Antagonistic Effects ◽  
Guideline Values

The trace metals and pesticides are commonly found in surface water receiving industrial and agricultural effluents. However, the potential negative effects of these compounds on aquatic ecosystems have not been deeply studied. Hence, the aim of this study is to assess the single and combined effects of aluminum (Al) and atrazine on the development and growth rate of duckweed, Lemna minor L. The single exposures were implemented with either Al or atrazine at the concentration of 5, 50 and 500 µg L-1 and a binary exposure was conducted with 50 µg L-1 of Al and 5 µg L-1 of atrazine for two weeks. The results revealed that both Al and atrazine at the concentration of 500 µg L-1 strongly inhibited the development and growth rate of the duckweed. On the contrary, the mixture of Al and atrazine showed antagonistic effects on the plant. To our knowledge, this is the first report on the combined effects of these two contaminants on the duckweed. Therefore, our results could be useful for environmental managers in setting up and adjusting the safe guideline values in Vietnam for Al and atrazine in natural waters in term of ecological health protection. Kim loại nặng và thuốc trừ sâu thường được tìm thấy trong các nguồn nước mặt, nơi tiếp nhận nước thải công nghiệp và nông nghiệp. Tuy nhiên, những ảnh hưởng tiềm tàng mang tính tiêu cực của những hợp chất này đối với hệ sinh thái thủy vực chưa được nghiên cứu đầy đủ. Do đó, mục tiêu của nghiên cứu này nhằm đánh giá những ảnh hưởng riêng lẻ và kết hợp của nhôm (Al) và atrazine lên sự phát triển và tốc độ sinh trưởng của bèo tấm, Lemma minor L. Sự phơi nhiễm riêng lẻ với Al hoặc atrazine được thực hiện ở các nồng độ 5, 50 và 500 µg L-1, trong khi đó, quá trình phơi nhiễm kết hợp được tiến hành với Al tại nồng độ 50 µg L-1 và atrazine tại nồng độ 5 µg L-1 trong hai tuần. Kết quả cho thấy cả Al và atrazine ở nồng độ phơi nhiễm 500 µg L-1 kìm hãm mạnh mẽ sự phát triển và tốc độ sinh trưởng của bèo tấm. Ngược lại, sự kết hợp Al và atrazine dẫn kết tác động triệt tiêu trên bèo tấm. Theo sự hiểu biết của chúng tôi, đây là ghi nhận đầu tiên về những ảnh hưởng kết hợp của hai chất gây ô nhiễm này lên bèo tấm. Vì vậy, những kết quả này có thể hữu ích cho các nhà quản lý môi trường tại Việt Nam trong việc thiết lập và điều chỉnh các giá trị an toàn đối với Al và Atrazie trong môi trường nước tự nhiên về khía cạnh bảo vệ sức khỏe sinh thái.  

scholarly journals Hot and sick: impacts of warming and oomycete parasite infection on endemic dominant zooplankter of Lake Baikal

2019 ◽  
Author(s):  
Ted Ozersky ◽  
Teofil Nakov ◽  
Stephanie E. Hampton ◽  
Nicholas L. Rodenhouse ◽  
Kirill Shchapov ◽  
...  
Keyword(s):  
Lake Baikal ◽  
Population Level ◽  
Monitoring Data ◽  
Negative Effects ◽  
Thermal Mismatch ◽  
Negative Effect ◽  
Survival And Reproduction ◽  
Long Term Monitoring ◽  
Term Monitoring

AbstractClimate warming impacts ecosystems through multiple interacting pathways, including via direct thermal responses of individual taxa and the combined responses of closely interacting species. In this study we examined how warming and infection by an oomycete parasite affect the dominant zooplankter of Russia’s Lake Baikal, the endemic cold-adapted stenotherm Epischura baikalensis (Copepoda). We used a combination of laboratory experiments, long-term monitoring data and population modeling. Experiments showed large thermal mismatch between host and parasite, with strong negative effects of warm temperatures on E. baikalensis survival and reproduction and a negative synergistic effect of Saprolegnia infection. However, Saprolegnia infection had an unexpected positive effect on E. baikalensis reproductive output, which may be consistent with fecundity compensation by infected females. Long-term monitoring data showed that Saprolegnia infections were most common during the warmest periods of the year and that infected individuals tended to accumulate in deep water. Population models, parameterized with experimental and literature data, correctly predicted the timing of Saprolegnia epizootics, but overestimated the negative effect of warming on E.baikalensis populations. Models suggest that diel vertical migration may allow E. baikalensis to escape the negative effects of increasing temperatures and parasitism and enable E. baikalensis to persist as Lake Baikal warms. Our results contribute to understanding of how multiple interacting stressors affect warming pelagic ecosystems of cold lakes and oceans and show that the population-level consequences of thermal mismatch between hosts and parasites can vary seasonally, interannual and spatially.

scholarly journals Changes in water chemistry can disable plankton prey defenses

2012 ◽  
Vol 109 (38) ◽  
pp. 15377-15382 ◽  
Author(s):  
Howard P. Riessen ◽  
Robert Dallas Linley ◽  
Ianina Altshuler ◽  
Max Rabus ◽  
Thomas Söllradl ◽  
...  
Keyword(s):  
Aquatic Ecosystems ◽  
Daphnia Pulex ◽  
Water Flea ◽  
Predator Prey ◽  
Defensive Responses ◽  
Chaoborus Americanus ◽  
Low Calcium ◽  
Softwater Lakes ◽  
Prey Defenses ◽  
Phantom Midge

The effectiveness of antipredator defenses is greatly influenced by the environment in which an organism lives. In aquatic ecosystems, the chemical composition of the water itself may play an important role in the outcome of predator–prey interactions by altering the ability of prey to detect predators or to implement defensive responses once the predator’s presence is perceived. Here, we demonstrate that low calcium concentrations (<1.5 mg/L) that are found in many softwater lakes and ponds disable the ability of the water flea, Daphnia pulex to respond effectively to its predator, larvae of the phantom midge, Chaoborus americanus. This low-calcium environment prevents development of the prey’s normal array of induced defenses, which include an increase in body size, formation of neck spines, and strengthening of the carapace. We estimate that this inability to access these otherwise effective defenses results in a 50–186% increase in the vulnerability of the smaller juvenile instars of Daphnia, the stages most susceptible to Chaoborus predation. Such a change likely contributes to the observed lack of success of daphniids in most low-calcium freshwater environments, and will speed the loss of these important zooplankton in lakes where calcium levels are in decline.

scholarly journals Environmental Risk Assessment of Drugs in Tropical Freshwaters Using Ceriodaphnia Silvestrii as Test Organism

2021 ◽  
Author(s):  
Lucas Lopes Caldas ◽  
Evaldo Espíndola ◽  
Raquel Moreira ◽  
Andrea Novelli
Keyword(s):  
Salicylic Acid ◽  
Sodium Salt ◽  
Diclofenac Sodium ◽  
Test Organism ◽  
Environmental Risks ◽  
Negative Effects ◽  
Limit Values ◽  
Tropical Regions ◽  
Tropical Freshwaters ◽  
Survival And Reproduction

Abstract The identification of drugs in aquatic environments, particularly in surface waters, has generated concerns about their potential toxic effects on the aquatic biota. In this study we evaluated the acute (immobility) and chronic (survival and reproduction) effects of the drugs caffeine, diclofenac sodium salt, ketoprofen, paracetamol and salicylic acid on the cladoceran Ceriodaphnia silvestrii. The environmental risks of these substances for tropical freshwaters were estimated from the risk quotient MEC/PNEC. Sensitivity in acute exposures varied up on the drug as follows: salicylic acid (EC50 = 69.15 mg L− 1) < caffeine (EC50 = 45.94 mg L− 1) < paracetamol (EC50 = 34.49 mg L− 1) < ketoprofen (EC50 = 24.84 mg L− 1) < diclofenac sodium salt (EC50 = 14.59 mg L− 1). Chronic toxicity data showed negative effects of the drugs on reproduction. Paracetamol and salicylic acid caused reduction in fecundity in concentrations starting from 10 mg L− 1 and 35 mg L− 1, respectively. Ketoprofen caused total inhibition at 5 mg L− 1. MEC/PNEC values were relatively low for all drugs. The risk was estimated as low or insignificant, except for caffeine, whose MEC/PNEC value was greater than 1 (moderate risk). Although the concentrations of the drugs that showed a toxic effect on C. silvestrii are still above the detected in the aquatic environment, long-term exposures and the evaluation of other endpoints, may result in potential environmental risks, therefore, they need to be studied. This knowledge is important, as up to now there are neither established limit values or guidelines to control the elimination of drugs in freshwater in Brazil and other countries in tropical regions.

scholarly journals Subway Gearbox Fault Diagnosis Algorithm Based on Adaptive Spline Impact Suppression

Entropy ◽  
2021 ◽  
Vol 23 (6) ◽  
pp. 660
Author(s):  
Zhongshuo Hu ◽  
Jianwei Yang ◽  
Dechen Yao ◽  
Jinhai Wang ◽  
Yongliang Bai
Keyword(s):  
Fault Diagnosis ◽  
Spline Interpolation ◽  
Reference Value ◽  
High Amplitude ◽  
Engineering Practice ◽  
Negative Effects ◽  
Short Term ◽  
Time Domain Signal ◽  
Gearbox Vibration ◽  
Long Time

In the signal processing of real subway vehicles, impacts between wheelsets and rail joint gaps have significant negative effects on the spectrum. This introduces great difficulties for the fault diagnosis of gearboxes. To solve this problem, this paper proposes an adaptive time-domain signal segmentation method that envelopes the original signal using a cubic spline interpolation. The peak values of the rail joint gap impacts are extracted to realize the adaptive segmentation of gearbox fault signals when the vehicle was moving at a uniform speed. A long-time and unsteady signal affected by wheel–rail impacts is segmented into multiple short-term, steady-state signals, which can suppress the high amplitude of the shock response signal. Finally, on this basis, multiple short-term sample signals are analyzed by time- and frequency-domain analyses and compared with the nonfaulty results. The results showed that the method can efficiently suppress the high-amplitude components of subway gearbox vibration signals and effectively extract the characteristics of weak faults due to uniform wear of the gearbox in the time and frequency domains. This provides reference value for the gearbox fault diagnosis in engineering practice.

Do researchers impact their study populations? Assessing the effect of field procedures in a long term population monitoring of sea kraits

2012 ◽  
Vol 33 (3-4) ◽  
pp. 365-372 ◽  
Author(s):  
Thomas Fauvel ◽  
François Brischoux ◽  
Marine Jeanne Briand ◽  
Xavier Bonnet
Keyword(s):  
Body Condition ◽  
New Caledonia ◽  
Stress Hormones ◽  
Population Level ◽  
Population Monitoring ◽  
Long Term Effects ◽  
Negative Effects ◽  
Short Term ◽  
Head Morphology

Long term population monitoring is essential to ecological studies; however, field procedures may disturb individuals. Assessing this topic is important in worldwide declining taxa such as reptiles. Previous studies focussed on animal welfare issues and examined short-term effects (e.g. increase of stress hormones due to handling). Long-term effects with possible consequences at the population level remain poorly investigated. In the present study, we evaluated the effects of widely used field procedures (e.g. handling, marking, forced regurgitation) both on short-term (hormonal stress response) and on long-term (changes in body condition, survival) scales in two intensively monitored populations of sea kraits (Laticauda spp.) in New Caledonia. Focusing on the most intensively monitored sites, from 2002 to 2012, we gathered approximately 11 200 captures/recaptures on 4500 individuals. Each snake was individually marked (scale clipping + branding) and subjected to various measurements (e.g. body size, head morphology, palpation). In addition, a subsample of more than 500 snakes was forced to regurgitate their prey for dietary analyses. Handling caused a significant stress hormonal response, however we found no detrimental long-term effect on body condition. Forced regurgitation did not cause any significant effect on both body condition one year later and survival. These results suggest that the strong short-term stress provoked by field procedures did not translate into negative effects on the population. Although similar analyses are required to test the validity of our conclusions in other species, our results suggest distinguishing welfare and population issues to evaluate the potential impact of population surveys.

Welfare Use in Japan: Trends and Determinants

2007 ◽  
pp. 88
Author(s):  
Wataru Suzuki ◽  
Yanfei Zhou
Keyword(s):  
Time Series ◽  
Longitudinal Data ◽  
Time Series Data ◽  
Positive Impact ◽  
Series Data ◽  
Negative Effects ◽  
Long Time ◽  
Welfare Use ◽  
The Impact

This article represents the first step in filling a large gap in knowledge concerning why Public Assistance (PA) use recently rose so fast in Japan. Specifically, we try to address this problem not only by performing a Blanchard and Quah decomposition on long-term monthly time series data (1960:04-2006:10), but also by estimating prefecturelevel longitudinal data. Two interesting findings emerge from the time series analysis. The first is that permanent shock imposes a continuously positive impact on the PA rate and is the main driving factor behind the recent increase in welfare use. The second finding is that the impact of temporary shock will last for a long time. The rate of the use of welfare is quite rigid because even if the PA rate rises due to temporary shocks, it takes about 8 or 9 years for it to regain its normal level. On the other hand, estimations of prefecture-level longitudinal data indicate that the Financial Capability Index (FCI) of the local government2 and minimum wage both impose negative effects on the PA rate. We also find that the rapid aging of Japan's population presents a permanent shock in practice, which makes it the most prominent contribution to surging welfare use.

Combined effects of aging and low temperature, long time heating on pork toughness

Meat Science ◽  
2019 ◽  
Vol 150 ◽  
pp. 33-39 ◽  
Author(s):  
Shengjie Li ◽  
Renchao Ma ◽  
Jinfeng Pan ◽  
Xinping Lin ◽  
Xiuping Dong ◽  
...  
Keyword(s):  
Low Temperature ◽  
Combined Effects ◽  
Long Time ◽  
Effects Of Aging

scholarly journals The Combined Effects of Financial Derivatives and Discretionary Accruals on the Value Relevance of Earnings and the Book Value of Equity

2015 ◽  
Vol 17 (2) ◽  
pp. 179 ◽  
Author(s):  
Etty Murwaningsari ◽  
Sidharta Utama ◽  
Hilda Rossieta
Keyword(s):  
Value Relevance ◽  
Positive Association ◽  
Wald Test ◽  
Discretionary Accruals ◽  
Financial Derivatives ◽  
Combined Effects ◽  
Price Model ◽  
Negative Effects ◽  
Book Value ◽  
Sfas 133

This study aimed to understand (1) the association between the use of discretionary accruals and financial derivatives, taking into consideration the implementation of revised PSAK 55 (1999), which was adopted from SFAS 133; (2) the combined effects of derivatives and discretionary accruals on the value relevance of earnings and equity. The analysis used panel data regressions and the Wald test over the period from 2001-2008. The results showed a positive or complementary association between derivatives and discretionary accruals. The positive association implied that managers tended to intensify the use of discretionary accruals to offset a higher use of derivatives. Price and return models demonstrated negative significant effects of derivatives on the value relevance of earnings. The return model showed negative significant effects of discretionary accruals on the value relevance of earnings but negative effects on the value relevance of equity with the price model.

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