The impact of food quantity on UV-B tolerance and recovery from UV-B damage in Daphnia pulex

Hydrobiologia ◽  
1996 ◽  
Vol 319 (2) ◽  
pp. 87-92 ◽  
Author(s):  
Iris D. Zellmer
Keyword(s):  
Daphnia Pulex ◽  
Food Quantity ◽  
The Impact

scholarly journals Impactos do Programa de Aquisição de Alimentos (PAA) no Rendimento Escolar dos Municípios do Paraná

2019 ◽  
Vol 20 (4) ◽  
pp. 446-451
Author(s):  
Renata Cattelan ◽  
Lirane Elize Defante Ferreto
Keyword(s):  
School Performance ◽  
Dropout Rate ◽  
Food Shortage ◽  
Early Years ◽  
Pass Rate ◽  
Food Quantity ◽  
Politica Publica ◽  
Keywords Education ◽  
The Impact ◽  
Distortion Rate

No Brasil, ao longo das últimas décadas, algumas políticas públicas procuraram sanar os problemas da carência alimentar. Contudo, a insegurança alimentar tem fatores multidimensionais e impacta de maneiras variadas na vida da população, especialmente de crianças e adolescentes. O impacto da quantidade e qualidade insuficiente dos alimentos pode ser um fator de redução do rendimento escolar. O Programa de Aquisição de Alimentos (PAA) é uma política pública que visa a distribuição de alimentos de qualidade nas escolas, bem como em outros órgãos, e que objetiva gerar renda no campo ao mesmo tempo em que oferece qualidade nutricional. Partindo do problema da carência alimentar para crianças e adolescentes e como isso afeta a produtividade escolar, o objetivo desta pesquisa é avaliar o impacto do PAA no rendimento escolar de crianças e adolescentes que estudam em escolas que são beneficiárias do programa. A metodologia utilizada foi o teste de Mann-Whitney e as variáveis utilizadas foram o IDEB, a taxa de aprovação, a taxa de abandono escolar e a taxa de distorção idade/série para o ensino fundamental séries iniciais e finais. O recorte geográfico é o estado do Paraná, e temporal, os anos de 2013 e 2015. O principal resultado do estudo mostrou que a variável taxa de distorção idade/série dos anos iniciais do ensino fundamental, para o grupo formado pelos municípios afetados pelo PAA, obteve melhora estatisticamente significativa em relação a municípios que não participaram do programa. Palavras-chave: Educação. Segurança Alimentar e Nutricional. Teste de Mann-Whitney. AbstractIn Brazil, over the last decades, some public policies have tried to remedy the problems of food shortage. However, food insecurity has multidimensional factors and impacts in various ways on the lives of the population, especially children and teenagers. The impact of insufficient food quantity and quality may be a factor in reducing school performance. The Food Acquisition Program (FAP) is a public policy aimed at the distribution of quality food in schools as well as other agencies, and which aims to generate income in the countryside while providing nutritional quality. Starting from the problem of food shortage for children and teenagers, and how it affects school productivity, the objective of this research is to evaluate the impact of FAP on the school performance of children and adolescents who study in schools that benefit from the program. The methodology used was the Mann-Whitney test and the variables used were the IDEB, the pass rate, the dropout rate and the age / grade distortion rate for elementary and early grades. The geographical cut is the state of Paraná, and temporal, the years 2013 and 2015. The main result of the study showed that the variable age / grade distortion rate of the early years of elementary school, for the group formed by the municipalities affected by the FAP, obtained statistically significant improvement compared to counties that did not participate in the program. Keywords: Education. Food Safety and Nutrition. Test of Mann-Whitney. 

scholarly journals Inducible morphological defense in Daphnia pulex: food quantity effects revised

2020 ◽  
Author(s):  
Sandra Klintworth ◽  
Eric von Elert
Keyword(s):  
Chemical Cues ◽  
Daphnia Pulex ◽  
Food Concentration ◽  
Bacterial Degradation ◽  
Inducible Defenses ◽  
Chemical Cue ◽  
High Food ◽  
Food Quantity ◽  
Morphological Defense ◽  
Food Concentrations

Abstract In aquatic systems, organisms largely rely on chemical cues to perceive information about the presence of predators or prey. Daphnia recognize the presence of the predatory larvae of Chaoborus via a chemical cue, emitted by the larvae, a so-called kairomone. Upon recognition, neckteeth, an alteration of the carapace, are induced in Daphnia that reduce predation rates of Chaoborus. Neckteeth induction was often reported to entail costs. In a previous study, food quantity affected the level of neckteeth induction, with stronger neckteeth induction at low food concentrations and weak induction at high food concentrations. However, reducing neckteeth induction at high food quantities seems to be maladaptive and not in accordance with the concept that inducible defenses are associated with costs. Here, we hypothesized that weaker neckteeth induction at high food concentrations is caused by increased bacterial degradation of the kairomone. More specifically, we assume that higher algal food concentration is associated with higher bacterial abundances, which degrade the kairomone during the experiment. We tested our hypothesis by treating food algae with antibiotics before providing them as food to Daphnia. Antibiotics reduced bacterial abundances at high and low food concentrations. Reduced bacterial abundances at high food concentrations led to the same level of neckteeth induction as at low food concentrations. A linear regression revealed a significant correlation of neckteeth induction to bacterial abundances. We therefore conclude that differences in neckteeth induction at different food concentrations are not caused by the food quantity effects but by differences in bacterial degradation of the kairomone.

Bottom-up Effects on Tri-trophic Interactions: Plant Fertilization Enhances the Fitness of a Primary Parasitoid Mediated by Its Herbivore Host

2020 ◽  
Vol 113 (6) ◽  
pp. 2619-2626
Author(s):  
Apostolos Pekas ◽  
Felix L Wäckers
Keyword(s):  
Natural Enemies ◽  
Nitrogen Concentration ◽  
Mass Rearing ◽  
Reproductive Capacity ◽  
Biological Pest Control ◽  
Tobacco Plants ◽  
Primary And Secondary Metabolites ◽  
Food Quantity ◽  
Nitrogen Treatment ◽  
The Impact

Abstract Plants play a pivotal role in interactions involving herbivores and their natural enemies. Variation in plant primary and secondary metabolites not only affects herbivores but, directly and indirectly, also their natural enemies. Here, we used a commercial NPK fertilizer to test the impact of three fertilizer, namely 50, 100, and 200 ppm nitrogen, and one control (i.e., water) treatments, on the weight of the nymphs of the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). Subsequently, the whitefly parasitoid Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae) was reared on the different groups of whitefly nymphs and upon parasitoid emergence, the number of oocytes was determined as a measure of reproductive capacity. Trials were done on tomato and tobacco plants. The level of nitrogen concentration in tobacco leaves was directly correlated with the fertilizer applications, thus confirming the effect of our fertilizer treatments. Both in tomato and tobacco plants, healthy as well as parasitized whitefly nymphs, were heaviest in the 200 ppm nitrogen treatment. The highest number of oocytes per female parasitoid was recorded in the 200 ppm nitrogen treatment in tomato (31% more oocytes as compared with the control) and in the 100 and 200 ppm nitrogen treatments in tobacco (200% more oocytes). We suggest that the increase in oocytes was the result of the enhanced size (food quantity) and/or nutritional quality of the whitefly host. The practical implications of these results for the mass rearing of whitefly parasitoids and for biological pest control are discussed.

The effect of transposon Pokey insertions on sequence variation in the 28S rRNA gene of Daphnia pulex

Genome ◽  
2008 ◽  
Vol 51 (12) ◽  
pp. 988-1000 ◽  
Author(s):  
Shiona K. Glass ◽  
Anna Moszczynska ◽  
Teresa J. Crease
Keyword(s):  
Sequence Variation ◽  
Insertion Site ◽  
Daphnia Pulex ◽  
Rrna Genes ◽  
Rrna Gene ◽  
28S Rrna ◽  
Intraindividual Variation ◽  
Rdna Array ◽  
The Impact ◽  
Host Genes

The goal of this study was to determine the impact of breeding system and the presence of the transposon Pokey on intraindividual variation in 28S rRNA genes. We PCR-amplified, cloned, and sequenced 1000 nucleotides downstream of the Pokey insertion site in genes with and without insertions from 10 obligately and 10 cyclically parthenogenetic isolates of Daphnia pulex. Variation among genes with Pokey insertions was higher than variation among genes without insertions in both cyclic and obligate isolates. Although the differences were not quite significant (p = 0.06 in both cases), the results suggest that Pokey insertions are likely to inhibit the homogenization of their host genes to some extent. We also observed that the complement of 28S rRNA alleles differed between genes with and without inserts in some isolates, suggesting that a particular inserted gene can persist for substantial periods of time and even spread within the rDNA array, despite the fact that insertions are deleterious. This apparently contradictory pattern can be explained if homogenization of rRNA genes occurs primarily by gene conversion, but copies with Pokey inserts can occasionally increase in frequency within arrays owing to unequal crossing over events that do not originate in the inserted genes themselves.

The impact of two Chaoborus species on a zooplankton community

1990 ◽  
Vol 68 (5) ◽  
pp. 981-985 ◽  
Author(s):  
Neil A. MacKay ◽  
Stephen R. Carpenter ◽  
Patricia A. Soranno ◽  
Michael J. Vanni
Keyword(s):  
Chlorophyll A ◽  
Daphnia Pulex ◽  
Zooplankton Community ◽  
Chlorophyll A Concentration ◽  
Chaoborus Flavicans ◽  
Chaoborus Americanus ◽  
Diaptomus Oregonensis ◽  
Herbivore Responses ◽  
The Impact

The responses of a zooplankton community to Chaoborus predation were studied in large in situ mesocosms in Peter Lake. Chaoborus flavicans, the native chaoborid, significantly reduced the density of the dominant grazer, Daphnia pulex, in relation to controls that lacked Chaoborus. Chaoborus americanus, a species found only in fishless bogs, reduced Da. pulex densities far more than the chaoborid found in Peter Lake, C. flavicans. Chaoborus americanus also significantly reduced the dominant copepod, Diaptomus oregonensis, in relation to both the control and the C. flavicans treatment. Chlorophyll a concentration did not differ among treatments, indicating that herbivore responses could not be explained by changes in food levels. Our results show that Chaoborus predation can greatly affect a zooplankton community, especially daphnids.

scholarly journals Increasing Student Awareness and Understanding of Food Security by Integrating a Service-learning Project into an Undergraduate Hydroponic Food Production Course

2018 ◽  
Vol 28 (4) ◽  
pp. 543-547
Author(s):  
Christopher J. Currey ◽  
Ann Marie VanDerZanden ◽  
Joshua J. Mitchell
Keyword(s):  
Food Security ◽  
Service Learning ◽  
Personal Growth ◽  
Food Production ◽  
Crop Production ◽  
The United States ◽  
Course Content ◽  
Community Benefits ◽  
Food Quantity ◽  
The Impact

Food security is a growing global concern. To meet the needs of an ever-growing population, food production practices will need to evolve to maximize food quantity and quality. Controlled-environment food production has increased significantly in the United States over the past 5 years, and a component of that production includes hydroponic food crops. In an effort to better prepare a workforce with knowledge of hydroponic crop production, a new course was added to an existing greenhouse curriculum. A service-learning project was integrated in the course that allowed students to experience both growing crops hydroponically and volunteering at a local food bank with a free meal program. Self-assessment showed a significant increase in student confidence in understanding food security by the end of the course. There was also a significant knowledge gained in defining terminology, factors, and the impact of food security in a community. The three guided reflections students completed during the course identified four common themes relative to the course content and service-learning project including the following: community benefits, value of volunteering, local and global effects of food insecurity, and personal growth.

scholarly journals Cladocera from the Sediment of High Arctic Lake in Svalbard (Norway)

2021 ◽  
Vol 23 (2) ◽  
pp. 13-20
Author(s):  
Vartika Singh ◽  
Sophia Barinova
Keyword(s):  
Hot Spots ◽  
Surface Sediments ◽  
Daphnia Pulex ◽  
High Arctic ◽  
Freshwater Ecosystems ◽  
Climate Conditions ◽  
Chydorus Sphaericus ◽  
Cladoceran Remains ◽  
The Impact ◽  
Palaeoenvironmental Conditions

Abstract The High Arctic Region’s freshwater ecosystems serve as hot spots to study the impact of extreme warming conditions on the biota. The cladoceran remains have been recovered from the surface sediments of a non-marine water body near Ny-Alesund, Svalbard, Norway. The cladoceran (crustaceans) belongs to the Chydorus sphaericus group Frey, 1980 and Daphnia pulex Leydig, 1860. The ecology of the species suggests that they lived in a well-developed ecosystem with Water Quality Class 3. This study has implications for understanding the response of the present-day biota experiencing the changing climate conditions and using these remains for assessing palaeoenvironmental conditions.

scholarly journals The impact of an income-generating activities programme on children and mothers’ undernutrition in extreme poor rural Bangladeshi households

2019 ◽  
Vol 22 (16) ◽  
pp. 3073-3082
Author(s):  
Rie Goto ◽  
Joe Devine ◽  
C.G. Nicholas Mascie-Taylor ◽  
Justin Ormand ◽  
Abdul Jabber Jufry
Keyword(s):  
Nutritional Status ◽  
Economic Status ◽  
Economic Security ◽  
Net Income ◽  
Energy Deficiency ◽  
Food Quantity ◽  
Poor Households ◽  
Before And After ◽  
Income Generating Activities ◽  
The Impact

AbstractObjective:The current study assessed changes in children and mothers’ nutritional status before and after raising Bangladeshi households out of extreme poverty through an income-generating activities (IGA) programme.Design:Extreme poor households took part in the IGA programme for 2 years and recruitment took place over four waves in annual cycles. Children and mothers were measured with regarding their nutritional status before and after the IGA programme commenced.Settings:Rural Bangladesh.Subjects:Three-hundred and eighty-two children under 5 years of age at recruitment, and their mothers.Results:After 2 years of the IGA programme, the prevalence of stunting significantly declined from 40·3 % to 33·0 % (P = 0·003), anaemia declined from 51·6 % to 44·0 % (P = 0·020) while mothers’ CED (Chronic Energy Deficiency) declined from 52·0 % to 42·7 % (P < 0·001), but no significant changes were found in children’s wasting, declining from 25·4 % to 21·5 %, underweight which remained the same at 43·2 %, while mothers’ anaemia rose from 39·3 % to 42·7 %. There were also highly significant improvements in household socio-economic status. Increases in socio-economic security (especially in relation to cash savings and net income) and improvements in food quantity and quality (indicated by greater food diversity and animal food intake) were associated with normal nutritional status, and cessation of open defecation was associated with reduction in mothers’ and child anaemia.Conclusion:The IGA programme was associated with increased household socio-economic security, such as asset accumulation, food security and sanitation, and with improvements in the nutritional status of children and their mothers in extreme poor households.

Vertical distributions and zooplankton predation in a small temperate pond

1981 ◽  
Vol 59 (9) ◽  
pp. 1720-1725 ◽  
Author(s):  
Guy E. Melville ◽  
Edward J. Maly
Keyword(s):  
Daphnia Pulex ◽  
Predation Rate ◽  
Invertebrate Predation ◽  
Chaoborus Americanus ◽  
Vertical Distributions ◽  
Zooplankton Communities ◽  
The Impact ◽  
Predation Rates

Depth-specific sampling in a small Quebec pond between April and October 1977 revealed that instars of Daphnia pulex less than 1.41 mm in length and instars of Diaptomus leptopus greater than 0.64 mm in length consistently had vertical distributions which were different from those of late instars of their predator Chaoborus americanus. Experiments were done to determine to what extent these distributions affected the rate of predation by Chaoborus. Vertical and horizontal 25-L enclosures, 1.4 m long, and 2.5-L enclosures, all containing Chaoborus–prey pairs, were introduced into a pond for 3-day periods weekly from July to September. Predation rates in vertical enclosures were considerably lower than those in small and horizontal enclosures. These results suggest that distributions of Diaptomus and Daphnia in vertical enclosures significantly reduce predation on them by Chaoborus. In horizontal and small enclosures where overlap of predator and prey was increased, predation rate of Chaoborus was higher. Results are discussed in relation to the impact of invertebrate predation on zooplankton and the structure of zooplankton communities.

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