Changes in reproductive potential of the leech Nephelopsis obscura (Erpobdellidae) as biomarkers for cadmium stress

1995 ◽  
Vol 73 (12) ◽  
pp. 2192-2196 ◽  
Author(s):  
Ronald W. Davies ◽  
R. N. Singhal ◽  
D. D. Wicklum
Keyword(s):  
Population Dynamics ◽  
Exposure Time ◽  
Sublethal Effects ◽  
Cadmium Concentration ◽  
Reproductive Potential ◽  
Cadmium Stress ◽  
Nephelopsis Obscura ◽  
The Masses

The effects of exposure for 4–24 days to 0, 58, 145, 290, 435, and 580 μg∙L−1 cadmium on the reproductive potential of the freshwater predatory leech Nephelopsis obscura were investigated. The numbers of ova and spermatozoa per unit biomass were significantly reduced with increasing cadmium concentration and exposure time, as were the masses of the ovisacs, testisacs, and epididymis plus cornu. It is concluded that these variables are effective biomarkers for identifying sublethal effects of direct importance to population dynamics.

scholarly journals Effects of cadmium stress on growth and physiological characteristics of sassafras seedlings

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hongyi Zhao ◽  
Juelan Guan ◽  
Qing Liang ◽  
Xueyuan Zhang ◽  
Hongling Hu ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Sugar Content ◽  
Soluble Sugar ◽  
Cadmium Concentration ◽  
Cadmium Stress ◽  
Proline Content ◽  
Physiological Characteristics ◽  
Control Treatment ◽  
Gas Exchange Parameters ◽  
Photosynthetic Gas Exchange

AbstractThe effects of cadmium stress on the growth and physiological characteristics of Sassafras tzumu Hemsl. were studied in pot experiments. Five Cd levels were tested [CT(Control Treatment) : 0 mg/kg, Cd5: 5 mg/kg, Cd20: 20 mg/kg, Cd50: 50 mg/kg, and Cd100: 100 mg/kg]. The growth and physiological characteristics of the sassafras seedlings in each level were measured. The results showed that soil Cd had negative influences on sassafras growth and reduced the net growth of plant height and the biomass of leaf, branch and root. Significant reductions were recorded in root biomass by 18.18%(Cd5), 27.35%(Cd20), 27.57%(Cd50) and 28.95%(Cd100). The contents of hydrogen peroxide decreased first then increased while malondialdehyde showed the opposite trend with increasing cadmium concentration. Decreases were found in hydrogen peroxide contents by 10.96%(Cd5), 11.82%(Cd20) and 7.02%(Cd50); increases were found in malondialdehyde contents by 15.47%(Cd5), 16.07%(Cd20) and 7.85%(Cd50), indicating that cadmium stress had a certain effect on the peroxidation of the inner cell membranes in the seedlings that resulted in damage to the cell membrane structure. Superoxide dismutase activity decreased among treatments by 17.05%(Cd5), 10,68%(Cd20), 20.85%(Cd50) and 8.91%(Cd100), while peroxidase activity increased steadily with increasing cadmium concentration; these results suggest that peroxidase is likely the main protective enzyme involved in the reactive oxygen removal system in sassafras seedlings. Upward trends were observed in proline content by 90.76%(Cd5), 74.36%(Cd20), 99.73%(Cd50) and 126.01%(Cd100). The increase in proline content with increasing cadmium concentration indicated that cadmium stress induced proline synthesis to resist osmotic stress in the seedlings. Compared to that in CT, the soluble sugar content declined under the different treatments by 32.84%(Cd5), 5.85%(Cd20), 25.55%(Cd50) and 38.69%(Cd100). Increases were observed in the soluble protein content by 2.34%(Cd5), 21.36%(Cd20), 53.15%(Cd50) and 24.22%(Cd100). At different levels of cadmium stress, the chlorophyll content in the seedlings first increased and then decreased, and it was higher in the Cd5 and Cd20 treatments than that in the CT treatment. These results reflected that cadmium had photosynthesis-promoting effects at low concentrations and photosynthesis-suppressing effects at high concentrations. The photosynthetic gas exchange parameters and photosynthetic light-response parameters showed downward trends with increasing cadmium concentration compared with those in CT; these results reflected the negative effects of cadmium stress on photosynthesis in sassafras seedlings.

scholarly journals Lifetime reproductive success in a population of female red kangaroos Macropus rufus in the sheep rangelands of western New South Wales: Environmental effects and population dynamics

2004 ◽  
Vol 26 (1) ◽  
pp. 45 ◽  
Author(s):  
AD Bilton ◽  
DB Croft
Keyword(s):  
Population Dynamics ◽  
Reproductive Success ◽  
Environmental Conditions ◽  
New South ◽  
New South Wales ◽  
Reproductive Potential ◽  
Lifetime Reproductive Success ◽  
South Wales ◽  
Macropus Rufus ◽  
Initial Starting

Female reproductive success and the recruitment of offspring to the next generation are key components of animal population dynamics. With an annual commercial harvest of between 13 and 22% of the red kangaroo (Macropus rufus) population, it is increasingly important that these processes are understood. We used data on the reproductive success of 33 free-ranging female M. rufus on Fowlers Gap station in far western New South Wales to determine the expected lifetime reproductive success (LRS) of females within an unharvested population. We also designed a model to generate predictions about female LRS incorporating empirical relationships between a mother?s reproductive success and maternal age, environmental conditions and the sex and survivorship of a previous reproductive attempt. Results from observations on female LRS (calculated from annual weaning rates) and those generated by the model predict that female M. rufus on ?Fowlers Gap? wean, on average, 3.7 young in a lifetime (ranges 0 - 11 and 0 - 20, respectively); representing only 41% of their maximum reproductive potential. Manipulation of initial starting conditions allowed the effect of varying environmental conditions on female LRS to be explored. The condition of the environment when females commence breeding does not appear to significantly affect their overall lifetime reproductive output. However, the occurrence of drought does. Females experiencing two droughts in a lifetime did not live as long and weaned fewer offspring and grandoffspring (from their daughters) than those females experiencing only one drought in a lifetime. In addition to the adverse effect of drought on the reproductive success of female M. rufus in this study, we suggest that, given the relatively high and stable population densities of M. rufus on ?Fowlers Gap?, other mechanisms (acting primarily on juvenile survival) must exist which limit population growth.

Biological control of the cassava mealybug, Phenacoccus manihoti by the exotic parasitoid Epidinocarsis lopezi in Africa

1988 ◽  
Vol 318 (1189) ◽  
pp. 319-333 ◽  
Keyword(s):  
Biological Control ◽  
Population Dynamics ◽  
South America ◽  
Reproductive Potential ◽  
Field Studies ◽  
Phenacoccus Manihoti ◽  
Epidinocarsis Lopezi ◽  
Southwestern Nigeria ◽  
Cassava Mealybug ◽  
Accidental Introduction

Since its accidental introduction into Africa, the cassava mealybug (CM) has spread to about 25 countries. The specific parasitoid Epidinocarsis lopezi , introduced from South America, its area of origin, into Nigeria in 1981, has since been released in more than 50 sites. By the end of 1986 it was established in 16 countries and more than 750 000 km 2 . In southwestern Nigeria, CM populations declined after two initial releases, and have since remained low. During the same period, populations of indigenous predators of CM , mainly coccinellids, have declined, as have indigenous hyperparasitoids on E. lopezi , because of scarcer hosts. Results from laboratory bionomic studies were incorporated into a simulation model. The model, field studies on population dynamics, and experiments excluding E. lopezi by physical or chemical means demonstrate its efficiency, despite its low reproductive potential.

scholarly journals Effect of cadmium on growth, micronutrient concentration, and δ-aminolevulinic acid dehydratase and acid phosphatase activities in plants of Pfaffia glomerata

2008 ◽  
Vol 20 (4) ◽  
pp. 285-294 ◽  
Author(s):  
Etiane C. Skrebsky ◽  
Luciane A. Tabaldi ◽  
Luciane B. Pereira ◽  
Renata Rauber ◽  
Joseila Maldaner ◽  
...  
Keyword(s):  
Acid Phosphatase ◽  
Aminolevulinic Acid ◽  
Chlorophyll Concentration ◽  
Cadmium Concentration ◽  
Dry Weight ◽  
Cadmium Stress ◽  
Pfaffia Glomerata ◽  
Acid Dehydratase ◽  
Micronutrient Concentration ◽  
Total Plant

Pfaffia glomerata (Spreng.) Pedersen plantlets were grown under different cadmium (Cd) concentrations (0, 20, 40, 60 and 80 μM) in a hydroponic system during 7 d. Plant growth, micronutrient, chlorophyll and carotenoid concentrations, as well as δ-aminolevulinic acid dehydratase (ALA-D; E.C.4.2.1.24) and acid phosphatase (AP; E.C.3.1.3.2) activities were then analysed. Cadmium concentration in both shoots and roots increased with increasing external Cd levels. Metal concentration was on average 12-fold greater in root than in shoot tissues. Root length was unaffected by Cd treatments. In contrast, dry weight of both shoot and roots increased significantly upon addition of 20 and 40 μM Cd. Moreover, shoot and total plant dry weight was only reduced in plants treated with 80 μM Cd. Conversely, root dry weight decreased significantly upon addition of Cd concentrations above 40 μM. A micronutrient- and organ-dependent response to Cd toxicity was observed. Zinc and Cu concentrations in both shoot and roots did not alter upon treatment with Cd. Cadmium stress reduced Mn uptake but not its translocation within the plant. A synergistic effect of Cd on Fe concentration in root at 20 μM and 80 μM Cd levels was observed. The activity of AP, and especially that of ALA-D, was reduced with increasing Cd levels. At those these Cd levels, chlorophyll concentration was also reduced. There was a positive correlation between concentrations of carotenoids and chlorophylls. Our results indicate that P. glomerata seems to have some degree of Cd tolerance.

The relationship between soybean cyst nematode seasonal population dynamics and soil texture

Nematology ◽  
2004 ◽  
Vol 6 (4) ◽  
pp. 511-525 ◽  
Author(s):  
Felicitas Avendaño ◽  
Francis J. Ierce ◽  
Haddish Melakeberhan
Keyword(s):  
Population Dynamics ◽  
Soil Texture ◽  
Soybean Cyst Nematode ◽  
Reproductive Potential ◽  
Cyst Nematode ◽  
Stable Relationship ◽  
Wide Range ◽  
The Relationship ◽  
Seasonal Population ◽  
Seasonal Population Dynamics

Abstract The soybean cyst nematode (SCN), Heterodera glycines Ichinohe, cyst population densities at planting and at harvest have been related to soil texture but the seasonal mechanisms by which these correlations are established are less well known. The purpose of this work was to analyse the relationship of SCN life stages and reproductive potential (number of eggs per cyst) with soil texture. Cyst population density was positively correlated with sand and negatively correlated with clay and silt percentage in the soil within the ranges of 45-80% sand, 8-23% clay, and 8-43% silt in one field, but not in the other at five sampling times. The relationship between soil texture and juvenile stages in roots was weak. The stable relationship between SCN spatial and seasonal population dynamics and soil properties provides further support for potential delineation of management zones in SCN infested fields with a wide range of soil textures.

scholarly journals Activity of the Photosynthetic Apparatus in Phaseolus vulgaris L. Leaves Under the Cadmium Stress

2018 ◽  
Vol 47 (2) ◽  
pp. 405-411
Author(s):  
Joanna PUŁA ◽  
Beata BARABASZ-KRASNY ◽  
Andrzej LEPIARCZYK ◽  
Peiman ZANDI ◽  
Katarzyna MOŻDŻEŃ
Keyword(s):  
Phaseolus Vulgaris ◽  
Photosynthetic Activity ◽  
Chemical Elements ◽  
Cadmium Concentration ◽  
Photosynthetic Apparatus ◽  
Cadmium Stress ◽  
Cadmium Nitrate ◽  
Phaseolus Vulgaris L ◽  
Cadmium Ions ◽  
Bean Leaves

The development of civilisation, urbanisation and industrialisation cause to ever increasing contamination of the natural environment. Cadmium belongs to this group of chemical elements, which represent a serious threat, not only for the proper development of plants but also for the health of humans and animals. Hence, the interest of scientists in the toxic effects of this kind chemical elements on the various life functions of organisms. The aim of this study was to investigate the effect of cadmium nitrate aqueous solutions on photosynthetic activity and degree of disorganisation of cell membranes in leaves of common bean (Phaseolus vulgaris L. cv. ‘Laurina’). A fully formed second leaves were wetted with cadmium solutions nitrate (Cd(NO3)2) at concentrations of 5 and 10 mM. With the increasing of cadmium concentration and time of its application (20, 40, 60 min and 24 h), the changes in the fluorescence of bean leaves were observed. Under the influence of cadmium ions, damage occurred both on the edge and the central part of the leaves, and then the whole surface. The highest changes of the chlorophyll fluorescence values were observed after 24 h of application the aqueous cadmium solutions. Use of SPAD chlorophyll Meter, the reduction of chlorophyll content was noticed over time. The flow of electrolytes from the bean leaves was increased with the time and concentration of applied cadmium compounds.

scholarly journals Population dynamics and reproductive biology ofAchatina fulica Bowdich, 1822 (Mollusca, Gastropoda) in Salvador - Bahia

2014 ◽  
Vol 14 (3) ◽  
Author(s):  
Eder Carvalho da Silva ◽  
Elianne Pessoa Omena
Keyword(s):  
Population Dynamics ◽  
Sexual Activity ◽  
Reproductive Biology ◽  
Disease Transmission ◽  
Rainy Season ◽  
Reproductive Potential ◽  
Principal Component ◽  
Biodiversity Loss ◽  
Climatic Variables ◽  
Shell Size

The risks following introduction of invasive species are enormous and incalculable. Achatina fulica is considered one of the 100 species of greatest invasive potential, stands out among the land pulmonate snails, mostly for its high reproductive potential that accelerates the process of dispersion, increasing the damages related to health (disease transmission), to economy (crops destruction) and to environment (biodiversity loss). In order to investigate the relationship of the African snail with the environment, trying to relate sexual activity with climatic variables (temperature, rainfall and humidity), a study was conducted on aspects of population dynamics and reproductive biology in Salvador city. The snails were collected by hand, monthly. Morphometric data were obtained in the field and dissections to analyze the reproductive system at laboratory. To test if there was a greater sexual activity in wet periods was performed first a Principal Component Analysis (PCA) with climatic variables, followed by a regression between precipitation (the most influential environmental variable) and the variable of interest (sexual activity). The results showed that there is an apparent annual cycle forA. fulica, with a recruitment period covering the end of rainy season and the dry season (August to December 2006 and February 2007). Increase of shell size (height) and of sexual activity were observed during the rainy season, although snails were found in full sexual activity during the whole period of study. The von Bertalanffy curve showed that the oldest specimen collected would have three years and eleven months. The regression between precipitation and sexual activity was significant (P = 0.002) showing that the higher rainfall increased sexual activity. In addition, it was observed that there is an increase in the thickness of peristome as the specimens reaches sexual maturity however this relationship isn’t precise (it were found individuals with sexual structures not consistent with the reproductive stage given by the thickness of peristome) and should be set for each region studied. As the eradication becomes impossible because of high level of invasion found in Salvador, it is recommended to control the population of African snails by continuously removing specimens, especially in the rainy periods.

Population Dynamics of Daphnia galeata mendotae as Modified by Chronic Cadmium Stress

1978 ◽  
Vol 35 (4) ◽  
pp. 461-469 ◽  
Author(s):  
J. S. Marshall
Keyword(s):  
Population Dynamics ◽  
Carrying Capacity ◽  
Brood Size ◽  
Lake Michigan ◽  
Cadmium Stress ◽  
Whole Body ◽  
Average Weight ◽  
Daphnia Galeata ◽  
Female Ratio ◽  
Daphnia Galeata Mendotae

Forty populations of Daphnia galeata mendotae were maintained for 22 wk (or until they became extinct) in a medium consisting of filtered Lake Michigan water to which Chlamydomonas reinhardi and different concentrations of a mixture of labelled (109Cd) plus stable CdCl2 were added 24 h before use. The medium was changed daily Monday through Fridays. Weekly determinations were made of total numbers, average individual dry weight, mean brood size, egg–female ratio, aborted eggs and embryos, and average whole-body 109Cd content. Chronic cadmium stress reduced the populations' average numbers and biomass, while it increased the populations' turnover rates, temporal variability, probability of extinction, and proportion of ovigerous females. For individuals there was increased prenatal mortality, reduced life expectancy, increased average weight, and increased brood size. Due to compensatory increases in the proportion of ovigerous females and mean brood size, the cadmium sensitivity of population attributes was considerably less than that of the most sensitive individual attribute, prenatal mortality. A linear relationship between population carrying capacity (relative mean numbers) and added cadmium concentration indicated that the effective concentration for a 50% reduction of carrying capacity (EC50) is 7.7 μg Cd/L and that for a 1% reduction (EC1) is 0.15 μg Cd/L. An increase of 0.15 μg Cd/L in Lake Michigan itself, barring synergistic interaction with other factors in the lake, would probably not have a detectable effect on the population dynamics of D. galeata mendotae. Key words: zooplankton dynamics, stress ecology, Daphnia galeata mendotae, cadmium, heavy metals, toxic substances, Laurentian Great Lakes

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