Size-dependent natural mortality of juvenile banana prawns Penaeus merguiensis in the Gulf of Carpentaria, Australia

1999 ◽  
Vol 50 (4) ◽  
pp. 313 ◽  
Author(s):  
You-Gan Wang ◽  
M. D. E. Haywood
Keyword(s):  
Marine Invertebrates ◽  
Significant Proportion ◽  
Early Life History ◽  
Natural Mortality ◽  
Parametric Function ◽  
Frequency Pattern ◽  
Life History Stages ◽  
Size Dependent ◽  
Very High ◽  
Extra Parameter

Natural mortality of marine invertebrates is often very high in the early life history stages and decreases in later stages. The possible size-dependent mortality of juvenile banana prawns, P. merguiensis (2–15 mm carapace length) in the Gulf of Carpentaria was investigated. The analysis was based on the data collected at 2-weekly intervals by beam trawls at four sites over a period of six years (between September 1986 and March 1992). It was assumed that mortality was a parametric function of size, rather than a constant. Another complication in estimating mortality for juvenile banana prawns is that a significant proportion of the population emigrates from the study area each year. This effect was accounted for by incorporating the size-frequency pattern of the emigrants in the analysis. Both the extra parameter in the model required to describe the size dependence of mortality, and that used to account for emigration were found to be significantly different from zero, and the instantaneous mortality rate declined from 0.89 week–1 for 2 mm prawns to 0.02 week–1 for 15 mm prawns.

scholarly journals High potential for formation and persistence of chimeras following aggregated larval settlement in the broadcast spawning coral, Acropora millepora

2011 ◽  
Vol 279 (1729) ◽  
pp. 699-708 ◽  
Author(s):  
E. Puill-Stephan ◽  
M. J. H. van Oppen ◽  
K. Pichavant-Rafini ◽  
B. L. Willis
Keyword(s):  
Marine Invertebrates ◽  
Larval Settlement ◽  
Early Life History ◽  
Experimental Conditions ◽  
Broadcast Spawning ◽  
Acropora Millepora ◽  
Reef Corals ◽  
Life History Stages ◽  
Potential Benefits ◽  
High Level

In sessile modular marine invertebrates, chimeras can originate from fusions of closely settling larvae or of colonies that come into contact through growth or movement. While it has been shown that juveniles of brooding corals fuse under experimental conditions, chimera formation in broadcast spawning corals, the most abundant group of reef corals, has not been examined. This study explores the capacity of the broadcast spawning coral Acropora millepora to form chimeras under experimental conditions and to persist as chimeras in the field. Under experimental conditions, 1.5-fold more larvae settled in aggregations than solitarily, and analyses of nine microsatellite loci revealed that 50 per cent of juveniles tested harboured different genotypes within the same colony. Significantly, some chimeric colonies persisted for 23 months post-settlement, when the study ended. Genotypes within persisting chimeric colonies all showed a high level of relatedness, whereas rejecting colonies displayed variable levels of relatedness. The nearly threefold greater sizes of chimeras compared with solitary juveniles, from settlement through to at least three months, suggest that chimerism is likely to be an important strategy for maximizing survival of vulnerable early life-history stages of corals, although longer-term studies are required to more fully explore the potential benefits of chimerism.

Effect of Temperature and Size on Development, Mortality, and Survival Rates of the Pelagic Early Life History Stages of Marine Fish

1991 ◽  
Vol 48 (3) ◽  
pp. 503-518 ◽  
Author(s):  
Pierre Pepin
Keyword(s):  
Early Life ◽  
Survival Rates ◽  
Early Life History ◽  
Mortality Rates ◽  
Yolk Sac ◽  
Vital Rates ◽  
Daily Mortality ◽  
Cumulative Mortality ◽  
Life History Stages ◽  
Size Dependent

This paper presents a comprehensive summary of development, mortality, and survival rates of fish eggs, yolk-sac larvae, and postlavae in relation to temperature and size. The general temperature- and, where applicable, size-dependent models explained 30–81% of the variance in vital rates. Daily development and mortality rates generally increased with increasing temperature. Temperature had an equal but opposite effect on stage-specific cumulative mortality rates of eggs and yolk-sac larvae. Stage-specific (length-dependent) cumulative mortality rates of postlarval fish were independent of temperature due to equal effects of temperature on daily growth and daily mortality rates. Size had no significant effect on daily or cumulative mortality rates of egg and yolk-sac stages. Daily mortality rates of postlarval fish were significantly influenced by mean size (i.e. length). The compensation of temperature effects between stages and/or vital rates may reduce the impact of environmental uncertainty on survival rates. It is suggested that the general temperature- and/or size-dependent relationships described in this study can serve as basic frameworks to assess whether there are significant effects resulting from species/stock-specific characteristics or environmental factors on the vital rates of the early life history stages of fish.

scholarly journals Tough Adults, Frail Babies: An Analysis of Stress Sensitivity across Early Life-History Stages of Widely Introduced Marine Invertebrates

PLoS ONE ◽  
2012 ◽  
Vol 7 (10) ◽  
pp. e46672 ◽  
Author(s):  
M. Carmen Pineda ◽  
Christopher D. McQuaid ◽  
Xavier Turon ◽  
Susanna López-Legentil ◽  
Víctor Ordóñez ◽  
...  
Keyword(s):  
Life History ◽  
Early Life ◽  
Marine Invertebrates ◽  
Early Life History ◽  
Stress Sensitivity ◽  
Life History Stages

scholarly journals Seeds and Seedlings in a Changing World: A Systematic Review and Meta-Analysis from High Altitude and High Latitude Ecosystems

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 768
Author(s):  
Jerónimo Vázquez-Ramírez ◽  
Susanna E. Venn
Keyword(s):  
Climate Change ◽  
High Altitude ◽  
High Latitude ◽  
Seedling Establishment ◽  
Early Life History ◽  
Life Stages ◽  
Qualitative And Quantitative Analysis ◽  
Qualitative And Quantitative ◽  
Life History Stages ◽  
Early Snowmelt

The early life-history stages of plants, such as germination and seedling establishment, depend on favorable environmental conditions. Changes in the environment at high altitude and high latitude regions, as a consequence of climate change, will significantly affect these life stages and may have profound effects on species recruitment and survival. Here, we synthesize the current knowledge of climate change effects on treeline, tundra, and alpine plants’ early life-history stages. We systematically searched the available literature on this subject up until February 2020 and recovered 835 potential articles that matched our search terms. From these, we found 39 studies that matched our selection criteria. We characterized the studies within our review and performed a qualitative and quantitative analysis of the extracted meta-data regarding the climatic effects likely to change in these regions, including projected warming, early snowmelt, changes in precipitation, nutrient availability and their effects on seed maturation, seed dormancy, germination, seedling emergence and seedling establishment. Although the studies showed high variability in their methods and studied species, the qualitative and quantitative analysis of the extracted data allowed us to detect existing patterns and knowledge gaps. For example, warming temperatures seemed to favor all studied life stages except seedling establishment, a decrease in precipitation had a strong negative effect on seed stages and, surprisingly, early snowmelt had a neutral effect on seed dormancy and germination but a positive effect on seedling establishment. For some of the studied life stages, data within the literature were too limited to identify a precise effect. There is still a need for investigations that increase our understanding of the climate change impacts on high altitude and high latitude plants’ reproductive processes, as this is crucial for plant conservation and evidence-based management of these environments. Finally, we make recommendations for further research based on the identified knowledge gaps.

Inbreeding depression and floral type fitness differences in Viola canadensis (Violaceae), a species with chasmogamous and cleistogamous flowers

2000 ◽  
Vol 78 (11) ◽  
pp. 1420-1429 ◽  
Author(s):  
Theresa M Culley
Keyword(s):  
Inbreeding Depression ◽  
Survival Rates ◽  
Early Life History ◽  
Flower Number ◽  
Life History Stages ◽  
The North ◽  
History Of ◽  
Vegetative Biomass ◽  
Similar Survival ◽  
Cross Type

Few studies of inbreeding depression have focused on species producing both showy, chasmogamous (CH) flowers and self-pollinated, cleistogamous (CL) flowers. The goals of this investigation were to measure the level of inbreeding depression in the North American violet, Viola canadensis L., and to determine if any fitness differences were linked to floral type (CH versus CL) rather than to cross type (self versus outcross). Hand pollinations were carried out to produce self- and outcross-pollinated CH progeny, and CL seeds were also collected. In a greenhouse, selfed and outcrossed CH flowers produced similar numbers of seeds, and both types of progeny had similar survival rates and comparable numbers of CH flowers, although outcrossed CH progeny had 14% greater vegetative biomass than selfed CH progeny. The level of inbreeding depression in V. canadensis was low, indicating that there may be few drawbacks to selfing in this species. A comparison of CL and self-pollinated CH progeny showed that, although there were differences in CH flower number, overall fitness differences were minimal. The similar performance of selfed (CL and CH) and outcrossed progeny in early life-history stages of V. canadensis suggests a history of inbreeding in the population.Key words: cleistogamy, inbreeding depression, outcrossing, selfing, Viola canadensis.

Responses of cerebral arteries and arterioles to acute hypotension and hypertension

1978 ◽  
Vol 234 (4) ◽  
pp. H371-H383 ◽  
Author(s):  
H. A. Kontos ◽  
E. P. Wei ◽  
R. M. Navari ◽  
J. E. Levasseur ◽  
W. I. Rosenblum ◽  
...  
Keyword(s):  
Pressure Range ◽  
High Pressures ◽  
Cerebral Arteries ◽  
Pial Arteries ◽  
Small Vessels ◽  
Size Dependent ◽  
Arterial Blood ◽  
Vascular Bed ◽  
Acute Hypotension ◽  
Very High

The responses of cerebral precapillary vessels to changes in arterial blood pressure were studied in anesthetized cats equipped with cranial windows for the direct observation of the pial microcirculation of the parietal cortex. Vessel responses were found to be size dependent. Between mean arterial pressures of 110 and 160 mmHg autoregulatory adjustments in caliber, e.g., constriction when the pressure rose and dilation when the pressure decreased, occurred only in vessels larger than 200 micron in diameter. Small arterioles, less than 100 micron in diameter, dilated only at pressures equal to or less than 90 mmHg; below 70 mmHg their dilation exceeded that of the larger vessels. When pressure rose to 170- 200 mmHg, small vessels dilated while the larger vessels remained constricted. At very high pressures (greater than 200 mmHg) forced dilation was frequently irreversible and was accompanied by loss of responsiveness to hypocapnia. Measurement of the pressure differences across various segments of the cerebral vascular bed showed that the larger surface cerebral vessels, extending from the circle of Willis to pial arteries 200 micron in diameter, were primarily responsible for the adjustments in flow over most of the pressure range.

Significance of Egg and Larval Size to Recruitment Variability of Temperate Marine Fish

1991 ◽  
Vol 48 (10) ◽  
pp. 1820-1828 ◽  
Author(s):  
Pierre Pepin ◽  
Ransom A. Myers
Keyword(s):  
Life History ◽  
Marine Fish ◽  
Early Life ◽  
Univariate Analysis ◽  
Early Life History ◽  
Fish Populations ◽  
Larval Size ◽  
Larval Phase ◽  
Life History Stages ◽  
Recruitment Variability

Recruitment variability is commonly associated with fluctuations in abundance of marine fish populations. Previous studies have focussed on stock-specific correlative or mechanistic models or on comparisons of recruitment variations of several stocks or species. The purpose of this study is to determine whether recruitment variability of commercial marine fish populations is associated with either size or the duration of early life history stages. The analysis was performed with data from 86 stocks representing 21 species of commercial marine fish. Univariate analysis shows that neither egg size nor the length at hatch is significantly correlated with recruitment variability. The change in length during the larval phase, which is representative of the duration of the stage, is significantly positively correlated with recruitment variability. Multivariate analysis shows that recruitment variability increases with increasing length at metamorphosis but that recruitment variability is poorly associated with length at hatch. The degree of serial correlation is related to the relative duration of egg and larval stages. The results clearly indicate that recruitment variability is linked to characteristics of early life history stages.

Experiments on the Effect of Residual Insecticides in Houses against Anopheles gambiae and A. funestus

1953 ◽  
Vol 44 (2) ◽  
pp. 231-254 ◽  
Author(s):  
G. Davidson
Keyword(s):  
Lethal Dose ◽  
Significant Proportion ◽  
Internal Surface ◽  
The Other ◽  
Wall Surface ◽  
The Third ◽  
Experimental Huts ◽  
Wettable Powder ◽  
Window Traps ◽  
Very High

Experimental huts similar in construction to the dwellings commonly used in East Africa, but with exit window traps, were sprayed with various formulations of the three residual insecticides, DDT, BHC, and dieldrin, and the effect on the A. gambiae and A. funestus entering them was observed.The almost complete absence of kill recorded by Muirhead Thomson (1950) in experiments in similar huts in Tanganyika treated with DDT Ditreen was not confirmed by these experiments.A significant proportion of the A. gambiae and A. funestus entering huts treated with DDT did, however, escape unharmed, even immediately after treatment, whereas with the other insecticides, BHC and dieldrin, none of these mosquitos escaped the effect at least in the first month after treatment.In preliminary experiments in which observations were carried on for nine months after treatments, BHC P.530 still showed some effect after seven months. This was almost certainly due to the fumigant effect of the small amount of insecticide still remaining below the wall surface. The irritant properties of the two DDT formulations, Ditreen and the oil-bound suspension “Supona” D, still existed after nine months.In a second group of experiments, dosages of less than 80 mg. DDT and less than 60 mg. BHC (8 mg. of the gamma isomer) per sq. ft. gave over 50 per cent. kills of A. gambiae and A. funestus for only one month.In a third group of experiments, using two formulations of BHC, five of DDT, one of a mixture of DDT and BHC and one of dieldrin:—(a) Dieldrin was by far the most efficient insecticide and gave very high kills for over seven months.(b) The DDT formulations, Murphy paste, Murphy wettable powder, suspensions of DDT crystals <30 μ and 30–70 μ in diameter, when applied to the whole internal surface of the huts, produced fairly high kills over the period of the observations (six to seven months), but significant proportions of the mosquitos escaped their action even immediately after treatment.(c) The BHC formulations, P.520 and the oil-bound suspension “Supona” B, gave high kills for three to four months only.(d) The mixture of BHC and DDT in oil-bound suspension “Supona” DB gave the high initial kill of BHC and the long-lasting moderately high kill of DDT.(e) Against C. fatigans all the DDT formulations used in the third group of experiments gave very low kills, the BHC formulations high initial kills and dieldrin high long-lasting kills.BHC has marked fumigant and particulate properties lasting for three to four months. Dieldrin has a remarkable particulate action, which produces for the whole six-month period of the experiment, very high kills among mosquitos suspended without actual contact with the insecticidal surfaces; DDT only shows this particulate effect to a slight extent.It is probable that the differences in the toxicities to mosquitos of the insecticides used in these experiments is due partly to differences in the irritant properties of the insecticides. In the case of DDT many of the mosquitos having contact with this insecticide are irritated and escape from the treated surface before acquiring a lethal dose.

scholarly journals On the ab initio calculation of vibrational formation entropy of point defect: the case of the silicon vacancy

2017 ◽  
Vol 8 ◽  
pp. 85505 ◽  
Author(s):  
Pia Seeberger ◽  
Julien Vidal
Keyword(s):  
Point Defect ◽  
First Principles ◽  
Defect Formation ◽  
Finite Size ◽  
Direct Calculation ◽  
Finite Size Effects ◽  
Numerical Errors ◽  
Silicon Vacancy ◽  
Size Dependent ◽  
Very High

Formation entropy of point defects is one of the last crucial elements required to fully describe the temperature dependence of point defect formation. However, while many attempts have been made to compute them for very complicated systems, very few works have been carried out such as to assess the different effects of finite size effects and precision on such quantity. Large discrepancies can be found in the literature for a system as primitive as the silicon vacancy. In this work, we have proposed a systematic study of formation entropy for silicon vacancy in its 3 stable charge states: neutral, +2 and –2 for supercells with size not below 432 atoms. Rationalization of the formation entropy is presented, highlighting importance of finite size error and the difficulty to compute such quantities due to high numerical requirement. It is proposed that the direct calculation of formation entropy of VSi using first principles methods will be plagued by very high computational workload (or large numerical errors) and finite size dependent results.

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