Seasonal variation in the relationship between growth rate and phlorotannin production in the kelp Ecklonia radiata

Oecologia ◽  
1995 ◽  
Vol 102 (2) ◽  
pp. 169-173 ◽  
Author(s):  
P. D. Steinberg
1990 ◽  
Vol 9 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Stefan Majoran

Abstract. about 200 right valves of Cytherella cf. ovata Roemer, were selected from a single sample of Cenomanian age (northeastern Algeria). The material can be subdivided into two parallel ontogenetic series which were quantitatively investigated by linear regression and eigenshape analysis. The corresponding growth stages of the two series are differentiated by size, growth rate, and, to a lesser extent, by shape. The relationship between the two series are discussed mainly in terms of seasonal variation in the environment.


1995 ◽  
Vol 52 (7) ◽  
pp. 1535-1545 ◽  
Author(s):  
Kim N. I. Bell ◽  
Joseph A. Brown ◽  
Pierre Pepin

We report on an 18-month field study of temporal pattern and interrelationships of size- and age-at-recruitment (to fresh waters) for two diadromous hill-stream gobies in Dominica, West Indies (15°30′N, 61°25′W). Recruitment is panseasonal in Sicydium punctatum and Sicydium antillarum and supports a directed fishery similar to other goby fry fisheries. We found both size and age of recruits to vary seasonally, but the relationship of size to age is complex. Although positively related within lunar-monthly recruiting cohorts, the overall relationship of size and age was poor because seasonal variation in size is out of phase with age. Among recruiting cohorts, mean (or predicted) size and age are negatively correlated. Recruitment (fishery yield) also varies seasonally, in phase with size and out of phase with age. Peak fishery yields coincide with the youngest, but largest, recruits; low yields coincide with the reverse, implicating growth rate variations in fishery yield. This is the first such report of systematic seasonal variation in age-at-recruitment. Given these findings, size- and age-at-recruitment (here similar to settlement or metamorphosis) should not be assumed invariant, even for tropical fishes.


2011 ◽  
Vol 56 (No. 5) ◽  
pp. 242-249 ◽  
Author(s):  
Z. Ledvinka ◽  
L. Zita ◽  
M. Hubený ◽  
E. Tůmová ◽  
M. Tyller ◽  
...  

We assessed the influence of the particular genotype, age of layers, feather growth-rate gene, and their mutual interactions on selected indicators of eggshell quality in six groups of hens of the laying type Dominant. The following genotypes were examined in the experiment: Barred Plymouth Rock, Dominant BPR 951 (K) strain, slow-feathering; Barred Plymouth Rock, Dominant BPR 901 (k) strain, fast-feathering; Blue Plymouth Rock, Dominant BLPR 954 (K) strain, slow-feathering; Blue Plymouth Rock, Dominant BLPR 894 (k) strain, fast-feathering; crossbreds of the above strains in the F<sub>1</sub> generation Dominant D 107 blue (K), slow-feathering and Dominant D 107 blue (k), fast-feathering. The layers were fed a feed mixture NP1 (16.64 % CP) from the 20<sup>th</sup> week of age and a feed mixture NP2 (15.02% CP) from the 42<sup>nd</sup> week. Husbandry conditions met the regular requirements of laying hens. Egg production and live weight of hens were monitored for the duration of the experiment (12 months). Eggshell quality was examined at the layers' age of 27, 35 and 56 weeks. The average hen-day egg production for the duration of the experiment (12 months) was not significantly influenced by the particular genotype or the feather growth-rate gene. The varying representation of the feather growth-rate gene significantly (P &le; 0.001) influenced the live weight; similarly, the relationship between the genotype and the representation of K/k alleles was significant. The average egg weight was influenced statistically significantly (P &le; 0.001) by the age of hens, their genotype (P &le; 0.05), feather growth-rate gene (P &le; 0.001), and the relationship between the age and genotype (P &le; 0.001). The age of hens, genotype, and the interaction of these two factors affected the egg shape index, as did the incidence of the feather growth-rate gene within the population (with a statistical significance of P &le; 0.001). The age, genotype and the feather growth-rate gene incidence within the population also significantly affected the eggshell quality indicators. In the eggshell to egg ratio, eggshell thickness and strength, an interaction was determined between the age of hens and their particular genotype. The eggshell colour was also significantly (P &le; 0.001) affected by hens' age, genotype (P &le; 0.001), as well as by the feather growth-rate gene (P &le; 0.001). No significant interaction between the age and the genotype was found for this indicator.


2009 ◽  
Vol 13 (1) ◽  
pp. 138-147 ◽  
Author(s):  
Yi Jin

This paper develops a monetary endogenous growth model with capital and skill heterogeneity to analyze the relationship among inflation, growth, and income inequality. In the model inflation, growth, and inequality are jointly determined. We show that an increase in the long-run money growth rate raises inflation and reduces growth, but its effect on income inequality depends on the relative importance of the two types of heterogeneity. Inequality shrinks with the rise of inflation when capital heterogeneity dominates and enlarges when skill heterogeneity dominates. Therefore, our model supports a negative (positive) inflation–inequality relationship and a positive (negative) growth–inequality relationship when capital (skill) heterogeneity dominates. In any event, inflation and growth are negatively related.


2021 ◽  
Author(s):  
Masayuki Tatsumi ◽  
Christopher J. T. Mabin ◽  
Cayne Layton ◽  
Victor Shelamoff ◽  
Matthew J. Cameron ◽  
...  

Author(s):  
Alheder Haled

The paper is devoted to determining the prospects for cooperation between Russia and the Syrian Arab Republic in various scenarios of military conflicts. In order to identify the relationship between the success of the country's foreign economic policy and the military conflicts waged on its territory, a study was conducted of such indicators of Syria as: the growth rate of the peace index and the GDP growth rate. A strong inverse correlation is revealed, which means that the level of political situation and peace in the state determines the efficiency of the economy. In view of this, various scenarios of the development of the military conflict in Syria have been studied: at the initial stage, at the stage of active hostilities, at the present stage of overcoming the crisis. The last stage involves four different scenarios for the development of a military conflict, including a local nature and a protracted nature with the involvement of other countries of the world. Options for developing cooperation between Russia and Syria have been identified for each scenario. Taking into account the assessment of the international political situation, the two most likely scenarios for further military events in Syria are identified, and the prospects for cooperation between Russia and Syria in these conditions are outlined.


2019 ◽  
Vol 13 (1) ◽  
pp. 60-76 ◽  
Author(s):  
Amine Lahiani

PurposeThe purpose of this paper is to explore the effect of oil price shocks on the US Consumer Price Index over the monthly period from 1876:01 to 2014:04.Design/methodology/approachThe author uses the Bai and Perron (2003) structural break test to split the data sample into sub-periods delimited by the computed break dates. Afterwards, the author uses the quantile treatment effects over the full sample and then, by including sub-periods dummies to accommodate the selected structural breaks that drive the relationship between inflation and oil price growth.FindingsThe findings include a decreased transmission effect of oil price changes on inflation in recent years; a varied elasticity of inflation to the growth rate of oil prices across the distribution; and, finally, evidence of asymmetry in the relationship between the growth rate of oil prices and inflation, with a higher transmission mechanism for decreasing rather than increasing oil prices.Practical implicationsPolicymakers should remain alert to monitoring potential inflation increases and should take precautionary measures to anchor inflation expectations, because inflation reacts differently to positive and negative oil price shocks. Moreover, authorities should consider the asymmetric reaction of inflation to oil price shocks to adopt an appropriate monetary policy strategy to achieve the price stability target.Originality/valueThe paper used a quantile regression model with structural breaks, which has not yet been used in the literature.


1996 ◽  
Vol 75 (2) ◽  
pp. 237-248 ◽  
Author(s):  
Christiani Jeyakumar Henry ◽  
Amal Ghusain-Choueiri ◽  
Philip R. Payne

AbstractThe relationship between essential fatty acids (EFA) deficiency and the utilization of dietary protein, growth rate and survival of offspring was investigated in rats during development and reproduction. EFA deficiency was induced by feeding a 200 g casein/kg-based diet containing 70 g hydrogenated coconut oil (HCO)/lkg as the only source of fat. The conversion efficiency of dietary protein was assessed as net protein utilization (NPU), using a 10 d comparative carcass technique. Consumption of the deficient diet during the 10 d assay period induced biochemical changes characteristic of mild EFA deficiency in humans (triene:tetraene 0·27 (SD 0·04) compared with 0·026 (SD 0·004) for wn-deficient controls), but there were no significant changes in growth rate or protein utilization. These variables were also unchanged when the deficient diet was fed for an additional 7 d before the assay, although triene: tetraene increased to 0.8 (SD 0·02). Feeding the deficient diet for 63 d before assay produced severe EFA deficiency (triene:tetraene 1.4 (SD 0·3) v. 0·036 (SD 0·005) for controls), a fall in growth rate (25% during assay period), and NPU (31.5 (SD 0·63) v. 39.0 (SD 0·93) for controls). These severely-EFA-deficient animals had a 30% higher fasting-resting rate of energy metabolism than that of age-matched controls. However, there was no change in the rate of endogenous N loss. Voluntary energy consumption was increased in animals fed on deficient diets, either with 200 g protein/kg, or protein free. The reduced efficiency of protein utilization could be entirely accounted for by the restricted amount of energy available for growth and protein deposition. Consumption of an EFA-deficient diet during pregnancy and lactation resulted in high mortality (11% survival rate at weaning compared with 79% for controls) and retarded growth in the preweaning offspring. It is concluded that animals are particularly sensitive to EFA deficiency during reproduction and pre- and post-natal stages of development. However, after weaning only severe EFA deficiency retarded growth, primarily through changes in energy balance.


1983 ◽  
Vol 36 (2) ◽  
pp. 159-164
Author(s):  
D. Croston ◽  
J. L. Read ◽  
D. W. Jones ◽  
D. E. Steane ◽  
C. Smith

ABSTRACTThirteen pairs of Suffolk rams were selected on high and low 18-month adjusted live weight from six farms over 2 years, to establish the relationship between 18-month weight and early lamb growth. Progeny were first produced in recorded crossbred flocks (618 lambs) and then in an experimental flock of crossbred ewes (1083 lambs). Different results were obtained from the recorded and experimental flocks. The regressions of lamb 12- to 13-week weight on ram 18-month weight (within farm deviation) were 0·053 ± 0·022 kg and –0·004 ± 0·020 kg, respectively. These regressions for indirect selection correspond to ‘effective’ heritabilities for direct selection for lamb growth of 0·18 ± 0·07 and 0·02 ± 0·06 respectively. Improvement of early Iamb growth is discussed and it is concluded that selection for 18-month weight is unlikely to be a useful method.


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