Variation In Growth Rate Research Articles

Assessing growth of pelagic sargassum in the Tropical Atlantic

Pelagic sargassum species, historically endemic to the North Atlantic, have now been identified in the Tropical Atlantic. For over a decade, massive blooms of pelagic sargassum have dispersed seasonally from this ‘new’ Tropical Atlantic source region, negatively impacting the coasts of Caribbean and West African countries. Significant strides have been made towards adaptation to this new ‘hazard’, yet many knowledge gaps remain that constrain improvements to these efforts. The key objective of this study was to add to the knowledge of pelagic sargassum growth rates in the Tropical Atlantic to better inform forecasting and innovative applications. Growth rates of the three commonly occurring morphotypes from the Tropical Atlantic source region, S. fluitans III, S. natans I and S. natans VIII, were studied in-situ using novel 'growth mesocosms' in neritic waters of Barbados under cool and warm ambient conditions. Overall, results reveal a significant difference in growth rates among all pelagic sargassum morphotypes, with S. fluitans III on average doubling its biomass in 13 days, S. natans I in 22 days and S. natans VIII in 31 days. Furthermore, growth rates of S. fluitans III decreased significantly with an increase in ambient temperature from the cool (mean 27.6 °C) to warm (mean 29.6 °C) water period. During both periods S. fluitans III grew significantly faster than the other two morphotypes. However, S. natans I only grew significantly faster than its conspecific morphotype, S. natans VIII, during the cool period. These findings highlight the different growth responses among sargassum morphotypes under varying conditions and add to the considerable variability in growth rates reported by recent similar studies conducted elsewhere in the Tropical Atlantic. As such, it is clear that further research will be needed to unravel the complex mechanisms affecting pelagic sargassum growth rates before they can confidently inform improvements in management applications.

Are early-life lambs’ characteristics and behavioural reactivity related to later survival and growth performance during artificial feeding?

The use of prolific sheep breeds often leads farmers to rear some lambs with an automatic milk feeder to improve survival and growth. However, the success of these challenging situations could depend on lamb’s early individual characteristics, and their behavioural reactivity in a stressful context. The study was performed on 567 Romane lambs. We tested the hypothesis that early-life characteristics, including behaviour and physiology, could predict survival and growth performances until weaning. In addition, on a random subsample of one third of these lambs we assessed whether behavioural reactivity to social isolation and unknown human presence was a further predictor of individual variability in growth rate. Lambs were characterised by birth weight, rectal temperature and scores for vigour, handling and sucking of first bottle milk on arrival at nursing. After three weeks of artificial rearing (i.e. halfway to weaning age), 202 randomly-chosen lambs were studied in a 2-phase test to record their reaction to social isolation in a novel arena test and presence of an unknown human. Test variables were summarised phase-wise by principal component analysis. The factor scores characterised lamb general activity in phase 1 and affinity to humans in phase 2. Data was examined using descriptive statistics, survival analysis and multivariate regression models to identify the key factors for survival and average daily gain (ADG) until weaning. Cumulative early death rate at one week was 5% and global death rate at the end of the rearing period was 11.6%. There was a higher hazard ratio for death for weak sucking at the first milk-bottle test (P = 0.011), low rectal temperature (P < 0.05), and dam age of 4–5 years versus 2–3 years (P < 0.01). A low ADG until weaning was associated with a low vigour score (P < 0.01), weak sucking (P < 0.05) and low birth weight (P < 0.001). Our data also supports the hypothesis of a relationship between growth and behavioural reactivity in artificially-reared lambs. A low growth rate until weaning was also associated with higher lamb affinity shown to humans (P < 0.001) and lower activity expressed in social isolation in a new arena (P < 0.05). Our study suggests that early-age characteristics but also reactivity to social isolation and affinity to humans could be valuable predictors of lamb survival and growth in artificial rearing. Our results possibly reveal an over-dependency on humans in some lambs in such a system.

Abstract 36: Comparing twenty-two matched patient-derived cell lines developed from either patient, PDX, or organoid tumor cell material

Abstract The National Cancer Institute has developed a Patient-Derived Models Repository (NCI PDMR; https://pdmr.cancer.gov) comprised of quality-controlled, early passage, and clinically-annotated patient-derived tumor xenografts (PDXs), organoids (PDOrgs), cell cultures (PDCs), and cancer associated fibroblasts (CAFs) available with genomic data to the extramural community for research use. Models are developed by the NCI PDMR in decreasing order of complexity, specifically 1) patient material can be used to develop PDXs, PDOrgs, PDCs, and CAFs, 2) PDX material for PDOrgs and PDCs, and 3) PDOrg material for PDCs, but a PDC is never used to develop a PDOrg or PDX. Eleven pairs of 22 matched PDCs have been developed in parallel from either patient, PDX, patient-derived organoid, or PDX-derived organoid tumor material and sequenced by WES and RNASeq. Genetic stability was assessed using multiple approaches including microsatellite instability (MSI) generated from MSISensor2, percentage of genomic loss of heterozygosity (LOH) using a set of ~800k heterozygous SNPs from a population level genomic database (gnomAD), pairwise Spearman correlation based on BIN level copy number (CN)/RNA expression profiles, and OncoKB annotated oncogenic/likely oncogenic variants. No systematic differences were observed within PDC pairs derived from different origins or compared to their patient and/or PDX material in MSI, LOH% and RNA expression profile but pairwise Spearman correlation (0.66-0.88) in CNV profiles were somewhat variable, likely due to low sequencing depth. In one PDC pair (299254), 3 out of 12 OncoKB annotated Indels and CNV showed opposite level of variant allele frequencies/CN when comparing a model derived from patient material to one developed from a PDX-derived organoid, possibly driven by a lineage-specific subclonal outgrowth when compared to patient and PDX data. Phenotypic characteristics of matched PDCs also overall show no major differences, though variability in growth rates and the ability to form spheroids in serum-free medium were noted. In one pair (919269), the PDC derived from patient material was able to form a cell line xenograft (CLX) in NSG mice but not the PDC developed from a patient-derived organoid. Overall, these models demonstrate a high degree of concordance at the genetic and phenotypic level when compared to the originating patient and/or PDX tumor. Though further characterization (e.g., preclinical drug testing) may be needed to define differences between matched PDC pairs, lack of access to patient tissue or failure to generate tumor cell cultures from one source of material should not hamper development of preclinical in vitro models from other patient-derived model types as long as the source-of-origin is clearly defined. Funded by NCI Contract No. HHSN261200800001E Citation Format: Cindy R. Timme, Ting-Chia Chang, Sergio Y. Alcoser, Gareth Bliss, Carrie Bonomi, Suzanne Borgel, John Carter, Alice Chen, Li Chen, Kevin Cooper, Biswajit Das, Kelly Dougherty, Lindsay Dutko, Marion Gibson, Michelle M. Gottholm-Ahalt, Tara Grinnage-Pulley, Shahanawaz Jiwani, Keegan Kalmbach, Chris Karlovich, Kimberly Klarmann, Tiffanie Chase, Michael Mullendore, Matthew Murphy, Kevin Plater, Gloryvee Rivera, Jessica Steed, Luke Stockwin, Yvonne A. Evrard, Mickey Williams, Dianne L. Newton, Melinda G. Hollingshead, James H. Doroshow. Comparing twenty-two matched patient-derived cell lines developed from either patient, PDX, or organoid tumor cell material [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 36.

Abstract 10: Orthotopic nGEM glioma growth rates in allogenic hosts associate with hypoxia and proximity to host cells

Abstract Genomic profiling of glioblastoma uncovers fundamental differences in the driver events of malignant transformation and progression, yet the nuances driving the particular growth rate of glioblastoma in individual patients remain poorly defined. We exploited the availability of fourteen histocompatibility-matched mouse hosts from the collaborative cross (CC) [PMID: 15514660] as hosts for a non-germline, engineered model of murine glioblastoma [PMCID: PMC4210043] to interrogate cell types, functional states and proximity in situ in tumors with varying growth rates. Specifically, Kaplan-Meier survival data was used to determine the rates of Nf1:TP53 null tumor growth in different cc host groups. Spatial transcriptomics and single nucleus RNA seq (sn-seq) analyses were conducted in tumor-bearing brain tissue from C57Bl/6 (syngeneic) and 2 CC histocompatible allogeneic mouse strains with differential survival outcomes. Spatial analysis was conducted using a disease-focused multiplexed mRNA probe set assembled from annotations of GBM/glioma specific genes reported in the literature. Cell segmentation of the data was performed to investigate the spatial pattern of single-cell level expression. The spatial transcriptomic dataset was also analyzed with a segmentation-free pipeline. In addition, to detect cell clusters, the probability of genes detected in close proximity (genes within a cell 5px radius [0.5 um]) was determined using Pdgfra as the tumor marker (anchor). We identified differential levels of spatially correlated expression of cell clusters expressing hypoxia markers such as HIF-1a and PDK1 between hosts with fast and slow growing tumors. Tumors from the 3 hosts were also processed for sn-seq. Integrated analysis of cell clustering was used to determine differences in clusters between the fast growing and slow growing groups. Enrichment of expression of Top2a, a gene associated with proliferation and poor prognosis in glioma, was detected in a unique cluster of cells in the slow-growing tumor when compared to the fast-growing group. This suggests that the host microenvironment may play a role in influencing the decelerated growth of this tumor. These results support the utility of spatial transcriptomics and sn-seq in understanding how differences in tumor:host cell interactions contribute to tumor growth. Future opportunities enabled by histocompatible allogeneic hosts for GEM and nGEM glioma models include unraveling host effects on drug sensitivity, tumor heterogeneity, molecular plasticity, angiogenesis, invasion, and lymphoid and myeloid microenvironmental dependencies, each with profound opportunities for clinical translation. Citation Format: Angela S. Baker. Orthotopic nGEM glioma growth rates in allogenic hosts associate with hypoxia and proximity to host cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 10.

Abstract 5189: Comparisons of Rituximab and CD19xCD3 BiTE antitumor response across multiple humanized NSG strains engrafted with human hematopoietic stem cells

Abstract Humanized NSG mice engrafted with hematopoietic stem cells (HSCs) is a well-known in vivo platform for reconstitution of human immune system in a mouse host. In this study we tried to dissect the role of various human cytokines in the generation of the human immune system, expansion of human B cell lymphoma cells, and drug response to two anti-cancer therapies - Rituximab and CD19XCD3 BiTE (Bispecific T-cell Engager). To exclude donor variabilities, we first humanized five NSG-based, human cytokine-transgenic mouse strains (NSG, NSG-IL15, NSG-SGM3, NSG-SGM3-IL15, and NSG-FLT3L) with HSCs from one donor (0084). We found that tumor growth was enhanced in NSG-SGM3 mice when compared to NSG mice. In contrast, IL15 expression suppressed tumor growth in NSG-IL15 and NSG-SGM3-IL15 mice. Furthermore, NK cell frequencies in blood are higher in NSG-IL15 and NSG-SGM3-IL15 than in other strains. suggesting that NK cell-mediated cytotoxicity is involved in suppression of tumor cell growth in the strains expressing human IL-15. Rituximab treatment resulted in tumor growth inhibition and significant B cell depletions across NSG-IL15, NSG-SGM3, and NSG-SGM3-IL15 mice engrafted with 0084 PBMC. We also observed a donor variability of tumor growth rates in NSG-SGM3-IL15 mice engrafted with donors 0084, 0662A, and 0733. The tumor growth in NSG-SGM3-IL15 mice engrafted with 0084 PBMC was significantly slower than the one in mice engrafted with the other two donors (0084 vs. 0662A, P=0.002; 0084 vs. 0733, P=0.004 on day 21); interestingly, this strain of mice exhibited higher frequencies of CD8+ T cells and lower frequencies of NK cells. Next, we tested CD19XCD3 BiTE treatment in multiple NSG strains engrafted with HSCs from different donors. The BiTE administration inhibited Raji tumor growth and significantly depleted B cells in all tested strains as NSG-SGM3-IL15 showed highest frequencies of NK cells and CD8+ T cells. The combination of Rituximab and BiTE showed even better tumor inhibition efficacy. In conclusion, regardless of the donor and strain variations in tumor growth and human immune cell subset development, the administrations of rituximab or BiTE significantly and consistently inhibited tumor growth and depleted peripheral B cells across all mouse strains. These results indicate that utilizing a comprehensive humanized mouse platform could drive more impactful conclusions in terms of evaluating the anti-tumor efficacy of immune therapies. Citation Format: Won Yeong Kang, Guoxiang Yang, Ilian Radichev, Li-Chin Yao, Mingshan Cheng, James G. Keck. Comparisons of Rituximab and CD19xCD3 BiTE antitumor response across multiple humanized NSG strains engrafted with human hematopoietic stem cells. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5189.

From molecular to sub-μm scale: The interplay of precursor concentrations, primary particle size, and carbon nanostructure during soot formation in counter-flow diffusion flames

The focus of this work is on counter-flow diffusion flames of C2H4/air near the sooting limit (fV < 500 ppb) to shed light on the transition of precursor molecules to primary soot particles and their nanostructure. The applied experimental techniques cover non-intrusive methods based on laser-induced incandescence (LII) for determination of soot volume fractions, primary particle sizes, and ratios of refractive indices for absorption at different wavelengths. The methods are complemented by intrusive methods such as sampling with microprobes and analysis of gas composition by gas chromatography and mass spectrometry, particle sizing by differential mobility analysis, and determining carbon nanostructures of particles by high-resolution transmission electron microscopy (HRTEM). For numerical simulation, the well-known ABF-model is applied.The experimentally determined structures of the counter-flow flames could be well reproduced within the experimental uncertainties by the ABF-model for varying fuel mass fractions and strain rates. The numerical simulations identify the different processes during particle formation and the main variation can be attributed to variation of surface growth rates when applying strain rates and fuel mass fractions leading to higher soot volume fractions. Particle size distributions detected in the fuel flow near and below the stagnation plane appear bimodal with distinct maxima at particles sizes about 5 nm and 20 nm. The nanostructure of the primary particles exhibits basic structural units (BSUs), that increase up to the size of 7 Å to 10 Å at increasing soot volume fractions from about 100 ppb to 300 ppb. This coincides with the increase of the mole fractions of the detectable soot precursors with increasing soot volume fraction. The ratios of refractive index functions for absorption E(m,λ532)/E(m,λ1064) and E(m,λ266)/E(m,λ1064) decrease approximately linearly with increasing soot volume fractions. This is corroborated by the analyses of HRTEM-images that clearly bring about increasing sized BSUs with increasing soot volume fractions causing a shift of the absorption to larger wavelengths.

Influence of a random phase plate on the growth of the backward stimulated Brillouin scatter.

We derive the analytical dispersion relation of a high-energy laser beam's backward stimulated Brillouin scattering (BSBS) in a hot plasma, that accounts both for the random phase plate (RPP) induced spatial shaping and its associated phase randomness. Indeed, phase plates are mandatory in large laser facilities where a precise control of the focal spot size is required. While the focal spot size is well controlled, such techniques produce small scale intensity variations that can trigger laser-plasma instabilities such as BSBS. Quantifying the resulting instability variability is shown to be crucial for understanding accurately the backscattering temporal and spatial growth as well as the asymptotic reflectivity. Our model, validated by means of a large number of three-dimensional paraxial simulations and experimental data, offers three quantitative predictions. The first one addresses the temporal exponential growth of the reflectivity by deriving and solving the BSBS RPP dispersion relation. A large statistical variability of the temporal growth rate is shown to be directly related to the phase plate randomness. Then, we predict the portion of the beam's sectionthat is absolutely unstable, thus helping to precisely assess the validity of the vastly used convective analysis. Finally, a simple analytical correction to the plane wave spatial gain is extracted from our theory giving a practical and effective asymptotic reflectivity prediction that includes the impact of phase plates smoothing techniques. Hence, our study sheds light on the long-time studied BSBS, deleterious to many high-energy experimental studies related to the physics of inertial confinement fusion.

Evidence for a trade-off between growth rate and xylem cavitation resistance in Callitris rhomboidea.

The ideal plant water transport system is one that features high efficiency and resistance to drought-induced damage (xylem cavitation), however species rarely possess both. This may be explained by trade-offs between traits, yet thus far, no proposed trade-off has offered a universal explanation for the lack water transport systems that are both highly drought-resistant and highly efficient. Here we find evidence for a new trade-off, between growth rate and resistance to xylem cavitation, in the canopies of a drought-resistant tree species (Callitris rhomboidea). Wide variation in cavitation resistance (P50) was found in distal branch tips (< 2mm in diameter), converging to low variation in P50 in larger diameter stems (> 2mm). We found a significant correlation between cavitation resistance and distal branchlet internode length across branch tips in C. rhomboidea canopies. Branchlets with long internodes (8mm or longer) were significantly more vulnerable to drought-induced xylem cavitation than shorter internodes (4mm or shorter). This suggests that varying growth rates, leading to differences in internode length, drive differences in cavitation resistance in C. rhomboidea trees. The only distinct anatomical difference found between internodes was the pith size, with the average pith to xylem area in long internodes, 5x greater than in short internodes. Understanding whether this trade-off exists within and between species will help us to uncover what drives and limits drought resistance across the world's flora.

Morphology, growth, and photosynthesis of Ulva prolifera O.F. Müller (Chlorophyta, Ulvophyceae) gametophytes, the dominant green tide species in the Southern Yellow Sea

Green tide with the main dominant species is Ulva prolifera O.F. Müller have been reported in the Southern Yellow Sea since 2007. This study investigated differences in the morphology, growth, chlorophyll fluorescence parameters, and chloroplast pigment content of different day-aged U. prolifera gametophytes. Gametes had two flagella and exhibited positive phototaxis. On the 7th day of culture, young gametophytes began to branch out. Changes in the length and width of the main branches, and the length of the first-level branches showed “S”-shaped growth within 0–30 days, while the fresh weight of single algae exhibited “J”-shaped growth. The average fresh and dry weight of U. prolifera was 12.32 and 1.38 g per thallus, respectively, when cultured from one gamete to 30 days. The average number of first-level branches of 10-day-aged thalli was 119 per blade, and the maximum branching level was one. The average number of first-level branches of 30-day-aged thalli was 243 per thallus, and the maximum branching level was five. Except for the NPQ and IK values of 0 d thalli compared with 10 d thalli, the IK value of 0 d compared with 20 d, the NPQ, ETRmax and IK value of 10 d compared with 20 d, and the Alpha value of 10 d compared with 30 d, the Fv / Fm, YII, NPQ, ETRmax, IK and Alpha values of the other 0 d, 10 d, 20 d and 30 d thalli showed significant or extremely significant differences. There was no significant difference in the Chl b / Car value between 0 d and 10 d, the Chl b value between 10 d and 20 d, the Chla / Car value between 10 d and 30 d, and the Car value between 20 d and 30 d was significantly different. The Chl a, Chl b, Car, Chl a / Chl b, Chl a / Car and Chl b / Car values of the other 0 d, 10 d, 20 d and 30 d were highly significantly different. These results not only verify that U. prolifera gametophytes can directly develop into new thalli by parthenogenesis, but also reveal the morphological and physiological characteristics of different day-aged gametophytes. In addition to presenting the typical morphology of different-day-aged gametophytes, this study also reports significant differences in growth, chlorophyll fluorescence parameters, and chloroplast pigment contents among them. This revealed the physiological mechanism of varying growth rates of different day-aged U. prolifera. These findings provide essential reference information for green tide prevention and outbreak mechanism research.

Improving Rice Yield by Promoting Pre-anathesis Growth in Subtropical Environments

Rice yield is greatly influenced by climatic factors and soil fertility in the location where it is grown, but information about the individual effects of climatic factors and soil fertility variables is difficult to distinguish because they are often not independent. The objective of this study was to demonstrate the effect of climatic factors on grain yield when soil fertility was not a confounding factor for explaining yield differences across two subtropical environments. Field and pot experiments with six rice cultivars were conducted in Deyang and Luzhou, Sichuan Province, China. We found that rice yield was higher in Deyang than in Luzhou by 7.0–16.8% for field experiments and by 57.6–87.4% for pot experiments. Biomass production rather than harvest index was responsible for the yield difference. Maximum and minimum temperatures and cumulative solar radiation (CSR) before heading (HD) were higher in Deyang than in Luzhou, whereas after HD, maximum and minimum temperatures were lower in Deyang than in Luzhou. Rice yield was more closely related to maximum and minimum temperatures and CSR before HD than to these parameters after HD. There was no difference in yield between soil types from Deyang and Luzhou within the same ecological condition. Thus, the yield difference between the two subtropical environments was mainly caused by the difference in climatic factors. The differences in biomass between Deyang and Luzhou were mostly due to variations in pre-heading crop growth rate (pre-CGR) and pre-heading radiation use efficiency (pre-RUE), which were induced by varying temperatures and CSR. We concluded that lower yield in Luzhou was associated with lower pre-CGR and pre-RUE. Our study suggests that developing rice cultivars with high pre-CGR and pre-RUE through a breeding program may also be a feasible approach to achieve high yield in subtropical environments.

Effects of range and niche position on the population dynamics of a tropical plant.

The center-periphery hypothesis predicts a decline in population performance toward the periphery of a species' range, reflecting an alteration of environmental conditions at range periphery. However, the rare demographic tests of this hypothesis failed to disentangle the role of geography from that of ecological niche and are biased toward temperate regions. We hypothesized that, because species are expected to experience optimal abiotic conditions at their climatic niche center, (1) central populations will have better demographic growth, survival, and fertility than peripheral populations. As a result, (2) central populations are expected to have higher growth rates than peripheral populations. Peripheral populations are expected to decline, thus limiting species range expansion beyond these boundaries. Because peripheral populations are expected to be in harsh environmental conditions, (3) population growth rate will be more sensitive to perturbation of survival-growth rather than fertility in peripheral populations. Finally, we hypothesized that (4) soils properties will drive the variations in population growth rates for narrowly distributed species for which small scale ecological factors could outweigh landscape level drivers. To test these hypotheses, we studied the demography of Thunbergia atacorensis (Acanthaceae), a range-limited herb in West Africa. We collected three years of demographic data to parameterize an integral projection model (IPM) and estimated population level demographic statistics. Demographic vital rates and population growth rates did not change significantly with distance from geographic or climatic center, contrary to predictions. However, populations at the center of the geographic range were demographically more resilient to perturbation than those at the periphery. Soil nitrogen was the main driver of population growth rate variation. The relative influence of survival-growth on population growth rates exceeded that of fertility at the geographic range center while we observed the opposite pattern for climatic niche. Our study highlights the importance of local scale processes in shaping the dynamics and distribution of range-limited species. Our findings also suggest that the distinction between geographic distribution and climatic niche is important for a robust demographic test of the center-periphery hypothesis.

Modelling Monetary Policy Mechanism in Driving the Control of Inflation Growth in Nigeria

The study examined Modeling Monetary Policy Mechanism in Driving the Control of Inflation Growth In Nigeria. Multiple Linear Regression Model (MLRM) estimating technique was adopted as a tool in fitting the model where inflation rate serves as response variable and income growth rate, money supply, exchange rate, domestic credit growth rate and government expenditure served as explanatory variables. Data made use of were collected from the Central Bank of Nigeria (CBN) Statistical Bulletin, December 2018, between 1998 to 2018. The R-Statistical software package was adopted to carry out the analysis. The result of the P-value of Money supply, Exchange rate and Domestic credit growth were all statistically significant with 0.00233, 0.0000696 and 0.01131 respectively at (0.05). Though, the real income growth rate and government expenditure do not appreciably contribute to controlling the inflation growth rate. The overall model contributes significantly to controlling the inflation growth rate with a P-value of 1.138 x 10-15. The coefficient of determination (R-square) is very high which implies that the model best captured the control of the inflation growth rate that is being considered. The study however concluded that three of the explanatory variables made much significant impact in controlling inflation growth rate in Nigeria.

Dietary plasticity linked to divergent growth trajectories in a critically endangered sea turtle

Foraging habitat selection and diet quality are key factors that influence individual fitness and meta-population dynamics through effects on demographic rates. There is growing evidence that sea turtles exhibit regional differences in somatic growth linked to alternative dispersal patterns during the oceanic life stage. Yet, the role of habitat quality and diet in shaping somatic growth rates is poorly understood. Here, we evaluate whether diet variation is linked to regional growth variation in hawksbill sea turtles (Eretmochelys imbricata), which grow significantly slower in Texas, United States versus Florida, United States, through novel integrations of skeletal growth, gastrointestinal content (GI), and bulk tissue and amino acid (AA)-specific stable nitrogen (δ15N) and carbon (δ13C) isotope analyses. We also used AA δ15N ΣV values (heterotrophic bacterial re-synthesis index) and δ13C essential AA (δ13CEAA) fingerprinting to test assumptions about the energy sources fueling hawksbill food webs regionally. GI content analyses, framed within a global synthesis of hawksbill dietary plasticity, revealed that relatively fast-growing hawksbills stranded in Florida conformed with assumptions of extensive spongivory for this species. In contrast, relatively slow-growing hawksbills stranded in Texas consumed considerable amounts of non-sponge invertebrate prey and appear to forage higher in the food web as indicated by isotopic niche metrics and higher AA δ15N-based trophic position estimates internally indexed to baseline nitrogen isotope variation. However, regional differences in estimated trophic position may also be driven by unique isotope dynamics of sponge food webs. AA δ15N ΣV values and δ13CEAA fingerprinting indicated minimal bacterial re-synthesis of organic matter (ΣV &amp;lt; 2) and that eukaryotic microalgae were the primary energy source supporting hawksbill food webs. These findings run contrary to assumptions that hawksbill diets predominantly comprise high microbial abundance sponges expected to primarily derive energy from bacterial symbionts. Our findings suggest alternative foraging patterns could underlie regional variation in hawksbill growth rates, as divergence from typical sponge prey might correspond with increased energy expenditure and reduced foraging success or diet quality. As a result, differential dispersal patterns may infer substantial individual and population fitness costs and represent a previously unrecognized challenge to the persistence and recovery of this critically endangered species.

Effects of temperature, salinity, and food availability on shell growth rates of the Yesso scallop.

Shell growth rates in relationship to seasonal changes of environmental factors were studied in a wild population of the Yesso scallop Mizuhopecten yessoensis inhabiting Amur Bay (Peter the Great Bay, Sea of Japan, Russia). It was found that food availability is not a limiting factor for the scallop growth in the study area. A phytoplankton biomass of 3.5-6.0 g m-3 provided high scallop growth rates. The largest daily shell increments were observed with a phytoplankton biomass of about 6 g m-3. With a decrease in the phytoplankton biomass to <2 g m-3, as well as with an increase to >11 g m-3, the daily shell increments reduced. It appeared that the main exogenous factors causing the seasonal variations in the scallop growth rates are the water temperature, which was too high in July and August (>18°C) and too low in November-April (<4°C), and the water salinity, which was too low (<30‰) for this stenohaline species in summer. The relationship of the daily shell increment in Yesso scallop with the water temperature can be described by a dome-shaped curve. The largest increments were observed at 8-16°C. The dependence of the daily shell increments on the water salinity was also best described by a dome-shaped curve, showing the optimal range of 32.5-33.5‰. The revealed relationships, approximated by dome-shaped curves, evidently indicate that both insufficient and excessive effect of the factor negatively affects scallop growth. A suggestion was made to describe the result of the combined impact of several environmental factors on the daily shell increment as a multiplication of the functions of its dependence on each of the factors.

Recent decrease of the impact of tropical temperature on the carbon cycle linked to increased precipitation

The atmospheric CO2 growth rate (CGR) variability is largely controlled by tropical temperature fluctuations. The sensitivity of CGR to tropical temperature left({{{{rm{gamma }}}}}_{{{{rm{CGR}}}}}^{{{{rm{T}}}}}right) has strongly increased since 1960, but here we show that this trend has ceased. Here, we use the long-term CO2 records from Mauna Loa and the South Pole to compute CGR, and show that {{{{rm{gamma }}}}}_{{{{rm{CGR}}}}}^{{{{rm{T}}}}} increased by 200% from 1960–1979 to 1979–2000 but then decreased by 117% from 1980–2001 to 2001–2020, almost returning back to the level of the 1960s. Variations in {{{{rm{gamma }}}}}_{{{{rm{CGR}}}}}^{{{{rm{T}}}}} are significantly correlated with changes in precipitation at a bi-decadal scale. These findings are further corroborated by results from a dynamic vegetation model, collectively suggesting that increases in precipitation control the decreased {{{{rm{gamma }}}}}_{{{{rm{CGR}}}}}^{{{{rm{T}}}}} during recent decades. Our results indicate that wetter conditions have led to a decoupling of the impact of the tropical temperature variation on the carbon cycle.

Daily growth rate variation in Tridacna shells as a record of tropical cyclones in the South China Sea: Palaeoecological implications

Tropical cyclones (TC) are one of the most destructive weather phenomena on Earth. However, the short duration of instrumental weather records mean that little is known of the frequency of TCs through geological time. Here we analyse a Tridacna squamosa shell with a life span about 6 years (from 12 May 2013 to 18 December 2018) from the northern South China Sea. Studies of daily growth rate variations (DGRV) were correlated with coeval environmental changes to develop a proxy for TC. Results reveal that the frequency and variation of extreme DGRV were conspicuously different between the typhoon-affected season (July to October) and relatively stable growth season (March to June). During the typhoon-affected season, the frequency of sudden onset of decreased sea surface temperature, attenuated solar radiation and heavy precipitation can result in more days for extreme decreases of DGRV. On interannual timescale, the frequency of extreme DGRV was significantly correlated with TC influence days. Our findings indicate that the frequency of extreme DGRV profile in Tridacna squamosa shells has potential to be a novel recorder for past TC activity. We conclude that fossil shells in different geological eras offer the potential to extend modern instrumental datasets and provide opportunities for investigating TC activity in response to past and future global change.

National culture and international business cycle co-movements

ABSTRACT We investigate the relationship between national culture and international business cycle co-movements. We first characterize international business cycle co-movements with a dynamic latent factor model that decomposes 101 countries’ real GDP growth rates into world, regional and country-specific factors and estimate the proportion of real GDP growth rate variance explained by the world, regional and country factors for each country. We then regress these proportions on each of the five dimensions of Hofstede’s national culture with a set of control variables. We find that four dimensions (except for power distance) are significantly related to business cycle co-movements, and they have different impacts. In countries with masculinity, uncertainty avoidance and long-term orientation preferences, the global factor explains a larger real GDP growth rate variance. Individualism weakens a country’s business cycle co-movement with the global business cycle. Countries with similar cultural values have similar economic structures and similar exposures to global shocks, which lead to business cycle co-movements. Our results are robust after addressing the issue of endogeneity and subsample analyses.

Fine-scale variability in catch and growth rates of western rock lobsters (

Context The western rock lobster fishery is recognised to be conservatively managed, with breeding stock levels estimated to be at record levels over the past decade. Despite this, anecdotal reports from commercial fishers identified an area of unexpectedly low catches in the centre of the fishery and lobsters’ biogeographic distribution. Aim To confirm the presence of this suspected ‘low-catch’ zone and examine the variability in catch and growth rates of lobsters if identified. Methods This study conducted an intensive mark–recapture survey over 8 months to explore catch rate, density, movement and growth rates across this ‘low-catch’ zone and three comparable locations. Key results In total, 9318 lobsters were caught and 7565 individuals were tagged during the study. Consistently low catch rates of under-sized lobsters were observed in the ‘low-catch’ zone, with catch rates increasing with distance from the zone. By contrast, similar catch rates of legal-sized lobsters were observed across all locations. Conclusions The study confirmed low catch rates, for under-sized lobsters, within an area of perceived low catch rates within the centre of the fishery. The lack of difference found in legal-sized catch rates among locations is likely to be due to the low fishing pressure in the ‘low-catch’ zone, resulting from hyperstability of fishers adapting to the historical perceived low catch rate. Modelled data demonstrated the ‘low-catch’ zone to be associated with faster growth rates and high fine-scale migration, indicating a potential release from density-dependent processes. Implications We anticipate that these results will be a useful starting point for future research into the mechanisms responsible for the unexpectedly low catch of sublegal lobsters within the ‘low-catch’ zone and the implications it may have on the wider population, both regionally and across the species distribution.

The Role of Manufacturing and Service Exports in Ethiopia’s Economic Growth Performance

The purpose of this study is to investigate the role of manufacturing and service exports in Ethiopia’s economic growth performance from 1995 until 2018. To accomplish the objective, the study developed two versions of an augmented Solow’s (1956) model. Both versions include manufacturing and service exports as potential determinants of total factor productivity (TFF). However, the first version proxies physical capital accumulation with the investment rate, and the second version uses capital per worker. The autoregressive distributed lag (ARDL) bounds testing results of the first version suggest that there is no long-run relationship among the variables. Moreover, the investment ratio and labour force growth rate variables are statistically insignificant, which contradicts the theoretical predictions of the Solow model. On the other hand, the second version of the Solow model with capital per worker shows evidence of a long-run cointegrating relationship among the variables which support the manufacturing export-led growth hypothesis in Ethiopia, in which manufacturing exports are statistically significant, while service exports are statistically insignificant in the long run. Conversely, the results of the first version show that capital per worker has a positive and significant effect on Ethiopia’s economic growth performance. Overall, the main findings suggest that the Ethiopian government should strengthen current policies that emphasize manufacturing exports and maintain high investment rates in physical capital.

Competition overwhelms environment and genetic effects on growth rates of endangered white sturgeon from a conservation aquaculture program

Improving the status of endangered species can be challenging because the efficacy of conservation actions is often uncertain. Conservation aquaculture has been the main recovery action for endangered white sturgeon ( Acipenser transmontanus) in the Transboundary Reach of the upper Columbia River. Using long-term mark-recapture data (2002–2018), we predicted variation in growth rates due to genetic, environmental, and competition effects to evaluate the efficacy of the aquaculture program. Environmental conditions (by season and country) and competition had the greatest effects on growth. Growth, length-at-age, weight-at-age, and condition factor were higher for fish residing in reservoir habitats (US) compared to those in riverine habitat (Canada). Growth declined over the study period but growth in length for larger fish remained higher in the US as fish &gt; 100 cm fork length in Canada were not growing. Small differences in growth among families indicate that differences in genetics among parents spawned in the hatchery had negligible effects on growth in the wild. Our estimate of substantive negative density-dependent growth in Canada is important for management of conservation aquaculture for sturgeons.