Effects Of Experimental Treatments Research Articles

Parental training and externalizing behaviors of children with severe hearing loss.

Background: Externalizing behavior in deaf children causes many psychological problems for their parents. Aggression and rule breaking behaviors in children with severe hearing loss may cause psychological problems in parents and in managing children's behavior. Consequently, the present study aimed at investigating the effect of parental behavioral training of mothers on reducing the externalized behaviors (aggression and rule breaking behavior) of their 9- to 10- year old children with severe hearing loss. Methods: This was an experimental study with pretest, posttest, and a control group. The research population included all students with severe hearing loss and their mothers. Thus, 30 mothers whose children had the most severe hearing loss were selected as our main sample among 80 mothers who had completed the Child Behavior Checklist. Then, they were placed into the experimental (n=15) and control groups (n=15) after being matched based on age, educational level, and socioeconomic status. The research tool was Child Behavior Checklist-Persian Version. The parental behavior training was provided for the experimental group in nine 90- minute sessions. Results: The results of the present study indicated the effectiveness of experimental treatment on decreasing the aggressive behaviors of children of mothers in the experimental group compared to mothers of the control group (p=0.001). Moreover, the results revealed a decrease in rule breaking behaviors (p= 0.007) in children of mothers of the experimental group compared to mothers of the control group. Conclusion: Parents’ behavioral training is important in decreasing the aggressive and offensive behaviors in children with severe hearing loss who are at risk of behavioral problems. Furthermore, some research has highlighted the necessity of such trainings for parents of these children. Thus, the present study, emphasizing the importance of childhood problems, found that mothers’ behavioral training could prevent behavioral problems of school-aged children with hearing loss and reduce the recurrence of such problems.

Shear stress upregulates regeneration-related immediate early genes in liver progenitors in 3D ECM-like microenvironments.

The role of fluid stresses in activating the hepatic stem/progenitor cell regenerative response is not well understood. This study hypothesized that immediate early genes (IEGs) with known links to liver regeneration will be upregulated in liver progenitor cells (LPCs) exposed to in vitro shear stresses on the order of those produced from elevated interstitial flow after partial hepatectomy. The objectives were: (1) to develop a shear flow chamber for application of fluid stress to LPCs in 3D culture; and (2) to determine the effects of fluid stress on IEG expression in LPCs. Two hours of shear stress exposure at ∼4 dyn/cm2 was applied to LPCs embedded individually or as 3D spheroids within a hyaluronic acid/collagen I hydrogel. Results were compared against static controls. Quantitative reverse transcriptase polymerase chain reaction was used to evaluate the effect of experimental treatments on gene expression. Twenty-nine genes were analyzed, including IEGs and other genes linked to liver regeneration. Four IEGs (CFOS, IP10, MKP1, ALB) and three other regeneration-related genes (WNT, VEGF, EpCAM) were significantly upregulated in LPCs in response to fluid mechanical stress. LPCs maintained an early to intermediate stage of differentiation in spheroid culture in the absence of the hydrogel, and addition of the gel initiated cholangiocyte differentiation programs which were abrogated by the onset of flow. Collectively the flow-upregulated genes fit the pattern of an LPC-mediated proliferative/regenerative response. These results suggest that fluid stresses are potentially important regulators of the LPC-mediated regeneration response in liver.

Post-experimental follow-ups—Fade-out versus persistence effects: The Rialto police body-worn camera experiment four years on

PurposeUnder certain conditions, experimental treatment effects result in behavioral modifications that persist beyond the study period, at times, even after the interventions are discontinued. On the other hand, there are interventions that generate brief, short-term effects that “fade out” once the manipulation is withdrawn or when the in-study follow-up period is completed. These scenarios are context specific. MethodsThis study reports the results from a three-year post-experimental follow-up from the world's first randomized controlled trial of police body-worn cameras. ResultsThe results show that initial falls in rates of complaints against police and police use of force during arrest were sustained during the four years following the cameras being introduced. ConclusionsThe findings suggest that police officers do not become habituated to the effect of the body-worn cameras, and that persistence rather than fade-out effects may characterize this emerging technology.

New Window for Motor Learning Research: Variables in Human Factors

New Window for Motor Learning Research: Variables in Human Factors

针灸治疗消化道肿瘤相关病症的临床研究进展

检索CNKI、万方、维普和PubMed等数据库，收集近5年国内外针灸治疗消化道肿瘤相关病症的临床对照研究文献，从实验设计、治疗方法、疗效评价等方面综合分析。结果表明针灸疗法在临床消化道肿瘤相关病症治疗中应用广泛，主要用于治疗癌症疼痛、术后并发症和化疗副反应等，疗效肯定。但高质量随机对照试验较少，今后应进一步完善实验设计，确定最佳配穴方案和最优治疗方法。 CNKI, WANfANG, VIP and PubMed databases were searched. The clinical control literatures of acupuncture and moxibustion treatment of gastrointestinal cancer related disorders of domestic and international in the last 5 years were collected and analyzed from the aspects of experimental design, treatment and curative effect evaluation. The results show that acupuncture therapy is widely used in the treatment of gastrointestinal cancer related disorders, mainly for the treatment of cancer pain, postoperative complications, side effects of chemotherapy and so on, and the effect is certain. But the quality of randomized controlled trials is less. In the future we should further improve the experimental design, to determine the best acupoints program and the best treatment.

At the Nexus of Observational and Experimental Research: Theory, Specification, and Analysis of Experiments with Heterogeneous Treatment Effects

Experimentalists are increasingly examining heterogeneous treatment effects, in which observed individual-level characteristics are hypothesized to moderate an experimental treatment effect. Such work places researchers at the nexus of experimental and observational approaches. In this paper, we discuss the theoretical and statistical issues that can arise in testing such hypotheses. We note that inclusion of an observed (as opposed to randomly-assigned) moderator introduces the possibility of confounds that are commonplace in observational data analysis but too-easily ignored in experimental data analysis. We simulate several different data generating processes that include heterogeneous treatment effects, and we discuss the implications of various statistical models. We aim to provide researchers who examine heterogeneous treatment effects with background and advice that enable them to identify where common issues may arise and to develop research designs and implement statistical tests that will mitigate them.

Effect of common and experimental anti-tuberculosis treatments on Mycobacterium tuberculosis growing as biofilms.

Much is known regarding the antibiotic susceptibility of planktonic cultures of Mycobacterium tuberculosis, the bacterium responsible for the lung disease tuberculosis (TB). As planktonically-grown M. tuberculosis are unlikely to be entirely representative of the bacterium during infection, we set out to determine how effective a range of anti-mycobacterial treatments were against M. tuberculosis growing as a biofilm, a bacterial phenotype known to be more resistant to antibiotic treatment. Light levels from bioluminescently-labelled M. tuberculosis H37Rv (strain BSG001) were used as a surrogate for bacterial viability, and were monitored before and after one week of treatment. After treatment, biofilms were disrupted, washed and inoculated into fresh broth and plated onto solid media to rescue any surviving bacteria. We found that in this phenotypic state M. tuberculosis was resistant to the majority of the compounds tested. Minimum inhibitory concentrations (MICs) increased by 20-fold to greater than 1,000-fold, underlying the potential of this phenotype to cause significant problems during treatment.

Molecular imaging of neuroinflammation in preclinical rodent models using positron emission tomography.

Neuroinflammation (NI) is an adaptive response to different noxious stimuli, involving microglia, astrocytes and peripheral immune cells. NI is a hallmark of several acute and chronic diseases of central nervous system (CNS) and contributes to both damage and repair of CNS tissue. Interventional or genetically modified rodent models mimicking human neuropathologies may provide valuable insights on basic mechanisms of NI, but also for improving the development of new diagnostic and therapeutic strategies. Preclinical positron emission tomography (PET) allows to investigate noninvasively the inflammatory response in CNS of rodent models at a molecular level, validating innovative probes for early diagnosis, and characterizing the time course of neuroinflammatory changes and their relationship with disease progression, as well as the effects of experimental treatments with high translational potential. In particular, recent efforts of preclinical PET field are intended to develop specific and selective radiotracers that target the activation of innate immune system in CNS. Here, we have reviewed the state of art for PET in relevant rodent models of acute and chronic neuropathologies associated with NI, with particular regard on imaging of activated microglia and astrocytes.

The highly variable microbiota associated to intestinal mucosa correlates with growth and hypoxia resistance of sea bass, Dicentrarchus labrax, submitted to different nutritional histories.

BackgroundThe better understanding of how intestinal microbiota interacts with fish health is one of the key to sustainable aquaculture development. The present experiment aimed at correlating active microbiota associated to intestinal mucosa with Specific Growth Rate (SGR) and Hypoxia Resistance Time (HRT) in European sea bass individuals submitted to different nutritional histories: the fish were fed either standard or unbalanced diets at first feeding, and then mixed before repeating the dietary challenge in a common garden approach at the juvenile stage.ResultsA diet deficient in essential fatty acids (LH) lowered both SGR and HRT in sea bass, especially when the deficiency was already applied at first feeding. A protein-deficient diet with high starch supply (HG) reduced SGR to a lesser extent than LH, but it did not affect HRT. In overall average, 94 % of pyrosequencing reads corresponded to Proteobacteria, and the differences in Operational Taxonomy Units (OTUs) composition were mildly significant between experimental groups, mainly due to high individual variability. The highest and the lowest Bray-Curtis indices of intra-group similarity were observed in the two groups fed standard starter diet, and then mixed before the final dietary challenge with fish already exposed to the nutritional deficiency at first feeding (0.60 and 0.42 with diets HG and LH, respectively). Most noticeably, the median percentage of Escherichia-Shigella OTU_1 was less in the group LH with standard starter diet. Disregarding the nutritional history of each individual, strong correlation appeared between (1) OTU richness and SGR, and (2) dominance index and HRT. The two physiological traits correlated also with the relative abundance of distinct OTUs (positive correlations: Pseudomonas sp. OTU_3 and Herbaspirillum sp. OTU_10 with SGR, Paracoccus sp. OTU_4 and Vibrio sp. OTU_7 with HRT; negative correlation: Rhizobium sp. OTU_9 with HRT).ConclusionsIn sea bass, gut microbiota characteristics and physiological traits of individuals are linked together, interfering with nutritional history, and resulting in high variability among individual microbiota. Many samples and tank replicates seem necessary to further investigate the effect of experimental treatments on gut microbiota composition, and to test the hypothesis whether microbiotypes may be delineated in fish.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-016-0885-2) contains supplementary material, which is available to authorized users.

Comparative study on the value of accessory examinations in the diagnosis of ocular myasthenia gravis

Objective To compare the sensitivity and specificity of ice test, neostigmine test and single fiber electromyography (SFEMG) in the diagnosis of ocular myasthenia gravis (OMG), so as to establish an appropriate process for the diagnosis of OMG. Methods A total of 116 patients with newly onset ptosis and/or diplopia were detected by ice test, neostigmine test and SFEMG. Patients were followed up for 6 months to observe the disease changes and experimental treatment effects. Results Apart from patients whose diagnosis was in doubt or lost to follow - up, and who were diagnosed as generalized myasthenia gravis (GMG), the definite diagnosis was finally made in 81 patients, including 21 OMG patients and 60 patients with ptosis and/or diplopia caused by other diseases. The sensitivity of ice test for diagnosis of OMG was 95.24% (20/21), and specificity was 98.33%(59/60). The sensitivity of neostigmine test for diagnosis of OMG was 90.48% (19/21), and specificity was 85% (51/60). The sensitivity of SFEMG for diagnosis of OMG was 95.24% (20/21), and specificity was 80% (48/60). Among 3 tests, only specificity was found significant difference ( χ 2 = 5.232, P = 0.022). The specificity of ice test was better than that of neostigmine test ( χ 2 = 5.707, P = 0.017) and SFEMG ( χ 2 = 6.023, P = 0.014). Conclusions The ice test achieved high sensitivity and specificity in the diagnosis of OMG. The combination of ice test, neostigmine test and SFEMG may have important clinical value for the early diagnosis of OMG. DOI: 10.3969/j.issn.1672-6731.2016.10.008

EFFECT OF IN-OVO INJECTION WITH L-CARNITINE ON HATCHABILITY AND POSTHATCHING PERFORMANCE OF GROWING DUCKLINGS UNDER SUMMER CONDITIONS IN EGYPT

The aim of this study was to investigate the effects of in-ovo L-carnitine injection on hatchability of Domyati duck eggs and posthatching growth performance of ducklings. A total of 540 eggs were randomly divided into six treatments group. The 1st, 2nd, and 3rd groups were: negative control (C); sham-injected control (P) and solution injected (S) groups, while, the 4th, 5th, and 6th groups were in-ovo injected with 0.1 ml/egg saline solution containing 10, 20 or 30 mg of L-car, respectively. A total number of 180 ducklings hatched from the six experimental treatment groups were weighed and distributed into six experimental groups (30 ducklings each) and reared during growth period (0-12 wks of age) to study the effect of in-ovo experimental treatments on growth performance, carcass traits, blood plasma parameters and breast muscle histology. The obtained results could be summarized as follows: In-ovo L-car (10 mg) injection had significantly (p≤0.01) the best value of hatchability (%) followed by control groups. All L-car doses (10, 20, and 30 mg) recorded high significant (p≤0.01) values for live body weight from hatch up to the end of experimental period, with the low dose (10 mg) being the best. The body weight gain, and feed conversion ratio were significantly increased, while, feed consumption was decreased in ducklings from L-car treated eggs during the overall periods compared to the control groups. Carcass traits for ducklings from all L-car treated eggs were significantly (p≤0.01) improved while, decreased in abdominal fat (%) as compared to control groups. Plasma HDL was significantly (p≤0.05) increased and LDL decreased in ducklings from in-ovo L-car injection treatments as compared with the control groups. Plasma triiodothyronine (T3) and Insulin-like growth factot-1 concentration were significantly (p≤0.01) higher for the in-ovo L-car injected groups than the control groups. Histological observations showed pronounced increases in myofibrils size and number in breast muscle sections of L-car ducklings compare to the control ones; the 10 mg injected group was the best. It is concluded that in-ovo injection of 10 mg L-car in Domyati duck eggs at day 17 of incubation period had positive effects on hatchability, blood plasma constituents, IGF-1, T3 hormone, growth performance and carcass traits during summer condition in Egypt.

Preparation of a standardised faecal slurry for ex-vivo microbiota studies which reduces inter-individual donor bias

BackgroundIn-vitro gut fermentation systems provide suitable models for studying gut microbiota composition and functionality. However, such methods depend on the availability of donors and the assumption of reproducibility between microbial communities before experimental treatments commence. The aim of this study was to develop a frozen standardised inoculum (FSI) which minimizes inter-individual variation and to determine its stability over time using culture-dependent and culture-independent techniques. ResultsA method for the preparation difference of a FSI is described which involves pooling the faecal samples, centrifugation and pelleting of the cell biomass and finally homogenising the cell pellets with phosphate buffer and glycerol. Using this approach, no significant difference in total anaerobe cell viability was observed between the fresh standardised inoculum (before freezing) and the 12days post freezing FSI. Moreover, Quantitative PCR revealed no significant alterations in the estimated bacterial numbers in the FSI preparations for any of the phyla. MiSeq sequencing revealed minute differences in the relative abundance at phylum, family and genus levels between the FSI preparations. Differences in the microbiota denoted as significant were limited between preparations in the majority of cases to changes in percentage relative abundance of ±0.5%. The independently prepared FSIs revealed a high degree of reproducibility in terms of microbial composition between the three preparations. ConclusionsThis study provides a method to produce a standardised human faecal inoculum suitable for freezing. Based on culture-dependent and independent analysis, the method ensures a degree of reproducibility between preparations by lessening the effect of inter-individual variation among the donors, thereby making the system more suitable for the accurate interpretation of the effects of experimental treatments.

Effects of 1.25-Dihydroxycholecalciferol and Hydroalcoholic Extract of Withania Coagulans Fruit on Bone Mineralization and Mechanical and Histological Properties of Male Broiler Chickens

An experiment was conducted to investigate the effects of hydroalcoholic extract of Withania coagulans (WC) fruit and 1.25-dihydroxycholecalciferol (1.25-(OH)2 D3) on bone mineralization, mechanical and histological properties of male broiler chickens at 21 and 42 d of age. A total of six hundred male day-old Ross 308 broiler chickens were randomly distributed according to a completely randomized experimental design in a 2×3×2 factorial arrangement with 12 treatments of five replicates of 10 birds each. Treatments consisted of two basal diets (positive control with adequate Ca level and negative control with 30% less Ca), three levels of WC (0, 100, or 200 mg/kg diet), and two levels of 1.25-(OH)2 D3 (0 or 0.5 µg/kg diet). Birds were housed in floor pens. The diets were fed ad libitum from one to 42 days of age. On day 21 and 42, one bird per replicate was sacrificed and its tibiae were removed. Both Ca and P retention increased when dietary Ca level was reduced (p<0.001). The addition of 200 mg WC/kg to positive control diet increased Ca retention (p<0.01). Except for tibia diameter, no significant main effects of experimental treatments were observed on tibia physical characteristics or on bone mineralization. The diet with 30% Ca reduction decreased tibia diameter at 42 days of age (p<0.05). The dietary addition of 1.25-(OH)2 D3 increased tibia fracture energy, width of tibia mineralized zone, and serum Ca at 42 days of age (p<0.05). At 21 days of age, supplementation of 100 mg WC/kg increased cortical thickness (p<0.05). At 42 days of age, supplementation of 100 mg WC/kg increased tibia shear force (p<0.05) and fracture energy (p<0.01). The results of this experiment showed that supplementation of 100 mg/kg hydroalcoholic extract of WC fruit increased tibia cortical thickness, shear force, and fracture energy.

Soil apparent conductivity measurements for planning and analysis of agricultural experiments: A case study from Western-Thailand

In experimental trials, the success or failure of agricultural improvements is commonly evaluated on the agronomic response of crops, using proper experimental designs with sufficient statistical power. Since fine-scale variability of the experimental site can reduce statistical power, efficiency gains in the experimental design can be achieved if this variation is known and used to design blocking, or some proxy variable is used as a covariate. Near-surface geophysical techniques such as electromagnetic induction (EMI), which describes subsurface properties non-invasively by measuring soil apparent conductivity (ECa), may be one source of this information. The motivation of our study was to investigate the effectiveness of EMI-derived ECa measurements for planning and analysis of agricultural experiments. ECa and plant height measurements (the response variable) were taken from an agroforestry experiment in Western Thailand, and their variability was quantified to simulate multiple realizations of ECa and the residuals of the response variable from treatment means. These were combined to produce simulated data from different experimental designs and treatment effects. The simulated data were then used to evaluate the statistical power by detecting three orthogonal contrasts among the treatments in the original experiment. We considered three experimental designs, a simple random design (SR), a complete randomized block design (CRB), and a complete randomized block design with spatially adjusted blocks on plot means of ECa (CRBECa). Using analysis of variance (ANOVA), the smallest effect sizes could be detected with the CRBECa design, which indicates that ECa measurements could be used in the planning phase of an experiment to achieve efficiencies by improved blocking. In contrast, analysis of covariance (ANCOVA) demonstrated that substantial power improvements could be gained when ECa was considered as a covariate in the analysis. We therefore recommend that ECa measurements should be used to characterize subsurface variability of experimental sites and to support the statistical analysis of agricultural experiments.

Estimating More Precise Treatment Effects in Natural and Actual Experiments

The importance of using natural experiments and experimental data in economic research has long been recognized. Yet, it is only in recent years that these approaches have become an integral part of the economist's analytical toolbox, thanks to the efforts of Meyer, Card, Peters, Krueger, Gruber, and others. This use has shed new light on a variety of public policy issues and has already caused a major challenge to some tightly held beliefs in economics, most vividly illustrated by the finding of a positive effect of a minimum wage increase on the employment of low-wage workers. Although currently in vogue in economic research, the analysis of experimental data and natural experiments could be substantially strengthened. This paper discusses how analysts could increase the precision with which they measure treatment effects. An underlying theme is how best to measure the effect of a treatment on a variable, as opposed to explaining a level or change in a variable.

Pinning in the Play Fighting of Rats: A Comparative Perspective With Methodological Recommendations

During play fighting, rats attack and defend the nape and during the course of this competitive interaction, they may adopt a configuration in which one animal stands over its supine partner (i.e., pin). Because the pin configuration is typically frequent and relatively easy to identify, it has been widely used as a marker to detect the effects of experimental treatments. In the present study, the frequency of pinning during standardized, 10min trials in three strains of rats, Long Evans hooded (LE), Sprague-Dawley (SD) and wild (WWCPS), was compared. LE and SD had higher rates than WWCPS rats (#/min: 6.5, 5.5, 1.5, respectively). When adjusted for strain differences in the frequency of attacks, SD as well as WWCPS rats had lower rates of pinning compared to LE rats. Both SD and WWCPS rats were less likely to use tactics of defense that promote pinning. Moreover, while the majority of the pins achieved in LE rats arose from the defender actively rolling over onto its back, the majority of pins in WWCPS rats arose because one partner pushed the other onto its back. SD rats were intermediate in this regard. Finally, once they do adopt the pin configuration, SD rats are less likely to remain supine than LE and WWCPS rats. That is, both SD and WWCPS rats have significantly fewer pins than LE rats, but a different combination of factors account for this. These data highlight the need to use a battery of measures for ascertaining the effects of experimental manipulations on play. Some suggested guidelines are provided.

Light extinction of wheat as affected by N fertilisation and plant parameters

Light absorption and light extinction of wheat (Triticum aestivum L.) are among the most important parameters affecting wheat growth and yield production. However, these properties are affected by plant and environmental factors. Despite wheat being an important food crop, there is not much information on these light parameters in wheat. Accordingly, light parameters were investigated in wheat plants in the present study in three field experiments under two distinct climatic conditions, a warm arid and semi-arid climate and a cool climate. The aims of the study were to determine how light absorption and light extinction of wheat are affected by: (1) planting date and plant genotype under arid and semi-arid conditions (Experiment I); and (2) N chemical fertilisation and plant genotype under arid and semi-arid conditions (Experiment II) and cool temperate conditions (Experiment III). Light absorption by the canopy was determined using a lightmeter and coefficients of extinction were calculated. Analyses of variance indicated significant effects of experimental treatments on light properties, wheat growth and yield production. There was a high rate of variability in light absorption, with a maximum of 59.27%, and light extinction coefficients were in the range 0.45–0.66. The experimental treatments resulted in high variability in the leaf area index (2.08–7.49), wheat biological yield (7831.1–22515.96 kg ha–1), grain yield (2481.3–9273.57 kg ha–1) and harvest index (32.86–53.90%). The interaction between planting date and plant genotypes indicated that the responses of different wheat genotypes to planting date were highly variable, significantly affecting light absorption and light extinction by wheat. It is possible to make the optimum use of solar light and produce the highest rate of yield if the most efficient genotype (Line 14-C81, Pishvaz and Pishtaz) is planted on the right planting date (15 November) using the optimum rate of N chemical fertilisation (50, 100, 150 kg ha–1).

Effect of Cycling and Swimming on Cardio-Respiratory Endurance among Long Distance Runners

The purpose of the study was to find out whether there would be any significant improvement on cardiorespiratory endurance as a result of cycling and swimming training among long distance runners. To achieve the purpose of the study, 45 long distance runners from different colleges and SDAT trainees were selected at random within Chennai. The selected subjects were in the age group of 18 to 22 years. The subjects were randomly divided in to three groups of 15 subjects in each group. Group one acted as experimental group I and group two acted as experimental group -II and group three acted as control group. Group three underwent routine without any special treatment and group I underwent cycling exercises and group II underwent swimming exercises for six weeks. Pre test scores were collected on selected criterion variable cardiorespiratory endurance through Coopers’ 12 minutes run/walk test. After six weeks of experimental treatments to the experimental groups, post test score on cardiorespiratory endurance was obtained. The differences between the initial and final score were the effect of respective experimental treatments. To test the statistical significance, the scores were subjected to ANCOVA and Scheffes’ post hoc test. The results of the study proved that cycling and swimming exercises significantly improved cardiorespiratory endurance of the long distance runners.

The Effect of Novel Research Activities on Long-term Survival of Temporarily Captive Steller Sea Lions (Eumetopias jubatus).

Two novel research approaches were developed to facilitate controlled access to, and long-term monitoring of, juvenile Steller sea lions for periods longer than typically afforded by traditional fieldwork. The Transient Juvenile Steller sea lion Project at the Alaska SeaLife Center facilitated nutritional, physiological, and behavioral studies on the platform of temporary captivity. Temporarily captive sea lions (TJs, n = 35) were studied, and were intraperitoneally implanted with Life History Transmitters (LHX tags) to determine causes of mortality post-release. Our goal was to evaluate the potential for long-term impacts of temporary captivity and telemetry implants on the survival of study individuals. A simple open-population Cormack-Jolly-Seber mark-recapture model was built in program MARK, incorporating resightings of uniquely branded study individuals gathered by several contributing institutions. A priori models were developed to weigh the evidence of effects of experimental treatment on survival with covariates of sex, age, capture age, cohort, and age class. We compared survival of experimental treatment to a control group of n = 27 free-ranging animals (FRs) that were sampled during capture events and immediately released. Sex has previously been show to differentially affect juvenile survival in Steller sea lions. Therefore, sex was included in all models to account for unbalanced sex ratios within the experimental group. Considerable support was identified for the effects of sex, accounting for over 71% of total weight for all a priori models with delta AICc <5, and over 91% of model weight after removal of pretending variables. Overall, most support was found for the most parsimonious model based on sex and excluding experimental treatment. Models including experimental treatment were not supported after post-hoc considerations of model selection criteria. However, given the limited sample size, alternate models including effects of experimental treatments remain possible and effects may yet become apparent in larger sample sizes.

Effect of Ocean Acidification and pH Fluctuations on the Growth and Development of Coralline Algal Recruits, and an Associated Benthic Algal Assemblage.

Coralline algae are susceptible to the changes in the seawater carbonate system associated with ocean acidification (OA). However, the coastal environments in which corallines grow are subject to large daily pH fluctuations which may affect their responses to OA. Here, we followed the growth and development of the juvenile coralline alga Arthrocardia corymbosa, which had recruited into experimental conditions during a prior experiment, using a novel OA laboratory culture system to simulate the pH fluctuations observed within a kelp forest. Microscopic life history stages are considered more susceptible to environmental stress than adult stages; we compared the responses of newly recruited A. corymbosa to static and fluctuating seawater pH with those of their field-collected parents. Recruits were cultivated for 16 weeks under static pH 8.05 and 7.65, representing ambient and 4× preindustrial pCO2 concentrations, respectively, and two fluctuating pH treatments of daily (daytime pH = 8.45, night-time pH = 7.65) and daily (daytime pH = 8.05, night-time pH = 7.25). Positive growth rates of new recruits were recorded in all treatments, and were highest under static pH 8.05 and lowest under fluctuating pH 7.65. This pattern was similar to the adults’ response, except that adults had zero growth under fluctuating pH 7.65. The % dry weight of MgCO3 in calcite of the juveniles was reduced from 10% at pH 8.05 to 8% at pH 7.65, but there was no effect of pH fluctuation. A wide range of fleshy macroalgae and at least 6 species of benthic diatoms recruited across all experimental treatments, from cryptic spores associated with the adult A. corymbosa. There was no effect of experimental treatment on the growth of the benthic diatoms. On the community level, pH-sensitive species may survive lower pH in the presence of diatoms and fleshy macroalgae, whose high metabolic activity may raise the pH of the local microhabitat.