Temperature affects susceptibility of intertidal limpets to bird predation.

High temperatures resulting in physiological stress and the reduced ability to resist predation can have life-or-death consequences for an organism. We investigated the effects of temperature on the susceptibility to predation for an ectothermic intertidal mollusc (the owl limpet, Lottia gigantea) and its predator (the black oystercatcher, Haematopus bachmani). The ability of L. gigantea to resist bird predation during low tide is determined by the tenacity of attachment to the rock. We developed a transducer to measure the force of predatory attacks on limpets by a captive black oystercatcher, and tested the hypothesis that exposure to warm temperatures during low tide emersion would affect the limpet's ability to resist dislodgement in trials with a morphometrically accurate beak mimic and a live bird. In beak mimic trials, four times as many limpets exposed to warm low tides were removed, as compared with limpets exposed to cool low tides or in 'no low tide' submerged conditions. Minimum time before limpet removal in captive bird trials was more than six times longer for limpets in cool low tide or no low tide treatments compared with limpets in the warm low tide treatment. We measured shear forces up to 36.63 N during predatory strikes. These direct measurements of the forces exerted by a living oystercatcher provide context for interactions with multiple prey species. Our data suggest that naturally occurring variation in body temperatures among individual prey items in the field could be an important driver of predator-prey interactions and subsequently community patterns.

The extraordinary joint material of an articulated coralline alga. I. Mechanical characterization of a key adaptation.

Flexibility is key to survival for seaweeds exposed to the extreme hydrodynamic environment of wave-washed rocky shores. This poses a problem for coralline algae, whose calcified cell walls make them rigid. Through the course of evolution, erect coralline algae have solved this problem by incorporating joints (genicula) into their morphology, allowing their fronds to be as flexible as those of uncalcified seaweeds. To provide the flexibility required by this structural innovation, the joint material of Calliarthron cheilosporioides, a representative articulated coralline alga, relies on an extraordinary tissue that is stronger, more extensible and more fatigue resistant than the tissue of other algal fronds. Here, we report on experiments that reveal the viscoelastic properties of this material. On the one hand, its compliance is independent of the rate of deformation across a wide range of deformation rates, a characteristic of elastic solids. This deformation rate independence allows joints to maintain their flexibility when loaded by the unpredictable - and often rapidly imposed - hydrodynamic force of breaking waves. On the other hand, the genicular material has viscous characteristics that similarly augment its function. The genicular material dissipates much of the energy absorbed as a joint is deformed during cyclic wave loading, which potentially reduces the chance of failure by fatigue, and the material accrues a limited amount of deformation through time. This limited creep increases the flexibility of the joints while preventing them from gradually stretching to the point of failure. These new findings provide the basis for understanding how the microscale architecture of genicular cell walls results in the adaptive mechanical properties of coralline algal joints.

The extraordinary joint material of an articulated coralline alga. II. Modeling the structural basis of its mechanical properties.

By incorporating joints into their otherwise rigid fronds, erect coralline algae have evolved to be as flexible as other seaweeds, which allows them to thrive - and even dominate space - on wave-washed shores around the globe. However, to provide the required flexibility, the joint tissue of Calliarthron cheilosporioides, a representative articulated coralline alga, relies on an extraordinary tissue that is stronger, more extensible and more fatigue resistant than that of other algae. Here, we used the results from recent experiments to parameterize a conceptual model that links the microscale architecture of cell walls to the adaptive mechanical properties of joint tissue. Our analysis suggests that the theory of discontinuous fiber-wound composite materials (with cellulose fibrils as the fibers and galactan gel as the matrix) can explain key aspects of the material's mechanics. In particular, its adaptive viscoelastic behavior can be characterized by two, widely separated time constants. We speculate that the short time constant (∼14 s) results from the viscous response of the matrix to the change in cell-wall shape as a joint is stretched, a response that allows the material both to remain flexible and to dissipate energy as a frond is lashed by waves. We propose that the long time constant (∼35 h), is governed by the shearing of the matrix between cellulose fibrils. The resulting high apparent viscosity ensures that joints avoid accumulating lethal deformation in the course of a frond's lifetime. Our synthesis of experimental measurements allows us to draw a chain of mechanistic inference from molecules to cell walls to fronds and community ecology.

Thermal variation, thermal extremes and the physiological performance of individuals.

In this review we consider how small-scale temporal and spatial variation in body temperature, and biochemical/physiological variation among individuals, affect the prediction of organisms' performance in nature. For 'normal' body temperatures - benign temperatures near the species' mean - thermal biology traditionally uses performance curves to describe how physiological capabilities vary with temperature. However, these curves, which are typically measured under static laboratory conditions, can yield incomplete or inaccurate predictions of how organisms respond to natural patterns of temperature variation. For example, scale transition theory predicts that, in a variable environment, peak average performance is lower and occurs at a lower mean temperature than the peak of statically measured performance. We also demonstrate that temporal variation in performance is minimized near this new 'optimal' temperature. These factors add complexity to predictions of the consequences of climate change. We then move beyond the performance curve approach to consider the effects of rare, extreme temperatures. A statistical procedure (the environmental bootstrap) allows for long-term simulations that capture the temporal pattern of extremes (a Poisson interval distribution), which is characterized by clusters of events interspersed with long intervals of benign conditions. The bootstrap can be combined with biophysical models to incorporate temporal, spatial and physiological variation into evolutionary models of thermal tolerance. We conclude with several challenges that must be overcome to more fully develop our understanding of thermal performance in the context of a changing climate by explicitly considering different forms of small-scale variation. These challenges highlight the need to empirically and rigorously test existing theories.

"You're a 'high-risk' customer": A qualitative study of women's experiences of receiving information from health professionals regarding health problems or complications in pregnancy.

BACKGROUND: Experiencing complications in pregnancy is stressful for women and can impact on fetal and maternal outcomes. Supportive encounters with health professionals can reduce the worry women experience. Further research is needed to understand women's perspectives on communicating with their healthcare providers about their concerns. AIM: This study explored women's experiences of receiving information about pregnancy complications from healthcare providers and their interactions with multiple professionals and services during pregnancy. METHODS: This was a qualitative interpretive study. Semi-structured interviews were conducted with 20 women experiencing pregnancy complications recruited from antenatal services at two hospitals in Sydney. Inductive thematic analysis was used to analyse the data. FINDINGS: Women had a range of reactions to their diagnoses, including concern for their baby, for themselves and for their labour. Most women reported that communication with healthcare providers was distressing, they were not listened to and staff used insensitive, abrupt language. Women were also distressed by delays in education, receiving contradictory information and having to repeatedly share their stories with different health professionals. In some cases, this damaged the therapeutic relationship and reduced trust towards healthcare providers. Midwives were generally preferred over doctors because they had a more woman-centred approach. CONCLUSION: To improve women's experiences of care for pregnancy complications, it is critical to improve the communication skills of maternity service providers. Women's need for information, resources and support can best be provided by continuity of care with a named health professional, for example, a midwife working within an integrated multidisciplinary antenatal service model.

Complications of Antenatal Corticosteroids in Infants Born by Early Term Scheduled Cesarean Section.

OBJECTIVE: To compare neonatal hypoglycemia and respiratory morbidity rates in pregnancies complicated by diabetes following early term scheduled cesarean section (ETSCS) with and without maternal corticosteroid administration. RESEARCH DESIGN AND METHODS: In a retrospective cohort study, women with any form of diabetes in pregnancy undergoing ETSCS were included. Primary outcomes were admission rates to the neonatal intensive care unit (NICU) for respiratory distress syndrome (RDS)/transient tachypnea of the newborn (TTN) and/or neonatal hypoglycemia. RESULTS: NICU admission rates for neonatal hypoglycemia were significantly higher (24.2% vs. 4.4%, P = 0.003) and RDS/TTN rates were nonsignificantly higher (15.2% vs. 7.2%, P = 0.209) following corticosteroid administration. CONCLUSIONS: Corticosteroids were not beneficial among women with any form of diabetes in pregnancy undergoing ETSCS and, indeed, may be harmful. In our hospital, we have ceased the use of corticosteroids for women under these circumstances.

Variation in Nugent score and leukocyte count in fluid collected from different vaginal sites.

OBJECTIVE: To assess the variability in Nugent score and leukocyte count measured in vaginal secretions collected from 3 vaginal sites. METHODS: Fifty pregnant women at less than 20 weeks of gestation were consecutively recruited at the time of their first prenatal visit. Three vaginal smears were collected from each woman, 1 from the posterior fornix, 1 from the mid-lateral wall, and 1 from the introitus. Smears were Gram stained and evaluated for bacterial vaginosis using Nugent's criteria. Each smear was classified as positive for bacterial vaginosis if the Nugent score was 7 or greater, intermediate if the score was between 4 and 6, and negative if the Nugent score was 3 or less. A mean leukocyte value was obtained for each slide by evaluating 5 fields under oil immersion. Repeated-measures analysis of variance was used to compare mean Nugent scores and leukocyte counts across sites. RESULTS: The sample consisted of mostly African-American, young, low-income women in their first trimester of pregnancy. Forty-seven percent were bacterial vaginosis-positive (Nugent score 7 or greater). Mean Nugent scores (+/- standard deviation) across the vaginal sample collection sites were similar: posterior fornix = 4.2 (4.4); mid-lateral wall = 4.2 (4.5); introitus = 4.2 (4.6). In contrast, the mean leukocyte count varied significantly across vaginal sample collection sites: 2.5 (4.2); mid-lateral wall = 2.8 (4.4); introitus = 6.5 (8.6) (F = 11.26 (1, 47.5); P = .002). CONCLUSION: Leukocyte counts vary according to the site from which vaginal secretions were obtained, with the highest leukocyte count in samples obtained from the introitus. Bacterial vaginosis diagnosis by Nugent score does not vary by site of sample collection.