Cortisol, blood pressure, and heart rate responses to food intake were independent of physical fitness levels in women

This research tested the hypothesis that women who had higher levels of physical fitness will have lower hypothalamo-pituitary-adrenal axis (cortisol) and sympatho-adrenal medullary system (blood pressure and heart rate) responses to food intake compared with women who had low levels of physical fitness. Lower fitness (n = 22; maximal oxygen consumption = 27.4 ± 1.0 mL∙kg(-1)·min(-1)) and higher fitness (n = 22; maximal oxygen consumption = 41.9 ± 1.6 mL∙kg(-1)·min(-1)) women (aged 30-50 years; in the follicular phase of the menstrual cycle) who participated in levels of physical activity that met (lower fitness = 2.7 ± 0.5 h/week) or considerably exceeded (higher fitness = 7.1 ± 1.4 h/week) physical activity guidelines made their own lunch using standardised ingredients at 1200 h. Concentrations of cortisol were measured in blood samples collected every 15 min from 1145-1400 h. Blood pressures and heart rate were also measured every 15 min between 1145 h and 1400 h. The meal consumed by the participants consisted of 20% protein, 61% carbohydrates, and 19% fat. There was a significant overall response to lunch in all of the parameters measured (time effect for all, p < 0.01). The cortisol response to lunch was not significantly different between the groups (time × treatment, p = 0.882). Overall, both groups showed the same pattern of cortisol secretion (treatment p = 0.839). Systolic blood pressure, diastolic blood pressure, mean arterial pressure, or heart rate responses (time × treatment, p = 0.726, 0.898, 0.713, and 0.620, respectively) were also similar between higher and lower fitness women. Results suggest that the physiological response to food intake in women is quite resistant to modification by elevated physical fitness levels.

Holocene record of Tuggerah Lake estuary development on the Australian east coast: sedimentary responses to sea-level fluctuations and climate variability

We investigated the Holocene palaeo-environmental record of the Tuggerah Lake barrier estuary on the south-east coast of Australia to determine the influence of local, regional and global environmental changes on estuary development. Using multi-proxy approaches, we identified significant down-core variation in sediment cores relating to sea-level rise and regional climate change. Following erosion of the antecedent land surface during the post-glacial marine transgression, sediment began to accumulate at the more seaward location at ~8500. years before present, some 1500. years prior to barrier emplacement and ~4000. years earlier than at the landward site. The delay in sediment accumulation at the landward site was a consequence of exposure to wave action prior to barrier emplacement, and due to high river flows of the mid-Holocene post-barrier emplacement. As a consequence of the mid-Holocene reduction in river flows, coupled with a moderate decline in sea-level, the lake experienced major changes in conditions at ~4000. years before present. The entrance channel connecting the lake with the ocean became periodically constricted, producing cyclic alternation between intervals of fluvial- and marine-dominated conditions. Overall, this study provides a detailed, multi-proxy investigation of the physical evolution of Tuggerah Lake with causative environmental processes that have influenced development of the estuary.

Small reptile community responses to rotational logging

Timber harvesting is a common global disturbance that has important effects on the ability of forests to provide ecosystems services and retain biodiversity. Using predictive frameworks to examine biodiversity responses to logging could assist in retaining natural forest values. The intermediate disturbance hypothesis (IDH) and the habitat accommodation model (HAM) potentially offer frameworks for explaining different coarse scale community responses to logging. We used a 60. year post-logging chronosequence to investigate small reptile community responses to age post-logging in temperate forests using three metrics (species richness, evenness and relative abundance). First, we evaluated if variation in these metrics adhered to prior predictions, including the IDH. Second, we evaluated how age post-logging influence community responses through fine scale vegetation elements. Third, we evaluated support for the HAM by measuring compositional change (species turnover) of small reptile community to age post-logging. Reptile relative abundance exhibited a curvilinear relationship to age since logging, contradicting our prior prediction of sustained increase. Species richness and evenness were unrelated to age since logging thus providing no support to IDH and other prior predictions. Relative abundance and richness did not relate to any vegetation characteristic tested. These metrics were also unrelated to logging method. Community composition was marginally significantly influenced by age since logging, thus supporting the HAM. Our results suggest that forest reptiles exposed to logging exhibit variable changes depending on the community metric in question, and that different approaches, including those based on species traits, are needed to improve evaluating disturbance related biodiversity responses.

Fish responses to experimental fragmentation of seagrass habitat

Understanding the consequences of habitat fragmentation has come mostly from comparisons of patchy and continuous habitats. Because fragmentation is a process, it is most accurately studied by actively fragmenting large patches into multiple smaller patches. We fragmented artificial seagrass habitats and evaluated the impacts of fragmentation on fish abundance and species richness over time (1 day, 1 week, 1 month). Fish assemblages were compared among 4 treatments: control (single, continuous 9-m(2) patches); fragmented (single, continuous 9-m(2) patches fragmented to 4 discrete 1-m(2) patches); prefragmented/patchy (4 discrete 1-m(2) patches with the same arrangement as fragmented); and disturbance control (fragmented then immediately restored to continuous 9-m(2) patches). Patchy seagrass had lower species richness than actively fragmented seagrass (up to 39% fewer species after 1 week), but species richness in fragmented treatments was similar to controls. Total fish abundance did not vary among treatments and therefore was unaffected by fragmentation, patchiness, or disturbance caused during fragmentation. Patterns in species richness and abundance were consistent 1 day, 1 week, and 1 month after fragmentation. The expected decrease in fish abundance from reduced total seagrass area in fragmented and patchy seagrass appeared to be offset by greater fish density per unit area of seagrass. If fish prefer to live at edges, then the effects of seagrass habitat loss on fish abundance may have been offset by the increase (25%) in seagrass perimeter in fragmented and patchy treatments. Possibly there is some threshold of seagrass patch connectivity below which fish abundances cannot be maintained. The immediate responses of fish to experimental habitat fragmentation provided insights beyond those possible from comparisons of continuous and historically patchy habitat.