Sarah Andrewartha | University of Tasmania (original) (raw)

Papers by Sarah Andrewartha

Many hybrids of marine molluscs show improved growth in comparison to their pure parental species... more Many hybrids of marine molluscs show improved growth in comparison to their pure parental species. Yet, little is known about the physiological mechanisms underlying the better hybrid performance. In this study, movement, oxygen consumption rate (ṀO 2), and heart rate were determined in 22 month old cultured abalone Haliotis rubra, H. laevigata and their interspecies hybrid, the latter of which exhibits improved growth rate. Abalone were exposed to an acute temperature increase following acclimation to 16 or 23°C at high and low oxygen levels (100% or 70% air saturation, respectively). Movement of hybrids and H. laevigata was generally not affected by temperature and oxygen levels, yet H. rubra showed a strong thermal response. Heart rate and ṀO 2 /temperature slopes revealed that hybrids were least affected by oxygen levels. Arrhenius break-point temperatures of hybrids and H. laevigata, but not H. rubra, were generally higher when abalone were acclimated to 23°C in comparison to 16°C. The hybrid had more stable maximum heart rate and ṀO 2 values across acclimation conditions in comparison to H. laevigata and H. rubra. Thus, it appears that hybrids are able to maintain physiological functions over a broader environmental range. This improved tolerance to environmental fluctuations may bolster energy metabolism and improve growth in variable environments such as aquaculture farms.

Temperature is one of the main factors influencing biological processes of ectothermic species. A... more Temperature is one of the main factors influencing biological processes of ectothermic species. An optimum
temperature of 16–18C has been suggested for the development of early life stages of temperate Australian abalone, yet there
are little physiological or behavioral data to support this suggestion. This study examines the acute thermal preferences (Tpref),
swimming speeds (U), and oxygen consumption rates (MO_ 2) of veliger larvae of blacklip abalone [Haliotis rubra (Leach, 1814)],
greenlip abalone [Haliotis laevigata (Donovan, 1808)], and their interspecies hybrid. Thermal preference and U were measured
in a thermal gradient with temperatures ranging from 12C to 25C, and MO_ 2 was measured at 4–7 temperatures between 12C
and 32C. Thermal preference increased in all three groups of abalone during development from a Tpref of 16C in 1-day-old
early veligers to a Tpref of 20C in 3-day-old late veligers. Swimming speed increased with temperature in all three groups of
abalone and increased with age in H. rubra and hybrids but not in H. laevigata. Veliger MO_ 2 increased throughout the
ecologically relevant temperature range in all three abalone groups. Higher temperatures were examined in hybrids, and it was
found that MO_ 2 reached a peak at 25C and declined thereafter. These results align with the temperatures that veligers may
experience in their natural habitat and provide support that current temperatures maintained at Australian aquaculture
hatcheries are within optimal ranges for larval performance.

Haemoglobin concentration ([Hb]) is measured for a wide variety of animal studies. The use of poi... more Haemoglobin concentration ([Hb]) is measured for a wide variety of animal studies. The use of point-of-care devices, such as the HemoCue, is becoming increasingly common because of their portability, relative ease of use and low cost. In this study, we aimed to determine whether the [Hb] of blue-tongued skink (Tiliqua nigrolutea) blood can be determined accurately using the HemoCue and whether the HemoCue overestimates the [Hb] of reptile blood in a similar manner to fish blood. Additionally, we aimed to test whether ploidy affected [Hb] determined by the HemoCue using blood from diploid and triploid Atlantic salmon (Salmo salar). The HemoCue Hb 201 + systematically overestimated [Hb] in both blue-tongued skinks and Atlantic salmon, and there was no difference between calibration equations determined for diploid or triploid salmon. The overesti-mation was systematic in both species and, as such, [Hb] determined by the HemoCue can be corrected using appropriate calibration equations. Cite as: Andrewartha SJ, Munns SL, Edwards A (2016). Calibration of the HemoCue point-of-care analyser for determining haemoglobin concentration in a lizard and a fish. Conserv Physiol 4: doi:10.1093/conphys/cow006.

Respiratory physiology & neurobiology, 2012

Acid-base and hematocrit (Hct) responses of vertebrate embryos to severe hypoxia are as yet unkno... more Acid-base and hematocrit (Hct) responses of vertebrate embryos to severe hypoxia are as yet unknown, but may reveal the maturation process of physiological regulatory mechanisms. The present study elucidated how acute, severe hypoxia (10% O 2 , with and without 5% CO 2 ) affects Hct and blood acid-base balance in late prenatal (days 11-19) chicken embryos. The time-course of the resulting Hct changes and blood acid-base disturbances was examined in detail in day 15 (d15) embryos to further understand the magnitude and time-components of these physiological changes. We hypothesized that Hct of developing embryos increases during severe hypoxia (10% O 2 ) and hypercapnic hypoxia (5%CO 2 , 10%O 2 ), due to increased mean corpuscular volume (MCV) and red blood cell concentration ([RBC]). We additionally hypothesized that 10% O 2 would induce anaerobic glycolysis and the attendant increase in lactate concentration ([La − ]) would create a severe metabolic acidosis. Hct increased in all embryos (d11-d19) during severe hypoxia (2 h) but, with the exception of d19 embryos, the increase was due to increased MCV and was therefore unlikely related to O 2 transport. The time-course of the d15 embryonic Hct response to hypoxic or hypercapnic hypoxic exposure was very rapid with MCV increasing within 30 min. Severe metabolic acidosis occurred in all developing embryos (d11-d19) during 2 h hypoxic exposure. Additionally, respiratory acidosis was induced in d15 embryos during hypercapnic hypoxia, with acid-base status recovering within 120 min in air. Throughout hypoxic exposure and recovery, changes in [HCO 3 − ] were matched by those in [La − ], indicating that anaerobic glycolysis is a key factor determining the metabolic alterations and overall acid-base status. Further, the blood gas and Hct values recovered in air and unchanged embryo mass suggest that the hypoxia-induced disturbances were only transient and may not affect long-term survival. (W.W. Burggren). acid transport systems modulated via changes in osmolality (Osm), P O 2 , P CO 2 and pH (for reviews see .

Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2007

environment where they can interact with each other. Since then, new simulations approaches were ... more environment where they can interact with each other. Since then, new simulations approaches were created and individualbased model (IBM) simulations have been widely used in population dynamics and they are thought considering that complex patterns can emerge from the interaction among individuals. In the IBM, populations are represented by entities, which are called individuals, with individualized propertieslife cycle, individual behavior and determined location. The IBM models a real individual with relevant attributes for simulation evolution, which makes this approach an excellent tool to simulate population dynamics with animals interacting with environment. Our work here presented uses IBM approach to investigate a population concerning distances covered and energetic budgets of each individual in a limited environment where the food availability can change due to competition or food existence.

Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2007

Aquaculture is globally the fastest growing primary industry (>6% per annum). Smart-farming, usin... more Aquaculture is globally the fastest growing primary industry (>6% per annum). Smart-farming, using sentinel animals equipped with miniature biosensors alongside environmental sensors and farm management systems has the potential to revolutionize all sectors of the industry. Real-time animal and environmental monitoring together, will support improved farm management decisions, animal welfare, social awareness and consequently sustainable productivity.
Biosensors that monitor the physiology and behavior of sentinel animals provide information on animal well-being
and its responses to environmental change and management actions. In turn, this information is extrapolated to help with stock management decisions. This paper introduces the sentinel animal concept to commercial aquaculture with a case study using oysters fitted with biosensors that measure heart rate, and other parameters. We demonstrate how sentinel animals can be effectively integrated alongside environmental sensors into an on-farm sensor network and decision support system.

Physiological and Biochemical Zoology, 2010

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.

An in situ optical oyster heart rate sensor generates signals requiring frequency estimation with... more An in situ optical oyster heart rate sensor generates
signals requiring frequency estimation with properties different
to human ECG and speech signals. We discuss the method
of signal generation and highlight a number of these signal
properties. An optimal heart rate estimation approach was
identified by application of a variety of frequency estimation
techniques and comparing results to manually acquired values.
Although a machine learning approach achieved the best
performance, accurately estimating 96.8% of the heart rates
correctly, a median filtered autocorrelation approach achieved
93.7% with significantly less computational requirement.
A method for estimating heart rate variation is also presented.

Marsupial joeys are born ectothermic and develop endothermy within their mother's thermally stabl... more Marsupial joeys are born ectothermic and develop endothermy within their mother's thermally stable pouch. We hypothesised that tammar wallaby joeys would switch from α-stat to pH-stat regulation during the transition from ectothermy to endothermy. To address this, we compared ventilation (VE), metabolic rate (VO2) and variables relevant to blood gas and acid-base regulation and oxygen transport including the ventilatory requirements (VE⁄VO2)and VE⁄VCO2), partial pressures of oxygen (PaO2), carbon dioxide (PaCO2), pHa and oxygen content (CaO2) during progressive hypothermia in ecto- and endothermic tammar wallabies. We also measured the same variables in the well-studied endotherm, the Sprague-Dawley rat. Hypothermia was induced in unrestrained, unanesthetized joeys and rats by progressively dropping the ambient temperature (Ta). Rats were additionally exposed to helox (80% helium, 20% oxygen) to facilitate heat loss. Respiratory, metabolic and blood-gas variables were measured over a large body temperature (Tb) range (~15-16°C in both species). Ectothermic joeys displayed limited thermogenic ability during cooling: after an initial plateau, VO2 decreased with the progressive drop in Tb. The Tb of endothermic joeys and rats fell despite VO2 nearly doubling with the initiation of cold stress. In all three groups the changes in VO2 were met by changes in VE, resulting in constant VE⁄VO2 and VE⁄VCO2, blood gases and pHa. Thus, although thermogenic capability was nearly absent in ectothermic joeys, blood acid-base regulation was similar to endothermic joeys and rats. This suggests that unlike some reptiles, unanesthetized mammals protect arterial blood pH with changing Tb, irrespective of their thermogenic ability and/or stage of development.

Crocodilians use a combination of three muscular mechanisms to effect lung ventilation: the inter... more Crocodilians use a combination of three muscular mechanisms to effect lung ventilation: the intercostal muscles producing thoracic movement, the abdominal muscles producing pelvic rotation and gastralial translation, and the diaphragmaticus muscle producing visceral displacement. Earlier studies suggested that the diaphragmaticus is a primary muscle of inspiration in crocodilians, but direct measurements of the diaphragmatic contribution to lung ventilation and gas exchange have not been made to date. In this study, ventilation, metabolic rate and arterial blood gases were measured from juvenile estuarine crocodiles under three conditions: (i) while resting at 30°C and 20°C; (ii) while breathing hypercapnic gases; and (iii) during immediate recovery from treadmill exercise. The relative contribution of the diaphragmaticus was then determined by obtaining measurements before and after transection of the muscle. The diaphragmaticus was found to make only a limited contribution to lung ventilation while crocodiles were resting at 30°C and 20°C, and during increased respiratory drive induced by hypercapnic gas. However, the diaphragmaticus muscle was found to play a significant role in facilitating a higher rate of inspiratory airflow in response to exercise. Transection of the diaphragmaticus decreased the exercise-induced increase in the rate of inspiration (with no compensatory increases in the duration of inspiration), thus compromising the exercise-induced increases in tidal volume and minute ventilation. These results suggest that, in C. porosus, costal ventilation alone is able to support metabolic demands at rest, and the diaphragmaticus is largely an accessory muscle used at times of elevated metabolic demand.

Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2011

Oxygen demand increases during embryonic development, requiring an increase in red blood cells (R... more Oxygen demand increases during embryonic development, requiring an increase in red blood cells (RBCs) containing hemoglobin (Hb) to transport O 2 between the respiratory organ and systemic tissues. A thorough ontogenetic understanding of the onset and maturation of the complex regulatory processes for RBC concentration ([RBC]), Hb concentration ([Hb]), hematocrit (Hct), mean corpuscular indices (mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration ([MCHb])) is currently lacking. We hypothesize that during the last half of incubation when the respiratory organ (the chorioallantoic membrane) envelops most of the egg contents, mean corpuscular indices will stabilize. Accordingly, Hct, [RBC] and [Hb] must also all change proportionally across development. Further, we hypothesize that the hematological respiratory variables develop and mature as a function of incubation duration, independently of embryonic growth. As predicted, a similar increase in Hct (from 18.7 ± 0.6% on day 10 (d10) to 34.1 ± 0.5% on d19 of incubation), [RBC] (1.13 ± 0.03 × 10 6 /μL to 2.50 ± 0.03 × 10 6 /μL) and [Hb] (6.1 ± 0.2 g% to 11.2 ± 0.1 g%) occurred during d10-19. Both [RBC] and [Hb] demonstrated high linear correlation with Hct, resulting in constant [MCHb] (~33 g% from d10 to d19). The decrease in MCV (from~165 μ 3 on d10 to~140 μ 3 on d13) and MCH (~55 pg to~45 pg) during d10-13, may be attributed to a changeover from larger primary to smaller secondary and adult-type erythrocytes with MCV and MCH remaining constant (~140 μ 3 and~45 pg respectively) for the rest of the incubation period (d13-19). Hematological respiratory values on a given incubation day were identical between embryos of different masses using either natural mass variation or experimental growth acceleration, indicating that the hematological variables develop as a function of incubation time, irrespective of embryo growth.

How the determinants of hematocrit (Hct) -alterations in mean corpuscular volume (MCV) and/or red... more How the determinants of hematocrit (Hct) -alterations in mean corpuscular volume (MCV) and/or red blood cell concentration ([RBC]) -are influenced by acid-base balance adjustments across development in the chicken embryo is poorly understood. We hypothesized, based on oxygen transport needs of the embryos, that Hct will increase during 1 day of hypercapnic hypoxia (5%CO 2 , 15%O 2 ) or hypoxia alone (0%CO 2 , 15%O 2 ), but decrease in response to hyperoxia (0%CO 2 , 40%O 2 ). Further, age-related differences in acid-base disturbances and Hct regulation may arise, because the O 2 transport and hematological regulatory systems are still developing in embryonic chickens. Our studies showed that during 1 day of hypoxia (with or without hypercapnia) Hct increased through both increased MCV and [RBC] in day 15 (d15) embryo, but only through increased MCV in d17 embryo and therefore enhancement of O 2 transport was age-dependent. Hypercapnia alone caused a ∼14% decrease in Hct through decreased [RBC] and therefore did not compensate for decreased blood oxygen affinity resulting from the Bohr shift. The 11% (d15) and 14% (d17) decrease in Hct during hyperoxia in advanced embryos was because of an 8% and 9% decrease, respectively, in [RBC], coupled with an associated 3% and 5% decrease in MCV. Younger, d13 embryos were able to metabolically compensate for respiratory acidosis induced by hypercapnic hypoxia, and so were more tolerant of disturbances in acid-base status induced via alterations in environmental respiratory gas composition than their more advanced counterparts. This counter-intuitive increased tolerance likely results from the relatively lowṀ O 2 and immature physiological functions of younger embryos.

The regulation of blood acid-base balance and hematology in day 15 chicken embryos in response to... more The regulation of blood acid-base balance and hematology in day 15 chicken embryos in response to partial water submersion (with egg's air cell in air) and complete submersion producing severe intrinsic hypercapnic hypoxia and recovery in air was studied. The acid-base disturbance during submersion was characterized by initial rapid respiratory changes and then superseded by metabolic processes, resulting in a large progressive hysteresis. Throughout submersion and recovery, blood lactate concentration changed swiftly along with the changes in bicarbonate concentration ([HCO 3 − ]), indicating that anaerobic glycolysis determined overall acid-base disturbances. Both partial and complete submersion produced large, rapid increases in hematocrit through proportional increases in mean corpuscular volume and red blood cell concentration. Death ensued once the internal pool of O 2 was exhausted and/or the acid-base disturbance became too severe for survival (i.e., [HCO 3 − ] a < ∼10 mmol L −1 ). However, embryos recovered from acid-base and hematological disturbances within 120 min recovery in air after short bouts of complete (20 min) or partial (60 min) submersion, suggesting that shorter severe intrinsic hypercapnic hypoxia does not compromise viability of embryos.

Respiratory Physiology & Neurobiology, 2011

Hematocrit (Hct) regulation is a complex process involving potentially many factors. How such reg... more Hematocrit (Hct) regulation is a complex process involving potentially many factors. How such regulation develops in vertebrate embryos is still poorly understood. Thus, we investigated the role of blood pH in the regulation of Hct across developmental time in chicken embryos. We hypothesized that blood pH alterations in vitro (i.e., in a test tube) would affect Hct far more than in vivo because of in vivo compensatory regulatory processes for Hct. Large changes in Hct (through mean corpuscular volume (MCV)) and blood osmolality (Osm) occur when the blood was exposed to varying ambient temperatures (T a 's) and P CO 2 in vitro alongside an experimentally induced blood pH change from ∼7.3 to 8.2. However, homeostatic regulatory mechanisms apparently limited these alterations in vivo. Changes in blood pH in vitro were accompanied by hydration or dehydration of red blood cells depending on embryonic age, resulting in changes in Hct that also were specific to developmental stage, due likely to initial blood gas and [HCO 3 − ] v values. Significant linear relationships between Hct and pH (Hct/ pH = −21.4%/(pH unit)), Hct and [HCO 3 − ] ( Hct/ [HCO 3 − ] = 1.6%/(mEq L −1 )) and the mean buffer value ( [HCO 3 − ]/ pH = −13.4 (mEq L −1 )/(pH unit)) demonstrate that both pH and [HCO 3 − ] likely play a role in the regulation of Hct through MCV at least in vitro. Low T a (24 • C) resulted in relatively large changes in pH with small changes in Hct and Osm in vitro with increased T a (42 • C) conversely resulting in larger changes in both Hct and Osm. In vivo exposure to altered T a caused age-dependent changes in Hct, demonstrating a trend towards increased Hct at higher T a . Further, exposing embryos to a gas mixture where P CO 2 = 5.1 kPa for >4 h period at T a of 37 or 42 • C also did not elicit a change in Hct or Osm. Presumably, homeostatic mechanisms ensured that in vivo Hct was stable during a 4-6 h temperature and/or hypercapnic stress. Thus, although blood pH decreases (induced by acute T a increase and exposure to CO 2 ) increase MCV and, consequently, Hct in vitro, homeostatic mechanisms operating in vivo are adequate to ensure that such environmental perturbations have little effect in vivo.

Respiratory Physiology & Neurobiology, 2011

Embryo and hatchlings Heart rate: mean and instantaneous, variability and irregularities Environm... more Embryo and hatchlings Heart rate: mean and instantaneous, variability and irregularities Environmental challenge: hypoxia, hyperoxia and temperature Thermoregulation Endothermic response a b s t r a c t Long-term measurements (days and weeks) of heart rate (HR) have elucidated infradian rhythms in chicken embryos and circadian rhythms in chicken hatchlings. However, such rhythms are lacking in emu embryos and only rarely observed in emu hatchlings. Parasympathetic control of HR (instantaneous heart rate (IHR) decelerations) occurs at ∼60% of incubation in both precocial and altricial avian embryos, with sympathetic control (IHR accelerations) becoming more prevalent close to hatching. A large increase in avian embryonic HR occurs during hatching (presumably an energetically expensive process, i.e. increased oxygen consumption (Ṁ O 2 )), beginning during pipping when a physical barrier to O 2 conductance is removed. Alterations in ambient O 2 have little effect on early embryonic HR, likely due to the low rate ofṀ O 2 of early embryos and the fact that adequate O 2 delivery can occur via diffusion. AsṀ O 2 increases in advanced embryos and circulatory convection becomes important for O 2 delivery, alterations in ambient O 2 have more profound effects on embryonic HR. Early embryos demonstrate a wide ambient temperature (T a ) tolerance range compared with older embryos. In response to a rapid decrease in T a , embryonic HR decreases (stroke volume and blood flow are preserved) in an exponential fashion to a steady state (from which it can potentially recover if re-warmed). A more severe decrease in T a results in complete cessation of HR; however, depending on developmental age, embryos are able to survive severe cold exposure and cessation of HR for up to 24 h in some instances. The development of endothermy can be tracked by measuring baseline HR during T a changes. HR patterns change from thermo-conformity to thermoregulation (reverse to T a changes). Further, IHR low frequency oscillations mediated by the autonomic nervous system are augmented at low T a s in hatchlings. Transitions of baseline HR during endothermic development are unique to individual avian species (e.g. chickens, ducks and emu), reflecting differences in life history.

Journal of Experimental Biology, 2008

The terrestrial embryos of many amphibians obtain water in two ways; in a liquid phase from the s... more The terrestrial embryos of many amphibians obtain water in two ways; in a liquid phase from the substrate on which eggs are deposited, and in a vapour phase from the surrounding atmosphere. We tested whether the mode of water flux (liquid or vapour) affected the morphology and metabolic traits of the terrestrial Victorian smooth froglet (Geocrinia victoriana) embryos by incubating eggs both with a liquid water source and at a range of vapour water potentials. We found that embryos incubated with a liquid water source (ψ π =0 kPa) were better hydrated than embryos incubated with a vapour water source (ψ v =0 kPa), and grew to a larger size. Eggs incubated in atmospheres with lower ψ v values showed significant declines in mass and in the thickness of the jelly capsule, while embryos primarily showed reductions in dry mass, total length, tail length and fin height. The most significant deviations from control (ψ v =0 kPa) values were observed when the ψ v of the incubation media was less than the osmotic water potential (ψ π ) of the embryonic interstitial fluid (approximately -425 kPa). Despite the caveat that a ψ v of 0 kPa is probably difficult to achieve under our experimental conditions, the findings indicate the importance for eggs under natural conditions of contacting liquid water in the nesting substrate to allow swelling of the capsule.

Respiratory physiology & neurobiology, 2012

Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2007

Physiological and Biochemical Zoology, 2010

Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2011

Respiratory Physiology & Neurobiology, 2011

Journal of Experimental Biology, 2008