Adult sockeye salmon (Oncorhynchus nerka) acquire infections with the myxosporean kidney parasite Parvicapsula minibicornis during their spawning migration in the Fraser River, British Columbia. Controlled infections with this parasite in wild sockeye salmon had no significant impact on plasma ionic status, metabolic rates, and initial maximum prolonged swimming performance (Ucrit) for fish ranked as either strongly, weakly, or noninfected by polymerase chain reaction analysis of kidney tissue. However, strongly infected fish had significantly lower second Ucrit and recovery ratio (8%) values, indicating decreased ability to recover from exercise. As the present study shows that the severity of infection is affected by time and temperature, the accumulated thermal units (ATU) of exposure in this study were compared with those experienced by naturally migrating sockeye salmon. A parallel telemetry study revealed that early-timed sockeye experienced significantly more ATU (741.4 ± 29.4 °C) than normally migrating salmon (436.0 ± 20.0 °C) prior to spawning because of a significantly longer holding period in the lake system. The present data are discussed in the context of a threshold of >450 °C ATU for severe infection that would first manifest in early-timed fish in the upper reaches of the Fraser River and certainly on the spawning grounds.

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.. The University of Chicago Press ABSTRACTWe present the first data on the differences in routine and active metabolic rates for sexually maturing migratory adult sockeye salmon (Oncorhynchus nerka) that were intercepted in the ocean and then held in either seawater or freshwater. Routine and active oxygen uptake rates (Mo 2 ) were significantly higher (27%-72%) in seawater than in freshwater at all swimming speeds except those approaching critical swimming speed. During a 45-min recovery period, the declining postexercise oxygen uptake remained 58%-73% higher in seawater than in freshwater. When fish performed a second swim test, active metabolic rates again remained 28%-81% higher for fish in seawater except at the critical swimming speed. Despite their differences in metabolic rates, fish in both seawater and freshwater could repeat the swim test and reach a similar maximum oxygen uptake and critical swimming speed as in the first swim test, even without restoring routine metabolic rate between swim tests. Thus, elevated Mo 2 related to either being in seawater as opposed to freshwater or not being fully recovered from previous exhaustive exercise did not present itself as a metabolic loading that limited either critical swimming performance or maximum Mo 2 . The basis for the difference in metabolic rates of migratory sockeye salmon held in seawater and freshwater is uncertain, but it could include differences in states of nutrition, reproduction, and restlessness, as well as ionic differences. Regardless, this study elucidates some of the metabolic costs involved during the migration of adult salmon from seawater to freshwater, which may have applications for fisheries conservation and management models of energy use.

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Employability development is a strategic priority for universities across advanced western economies. Despite this, there is no systematic study of employability development approaches internationally. In this study, we considered how universities portray employability on the public pages of their websites. We undertook website content analysis of 107 research-intensive universities in Australia, Canada, the United Kingdom (UK) and the United States (US). Using Farenga and Quinlan (2015), we classified these strategies as Portfolio, Handsoff, Award and Non-embedded. Portfolio or Award strategies were the most common across all four locations; Hands-off and Non-embedded strategies were more common to US universities; and Award was more common in the UK.Universities focused on either possessional or positional approaches to employability (Holmes, 2015). We advocate for a pedagogical shift towards processual approaches in which responsibility for employability development is shared.

Communication skills are one of five nationally recognised learning outcomes for an Australian Bachelor of Science (BSc) degree. Previous evidence indicates that communication skills taught in Australian undergraduate science degrees are not developed sufficiently to meet the requirements of the modern-day workplace-a problem faced in the UK and USA also. Curriculum development in this area, however, hinges on first evaluating how communication skills are taught currently as a base from which to make effective changes. This study aimed to quantify the current standard of communication education within BSc degrees at Australian research-intensive universities. A detailed evidential baseline for not only what but also how communication skills are being taught was established. We quantified which communication skills were taught and assessed explicitly, implicitly, or were absent in a range of undergraduate science assessment tasks (n = 35) from four research-intensive Australian universities. Results indicate that 10 of the 12 core science communication skills used for evaluation were absent from more than 50% of assessment tasks and 77.14% of all assessment tasks taught less than 5 core communication skills explicitly. The design of assessment tasks significantly affected whether communication skills were taught explicitly. Prominent trends were that communication skills in tasks aimed at non-scientific audiences were taught more explicitly than in tasks aimed at scientific audiences, and the majority of group and multimedia tasks taught communication elements more explicitly than individual, or written and oral tasks. Implications for science communication in the BSc and further research are discussed.

The hypothesis that cold air temperatures (Ta) constrain the metabolic diversity of high-latitude endotherms is based on the observation among birds and mammals that mean field metabolic rate (FMR) increases, whereas the variability of FMR decreases, from the warm tropics to the cold poles. However, there is a paucity of FMR measurements from above 60° latitude and below 0 °C. We measured the daily energy expenditure of a high-latitude population of free-ranging snowshoe hares ( Lepus americanus Erxleben, 1777) in Yukon, Canada, in winter (Ta-mean = –16.4 °C) and in autumn (Ta-mean = 0.5 °C). Doubly labelled water measures of FMR were approximately 20% lower in winter than in autumn, and were a similar, low multiple of resting metabolic rate in both seasons (2.04 and 1.94, respectively). The mass-corrected FMR of snowshoe hares in winter was only half the value predicted by extrapolating the relationship between FMR and Ta > 0 to –16.4 °C. These results contribute to an emerging pattern of a reversal in the relationship between FMR and Ta in free-ranging mammals from negative above 0 °C to positive below 0 °C. We refer to the positive, low Ta portion of this relationship as the cold shoulder, and suggest that it may reflect the general necessity for free-ranging mammals to use behavioural and (or) physiological means to conserve energy during long winters when cold conditions coincide with resource scarcity.

SUMMARYThe armoured catfish, Pterygoplichthys pardalis, is known to be extremely tolerant of environmental hypercarbia (elevated water CO 2 tensions), which occurs in their natural environment. In addition, previous studies have demonstrated that during exposure to hypercarbia, P. pardalis does not exhibit extracellular pH compensation and thus the heart and other organs must continue to function despite a severe extracellular acidosis. We used an in situ perfused heart preparation to determine the effects of an extracellular hypercapnic (elevated CO 2 in the animal) acidosis (1-7.5% CO 2 ) on heart function, specifically cardiac output, power output, heart rate and stroke volume. The present study is the first to comprehensively examine cardiac function in an acidosistolerant teleost. When compared with control conditions, maximum cardiac performance was unaffected at levels of CO 2 as high as 5%, far exceeding the hypercapnic tolerance of other teleosts. Moreover, P. pardalis exhibited only a moderate decrease (~35%) in cardiac performance when exposed to 7.5% CO 2 , and full cardiac performance was restored in six out of seven hearts upon return to control conditions. Myocardial intracellular pH (pH i ) was protected in situ, as has been found in vivo, and this protection extended to the highest level of CO 2 (7.5%) investigated. Thus, maintained heart function during a hypercapnic acidosis in P. pardalis is probably associated with preferential pH i regulation of the heart, but ultimately is not sufficient to prevent loss of cardiac function. Our findings suggest the need for further study to elucidate the mechanisms behind this remarkable cardiac hypercapnic tolerance.