Search

Balancing urban development with environmental sustainability is a major challenge that is increasingly recognized in planning decisions. Urban development proposals are often approved with the expectation that deleterious impacts on native species will be constrained, but this assumption is rarely tested over sufficient timelines to confirm its validity for long‐lived, at‐risk species. We tracked changes in Blanding's turtle (Emydoidea blandingii) habitat availability and demography over 10 years near Ottawa, ON, Canada, to determine whether urban development and associated mitigation measures were sufficient to ensure long‐term population persistence. Suitable turtle habitat declined by 10% during the study, and wetland corridors were essentially lost. Habitat loss coincided with a marked reduction in adult turtle apparent survival, resulting in a 70% decline in population size. Adult females experienced the greatest decline, and despite wildlife fencing and culvert placement as conditions of project approval, turtle road mortality likely was the primary cause of the decline. Deterministic population viability analysis revealed that ~4 adult female road mortalities (of an initial 56 females) per year produced a comparable decline to that observed in our population estimates; at this rate, the population will likely breach its quasi‐extinction threshold (4 females) in under a decade. Accordingly, we infer that in our study area, approved urban development was not compatible with at‐risk turtle population viability. Our findings imply that urban development approval conditions, even when conducted in the context of seemingly robust species‐at‐risk protection, can be inadequate to ensure sustainability. We contend that if environmental sustainability is to be prioritized, urban development projects in areas occupied by at‐risk species must be subject to more stringent oversight during the planning, approval and implementation phases. [ABSTRACT FROM AUTHOR]

The current study investigated the behavioural response of Lepomis macrochirus following exposures to elevated carbon dioxide ( CO2). For this, L. macrochirus were held at ambient p CO2 (160 μatm p CO2) for 7 days, then exposed to elevated p CO2 (8300 μatm p CO2) for 5 days, and then returned to ambient conditions for a further 5 days to recover. At the end of each exposure period, several behavioural metrics were quantified (boldness, lateralization and activity). Data showed no change in lateralization and most metrics associated with performance and boldness. During the boldness test, however, average velocity, velocity in the thigmotaxis (outer) zone and proportion of activity in the thigmotaxis zone increased with p CO2 exposure. During post-exposure, average velocity of L. macrochirus decreased. In addition, individual rank was repeatable during the pre-exposure and post-exposure period in three of the 17 metrics investigated (average velocity in the middle zone, average velocity near object and total shuttles to the object zone), but not during the CO2 exposure period, suggesting that elevated p CO2 disrupted some behavioural performances. Overall, this study found elevated p CO2 caused disruption to behaviours of freshwater fishes such as L. macrochirus and effects do not appear to be as serious as has been shown for marine fishes. [ABSTRACT FROM AUTHOR]

Understanding how released fish recover following capture is vital information for researchers examining the effects of angling on exploited populations. This information is virtually non-existent for fish angled through the ice in winter, despite the popularity of ice-angling in many northern areas. To address this gap, 60 northern pike, Esox lucius L., were angled through the ice from an impoundment in eastern Wisconsin, USA, and subjected to one of ten combinations of handling and recovery duration. Plasma samples were collected and analysed for cortisol, lactate and glucose. The results showed a delayed response in the elevation of plasma variables, and a significant interaction between air exposure and recovery time for plasma lactate. No fish suffered mortality during the period of holding. Collectively, these data suggest that northern pike are physiologically resilient to ice-angling capture stress as long as air exposure times are kept at 4 min or less. [ABSTRACT FROM AUTHOR]

Laboratory-based studies of locomotory performance in many taxa have noted that individuals form stable hierarchies of organismal performance. Though laboratory studies of teleost fishes have consistently demonstrated individual repeatability of swimming performance, this phenomenon has rarely been studied in the field and never across multiple years. Using a whole-lake acoustic telemetry array with submetre accuracy, we assessed the individual repeatability of two metrics of swimming performance (daily distance traveled and mean daily swimming speed) within four seasons during a year (fall, winter, spring, and summer), among these seasons, and between winters of 2 years. Largemouth bass (Micropterus salmoides (Lacepède, 1802)) formed stable performance hierarchies within seasons except spring and no sex-specific differences in rankings were noted. Individual swimming performance was not repeatable among seasons during 1 year or across multiple winters. Seasonal changes in environmental and intrinsic biological conditions appear to result in a reshuffling of performance hierarchies, perhaps reflecting individual differences in organismal physiology. [ABSTRACT FROM AUTHOR]

In this study, field biotelemetry and laboratory physiology approaches were coupled to allow understanding of the behavioral and physiological responses of fish to winter hypoxia. The biotelemetry study compared dissolved oxygen levels measured throughout the winter period with continually tracked locations of nine adult largemouth bass obtained from a whole-lake submerged telemetry array. Fish habitat usage was compared with habitat availability to assess whether fish were selecting for specific dissolved oxygen concentrations. The laboratory study examined behavioral and physiological responses to progressive hypoxia in juvenile largemouth bass acclimated to winter temperatures. Results from the dissolved oxygen measurements made during the biotelemetry study showed high variance in under-ice dissolved oxygen levels. Avoidance of water with dissolved oxygen <2.0 mg/L by telemetered fish was demonstrated, but significant use of water with intermediate dissolved oxygen levels was also found. Results from the lab experiments showed marked changes in behavior (i.e., yawning and vertical movement) at <2.0 mg/L of dissolved oxygen but no change in tissue lactate, an indicator of anaerobic metabolism. Combined results of the biotelemetry and laboratory studies demonstrate that a dissolved oxygen content of 2.0 mg/L may be a critical threshold that induces behavioral responses by largemouth bass during the winter. In addition, the use by fish of areas with intermediate levels of dissolved oxygen suggests that there are multiple environmental factors influencing winter behavior. [ABSTRACT FROM AUTHOR]

Because fish are poikilothermic, water temperature is regarded as a primary factor influencing their activity and behaviour. Rarely have field studies been conducted with the spatiotemporal resolution to enable rigorous quantitative assessments of that relationship. Furthermore, there have been few studies that have considered the influence of sex on the seasonal behaviour of fish. Twenty largemouth bass (Micropterus salmoides (Lacepède, 1802)) were implanted with coded acoustic telemetry transmitters and remotely tracked in near real time in a small lake in Ontario, Canada, via a whole-lake hydrophone array between 1 November 2004 and 30 September 2005. Fish inhabited the deepest waters and were least active during the winter months under ice. During the warmest months, fish were most active and inhabited the littoral zone. Sex-specific differences were noted year-round. Reproductive males were less active and inhabited shallower depths during the spawning and post-reproductive periods. Reproductive males inhabited the deepest depths during winter and fall, with nonreproductive males at the shallowest depths. Throughout the year, the behaviour of nonreproductive males and females was similar. While differences in behaviour of bass are primarily driven by water temperature, sex and reproductive status play important roles year-round, especially during and after the reproductive period. Parce que les poissons sont des poïkilothermes, la température de l’eau est considérée comme un des facteurs principaux qui influencent leur activité et leur comportement. De rares études ont été menées à une échelle spatio-temporelle assez fine pour permettre des évaluations quantitatives rigoureuses de cette relation. De plus, peu d’études ont pris en considération l’influence du sexe sur le comportement saisonnier des poissons. Nous avons muni 20 achigans à grande bouche (Micropterus salmoides (Lacepède, 1802)) d’émetteurs acoustiques codés de télémétrie et nous les avons suivis en temps quasi réel dans un petit lac de l’Ontario, Canada, à l’aide d’un réseau d’hydrophones répartis sur l’ensemble du lac entre le 1er novembre 2004 et le 30 septembre 2005. Les poissons se retrouvent dans les eaux les plus profondes et sont le moins actifs durant les mois d’hiver sous la glace. Durant les mois les plus chauds, les poissons sont le plus actifs et ils habitent la zone littorale. Il existe des différences spécifiques au sexe pendant toute l’année. Les mâles reproducteurs sont moins actifs et se retrouvent dans les eaux les moins profondes durant la fraye et la période qui suit la reproduction. Les mâles reproducteurs sont dans les profondeurs les plus grandes durant l’hiver et l’automne, alors que les mâles non reproducteurs se trouvent dans les sites moins profonds. Durant toute l’année, les comportements des mâles non reproducteurs et des femelles sont semblables. Bien que les différences de comportement des achigans s’expliquent principalement par la température de l’eau, le sexe et le statut reproducteur jouent un rôle important pendant toute l’année, mais particulièrement durant et après la période de reproduction. [ABSTRACT FROM AUTHOR]

A whole-lake acoustic telemetry observatory situated in eastern Ontario was used to continuously monitor the three-dimensional position of 20 largemouth bass ( Micropterus salmoides) over a 120-h period during the winter and a separate 120-h period during the early spring. These data were used to evaluate the frequency and stability of associations among fish to provide an understanding of seasonal aggregations and the sociobiology of largemouth bass. The temporal and spatial proximity of each fish relative to the other 19 individuals was assessed and, based on our definition of spatial/temporal proximity (i.e., two fish having an average hourly position <2 m apart), associations were shown to vary among fish, as well as diurnally, daily and seasonally. Associations during the winter were found to be more stable and involved fewer fish than associations during the spring. Of those fish that formed pair aggregations during the winter and spring study periods, male–female pairs occurred more often than male–male and female–female pairs. Our analysis also demonstrated that associations occurred primarily during daylight hours, suggesting that fish may use visual cues to form these aggregations. [ABSTRACT FROM AUTHOR]

The behaviour of free-swimming, telemetered, adult largemouth bass, Micropterus salmoides (L.), was monitored using a whole lake, three-dimensional acoustic telemetry array to test the hypothesis that fish activity and depth distribution are influenced by lunar phase. The percent of lunar face shining and whether the moon was waxing or waning were significant determinants of swimming activity and depth distribution during most of the lunar cycles evaluated, although these patterns were not consistent across the year. In spring and summer, daily depth distribution followed a pattern in which the fish inhabited greater depths on the 26–50% and 51–75% waxing moon. Fish daily movement distances were five times greater during spring and summer than in winter, but no repeatable patterns were noted in relation to lunar periodicity. This research suggests that solunar tables frequently consulted by recreational anglers may have little predictive value for identifying peak fishing time. [ABSTRACT FROM AUTHOR]

The aims of this study were to provide a population-based prevalence for congenital talipes equinovarus (CTEV), to conduct an epidemiological investigation into the risk factors for CTEV and describe associated features. The study used a retrospective case-control design of CTEV notified to the South Australian Birth Defects Register between 1986 and 1996 inclusive, linking characteristics of mother and baby from the perinatal data collection. The prevalence of isolated CTEV was 1.1/1000 total births (n = 231). Four factors were significantly associated with an increased risk of CTEV: maternal Aboriginal race (ORadj = 2.0; 95% CI 1.1, 3.6), male gender (ORadj = 2.4; 95% CI 1.8, 3.2), maternal anaemia (ORadj = 1.8; 95% CI 1.0, 2.9) and maternal hyperemesis (ORadj = 3.6; 95% CI 1.3, 9.8). The prevalence of CTEV associated with another birth defect or syndrome (n = 157) was 0.7/1000 total births. CTEV was associated with specific birth defects and also with oligohydramnios when another birth defect was present. [ABSTRACT FROM AUTHOR]

Abstract: The spine is a complex structure that provides motion in three directions: flexion and extension, lateral bending and axial rotation. So far, the investigation of the mechanical and kinematic behavior of the basic unit of the spine, a motion segment, is predominantly a domain of in vitro experiments on spinal loading simulators. Most existing approaches to measure spinal stiffness intraoperatively in an in vivo environment use a distractor. However, these concepts usually assume a planar loading and motion. The objective of our study was to develop and validate an apparatus, that allows to perform intraoperative in vivo measurements to determine both the applied force and the resulting motion in three dimensional space. The proposed setup combines force measurement with an instrumented distractor and motion tracking with an optoelectronic system. As the orientation of the applied force and the three dimensional motion is known, not only force–displacement, but also moment-angle relations could be determined. The validation was performed using three cadaveric lumbar ovine spines. The lateral bending stiffness of two motion segments per specimen was determined with the proposed concept and compared with the stiffness acquired on a spinal loading simulator which was considered to be gold standard. The mean values of the stiffness computed with the proposed concept were within a range of ±15% compared to data obtained with the spinal loading simulator under applied loads of less than 5Nm. [Copyright &y& Elsevier]