Refugia under threat: Mass bleaching of coral assemblages in high-latitude eastern Australia.

Environmental anomalies that trigger adverse physiological responses and mortality are occurring with increasing frequency due to climate change. At species' range peripheries, environmental anomalies are particularly concerning because species often exist at their environmental tolerance limits and may not be able to migrate to escape unfavourable conditions. Here, we investigated the bleaching response and mortality of 14 coral genera across high-latitude eastern Australia during a global heat stress event in 2016. We evaluated whether the severity of assemblage-scale and genus-level bleaching responses was associated with cumulative heat stress and/or local environmental history, including long-term mean temperatures during the hottest month of each year (SSTLTMAX ), and annual fluctuations in water temperature (SSTVAR ) and solar irradiance (PARZVAR ). The most severely-bleached genera included species that were either endemic to the region (Pocillopora aliciae) or rare in the tropics (e.g. Porites heronensis). Pocillopora spp., in particular, showed high rates of immediate mortality. Bleaching severity of Pocillopora was high where SSTLTMAX was low or PARZVAR was high, whereas bleaching severity of Porites was directly associated with cumulative heat stress. While many tropical Acropora species are extremely vulnerable to bleaching, the Acropora species common at high latitudes, such as A. glauca and A. solitaryensis, showed little incidence of bleaching and immediate mortality. Two other regionally-abundant genera, Goniastrea and Turbinaria, were also largely unaffected by the thermal anomaly. The severity of assemblage-scale bleaching responses was poorly explained by the environmental parameters we examined. Instead, the severity of assemblage-scale bleaching was associated with local differences in species abundance and taxon-specific bleaching responses. The marked taxonomic disparity in bleaching severity, coupled with high mortality of high-latitude endemics, point to climate-driven simplification of assemblage structures and progressive homogenisation of reef functions at these high-latitude locations.

Comparative spatial resolution of 12-lead electrocardiography and an automated algorithm.

BACKGROUND: The spatial resolution of pacemapping using 12-lead electrocardiography (ECG) or PaSo software is unknown. OBJECTIVE: The purpose of this study was to determine the spatial resolution of traditional ECG pacemapping and pacemapping using the PaSo coefficients. METHODS: Seventeen patients undergoing ablation of supraventricular tachycardias or atrioventricular node were included. After ablation, chamber (right ventricular outflow tract/rest of the right ventricle/left ventricle) geometry was created with Carto 3. Pacingwas performed from any point in these cardiac regions, the QRS morphology being the template and the point being considered as arrhythmia "origin." Subsequently, pacing was performed from points around the "origin" (1538 points). The QRS of these tagged points were compared by traditional ECG pacemapping and PaSo coefficients. The spatial resolution was calculated using correlations between the distance away from the origin (measured by 3 computational methods) and traditional ECG pacemapping and PaSo coefficients, independently. RESULTS: A 0.01-unit decrease in the PaSo coefficient resulted in 1.1 mm increased Cartesian distance (95% confidence interval [CI] 0.9-1.3 mm; P < .001) and 2.4 mm increased geodesic distance (95% CI 1.9-2.9 mm; P < .001) and 664 mm3 increase in convex hull volume (95% CI 423-906 mm3; P < .0001). For traditional ECG pacemapping, each decrease in lead match resulted in 1.7 mm increased Cartesian distance (95% CI 1.5-2.0 mm; P < .001) and 3.4 mm increased geodesic distance (95% CI 2.8-4.1 mm; P < .001) and 712 mm3 increase in convex hull volume (95% CI 599-830 mm3; P < .0001). Both PaSo coefficients and traditional pacemapping showed a significant inverse linear correlation with distance from the "origin." CONCLUSION: The resolution of mapping using the Paso software is better than that of traditional pacemapping.