Showing papers by "Sharon A. Robinson published in 2020"

The 2019/2020 summer of Antarctic heatwaves.

Abstract: This summer, a heatwave across Antarctica saw temperatures soar above average. Temperatures above zero are especially significant because they accelerate ice melt. Casey Station had its highest temperature ever, reaching a maximum of 9.2°C and minimum of 2.5°C. The highest temperature in Antarctica was 20.75°C on 9 February. Here we discuss the biological implications of such extreme events.

It Is Hot in the Sun: Antarctic Mosses Have High Temperature Optima for Photosynthesis Despite Cold Climate

Abstract: The terrestrial flora of Antarctica's frozen continent is restricted to sparse ice-free areas and dominated by lichens and bryophytes. These plants frequently battle sub-zero temperatures, extreme winds and reduced water availability; all influencing their ability to survive and grow. Antarctic mosses, however, can have canopy temperatures well above air temperature. At midday, canopy temperatures can exceed 15°C, depending on moss turf water content. In this study, the optimum temperature of photosynthesis was determined for six Antarctic moss species: Bryum pseudotriquetrum, Ceratodon purpureus, Chorisodontium aciphyllum, Polytrichastrum alpinum, Sanionia uncinata, and Schistidium antarctici collected from King George Island (maritime Antarctica) and/or the Windmill Islands, East Antarctica. Both chlorophyll fluorescence and gas exchange showed maximum values of electron transport rate occurred at canopy temperatures higher than 20°C. The optimum temperature for both net assimilation of CO2 and photoprotective heat dissipation of three East Antarctic species was 20-30°C and at temperatures below 10°C, mesophyll conductance did not significantly differ from 0. Maximum mitochondrial respiration rates occurred at temperatures higher than 35°C and were lower by around 80% at 5°C. Despite the extreme cold conditions that Antarctic mosses face over winter, the photosynthetic apparatus appears optimised to warm temperatures. Our estimation of the total carbon balance suggests that survival in this cold environment may rely on a capacity to maximize photosynthesis for brief periods during summer and minimize respiratory carbon losses in cold conditions.

Civil disobedience movements such as School Strike for the Climate are raising public awareness of the climate change emergency

Abstract: The IPCC (Intergovernmental Panel on Climate Change) “Special Report on Global Warming of 1.5°C” presented the ambitious target of needing to achieve zero net emissions by 2050 in order to meet the goals of the Paris Agreement (IPCC, 2018). This report led some governments and jurisdictions to declare a climate emergency (Climate Emergency Declaration, 2019) and prompted the rise of movements of activism and civil disobedience such as the School Strike for the Climate and Extinction Rebellion. The reach of these civil actions extends beyond those directly involved, potentially increasing wider public awareness of climate change. Here, we examine trends in indicators of this wider public awareness and engagement and compare these with major global movements of civil disobedience focussed on climate, the release of substantive climate reports, and global governmental gatherings on climate change. We show that these global movements may be increasing public awareness of, and stimulating public engagement with, issues of climate change. It is not easy to accurately measure public awareness and engagement with the issue of climate change at a global scale. We use two sources of information as indicators of that engagement. First, we used data on the scaled relative frequency of pertinent terms in Google searches (\"global warming,\" \"climate change,\" \"climate action,\" \"climate emergency,\" \"climate crisis,\" downloaded from Google Trends on October 31, 2019, https ://www.google.com/trends). Second, we used data on mentions of the terms \"climate change\" and \"global warming\" by the global media, assembled by the Media and Climate Change Observatory, MeCCO (Boykoff et al., 2019, downloaded on December 4, 2019). These sources provide monthly data on the attention paid to climate change by anyone searching the internet (from the Google data), and by the newspapers, radio, and television (from the MeCCO data). We focus on 2017 onwards; a period that includes the recent rise in activism and civil disobedience associated with climate change. Although there exists substantial month-to-month variation, both data sources show an overall increase in public engagement with climate change, especially after mid-2018 (Figure 1). The Google search data also suggest an interesting evolution of the language of climate change. While the relative popularity of the search term \"global warming\" has shown little systematic change, public interest in “climate action” has increased greatly since 2018. In addition, \"climate crisis\" and \"climate emergency\" have become popular search terms since early 2019. Peaks in internet searches for these specific terms coincide with the first and second global school strikes, and New York Climate Week (Figure 1a). Searches for “climate emergency” and “climate crisis” were rare before 2019, but the use of these search terms increased 20-fold during that year. Furthermore,

Reframing conservation physiology to be more inclusive, integrative, relevant and forward-looking: reflections and a horizon scan.

Abstract: Applying physiological tools, knowledge and concepts to understand conservation problems (i.e. conservation physiology) has become commonplace and confers an ability to understand mechanistic processes, develop predictive models and identify cause-and-effect relationships. Conservation physiology is making contributions to conservation solutions; the number of 'success stories' is growing, but there remain unexplored opportunities for which conservation physiology shows immense promise and has the potential to contribute to major advances in protecting and restoring biodiversity. Here, we consider how conservation physiology has evolved with a focus on reframing the discipline to be more inclusive and integrative. Using a 'horizon scan', we further explore ways in which conservation physiology can be more relevant to pressing conservation issues of today (e.g. addressing the Sustainable Development Goals; delivering science to support the UN Decade on Ecosystem Restoration), as well as more forward-looking to inform emerging issues and policies for tomorrow. Our horizon scan provides evidence that, as the discipline of conservation physiology continues to mature, it provides a wealth of opportunities to promote integration, inclusivity and forward-thinking goals that contribute to achieving conservation gains. To advance environmental management and ecosystem restoration, we need to ensure that the underlying science (such as that generated by conservation physiology) is relevant with accompanying messaging that is straightforward and accessible to end users.

Latitudinal Biogeographic Structuring in the Globally Distributed Moss Ceratodon purpureus.

Abstract: Biogeographic patterns of globally widespread species are expected to reflect regional structure, as well as connectivity caused by occasional long-distance dispersal. We assessed the level and drivers of population structure, connectivity and timescales of population isolation in one of the most widespread and ruderal plants in the world – the common moss Ceratodon purpureus. We applied phylogenetic, population genetic and molecular dating analyses to a global (n = 147) sampling dataset, using three chloroplast loci and one nuclear locus. The plastid data revealed several distinct and geographically structured lineages, with connectivity patterns associated with worldwide, latitudinal ‘bands’. These imply that connectivity is strongly influenced by global atmospheric circulation patterns, with dispersal and establishment beyond these latitudinal bands less common. Biogeographic patterns were less clear within the nuclear marker, with gene duplication likely hindering the detection of these. Divergence time analyses indicated that the current matrilineal population structure in C. purpureus has developed over the past six million years, with lineages diverging during the late Miocene, Pliocene and Quaternary. Several colonisation events in the Antarctic were apparent, as well as one old and distinct Antarctic clade, possibly isolated on the continent since the Pliocene. As C. purpureus is considered a model organism, the matrilineal biogeographic structure identified here provides a useful framework for future genetic and developmental studies on bryophytes. Our general findings may also be relevant to understanding global environmental influences on the biogeography of other organisms with microscopic propagules (e.g. spores) dispersed by wind.

Semi-Automated Analysis of Digital Photographs for Monitoring East Antarctic Vegetation

Abstract: Climate change is affecting Antarctica and minimally destructive long-term monitoring of its unique ecosystems is vital to detect biodiversity trends, and to understand how change is affecting these communities. The use of automated or semi-automated methods is especially valuable in harsh polar environments, as access is limited and conditions extreme. We assessed moss health and cover at six time points between 2003 and 2014 at two East Antarctic sites. Semi-automatic object-based image analysis (OBIA) was used to classify digital photographs using a set of rules based on digital red, green, blue (RGB) and hue-saturation-intensity (HSI) value thresholds, assigning vegetation to categories of healthy, stressed or moribund moss and lichens. Comparison with traditional visual estimates showed that estimates of percent cover using semi-automated OBIA classification fell within the range of variation determined by visual methods. Overall moss health, as assessed using the mean percentages of healthy, stressed and moribund mosses within quadrats, changed over the 11 years at both sites. A marked increase in stress and decline in health was observed across both sites in 2008, followed by recovery to baseline levels of health by 2014 at one site, but with significantly more stressed or moribund moss remaining within the two communities at the other site. Our results confirm that vegetation cover can be reliably estimated using semi-automated OBIA, providing similar accuracy to visual estimation by experts. The resulting vegetation cover estimates provide a sensitive measure to assess change in vegetation health over time and have informed a conceptual framework for the changing condition of Antarctic mosses. In demonstrating that this method can be used to monitor ground cover vegetation at small scales, we suggest it may also be suitable for other extreme environments where repeat monitoring via images is required.

Anatomy of a heatwave: how Antarctica recorded a 20.75°C day last month

Abstract: While the world rightfully focuses on the COVID-19 pandemic, the planet is still warming. This summer’s Antarctic weather, as elsewhere in the world, was unprecedented in the observed record.