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Rock glaciers in crystalline catchments: hidden permafrost-related threats to alpine headwater lakes

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Abstract

A global warming-induced transition from glacial to periglacial processes has been identified in mountainous regions around the world. Degrading permafrost in pristine periglacial environments can produce acid rock drainage (ARD) and cause severe ecological damage in areas underlain by sulfide-bearing bedrock. Limnological and paleolimnological approaches were used to assess and compare ARDs generated by rock glaciers, a typical landform of the mountain permafrost domain, and their effects on alpine headwater lakes with similar morphometric features and underlying bedrock geology, but characterized by different intensities of frost action in their catchments during the year. We argue that ARD and its effects on lakes are more severe in the alpine periglacial belt with mean annual air temperatures (MAAT) between −2 °C and +3 °C, where groundwater persists in the liquid phase for most of the year, in contrast to ARD in the periglacial belt where frost action dominates (MAAT < −2 °C). The findings clearly suggest that the ambient air temperature is an important factor affecting the ARD production in alpine periglacial environments. Applying the paleoecological analysis of morphological abnormalities in chironomids through the past millennium, we tested and rejected the hypothesis that unfavorable conditions for aquatic life in the ARD-stressed lakes are largely related to the temperature increase over recent decades, responsible for the enhanced release of ARD contaminants. Our results indicate that the ARDs generated in the catchments are of a long-lasting nature and the frequency of chironomid morphological deformities was significantly higher during the Little Ice Age (LIA) than during pre- or post-LIA periods, suggesting that lower water temperatures may increase the adverse impacts of ARD on aquatic invertebrates. This highlights that temperature-mediated modulations of the metabolism and life cycle of aquatic organisms should be considered when reconstructing long-term trends in the ecotoxicological state of lakes.

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sarcozona
5 hours ago
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Multifarious anchovy and sardine regimes in the Humboldt Current System during the last 150 years

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Abstract

The Humboldt Current System (HCS) has the highest production of forage fish in the world, though it is highly variable and the future of the primary component, anchovy, is uncertain in the context of global warming. Paradigms based on late 20th century observations suggest that large-scale forcing controls decadal-scale fluctuations of anchovy and sardine across different boundary currents of the Pacific. We develop records of anchovy and sardine fluctuations since 1860 AD using fish scales from multiple sites containing laminated sediments and compare them with Pacific basin-scale and regional indices of ocean-climate variability. Our records reveal two main anchovy and sardine phases with a timescale that is not consistent with previously proposed periodicities. Rather, the regime shifts in the HCS are related to 3D habitat changes driven by changes in upwelling intensity from both regional and large-scale forcing. Moreover, we show that a long-term increase in coastal upwelling translates via a bottom-up mechanism to top predators suggesting that the warming climate, at least up to the start of the 21st century, was favourable for fishery productivity in the HCS.

This article is protected by copyright. All rights reserved.

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sarcozona
5 hours ago
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Using connectivity to identify climatic drivers of local adaptation

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Abstract

Understanding the climatic drivers of local adaptation is vital. Such knowledge is not only of theoretical interest but is critical to inform management actions under climate change, such as assisted translocation and targeted gene flow. Unfortunately, there are a vast number of potential trait–environment combinations, and simple relationships between trait and environment are ambiguous: representing either plastic or evolved variation. Here, we show that by incorporating connectivity as an index of gene flow, we can differentiate trait–environment relationships reflecting genetic variation vs. phenotypic plasticity. In this way, we rapidly shorten the list of trait–environment combinations that are of significance. Our analysis of an existing data set on geographic variation in a tropical lizard shows that we can effectively rank climatic variables by the strength of their role in local adaptation. The promise of our method is a rapid and general approach to identifying the environmental drivers of local adaptation.

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sarcozona
5 hours ago
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Sex differences in adult mortality rate mediated by early-life environmental conditions

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Abstract

Variation in sex differences is affected by both genetic and environmental variation, with rapid change in sex differences being more likely due to environmental change. One case of rapid change in sex differences is human lifespan, which has become increasingly female-biased in recent centuries. Long-term consequences of variation in the early-life environment may, in part, explain such variation in sex differences, but whether the early-life environment mediates sex differences in life-history traits is poorly understood in animals. Combining longitudinal data on 60 cohorts of pre-industrial Finns with environmental data, we show that the early-life environment is associated with sex differences in adult mortality and expected lifespan. Specifically, low infant survival rates and high rye yields (an important food source) in early-life are associated with female-bias in adult lifespan. These results support the hypothesis that environmental change has the potential to affect sex differences in life-history traits in natural populations of long-lived mammals.

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sarcozona
5 hours ago
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Twice in a lifetime: South Texas snowfall!

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Last time, I only saw the aftermath.

This time, I got to see it happen.


Snow!


There hadn’t been snow in a century before 2004, and now twice in less than 20 years? This is crazy.


It started around 9:00 am, and ran for a couple of hours. It was big fluffy flakes that was coming down quite thick at one point.


I asked everyone I saw, “Are we having fun yet?!” Everyone was having fun. Everyone was happy. One student said, “This is the best thing that could have happened during finals!”


There were snowball fights outside the library.


Alas, it dod not last long. After a couple of hours, it had stopped. But there was so much snow on the trees, that as it melted, it sounded like a downpour.


Last time, I made a snowman. This time, I made something different:


A South Texas snow angel!

I can’t believe I got to see snow twice in South Texas during my time there. Today was pretty magical.

I’ve been inside for an hour now, and my fingers are still numb.

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sarcozona
5 hours ago
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Leadership search pools and Coordinator Syndrome

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A data-curator friend of the Loon’s groused recently about a job listing in a social-media backwater the Loon frequents. As usual, the Loon will not link where she cannot praise, but she did dive for the listing. It includes the following in its requirements list:

The successful candidate must have an advanced degree in the humanities, social sciences, sciences or library or information science with a focus on digital scholarship or data curation; and a minimum of 4 years of experience in an administrative position that includes successful management and supervision of personnel.

The Loon supposes that the institution in question is aiming for a data curator or digital humanist, though (e.g.) a GIS or statistics specialist, an institutional-repository manager, or similar might not go amiss. The Loon also supposes that unless this is a done deal already—internal candidate, poaching, or sweetheart deal—this search is highly liable to fail.

Why? In a phrase, Coordinator Syndrome. Practically the defining trait of Coordinator Syndrome is zero authority—no budget, no reports, no voice in organizational strategy or governance. In other words, no accumulation of documented “management and supervision of personnel” or much of anything else that readies someone’s résumé for a management job in libraries.

“Digital scholarship” and “data curation” positions are highly prone to Coordinator Syndrome at present. This institution can therefore have the expertise it desires or it can have four years of supervisory experience, but it probably can’t have both unless it’s paying enough to poach someone in the (currently rather few) line-manager or skunkworks-manager positions in these areas.

If the institution writing this ad had more brains than would fit in a pitcher plant, it would broaden its definition of leadership. Project management should count; enough Coordinators learn their way around it. Also, Coordinators are often highly active in professional organizations, conference planning, and similar extra-workplace pursuits—they have to be; it is often the only way they can find some sense of professional community, since within their workplaces they are lone wolves—such that counting these activities toward leadership potential would turn up quite a few valuable candidates.

The Loon feels both angry and schadenfreudish about this. Angry, because her friends and colleagues who do data-curation and digital-scholarship work fully deserve upward career trajectories that are too often well out of reach for no fault of theirs. Schadenfreudish, because academic libraries moaning and groaning about the paucity of eligible candidates for this sort of job created their own damned problem and the Loon rather enjoys cackling her Loonish laugh at them for it.

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sarcozona
6 hours ago
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acdha
2 days ago
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Washington, DC
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