Divergent bleaching and recovery trajectories in reef-building corals following a decade of successive marine heatwaves.

Increasingly frequent marine heatwaves are devastating coral reefs. Corals that survive these extreme events must rapidly recover if they are to withstand subsequent events, and long-term survival in the face of rising ocean temperatures may hinge on recovery capacity and acclimatory gains in heat tolerance over an individual's lifespan. To better understand coral recovery trajectories in the face of successive marine heatwaves, we monitored the responses of bleaching-susceptible and bleaching-resistant individuals of two dominant coral species in Hawai'i, Montipora capitata and Porites compressa, over a decade that included three marine heatwaves. Bleaching-susceptible colonies of P. compressa exhibited beneficial acclimatization to heat stress (i.e., less bleaching) following repeat heatwaves, becoming indistinguishable from bleaching-resistant conspecifics during the third heatwave. In contrast, bleaching-susceptible M. capitata repeatedly bleached during all successive heatwaves and exhibited seasonal bleaching and substantial mortality for up to 3 y following the third heatwave. Encouragingly, bleaching-resistant individuals of both species remained pigmented across the entire time series; however, pigmentation did not necessarily indicate physiological resilience. Specifically, M. capitata displayed incremental yet only partial recovery of symbiont density and tissue biomass across both bleaching phenotypes up to 35 mo following the third heatwave as well as considerable partial mortality. Conversely, P. compressa appeared to recover across most physiological metrics within 2 y and experienced little to no mortality. Ultimately, these results indicate that even some visually robust, bleaching-resistant corals can carry the cost of recurring heatwaves over multiple years, leading to divergent recovery trajectories that may erode coral reef resilience in the Anthropocene.

Ecological memory of daily carbon exchange across the globe and its importance in drylands.

How do antecedent (past) conditions influence land-carbon dynamics after those conditions no longer persist? In particular, quantifying such memory effects associated with the influence of past environmental (exogenous) and biological (endogenous) conditions is crucial for understanding and predicting the carbon cycle. Here we show, using data from 42 eddy covariance sites across six major biomes, that ecological memory-decomposed into environmental and biological memory components-of daily net carbon exchange (NEE) is critical for understanding the land-carbon metabolism, especially in drylands for which memory explains ~ 32% of the variation in NEE. The strong environmental memory in drylands was primarily driven by short- and long-term moisture status. Moreover, the strength of environmental memory scales with increasing water stress. This universal scaling relationship, emerging within and among major biomes, suggests a potential adaptive response to water limitation. Our findings underscore the necessity of considering ecological memory in experiments, observations and modelling.

Epigenetic control of plant abiotic stress responses.

On top of genetic information, organisms have evolved complex and sophisticated epigenetic regulation to adjust gene expression in response to developmental and environmental signals. Key epigenetic mechanisms include DNA methylation, histone modifications and variants, chromatin remodeling, and chemical modifications of RNAs. Epigenetic control of environmental responses is particularly important for plants, which are sessile and unable to move away from adverse environments. Besides enabling plants to rapidly respond to environmental stresses, some stress-induced epigenetic changes can be maintained, providing plants with a pre-adapted state to recurring stresses. Understanding these epigenetic mechanisms offers valuable insights for developing crop varieties with enhanced stress tolerance. Here, we focus on abiotic stresses and summarize recent progress in characterizing stress-induced epigenetic changes and their regulatory mechanisms and roles in plant abiotic stress resistance.

Acute heat priming promotes short-term climate resilience of early life stages in a model sea anemone.

Across diverse taxa, sublethal exposure to abiotic stressors early in life can lead to benefits such as increased stress tolerance upon repeat exposure. This phenomenon, known as hormetic priming, is largely unexplored in early life stages of marine invertebrates, which are increasingly threatened by anthropogenic climate change. To investigate this phenomenon, larvae of the sea anemone and model marine invertebrate Nematostella vectensis were exposed to control (18 °C) or elevated (24 °C, 30 °C, 35 °C, or 39 °C) temperatures for 1 h at 3 days post-fertilization (DPF), followed by return to control temperatures (18 °C). The animals were then assessed for growth, development, metabolic rates, and heat tolerance at 4, 7, and 11 DPF. Priming at intermediately elevated temperatures (24 °C, 30 °C, or 35 °C) augmented growth and development compared to controls or priming at 39 °C. Indeed, priming at 39 °C hampered developmental progression, with around 40% of larvae still in the planula stage at 11 DPF, in contrast to 0% for all other groups. Total protein content, a proxy for biomass, and respiration rates were not significantly affected by priming, suggesting metabolic resilience. Heat tolerance was quantified with acute heat stress exposures, and was significantly higher for animals primed at intermediate temperatures (24 °C, 30 °C, or 35 °C) compared to controls or those primed at 39 °C at all time points. To investigate a possible molecular mechanism for the observed changes in heat tolerance, the expression of heat shock protein 70 (HSP70) was quantified at 11 DPF. Expression of HSP70 significantly increased with increasing priming temperature, with the presence of a doublet band for larvae primed at 39 °C, suggesting persistent negative effects of priming on protein homeostasis. Interestingly, primed larvae in a second cohort cultured to 6 weeks post-fertilization continued to display hormetic growth responses, whereas benefits for heat tolerance were lost; in contrast, negative effects of short-term exposure to extreme heat stress (39 °C) persisted. These results demonstrate that some dose-dependent effects of priming waned over time while others persisted, resulting in heterogeneity in organismal performance across ontogeny following priming. Overall, these findings suggest that heat priming may augment the climate resilience of marine invertebrate early life stages via the modulation of key developmental and physiological phenotypes, while also affirming the need to limit further anthropogenic ocean warming.

Histone modifications and their regulatory roles in plant development and environmental memory.

Plants grow in dynamic environments where they receive diverse environmental signals. Swift and precise control of gene expression is essential for plants to align their development and metabolism with fluctuating surroundings. Modifications on histones serve as "histone code" to specify chromatin and gene activities. Different modifications execute distinct functions on the chromatin, promoting either active transcription or gene silencing. Histone writers, erasers, and readers mediate the regulation of histone modifications by catalyzing, removing, and recognizing modifications, respectively. Growing evidence indicates the important function of histone modifications in plant development and environmental responses. Histone modifications also serve as environmental memory for plants to adapt to environmental changes. Here we review recent progress on the regulation of histone modifications in plants, the impact of histone modifications on environment-controlled developmental transitions including germination and flowering, and the role of histone modifications in environmental memory.

A spatial memory signal shows that the parietal cortex has access to a craniotopic representation of space.

Humans effortlessly establish a gist-like memory of their environment whenever they enter a new place, a memory that can guide action even in the absence of vision. Neurons in the lateral intraparietal area (LIP) of the monkey exhibit a form of this environmental memory. These neurons respond when a monkey makes a saccade that brings the spatial location of a stimulus that appeared on a number of prior trials, but not on the present trial, into their receptive fields (RFs). The stimulus need never have appeared in the neuron's RF. This memory response is usually weaker, with a longer latency than the neuron's visual response. We suggest that these results demonstrate that LIP has access to a supraretinal memory of space, which is activated when the spatial location of the vanished stimulus can be described by a retinotopic vector from the center of gaze to the remembered spatial location.

Sinos River Hydrographic Basin: urban occupation, industrialization and environmental memory / Bacia Hidrográfica do Rio dos Sinos: ocupação urbana, industrialização e memória ambiental.

This article presents an analysis of the process of industrialization and urbanization of the Sinos Valley in Rio Grande do Sul state, Brazil, starting from the establishment of leather goods and footwear manufacturing in the region during the 19th century when tanneries and factories producing footwear and/or components for footwear began to appear, and with special attention to aspects related to the environmental impact on the Sinos river hydrographic basin. The article is based on both bibliographic and documentary research and also draws on biographical narratives of workers with links to the leather goods and footwear industry obtained using ethnographic method. It was found that contemporary environmental conflicts emerge from within a memory of work and an environmental memory in which the factories, the unplanned urbanization, and the utilization of water and other natural resources form a chain of significance. Significance that precludes any form of fragmented analysis that isolates any of these aspects from the others: the economic, socio-historic, cultural, political, or the environmental.

Resumo O artigo aborda o processo de industrialização e urbanização do Vale do Rio dos Sinos/Rio Grande do Sul/Brasil, desde a implantação da indústria coureiro-calçadista na região, no século XIX, com o surgimento dos curtumes e das fábricas de calçados e/ou componentes para calçados, destacando, em especial, os aspectos ligados ao impacto ambiental na Bacia Hidrográfica dos Sinos. Faz-se uso de pesquisa bibliográfica e documental, além da exposição de narrativas biográficas de trabalhadores ligados à indústria coureiro-calçadista, obtidas por meio do método etnográfico. Verifica-se que os conflitos ambientais contemporâneos emergem do interior de uma memória do trabalho e de uma memória ambiental, nas quais a fábrica, a ocupação urbana desordenada, o uso da água e dos demais recursos naturais formam um encadeamento de sentido que impede qualquer análise fragmentada que isole um destes aspectos: o econômico, o socio-histórico, o cultural, o político, o ambiental.

Sinos River Hydrographic Basin: urban occupation, industrialization and environmental memory

This article presents an analysis of the process of industrialization and urbanization of the Sinos Valley in Rio Grande do Sul state, Brazil, starting from the establishment of leather goods and footwear manufacturing in the region during the 19th century when tanneries and factories producing footwear and/or components for footwear began to appear, and with special attention to aspects related to the environmental impact on the Sinos river hydrographic basin. The article is based on both bibliographic and documentary research and also draws on biographical narratives of workers with links to the leather goods and footwear industry obtained using ethnographic method. It was found that contemporary environmental conflicts emerge from within a memory of work and an environmental memory in which the factories, the unplanned urbanization, and the utilization of water and other natural resources form a chain of significance. Significance that precludes any form of fragmented analysis that isolates any of these aspects from the others: the economic, socio-historic, cultural, political, or the environmental.

Resumo O artigo aborda o processo de industrialização e urbanização do Vale do Rio dos Sinos/Rio Grande do Sul/Brasil, desde a implantação da indústria coureiro-calçadista na região, no século XIX, com o surgimento dos curtumes e das fábricas de calçados e/ou componentes para calçados, destacando, em especial, os aspectos ligados ao impacto ambiental na Bacia Hidrográfica dos Sinos. Faz-se uso de pesquisa bibliográfica e documental, além da exposição de narrativas biográficas de trabalhadores ligados à indústria coureiro-calçadista, obtidas por meio do método etnográfico. Verifica-se que os conflitos ambientais contemporâneos emergem do interior de uma memória do trabalho e de uma memória ambiental, nas quais a fábrica, a ocupação urbana desordenada, o uso da água e dos demais recursos naturais formam um encadeamento de sentido que impede qualquer análise fragmentada que isole um destes aspectos: o econômico, o socio-histórico, o cultural, o político, o ambiental.