More Like this

1. A series of unfortunate events: characterizing the contingent nature of physiological extremes using long-term environmental records

   https://doi.org/10.1098/rspb.2019.2333  

   Dowd, W. Wesley; Denny, Mark W. (January 2020, Proceedings of the Royal Society B: Biological Sciences)

   Accelerating shifts in global climate have focused the attention of ecologists and physiologists on extreme environmental events. However, the dynamic process of physiological acclimatization complicates study of these events' consequences. Depending on the range of plasticity and the amplitude and speed of environmental variation, physiology can be either in tune with the surroundings or dangerously out of synch. We implement a modified quantitative approach to identifying extreme events in environmental records, proposing that organisms are stressed by deviations of the environment from the current level of acclimatization, rather than by the environment's absolute state. This approach facilitates an unambiguous null model for the consequences of environmental variation, identifying a unique subset of events as ‘extremes’. Specifically, it allows one to examine how both the temporal extent (the acclimatization window) and type of an environmental signal affect the magnitude and timing of extreme environmental events. For example, if physiology responds to the moving average of past conditions, a longer acclimatization window generally results in greater imposed stress. If instead physiology responds to historical maxima, longer acclimatization windows reduce imposed stress, albeit perhaps at greater constitutive cost. This approach should be further informed and tested with empirical experiments addressing the history-dependent nature of acclimatization. 

   more » « less
2. Effect of environmental history on the physiology and acute stress response of the eastern oyster Crassostrea virginica

   https://doi.org/10.3354/meps13826  

   Ashey, J; Rivest, EB (September 2021, Marine Ecology Progress Series)

   Environmental history (regimes of water quality to which an organism has been exposed in the past) may influence how the physiology of eastern oysters Crassostrea virginica responds to future environmental conditions caused by climate change. Previous research has examined environmental history in a 1-dimensional framework, failing to capture environmental history complexity through space and time. In this study, we examined environmental history as a multi-faceted parameter, incorporating abiotic water quality components, such as temperature, pH, and salinity, that differ among locations. We also assessed how different lengths of environmental histories, defined as proximal and distal, affected oyster physiology and stress response. Finally, we compared the relative influence of abiotic components of environmental history on oyster physiology. We found that physiology and stress response are differentially affected by proximal and distal environmental history, demonstrating the importance of examining environmental history as a multi-faceted and dynamic parameter. Specifically, distal environmental history primarily influenced condition index and total antioxidant potential, while proximal environmental history primarily influenced glycogen content. Salinity of distal environmental history significantly shaped condition index, establishing salinity as a principal factor when considering acclimatization to variable environments. No water quality components were significant influences on glycogen and total antioxidant potential, providing opportunities for research on other components of environmental history. Identifying the temporal portion of oysters’ environmental history that influences physiology supports future efforts to predict population tolerance to climate change. Additionally, examining multiple abiotic and biotic components of environmental history can elucidate means of acclimatization to future environmental change. 

   more » « less
3. Survival in spatially variable environments: consequences of induced thermal defense.

   https://doi.org/doi:10.1111/1749-4877.12308  

   Denny, Mark (January 2018, Integrative zoology)

   As Earth’s climate warms, plants and animals are likely to encounter increased frequency and severity of extreme thermal events, and the ensuing destruction is likely to play an important role in structuring ecological communities. However, accurate prediction of the population-scale consequences of extreme thermal events requires detailed knowledge of the small-scale interaction between individual organisms and their thermal environment. In this study I propose a simple model that allows one to explore how individual-to-individual variation in body temperature and thermal physiology determines what fraction of a population will be killed by an extreme thermal event. The model takes into account the possibility that each individual plant or animal can respond to an event by adjusting its thermal tolerance in proportion to the stress it encounters. When thermal stress is relatively mild, the model shows that a graded physiological response of this sort leads to increased survivorship. However, the model predicts that in more severe events a proportional induced defense can actually reduce survivorship, a counterintuitive possibility that is not predicted by standard theory. The model can easily be tailored to different species and thermal environments to provide an estimate of when, where and how physiology can buffer the effects of climate warming. 

   more » « less
4. The timing of heat waves has multiyear effects on milkweed and its insect community

   https://doi.org/10.1002/ecy.3988  

   Cope, Olivia L.; Zehr, Luke N.; Agrawal, Anurag A.; Wetzel, William C. (March 2023, Ecology)

   Abstract Extreme heat events are becoming more frequent and intense as climate variability increases, and these events inherently vary in their timing. We predicted that the timing of a heat wave would determine its consequences for insect communities owing to temporal variation in the susceptibility of host plants to heat stress. We subjected common milkweed (Asclepias syriaca) plants to in‐field experimental heat waves to investigate how the timing of heat waves, both seasonally and relative to a biotic stressor (experimental herbivory), affected their ecological consequences. We found that heat waves had multiyear, timing‐specific effects on plant–insect communities. Early‐season heat waves led to greater and more persistent effects on plants and herbivore communities than late‐season heat waves. Heat waves following experimental herbivory had reduced consequences. Our results show that extreme climate events can have complex, lasting ecological effects beyond the year of the event—and that timing is key to understanding those effects. 

   more » « less
5. The Costs and Benefits of Environmental Memory for Reef-Building Corals Coping with Recurring Marine Heatwaves

   https://doi.org/10.1093/icb/icac074  

   Brown, Kristen T.; Barott, Katie L. (June 2022, Integrative And Comparative Biology)

   Abstract Marine heatwaves are occurring more frequently as climate change intensifies, resulting in global mass coral bleaching events several times per decade. Despite the time between marine heatwaves decreasing, there is evidence that reef-building corals can develop increased bleaching resistance across repetitive marine heatwaves. This phenomenon of acclimatization via environmental memory may be an important strategy to ensure coral persistence; however, we still understand very little about the apparent acclimatization or, conversely, sensitization (i.e., stress accumulation or weakening) of reef-building corals to consecutive heatwaves and its implications for the trajectory and resilience of coral reefs. Here, we highlight that not only will some corals become stress hardened via marine heatwaves, but many other individuals will suffer sensitization during repeat heatwaves that further exacerbates their stress response during repeat events and depresses fitness. Under current and predicted climate change, it is necessary to gain a better understanding of the acclimatization vs. sensitization trajectories of different species and individuals on the reef, as well as identify whether changes in bleaching susceptibility relates to physiological acclimatization, trade-offs with other biological processes, and ultimately coral persistence in the Anthropocene. 

   more » « less