Open research questions in Physiological and biochemical adaptations

What the literature leaves open

• The regulatory mechanism of rainbow trout spleen under different levels of hypoxia is unclear. The effects of moderate and severe hypoxia on the biochemical parameters of rainbow trout spleen are unknown. The transcriptomic changes in response to hypoxia in rainbow trout spleen have not been investigated.

  Integrated biochemical and transcriptomic profiling reveals the graded response mechanisms of rainbow trout (Oncorhynchus mykiss) spleen to moderate and severe hypoxia · 2026 · DOI

• The evidence base for ammonia stress in fish is methodologically heterogeneous. There is a need for robust ecological surveillance of ammonia stress in fish. Transcriptional indicators of ammonia stress have been reported across disparate species, tissues, and exposure regimes, but a unified framework is lacking.

  Development of transcriptional biomarkers for ammonia stress in fish · 2026 · DOI

• There is a lack of understanding of the effects of chronic saline-alkaline stress on Hong Kong catfish. The physiological tolerance of Hong Kong catfish to saline-alkaline stress is not well studied. There is a need for research on the impact of saline-alkaline stress on fish growth performance, histopathological alterations, and muscle quality.

  Effects of chronic saline-alkaline stress on growth performance, histopathological alterations, and muscle quality in Hong Kong catfish (Clarias fuscus) · 2026 · DOI

• There is a limited understanding of the physiological responses of H. crassispina to environmental stressors. The paper aims to address this gap by investigating the effects of salinity on the survival and metabolic strategies of H. crassispina.

  Ontogenetic shifts in salinity tolerance and metabolic strategies of Heliocidaris crassispina: implications for aquaculture management · 2026 · DOI

• To better understand these fundamental mechanisms of intertidal freeze tolerance, we propose that future work should explore direct evidence for freezing damage and repair processes. It is possible that byproducts were cleared by that time and thus the timepoint immediately after thawing should be examined instead to see whether significant anaerobic activity occurs during freezing.

  Energetic consequences of single and repeated freezing in the intertidal mussel, Mytilus trossulus · 2026 · DOI

• Additional factors known to influence growth and cell-cycle regulation, including food availability, temperature, and exposure duration, also warrant further investigation (Salazar-Roa 2017). Because we were unable to distinguish the effects of isolated heat stress from those of combined heat and hypoxia exposure, future studies are needed to evaluate potential interactive effects of these stressors.

  Cell-cycle genes in the mussel Mytilus galloprovincialis are cued by aerial heat stress in a fluctuating tidal environment · 2026 · DOI

• The study aims to investigate the impact of prolonged high temperatures on the growth, antioxidant capacity, apoptosis, and transcriptome analysis of Hong Kong catfish. The study identifies the need to investigate the molecular biological mechanism underlying the response to high temperatures.

  Effects of Chronic Heat Stress on Growth, Apoptosis, Antioxidant Enzymes, Transcriptomic Profiles, and Immune-Related Genes of Hong Kong Catfish (Clarias fuscus) · 2024 · DOI

• There has been limited reporting on the evaluation to identify LMB with better thermal resistance. The thermal tolerance ability of LMB is not well understood, particularly in terms of biomarkers. The comparison of thermal resistance between northern and Florida largemouth bass is lacking.

  Screening and Identification of the Biomarkers Applied for the Evaluation of Acute and Chronic Thermal Tolerance Ability in Largemouth Bass (Micropterus salmoides) · 2024 · DOI

• The different responses of fish to intermittent and chronic hypoxia have not been well-known. The effects of intermittent and chronic hypoxia on fish size and nutrient metabolism are not well understood.

  Effects of Intermittent and Chronic Hypoxia on Fish Size and Nutrient Metabolism in Tiger Puffer (Takifugu rubripes) · 2024 · DOI

• The conversion from total mass to shell-free mass was estimated based on related species from similar habitats for some species. The values used to calculate the shell-free mass could only be determined as rough estimates due to a lack of precise data. The comparison of the results to other studies should be regarded as tentative.

  Thermal Impact and the Relevance of Body Size and Activity on the Oxygen Consumption of a Terrestrial Snail, Theba pisana (Helicidae) at High Ambient Temperatures · 2024 · DOI

• The lack of precise data on the conversion of total mass to shell-free mass for some snail species. The need to relate experimental temperatures to maximum habitat temperatures for snail species.

  Thermal Impact and the Relevance of Body Size and Activity on the Oxygen Consumption of a Terrestrial Snail, Theba pisana (Helicidae) at High Ambient Temperatures · 2024 · DOI

• The effects of temperature trends on fish growth, physiology, metabolism, and immune responses are not well understood.

  Effects of Extreme-Ambient Temperatures in Silver Barb (Barbonymus gonionotus): Metabolic, Hemato-Biochemical Responses, Enzymatic Activity and Gill Histomorphology · 2024 · DOI

• Our observation that the acceleration of ventilation and circulation rates slows down under warm conditions (Fig 4B and 4C and Fig C in S1 Text) also needs to be investigated more closely, as we only obtained 10 datasets that allowed this estimation.

  Thermal optima in the hypoxia tolerance of marine ectotherms: Physiological causes and biogeographic consequences · 2024 · DOI

• The choice of control group (0‰) is a primary limitation of this study that must be addressed.

  Transcriptome-Based Analysis of the Effects of Salt Stress on the Embryos of Hypomesus nipponensis · 2026 · DOI

• Boxplots show the median; whiskers extend to the full data range, and the boxes are limited by the 25th and 75th percentiles. Blue lines indicate the median; boxplots are limited by the 25th and 75th percentiles.

  Salmonids elicit an acute behavioral response to heterothermal environments · 2026 · DOI

• It remains to be determined whether this queen-specific metabolic shift reflect a general reproductive effect, potentially influenced by hormonal factors such as estrogen or prolactin, or represents a specialized adaptation unique to NMRs.

  IGF-mediated glucose signalling is retained in adult naked mole-rats · 2026 · DOI

• For most species, those classified as chill susceptible, cold tolerance is limited by the ability to maintain vital physiological functions at low temperature.

  A conserved cold stress syndrome defines insect chill tolerance · 2026 · DOI

• Investigate the effects of other environmental factors on H. crassispina, - Examine the responses of H. crassispina to different salinity regimes in a natural setting, - Study the metabolic strategies of H. crassispina under different salinity conditions, - Explore the potential applications of the atomic O:N ratio as an indicator of salinity stress in H.

  Ontogenetic shifts in salinity tolerance and metabolic strategies of Heliocidaris crassispina: implications for aquaculture management · 2026 · DOI

• The experiment was conducted in the non-breeding season. The study only examined the effects of temperature stress on mitochondrial PCGs in S. incognitus. The sample size was limited to 50 lizards.

  Mitochondrial Protein-Coding Gene Expression in the Lizard Sphenomorphus incognitus (Squamata:Scincidae) Responding to Different Temperature Stresses · 2024 · DOI

• The study was conducted in a laboratory setting, - The sample size was limited to 15 individuals per aquarium, - The study only considered four distinct temperatures (22, 26, 30 and 34 °C), - The study did not consider other environmental factors that may impact the growth and health of B.

  Effects of Extreme-Ambient Temperatures in Silver Barb (Barbonymus gonionotus): Metabolic, Hemato-Biochemical Responses, Enzymatic Activity and Gill Histomorphology · 2024 · DOI

• In this review I have collated evidence to support my argument that a comprehensive understanding of the “fire of life” and its scaling with body mass requires a complete Journal of Comparative Physiology B1…

  The “fire of life cycles”: age-specific metabolic scaling within and among species · 2026 · DOI

• Birds with highly flexible thermogenic capacity and BMR may be more prepared to deal with temperature oscillations, which may be especially advantageous during migration 1 3Journal of Comparative Physiology…

  Nomadic songbirds achieve rapid increases in thermogenic capacity during cold acclimation while maintaining low corticosterone · 2026 · DOI

• Investigating the effects of different temperature ranges on gill remodeling - Studying the long-term effects of elevated temperatures on rainbow…

  Morphometric and Enzymatic Changes in Gills of Rainbow Trout after Exposure to Elevated Temperature—Indications for Gill Remodeling · 2024 · DOI

• Further investigation of physiological changes in S. incognitus under low- and high-temperature stresses. Examination of changes in various heat acclimation indicators.

  Mitochondrial Protein-Coding Gene Expression in the Lizard Sphenomorphus incognitus (Squamata:Scincidae) Responding to Different Temperature Stresses · 2024 · DOI

• The scope for tolerance in marine fishes to intensifying climate extremes remains debated…

  Thermal history and behavioural plasticity shape reef fish tolerance to marine heatwaves · 2026 · DOI

Most-cited papers in Physiological and biochemical adaptations

• Effects of Size and Temperature on Metabolic Rate · Science · 2001 · 3,286 citations
• Physiology and Climate Change · Science · 2008 · 2,219 citations
• Size, temperature, and fitness: three rules · Carolina Digital Repository (University of North Carolina at Chapel Hill) · 2021 · 861 citations
• Thermal bottlenecks in the life cycle define climate vulnerability of fish · Science · 2020 · 675 citations
• Complex responses of global insect pests to climate warming · Frontiers in Ecology and the Environment · 2020 · 458 citations
• Regulation of intracellular pH · AJP Advances in Physiology Education · 2004 · 316 citations
• The Covariance between Genetic and Environmental Influences across Ecological Gradients · Annals of the New York Academy of Sciences · 2009 · 307 citations
• Neurons that regulate mouse torpor · Nature · 2020 · 298 citations
• Responses of aquaculture fish to climate change‐induced extreme temperatures: A review · Journal of the World Aquaculture Society · 2021 · 282 citations
• A discrete neuronal circuit induces a hibernation-like state in rodents · Nature · 2020 · 279 citations

Most recent work

• Molecular mechanisms of antifreeze activity in wheat bran arabinoxylan: The role of fine structure in modulating water-ice dynamic changes · Food Research International · 2026
• Long-term warming reduces fish biomass, but heatwaves shift it · Nature Ecology & Evolution · 2026
• Highly and Lowly Domesticated Endangered Fish From a Conservation Hatchery Diverge in Their Thermal Physiology, Transcriptome, and Methylome · Evolutionary Applications · 2026
• Heatwaves impair female but not male fertility in a subsocial insect · Biology Letters · 2026
• Multiomics profiling reveals the adaptive responses of largemouth bass to high temperature stress · Genome biology · 2026
• The aerobic scope is clearly linked to the supply–demand spectrum as quantified by DEB theory · Ecological Modelling · 2026
• Early-life thermal stress reduces survival but has no long-term effects on reproduction in an insect · Journal of Thermal Biology · 2026
• Warm and cool temperatures decrease early‐life telomere length in wild pied flycatchers · Journal of Avian Biology · 2026
• Order matters: Autocorrelation of temperature dictates extinction risk in populations with nonlinear thermal performance · Ecology · 2026
• Heat Tolerance and Its Plasticity in Freshwater and Marine Fishes Reflect Exposure to Extremes and Seasonal Variation in Habitat Temperatures · Ecology Letters · 2026

Related topics in Environmental Science