Thermal Ecology of Antarctic Marine Invertebrates

Antarctic marine invertebrates inhabit one of the most thermally stable and cold environments on Earth, where water temperatures rarely exceed 1 °C and may fall below freezing. This narrow thermal window has driven the evolution of stenothermy, with many species exhibiting limited capacity to tolerate even slight warming. Thermal tolerance in these ectotherms is governed by a balance between metabolic demands and oxygen supply, often quantified through measures such as critical thermal maximum (CTmax) and aerobic scope. Physiological and molecular adaptations—including the synthesis of heat shock proteins—underpin resilience to acute temperature increases, yet the diversity of responses among taxa remains striking. Some species display marked phenotypic plasticity, adjusting cellular and whole‐organism processes, whereas others lack long‐term acclimatisation potential. Assemblage-level experiments reveal that modest warming can shift community structure, favouring opportunistic or pioneer species and reducing biodiversity. As the Southern Ocean warms—models predict rises of up to 2 °C by 2100—understanding species-specific thresholds and ecosystem-level consequences is crucial. Insights from multi-omics, in situ warming experiments and chronic exposure studies inform global biogeochemical modelling, aid conservation planning and guide management of fisheries and benthic habitats under climate change.

Research from Nature Portfolio

Studies using heated settlement panels in Antarctic benthic habitats have shown that encrusting metazoan communities fail to acclimate after prolonged exposure to temperatures 1–2 °C above ambient. Despite significant up-regulation of cellular stress pathways, their upper lethal temperatures decline, and no genotype sorting occurs under warming treatments. In contrast, associated bacterial biofilms maintain stable community structures, revealing divergent responses between metazoans and microbes. These findings emphasise that ecosystem responses to climate warming will be complex and cannot be inferred solely from single-species experiments.

Thermal Ecology of Antarctic Marine Invertebrates publication trend

The graph below shows the total number of articles in thermal ecology of antarctic marine invertebrates across all publications each year (not limited to Nature Index journals).

Technical terms

Critical thermal maximum (CTmax): the highest temperature at which an organism can maintain coordinated function before succumbing to heat stress.

Aerobic scope: the range between an organism’s minimal and maximal oxygen consumption, reflecting its capacity for activity under varying conditions.

Stenothermy: narrow tolerance to temperature variation, characteristic of many polar species.

Phenotypic plasticity: ability of an organism to alter its physiology or morphology in response to environmental change.

Heat shock proteins (HSPs): molecular chaperones synthesised under stress to stabilise and refold damaged proteins.

Hyperoxia: elevated oxygen levels above ambient concentrations, used to test oxygen‐limitation effects on thermal tolerance.

References

1. Testing the Resilience, Physiological Plasticity and Mechanisms Underlying Upper Temperature Limits of Antarctic Marine Ectotherms. Biology (2024).
2. Lack of long-term acclimation in Antarctic encrusting species suggests vulnerability to warming. Nature Communications (2019).
3. Biodiversity in marine invertebrate responses to acute warming revealed by a comparative multi‐omics approach. Global Change Biology (2016).
4. Warming by 1°C Drives Species and Assemblage Level Responses in Antarctica’s Marine Shallows. Current Biology (2017).
5. Can heat shock protein 70 (HSP70) serve as biomarkers in Antarctica for future ocean acidification, warming and salinity stress?. Polar Biology (2022).