Is oxygen limitation in warming waters a valid mechanism to explain decreased body sizes in aquatic ectotherms?

  title={Is oxygen limitation in warming waters a valid mechanism to explain decreased body sizes in aquatic ectotherms?},
  author={Asta Audzijonyte and Diego R. Barneche and Alan Ronan Baudron and Jonathan Belmaker and Timothy D. Clark and Caroline T. Marshall and John R. Morrongiello and Itai van Rijn},
  journal={Global Ecology and Biogeography},
Aim: The negative correlation between temperature and body size of ectothermic animals (broadly known as the temperature‐size rule or TSR) is a widely observed pattern, especially in aquatic organisms. Studies have claimed that the TSR arises due to decreased oxygen solubility and increasing metabolic costs at warmer temperatures, whereby oxygen supply to a large body becomes increasingly difficult. However, mixed empirical evidence has led to a controversy about the mechanisms affecting… 

Investigating the gill-oxygen limitation hypothesis in fishes: intraspecific scaling relationships of metabolic rate and gill surface area.

The need to investigate hypotheses other than the GOL hypothesis to help explain the observed declines in maximum fish body sizes concurrent with climate warming is identified, in order to facilitate accurate predictions of fish community structure and manage fisheries in the face of climate change.

Quantitative mismatch between empirical temperature-size rule slopes and predictions based on oxygen limitation

In ectotherms, adult body size commonly declines with increasing environmental temperature, a pattern known as the temperature-size rule. One influential hypothesis explaining this observation is

Body Size of Temperate Sea Spiders: No Evidence of Oxygen-Temperature Limitations

Testing the effects of temperature on the rate of oxygen consumption of two temperate sea spider species found no evidence to support the oxygen-temperature hypothesis, and suggests that the generally small size of warm-water sea spiders may be due to selective factors other than oxygen limitation.

Scaling of thermal tolerance with body mass and genome size in ectotherms: a comparison between water- and air-breathers

The results demonstrate that thermal tolerance in ectotherms is dependent on body mass and genome size and these relationships became especially evident in prolonged experimental trials where energy efficiency gains importance.

Reconsidering the oxygen-temperature hypothesis of polar gigantism: successes, failures, and nuance.

  • H. WoodsA. Moran
  • Environmental Science, Biology
    Integrative and comparative biology
  • 2020
Evidence for and against the oxygen-temperature hypothesis is reviewed, suggesting that the hypothesis may apply most meaningfully to organisms with poorly developed physiological systems (eggs, embryos, egg masses, juveniles or adults without mechanisms for ventilating internal or external surfaces).

The role of mechanistic physiology in investigating impacts of global warming on fishes

Thermal performance curves are important for predicting warming effects on fish, and the continued importance of experimental physiology is emphasised, particularly in advancing the understanding of underlying mechanisms, but also the challenge of making this knowledge relevant to the more complex reality.

Warm and out of breath: Thermal phenotypic plasticity in oxygen supply

Empirical evidence is provided that the oxygen challenge in aquatic ectotherms increases with increasing temperature, even in the presence of phenotypic plasticity in oxygen supply.

Shrinking body sizes in response to warming: explanations for the temperature–size rule with special emphasis on the role of oxygen

Temperature–size responses can be explained by the ‘Ghost of Oxygen‐limitation Past’, whereby the resulting (evolved) T–S responses safeguard sufficient oxygen provisioning under warmer conditions, reflecting the balance between oxygen supply and demands experienced by ancestors.

Oxygen limitation fails to explain upper chronic thermal limits and the temperature size rule in mayflies

Chronic (whole-life) studies do not support a causative role for oxygen limitation in setting upper chronic thermal limits or temperature-size patterns in mayflies, and it is concluded that a failure to meet tissue oxygen demands is not a viable hypothesis for explaining either the chronic thermal limit or TSR pattern.

Temperature-related body size change of marine benthic macroinvertebrates across the Early Toarcian Anoxic Event

A strong negative correlation between the mean shell size of bivalve communities and isotope-derived temperature estimates is found, suggesting heat stress as a main cause of body size reduction.



Warming-induced reductions in body size are greater in aquatic than terrestrial species

It is proposed that oxygen supply plays a central role in explaining the magnitude of ectothermic temperature-size responses and the environment-dependent differences parallel latitudinal body size clines will influence predicted impacts of climate warming on food production, community structure, and food-web dynamics.

Warming temperatures and smaller body sizes: synchronous changes in growth of North Sea fishes

A recent model-derived prediction that fish size will shrink in response to climate-induced changes in temperature and oxygen is supported, as the smaller body sizes being projected for the future are already detectable in the North Sea.

The Temperature‐Size Rule in Ectotherms: Simple Evolutionary Explanations May Not Be General

Little evidence is found that growth efficiency is negatively related to environmental temperature within the thermal range that is relevant to the temperature‐size rule, and growth efficiency was either positively related or insensitive to environmentalTemperature in the majority of cases.

Climate warming and ectotherm body size – from individual physiology to community ecology

This review discusses the underlying physiological mechanisms of changes in ectotherm body size and addresses observed responses within a broad ecological context at different levels of organization, from individuals to communities, particularly in aquatic systems.

Is the temperature-size rule mediated by oxygen in aquatic ectotherms?

Oxygen supply in aquatic ectotherms: partial pressure and solubility together explain biodiversity and size patterns.

A reappraisal of how organismal thermal physiology and oxygen demands together shape aerobic performance in aquatic ectotherms and the new insight of how these components change with temperature have broad implications for predicting the responses of aquatic communities to ongoing global climate shifts.

Temperature, Growth Rate, and Body Size in Ectotherms: Fitting Pieces of a Life-History Puzzle1

A multivariate theory that focuses on the coevolution of thermal reaction norms for growth rate and size at maturity is recommended, which should incorporate functional constraints on thermal Reaction norms, as well as the natural covariation between temperature and other environmental variables.

The temperature size rule in arthropods: independent of macro-environmental variables but size dependent.

Considerable variation among species exists in the TSR, suggesting either strong interactions with nutrition, or selection based on microclimatic or seasonal variation not captured in classic macro-environmental variables.

Seasonal time constraints do not explain exceptions to the temperature size rule in ectotherms

It is concluded that time constraints do not account for any reported counter-TSR relationship and is suggested that gaps in the data and/or experimental design can explain the apparent exceptions.

Large but uneven reduction in fish size across species in relation to changing sea temperatures

The results suggest that ocean warming will result in a sharp, but uneven, reduction in fish size that will cause major shifts in size‐dependent interactions and have major implications for fisheries as the main species targeted for harvesting will show the most substantial declines in biomass.