A recent study published in Journal of Thermal Biology provides the first experimentally derived thermal optimum for octopus paralarvae and offers new insight into one of the most challenging stages of cephalopod aquaculture. The research focused on the gloomy octopus (Octopus tetricus) and investigated how temperature affects metabolic performance during the first four days after hatching.

The work addresses a fundamental problem in both aquaculture and ecology. Survival during the paralarval stage remains a major bottleneck for octopus culture, while warming ocean temperatures may increasingly affect the early life stages of cephalopods. Temperature influences developmental rate, metabolic demand, yolk utilisation, feeding success, and ultimately survival. Understanding the thermal requirements of paralarvae is therefore essential for improving rearing protocols and assessing how populations may respond to environmental change.

The researchers measured standard metabolic rate (SMR), routine metabolic rate (RMR), maximum metabolic rate (MMR), and aerobic scope (AS) across temperatures ranging from 12°C to 27°C. Aerobic scope is particularly informative because it reflects the metabolic capacity available for oxygen-demanding activities such as swimming, prey capture, and feeding.

The microplate respirometry system enabled high-throughput measurements of individual octopus paralarvae. Researchers placed individual animals into the wells of the microplate, where oxygen consumption could be continuously monitored under controlled temperature conditions. The system allowed simultaneous measurement of multiple animals while accounting for background microbial respiration.

Following initial measurements, paralarvae were exercised to exhaustion and then returned to the sensor plate for post-exercise measurements. This enabled the researchers to quantify maximum metabolic performance and calculate aerobic scope across temperatures.

The results revealed a clear temperature-dependent pattern. Aerobic scope was highest between 15 and 21°C, with a model-derived optimum temperature of approximately 18.98°C. At cooler and warmer temperatures, aerobic scope declined, indicating reduced physiological capacity. The findings suggest that octopus paralarvae possess a relatively narrow thermal window during which performance is maximized.

Beyond aquaculture, the findings have broader ecological significance. The authors note that higher ocean temperatures and marine heatwaves could expose early-life stages to conditions outside their optimal physiological range, potentially affecting feeding success, survival, and recruitment. The ability to identify thermal optima through respirometry therefore provides an important tool for evaluating how cephalopods may respond to future environmental change.

The paper titled Thermal sensitivity and aerobic scope in paralarvae of Octopus tetricus is published Journal of Thermal Biology and can be found online at https://doi.org/10.1016/j.jtherbio.2026.104561

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