Spiny Lobsters Can Handle Some Ocean Warming, But Temperature Extremes Prove Deadly

We heated seawater to 26°C—near the upper limit of what California spiny lobsters experience in their natural range— This stark result from temperature experiments, conducted by Bartholomew DiFiore, Krista Kraskura, Emily Hardison, Joseph Curtis, Erika Eliason, and Adrian Stier, revealed just how narrow the thermal window might be for these iconic predators as oceans warm.

We wanted to answer a fundamental question about marine predators in a warming world: as temperatures rise and metabolism increases, can animals eat enough to fuel their higher energy demands? Working with 24 male spiny lobsters collected from Santa Barbara County kelp forests, they acclimated groups to four temperatures spanning their natural range: 11, 16, 21, and 26°C. After acclimation, they measured each lobster's oxygen consumption using respirometry chambers, then tested how many mussels they could consume.

What We found challenged their initial hypothesis. They expected metabolism to outpace consumption, potentially leaving lobsters in caloric deficit. Instead, rising temperatures caused lobster consumption rates to increase at a faster rate than increases in metabolic demand. In the middle range of temperatures, these predators appeared capable of ramping up their feeding to meet their heightened energy needs. The relationship between their absolute aerobic scope—the difference between maximum and resting metabolic rates—and their predation intensity suggested they had the physiological capacity to support increased hunting.

"At 11°C, lobsters had almost no metabolic activity, essentially shutting down in the cold."

But the temperature extremes told a different story entirely. At 11°C, lobsters had almost no metabolic activity, essentially shutting down in the cold. At the other extreme, that 33% mortality rate at 26°C was impossible to ignore. The lobsters that survived showed they could theoretically meet their metabolic demands through increased consumption, but clearly something about that temperature pushed many individuals past their physiological limits.

These results suggest temperature plays a key role in driving the geographic range of spiny lobsters, and that spatial and temporal shifts in temperature can critically alter the strength of species interactions. As both important predators in temperate reef ecosystems and economically valuable fishery species, spiny lobsters face a complex future. They might handle moderate warming by eating more, but temperature extremes could force range shifts or population declines.

Questions remain about what happens in real ocean conditions, where temperatures don't stay constant and prey availability fluctuates. Can lobsters maintain these higher consumption rates when faced with variable food supplies? And what exactly causes that lethal threshold at high temperatures? Until the physiological mechanisms behind thermal limits are better understood, predicting how these predators will navigate an increasingly warm ocean remains challenging.

Citation

Csik, Samantha R.; DiFiore, Bartholomew P.; Kraskura, Krista; Hardison, Emily A.; Curtis, Joseph S.; Eliason, Erika J.; Stier, Adrian C. (2023). The metabolic underpinnings of temperature-dependent predation in a key marine predator. Frontiers in Marine Science.

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This paper is Open Access.