Lobsters face serious risks as oceans heat up

The Gulf of Maine is warming faster than almost every other ocean region on Earth. That single fact has scientists worried about the future of the American lobster, the backbone of a two billion dollar fishery.

Warming, acidification, and marine heatwaves are not just abstract trends here. They are daily realities, reshaping one of the most iconic species in New England waters.

Communities along the coast depend on lobsters not only for income but also for identity. A shift in lobster health could ripple far beyond science labs and touch entire economies.

To understand what lies ahead, researchers at William & Mary’s Batten School and the Virginia Institute of Marine Science (VIMS) have been testing how lobster embryos respond to future ocean conditions. The results point to temperature as the main danger.

Inside the experiment

At the Seawater Research Laboratory, Professor Emily Rivest and her colleagues recreated the Gulf of Maine of 2060. Egg-bearing lobsters collected from Maine and Massachusetts were placed in tanks with different combinations of temperature and acidity. The study ran for five months – long enough to track development across multiple stages.

The outcome was striking. Embryos tolerated acidification, but warmer water stressed them in measurable ways. Metabolic rates rose, development sped up, and the larvae that hatched were smaller.

“American lobsters are dynamic creatures that have been shown to tolerate highly variable conditions as they move from coastal waters to the deeper ocean,” said Brittany Jellison, the study’s lead author.

“However, as we observe rising ocean temperatures, increased acidification and more frequent marine heat waves, it’s important to understand how future environmental changes might impact this economically and culturally important species.”

Lobsters resist acidification

The research showed that acidification alone caused little disruption. Lobsters seem well prepared for fluctuating pH because females carrying eggs already expose embryos to natural swings in estuaries and coastal zones.

Lobster physiology also helps. Specialized enzymes allow embryos to regulate acid-base balance efficiently.

The researchers found no clear changes in oxygen consumption or enzyme activity under lower pH. That resilience suggests acidification, while important, may not be the decisive factor for embryo survival in the Gulf of Maine.

Lobsters under warming stress

Temperature told a different story. Warmer water pushed embryos into overdrive. Heart rates increased, oxygen consumption jumped, and enzyme activity climbed. All of that energy came with a price: smaller larvae at hatching.

“Their ability to withstand increased acidification may be in part due to the varying pH levels found in their natural environments. However, the larvae hatched in warmer waters were noticeably smaller, which may result in decreased survival in the wild,” said Jellison.

She noted that releasing larvae in batches during migration may be a natural strategy to hedge survival odds.

Dramatic changes in warmer months

Embryos did not deplete yolk reserves faster under warming, but energy use shifted. Protein and yolk were consumed steadily, and metabolism accelerated.

This balance allowed embryos to keep developing, yet the larvae still emerged undersized. That mismatch echoes a biological rule observed in many cold-blooded animals: faster development under heat often means smaller body size.

The study also found seasonal patterns. The most dramatic changes occurred during the warmest months, raising alarms about what might happen as marine heatwaves strike more often.

Lobsters with warming larvae

Lobsters held in ambient conditions produced larvae for longer periods and in greater numbers. Those raised in warmer tanks released fewer larvae and consistently smaller ones. Acidification did not alter size, but temperature did.

Such results matter because larval survival in the wild is already low. Only a small fraction ever reach adulthood. If warming trims larval size and weakens survival chances further, the fishery could feel the impact in coming decades.

A fishery at risk

The Gulf of Maine has remained productive, but the southern New England lobster fishery has already collapsed under rising temperatures. A similar decline farther north is no longer unthinkable.

“Additional research is needed to better understand how these changes extend to influence the performance and success of free-swimming larval stages,” said Rivest.

“These negative carryover effects have been found in other crustaceans, and this knowledge will help determine the impacts on future recruitment and the overall success of the fishery.”

Lobsters in a warming world

Future work will test whether resilience to acidification can be inherited and how offshore environments shape embryo development. For now, the evidence is clear. Acidification may be survivable, but warming strikes at the heart of lobster reproduction.

The Gulf of Maine is already a hotspot of ocean change. How well the lobster adapts will determine not only the fate of a species but also the future of one of North America’s most valuable fisheries.

The study is published in the journal Marine Ecology Progress Series.

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