As ocean temperatures rise and marine ecosystems change, scientists are working to understand how valuable species like the American lobster will respond. New research from William & Mary's Batten School of Coastal & Marine Sciences & VIMS suggests one source of resilience may come from the microscopic bacterial communities living on lobster embryos.
The study, published in Scientific Reports , found that lobster eggs host surprisingly diverse microbiomes that change as the embryos develop but otherwise remain remarkably stable even under conditions simulating future environmental conditions. The findings challenge decades of assumptions that lobster eggs contained only a few key bacterial species and could help scientists better understand disease risks in one of North America's most valuable fisheries.
"We were hoping to discover one dominant microbe early on," said study coauthor Jeffrey Shields, a professor at the Batten School & VIMS who collaborated with several of his students on the research, including lead author Sarah Koshak. "Instead, it was a mishmash, a rich community of different bacteria whose roles we don't yet fully understand."
A hidden ecosystem on lobster eggs
Using advanced genetic sequencing techniques, researchers analyzed microbial communities on lobster embryos and newly hatched larvae raised under varying temperatures and pH conditions designed to mimic present-day and future ocean conditions in the Gulf of Maine.
Researchers identified thousands of unique bacterial variants across the embryos, larvae and tank water samples. Diversity increased steadily as the embryos developed, with late-stage embryos and larvae hosting more complex microbial communities than early-stage embryos.
Scientists believe several factors may drive that increase. As embryos grow, their surface area nearly doubles, creating more space for microbes to colonize. Developing embryos also release metabolic byproducts that may provide food for bacteria. Some microbes may even prey on other bacteria, creating an increasingly dynamic ecosystem over time.
The study also revealed that the microbiome on lobster embryos was distinctly different from the surrounding seawater, suggesting the embryos themselves actively shape which microbes can colonize them.
"The embryo's outer coat is a very selective surface," Koshak said. "It creates a unique microhabitat that shapes the microbial community."
The researchers also suspect some microbes may originate from the mother rather than the surrounding environment, potentially giving embryos a head start in establishing beneficial microbial communities. They hope to explore microbial origins further in future studies.
Surprisingly resilient to environmental changes
One of the study's biggest surprises was that warmer temperatures and more acidic conditions had little effect on the overall structure of the microbiome.
"That goes against what you might expect," Shields said. "We often think bacteria respond strongly to temperature, but here they all seem to be responding at about the same rate."
The result suggests lobster embryos may be more resilient to near-term climate change than scientists previously thought.
"There's a natural progression in these communities as the embryos develop," Shields said. "Temperature and pH don't seem to disrupt that very much."
The findings are particularly important because the Gulf of Maine is one of the fastest-warming marine regions in the world. Warming waters are suspected of already contributing to disease outbreaks and population declines in southern New England lobster populations, raising concerns about how early life stages may respond to environmental stress.
Implications for lobster health and fisheries
The study could help scientists better understand disease risks in the American lobster fishery, which generates hundreds of millions of dollars annually in the United States and Canada. Egg mortality is a major issue in crustaceans, and microbial infections are a leading cause of embryo loss.
Whereas past research identified bacteria capable of suppressing fungal growth on lobster eggs, this new study found a small "core microbiome" shared across life stages that included bacterial groups known in other marine organisms to provide probiotic or protective functions.
"We think some of these microbes may help defend the embryos against pathogens," Koshak said. "But we're still early in understanding what roles they play."
The findings build on several related Batten School & VIMS studies examining how warming waters and ocean acidification affect lobster embryos and egg-bearing females. Part of the National Oceanic and Atmospheric Administration Sea Grant American Lobster Initiative, earlier research found that climate-related stressors can alter embryo development and influence maternal grooming behaviors, with mixed implications related to environmental changes.
For Shields, the study underscores the importance of establishing scientific baselines before environmental conditions shift further.
"If we want to understand how things change in the future, we need to know what 'normal' looks like now," he said.
