Researchers hope to assess the potential impact of global warming on marine ecosystems by examining tiny worms that inhabit the Southern Ocean around Antarctica.

A study by the National Science Foundation focuses not only on how the polar worm Capitella perarmata adapts to the frigid waters and survives temperature changes, but also on how it adapts compared with a close relative that inhabits temperate waters, the Capitella teleta.

Led by Adam Marsh, associate professor of marine biosciences in UD's College of Earth, Ocean, and Environment, the research team undertook a series of dives in the freezing waters for two months to collect the polar sea worms, which are segmented like earthworms but belong to the class known as polychaetes.

"By comparing these two marine species, we hope to assess how a polar environment shapes responses to environmental stress," said Marsh. "By better understanding how the environment can trigger genetic changes - through the genes the polar worm turns on or ‘expresses' - we can gain insight into the potential impact of global warming on marine ecosystems."

Marsh and his team focused on identifying epigenetic changes in DNA methylation in these worms, or how the environment is influencing the worms' genetic code. DNA methylation is a process in animals and plants where environmental signals are "imprinted" on genes in a genome by chemical modification of cytosine, one of the bases of the DNA code, to 5'-methyl-cytosine.

Researchers said that by tracking changes in metabolic activity and locating genes where methylation changes are active, they will be able to pinpoint the types of genes involved in the temperature acclimation process.

Marsh hopes the study will shed light on the ability of some Antarctic species to survive ocean warming.

"The coastal waters around Antarctica have been at very stable temperatures for millions of years," Marsh says.

"This low-temperature environment has led to the evolution of many endemic polar marine species. As global sea-surface temperatures rise, temperatures in Antarctica will also increase. For animals that are used to constant cold conditions, even slight increases in temperature can have large impacts on survival," he added.