Each year between January and April, a blob of cold water rises from the depths of the Gulf of Panama to the surface, playing an essential role in supporting marine life in the region. But this year, it never arrived.

“It came as a surprise,” said Ralf Schiebel, a paleoceanographer at the Max Planck Institute for Chemistry who studies the region. “We’ve never seen something like this before.”

The blob is as much as 10 degrees Celsius, or 18 degrees Fahrenheit, colder than the surface water. It is also rich in nutrients from decomposing matter that falls to the ocean floor, providing food for local fisheries and wildlife.

Dr. Schiebel was one of the scientists who recently documented the lack of this yearly upwelling in a paper in Proceedings of the National Academy of Sciences and identified a likely culprit: The lack of strong trade winds, which typically blow across Panama and kick off the dry season in January.

When the trade winds reach the Gulf of Panama they push hot surface water away from the coast, which makes room for cold water to rise from the deep.

Steven Paton, one of the paper’s co-authors, runs a large environmental monitoring program at the Smithsonian Tropical Research Institute. The record he helps maintain shows the upwelling has taken place annually for at least 40 years. With that data and other long term records, “we can very clearly say something very unusual happened that we need to pay attention to,” he said.