Deadly deficiency at the heart of an environmental mystery

Abstract

Researchers are puzzling over a widespread vitamin B shortage that appears to be killing wildlife . During spring and summer, busy colonies of a duck called the common eider ( Somateria mollissima ) and other wild birds are usually seen breeding on the rocky coasts around the Baltic Sea. Thousands of eager new parents vie for the best spots to build nests and catch food for their demanding young broods. Researchers observed herring gulls, such as this one, that couldn’t stand because of paralyzed legs. This bird and others also had squinting eyes, discolored pupils, and wings that didn’t fold back close to the body. All are symptoms of thiamine deficiency. Image courtesy of Lennart Balk and Per-Ake Hagerroth (Stockholm University, Stockholm). But Lennart Balk, an environmental biochemist at Stockholm University, witnessed a dramatically different scene when he visited Swedish coastal colonies during a 5-year period starting in 2004. Many birds couldn’t fly. Others were completely paralyzed. Birds also weren’t eating and had difficulty breathing. Thousands of birds were suffering and dying from this paralytic disease, says Balk. “We went into the bird colonies, and we were shocked. You could see something was really wrong. It was a scary situation for this time of year,” he says. Based on his past work documenting a similar crisis in several Baltic Sea fish species, Balk suspected that the birds’ disease was caused by a thiamine (vitamin B1) deficiency. Thiamine is required for critical metabolic processes, such as energy production and proper functioning of the nervous system. This essential micronutrient is produced mainly by plants, including phytoplankton, bacteria, and fungi; people and animals must acquire it through their food. Scenes such as the one in Sweden, seen again and again in recent years in a variety of species in Europe and North America, have Balk …