A recently published research reveals queen bumblebees can endure full submersion in water for roughly a week and then recover. Researchers say this capacity could buffer wild populations against increasingly frequent winter floods that saturate underground hibernation chambers as the climate warms.
Ecologist Sabrina Rondeau from the University of Guelph was shocked to discover diapausing Bombus impatiens queens alive in a puddle of condensation water following a refrigerator malfunction in her lab. “I couldn’t believe it,” she said, according to Science.
She then deliberately repeated the submersion with more than 100 additional queens to test the phenomenon. Survival rates in some trials reached about 89.5 percent. In others they remained around 81 percent.
Not just holding their breath
Rondeau then partnered with ecological physiologist Charles Darveau to measure gas exchange and metabolism during submersion. Results from the research published in Proceedings of the Royal Society B indicate the bees are not simply holding their breath.
According to the study, submerged queens appear to employ passive aquatic respiration using physical gill formed when dense body hairs trap air around the cuticle. They simultaneously throttle down energy use to an extreme low level. In diapause, and especially when underwater, their metabolic rate can fall to one-sixth of its initial value.
The team recorded that submerged queens continued to release small amounts of carbon dioxide, indicating respiration of some kind continued even underwater. Queens appeared to take in small amounts of oxygen from the water, then switch to anaerobic metabolism when needed.
By day eight, tubes holding submerged queens contained less than 40 percent of the oxygen measured in control tubes without bees. Upon removal from water, the queens’ metabolic rates rose sharply for two to three days during a recovery process in which they cleared lactate accumulated during anaerobic activity.