New research from the Australian Antarctic Division aquarium shows that darkness can be used to influence the maturation cycle of krill.
Previous attempts to influence the development of krill through exposure to light and dark had shown that krill maintain their matings patterns regardless of environmental factors. Then, Japanese research in 2003 suggested that abrupt changes in the daily light and dark patterns could alter maturation and spawning.
The lab at AAD has shown that one month of the natural Antarctic light cycle, followed by two months of darkness, and nine months of light makes krill reach sexual maturity three months earlier than control groups. The findings were published in The Journal of Plankton Research and displayed in a graph here:
Principal researcher, Dr So Kawaguchi said:
“We’ve been able to reset the animals’ internal clocks, so that they become sexually mature three months earlier than if they were exposed to a natural Antarctic light cycle.[Previous] research suggested that the cycle of regression, maturation and reproduction was controlled by an internal biorhythm rather than environmental factors.
For many crustaceans and other animals, environmental cues like changes in light and temperature, influence when they reproduce, so previous research has only focused on the timings of changes in light, not darkness.”
“This study has shown that the transition from light to dark to light is important in controlling the timing of spawning under laboratory conditions.
“‘We have more work to do to fine tune our methods and repeat our results. We also need to look at any physiological changes in krill that might result from this “resetting” process.”
Krill are an important part of the food chain, feeding on phytoplankton and some zooplankton. In turn, krill provide a vital part of the diet of larger animals such as; whales, seals, penguins, squid and fish. Krill provide food for predators near the surface at night and in deeper waters during the day. There is an estimated 500 million tonnes of Antarctic krill in the Southern Ocean – around twice the biomass of humans.