The worms that turned into mega-breeders

By Jon Copley MARINE biologists have tricked ragworms into breeding at any time of the year. This means that the worms can now be farmed, which should protect the fragile ecosystems of beaches that are regularly dug up to harvest the animals for fishing bait. Simon Rees and Peter Olive of the University of Newcastle studied the effect of day length on ragworm reproduction. Although they can live for several years, these marine worms put all their efforts into reproducing only once—after which they die. The timing of breeding is crucial, as the worms release their eggs and sperm into the water, where they mix and fertilise. If one worm spawns just a few hours early, for example, its reproductive cells will not meet those of the other worms and all its efforts will be wasted. The researchers found that the animals have an internal clock that follows an annual rhythm, but they also rely on changes in day length to synchronise their reproductive efforts. By exposing the worms to 8 hours of light and 16 hours of darkness in a 24-hour cycle, Rees and Olive were able to stimulate the growth of their eggs. In contrast, simulating a long day slowed the development of the growing eggs. Keeping the worms in cold water further enhanced the growth of their eggs. “To get the strongest effect, we combine photoperiod and temperature,” says Rees. “In effect, we’re creating winter or summer conditions.” The researchers have applied for a patent on their system, which they have already used to produce 20 tonnes of ragworms in just one year. Digging for fishing bait has a major impact on the ecology of beaches, says Rees,
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