A gender-bending parasite has been discovered which is believed to be responsible for turning male shrimps and other crustaceans into females.
Scientists believe the discovery could be a breakthrough for commercial mussel and oyster bed operations which suffer major consequences from the sex-change problem.
Microbiologists at the University of Portsmouth have found that the new species of paramyxean is responsible for the changes which were previously put down to a parasite known as microsporidians.
But their research, funded by the Natural Environment Research Council, has shown that the microsporidians simply "hitch-hike" on the newly found parasite which causes the sexual dysfunction in various types of crustaceans.
Dr Alex Ford, from the university's Institute of Marine Science (IMS), said that the discovery could rewrite the textbooks.
He said: "This is vital research because we're seeing a gender imbalance which is a serious ecological problem affecting species further up the food chain.
"Marine creatures such as shrimps and molluscs are food for fish and seabirds which mean the consequences could be profound."
Dr Stephen Short, from the IMS, explained that these species were additionally vulnerable because industrial pollutants such as plastics, oils and toxic PCBs in the water made them less able to fight infection or attack.
He said: "Newborn crustaceans are sexless and are very open to being directed a particular way.
"What we're currently seeing is worrying for our marine habitats because the problem is chronic and widespread."
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