Warmer waters prime fish species for more sperm

Sydney, April 11 (IANS) Warmer waters can spike the reproductive capacity of the 'pest' fish known as gambusia and also invest them with faster swimming speeds, says a new study that may have implications for the fertility of fish in response to climate change.

Gambusia, a widely distributed species, is native to southeastern US. It has been introduced in Europe, Australia and elsewhere to control mosquito larvae.

Male gambusia in warmer waters produce about three times more sperm than those kept in much colder water, says a team led by Bart Adriaenssens, from the University of New South Wales (UNSW) Evolution and Ecology Research Centre.

The finding may have significant implications for the fertility of fish populations in response to climate change, the journal Global Change Biology quoted researchers as saying.

"Hundreds of studies have examined how whole organisms can modify their physiology and behaviour in response to environmental temperature changes," notes Adriaenssens, according to a UNSW statement.

"Surprisingly, though, virtually nothing is known about the ability of sex cells to adjust to different temperature conditions," adds Adriaenssens.

Study co-author Robbie Wilson, University of Queensland, adds: "Our study suggests that the implications for fish fertility alone could be large indeed in response to climate change."

Gambusia have become a notorious pest, however, because they prey on many other species, notably frogs and aquatic insects.

Researchers warn that gambusia's environmental impact may be worsened if warming temperatures enhance its ability to reproduce. How the sperm production of other species may be affected by warming remains unknown.

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