Effects of photoperiod on the reproductive success of fathead minnows (Pimephales promelas)

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Title: Effects of photoperiod on the reproductive success of fathead minnows (Pimephales promelas)
Author: Clayton, John Buchanan
Abstract: Rhythms in fish have long been recognized by man ; there are several ancient writings describing the rhythms of seasonal and daily migrations as well as seasonal reproduction . These seasonal rhythms allow organisms to coordinate their biological processes with favorable environmental conditions . For maximum reproductive success to occur , it is necessary that environmental conditions , such as available food supply and proper water quality , are present at the time of spawning . By measuring day length (photoperiod ) , organisms are able to measure the passage of time and coordinate their biological processes with favorable environmental conditions . Recent experimental study has shown that photoperiod is one of the most influential environmental factors effecting rhythms . The length and sequence of day and night cycles was manipulated to determine the effects of photoperiod on reproductive success of fathead minnows , Pimephales promelas (Rafinesque ) . Spawning success of fathead minnows was evaluated under four photoperiod treatments consisting of— (1 ) complete photoperiods , (2 ) skeleton photoperiods , and (3 ) 24 hours of light and (4 ) 24 hours of darkness . Reproductive success was significantly different within each experiment . Fathead minnows appear to require a long photoperiod of at least 14 hours of light , placing them into the category of long -day animals . Exposures to skeleton photoperiods show the possibility of a "daily" rhythm of sensitivity of light . Through this sensitivity rhythm , fathead minnows are most likely able to synchronize their reproduction with favorable environmental conditions . As interpreted day length grew longer , overall egg production increased . Results indicate that the longer the "day" the higher the reproductive success , especially if there is some period of darkness associated with it .
URI: http : / /hdl .handle .net /2346 /15825
Date: 1997-12

Citation

Effects of photoperiod on the reproductive success of fathead minnows (Pimephales promelas). Master's thesis, Texas Tech University. Available electronically from http : / /hdl .handle .net /2346 /15825 .

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