Rapid phenotypic changes of reproductive traits in response to experimental modifications of spatial structure in Nile tilapia, Oreochromis niloticus

Publication Type:Journal Article
Year of Publication:2001
Authors:F. Duponchelle, Legendre M.
Journal:Aquatic Living Resources
Date Published:MAR-APR
Accession Number:ISI:000169170900007
Keywords:adaptability, behavior, cichlidae, cote-divoire, egg size, fecundity, fishes, ivory coast, man-made lakes, maturity, phenotypic plasticity, Pisces, populations, reproduction, spatial organisation, tilapia

The reproductive characteristics of Oreochromis niloticus, a multiple spawner, have been compared between populations submitted experimentally to three types of spatial structure. Fish from a same original stock were divided and reared for 2 months in: 1) concrete tanks with a bare bottom, 2) concrete tanks with a sandy bottom, or 3) concrete tanks equipped with an artificial reef. The females were then killed and their gonads examined for sexual stage and fecundity determination. Fecundity was inversely correlated to the spatial complexity of the environment whereas oocyte size tented to increase together with spatial complexity. Females placed in tanks with artificial reefs presented a lower fecundity and reproductive investment and bigger oocytes than those maintained in the bare bottom tanks. Fish reared in tanks with a sandy bottom had intermediate reproductive traits. The response of females to changes in the spatial structure of their environment was observed after only one or two reproductive cycles, providing the first experimental evidence of such rapid phenotypic adaptation to environmental complexity. The results also indicate that the perception of living space, arising from the availability of refuges and spawning sites, is more likely to influence the reproduction of tilapias than substrate quality.

Alternate Journal:Aquat Living Resour

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