ISSN:
1573-5117
Keywords:
Gambusia holbrooki
;
Poeciliidae
;
growth
;
reproduction
;
life history tactics
;
Mediterranean estuary
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract We studied age, growth and reproduction of an introduced poeciliid, Gambusia holbrooki (Agassiz, 1859), in the Ebro delta marshes. Maximum ages observed were 2+ in females and 0+ in males. Growth commenced in March and continued until September. Females reached greater sizes, had a higher rate of growth and lived longer than males. The largest sizes found were 63 mm ♀♀ versus 32 mm ♂♂. Multiple spawning occurred throughout the reproductive cycle (from May to September). The average brood size per female reached its maximum in July in the parental cohort (86 embryos/♀) and in August in the offspring cohort (29 embryos/♀). After reproduction the parental cohort decreased drastically. The relationship between fecundity (F) and total length (mm) was calculated for each month of the reproductive period. Sex-ratio deviated significantly from unity. Viviparity, several broods and large larvae provide G. holbrooki with several advantages over oviparous species. The capacity to adjust its life history to a particular environment could explain the life history differences between those in the Ebro delta and other populations.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00014686
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