Please use this identifier to cite or link to this item: http://hdl.handle.net/10348/4332
Title: Life history, population dynamics and production of eastern mosquitofish, Gambusia holbrooki (Pisces, Poeciliidae), in rice fields of the Lower Mondego River Valley, West Portugal.
Authors: Cabral, João Alexandre
Marques, João Carlos
Keywords: Mosquitofish
Gambusia holbrooki
Poeciliidae
Growth
Reproduction
Population dynamics
Production
Issue Date: 1999
Citation: Cabral J. A. and Marques J. C., 1999
Series/Report no.: 20;6
Abstract: The introduced population of Gambusia holbrooki from the rice fields of the lower Mondego River Valley, Portugal, was studied for 15 months, relating their life cycle and population dynamics with its production, in order to assess the role of the species in the energy flow and secondary production in this type of agro-ecosystem. Two main annual cohorts (1995 and 1996 cohorts) were identified. The females outnumbered males and the average female/male-ratio was 4. The inspection of ovary developmental stages of this viviparous fish, revealed that the most important reproductive period was between April and August. The first recruits were recorded in June and were present thereafter until October. Males from the parental cohort died before August, whereas parental females could survive until October. Mean adjusted fecundity (number of embryos divided by female standard length) peaked in July 1996 (0.95) and in June 1997 (1.05). Females reached greater sizes, had a higher growth rate and lived longer than males. Annual production was estimated at 3.101 g×m–2×year–1 (ash-free dry weight, AFDW), the average biomass at 2.896 g×m–2 (AFDW), and the P/B ratio was 1.071. A conjugation of life history, population dynamics, production and ecological traits (e.g. fast growth, reduced longevity, viviparity, high productivity, an intermediate position in food chain, and no special habitat requirements for reproduction) clearly show that the populations of G. holbrooki, introduced into rice fields all over the world, may play an important role in the structure and functioning of the biological communities of these important agro-ecosystems.
Peer Reviewed: yes
URI: http://hdl.handle.net/10348/4332
Document Type: Article
Appears in Collections:DEBA - Artigo publicado em Revista Científica Indexada

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