Dynamics of sex reversal in the marbled swamp eel (Synbranchus marmoratus bloch, 1795), a diandric hermaphrodite from Marechal Dutra Reservoir, northeastern Brazil
This study characterizes the dynamics of sex reversal in the marbled swamp eel, Synbranchus marmoratus (Osteichthyes: Synbranchidae), a diandric hermaphrodite, within the context of managing species with complex sex allocations. Monthly sampling in Marechal Dutra Reservoir, northeastern Brazil, w...
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Principais autores: | , , , |
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Formato: | article |
Idioma: | eng |
Publicado em: |
Wiley
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Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/24651 |
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Resumo: | This study characterizes the dynamics of sex reversal in the marbled swamp eel,
Synbranchus marmoratus (Osteichthyes: Synbranchidae), a diandric hermaphrodite,
within the context of managing species with complex sex allocations. Monthly sampling
in Marechal Dutra Reservoir, northeastern Brazil, was conducted using metal eel
traps from July, 2013, to June, 2014, during which a total of 288 individuals were
captured. Morphological and histological comparisons of gonads identified four sex
types: primary males (n = 18), females (n = 197), transitional individuals (n = 30), and
secondary males (n = 43). Primary males were smallest, ranging 18–32 cm total length.
Females were numerically dominant throughout the 1-year
sampling period, and
ranged 20–60 cm. Transitional individuals ranged 32–60 cm, and secondary males
ranged 46–74 cm. The otolith-based
age of 52 specimens ranged 0.5 to 5+ year.
Primary males were only observed at ages 0.5 and 1, and transitional individuals were
only observed at ages 3 and 4 during the female-to-
secondary-
male
transition, supporting
the existence of two types of individuals: gonochoristic males and protogynous
hermaphrodites. This observation was further supported by histological
observations of deteriorating ovarian tissue in transitional individuals. Given the
length of time required for individuals to attain secondary male status, this species appears
to be particularly vulnerable to over-exploitation.
Comparisons with results from
other studies suggest sex allocations and adult size distributions vary substantially
within this species’ range, adding complexity to management efforts |
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