Reproductive strategy of a non-annual rivulid in a perennial wetland

Clarice B. Fialho,Laísa W. Cavalheiro

doi:10.1590/1678-476620151053288296

Clarice B. Fialho, Laísa W. Cavalheiro

Open Access

https://doi.org/10.1590/1678-476620151053288296

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Abstract

ABSTRACT Atlantirivulus riograndensis (Costa & Lanés, 2009) is a fish registered to the basin of Patos lagoon and the adjacent coastal plains in southern states of Rio Grande do Sul and Santa Catarina, Brazil, found in shallow water courses with that have large quantities of aquatic vegetation and forest edges. The objective of this study was to investigate the reproductive strategy and tactics of this species including the sex ratio, the length at first maturity, spawning type, fecundity and the possible associations among reproduction and abiotic factors. Sampling of specimens occurred in perennial wetlands within the Banhado dos Pachecos wildlife refuge, in the city of Viamão, state of Rio Grande do Sul, Brazil, which is a conservation unit that belongs to an area of environmental protection in the Pampa Biome. The capture of 30 A. riograndensis specimens per month occurred from January to December of 2012. A total of 188 females and 172 males were captured and the total sex ratio was 1:1 in the sampled population. Sexual maturity of the species occurs after 13.59 and 11.92 mm (SL) for females and males, respectively. Both a multiple spawning and a long reproductive period (since August to March) were confirmed by the presence of post-ovulatory follicles that were observed through histological analysis and the values of the gonadosomatic index in females considered spawning capable. The average absolute fecundity of the species is of 19.33 (± 6.18) vitellogenic oocytes in mature ovaries. No significant relationship was found between mean GSI and the abiotic data. Reproductive tactics presented by A. riograndensis indicate a species with an opportunistic reproductive strategy, following the pattern of other species of the Rivulidae family.

Highlights

IntroductionO objetivo deste estudo consistiu em investigar a estratégia e as táticas reprodutivas desta espécie, incluindo a proporção sexual, o comprimento de primeira maturação, o tipo de desova, a fecundidade e possíveis associações entre a reprodução e fatores abióticos
The long reproductive period described for A. riograndensis in this study is quite well known among individuals of the Rivulidae family (Arenzon et al, 1999; Arezo et al, 2007; Gonçalves et al, 2011; Cassel et al, 2013)
Austrolebias charrua Costa & Cheffe, 2001 showed all phases of sexual maturation from May to December, with December characterized as the month of senescence since the adults of this species die in the dry season (Arezo et al, 2007)

Summary

Introduction

O objetivo deste estudo consistiu em investigar a estratégia e as táticas reprodutivas desta espécie, incluindo a proporção sexual, o comprimento de primeira maturação, o tipo de desova, a fecundidade e possíveis associações entre a reprodução e fatores abióticos. The non-annual rivulids of Atlantirivulus riograndensis (Costa & Lanés, 2009) are the object of this study. This species is included on the list of species threatened by extinction in the state of Rio Grande do Sul, and classified as in danger (Rio Grande do Sul, 2014). Studies related to reproductive biology of this group are scarce and are available only for Melanorivulus punctatus (Boulenger, 1895) species, which presents a long reproductive period and a multiple spawn (Cassel et al, 2013)

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