Reproductive biology of the Neotropical electric fish Brachyhypopomus draco (Teleostei: Hypopomidae) from southern Brazil

Abstract

The reproductive biology of a population of the weakly electric fish Brachyhypopomus draco from southern Brazil is described. Information is provided on the establishment of the reproductive period in this species and its relations with environmental and feeding factors, as well as on the absolute and relative fecundities, spawning type, sex ratio and sexual dimorphism. The species exhibits a relatively long reproductive period, a relative fecundity of 0.173 oocytes per mg of female total weight, and fractional spawning. The sex ratio did not differ from 1:1 during all sampled months. Sexual dimorphism related to hypertrophy of the male's distal portion of caudal filament was observed and males grew to greater lengths than females. Male gonadosomatic index (GSI) was significantly related to water depth, oxygen saturation and temperature. Female GSI was significantly related to water depth and hepatosomatic index.Descreve-se a biologia reprodutiva de uma população do peixe elétrico Brachyhypopomus draco do sul do Brasil. São apresentadas informações a respeito do período reprodutivo estabelecido e suas relações com fatores ambientais e alimentares, bem como a fecundidade absoluta e relativa, tipo de desova, proporção sexual e dimorfismo sexual. A espécie apresentou um período reprodutivo relativamente longo, uma fecundidade relativa de 0,173 ovócitos por mg de peso total da fêmea e uma desova do tipo parcelada. A proporção sexual encontrada foi de 1:1 durante todos os meses amostrados. Dimorfismo sexual relacionado com a hipertrofia da porção distal do filamento caudal dos machos e com o tamanho total dos espécimes -machos atingindo tamanhos maiores do que as fêmeas -foi encontrado. O IGS dos machos foi significativamente relacionado com a profundidade da água, a saturação de oxigênio e a temperatura; o IGS das fêmeas foi significativamente relacionado com a profundidade da água e o índice hepatossomático.

Geometric morphometric analysis of cyclical body shape changes in color pattern variants of Cichla temensis Humboldt, 1821 (Perciformes: Cichlidae) demonstrates reproductive energy allocation

“…Although Arrington et al (2006) found a significant relationship between lipid liver content and the mesenteric fat index, analysis of the relationship between HSI and GSI in C. temensis segregated by CPV grade, shows that after an initial period of increase in both indices, HSI stabilizes and then drops as GSI increases to its maximum. This effect is even more pronounced in females and is similar to that shown in another Neotropical flood pulse river species, Brachyhypopomus draco (Schaan et al, 2009). In summary, as C. temensis individuals approach the açu form and gametes and gonads mature, HSI begins to decrease while corporal reserves continue to increase.…”

“…Second, although patterns of reserve deposition (specifically regarding liver reserve versus alternate corporal reserve deposition) vary with species and life history parameters, the literature shows that fishes whose reproductive period does not coincide precisely with periods of low food availability or high energy requirements may have offset periods of reserve deposition and consumption between the liver and corporal deposits. When reproductive maturation is disengaged from migration, maintenance or periods of minimal food availability, increases in hepatosomatic index (HSI) are not necessarily synchronized with increases in corporal reserve deposition or utilization (Larson, 1991;Schaan et al, 2009). Further it is suggested that materials essential to gametogenesis are stored in the liver (Craig et al, 2000;Regost et al, 2001) and that body fat is not metabolically essential for reproduction; rather it is used primarily for maintenance during low food or high energy consumption periods, such as winter in temperate zone fishes (Larson, 1991).…”

A taxonomic revision of the Neotropical electric fish genus Brachyhypopomus (Ostariophysi: Gymnotiformes: Hypopomidae), with descriptions of 15 new species

“…Reproductive biology and life history: Detailed accounts of the reproductive ecology and life history of Brachyhypopomus are available for B. occidentalis from Panama (Hagedorn, 1986;, and for three species from southern subtropical systems: B. bombilla , B. draco (Schaan et al, 2009), and B. gauderio (Giora et al, 2014;Miranda et al, 2008;Quintana et al, 2004;Silva et al, 2007;Silva et al, 2002; (and see species descriptions herein). The reproductive ecology of Amazon and Orinoco species is largely undocumented, although Alves-Gomes (1997) noted spawning preceding seasonal flooding in the rio Branco system of Roraima, Brazil, and Crampton (1996a) observed spawning coincident with the rising-water period and high water period in species from Amazonian floodplains.…”

“…At extreme southern latitudes Brachyhypopomus exhibit several adaptations to the austral winter -including gonadal quiescence, a general reduction in activity and feeding, and an accompanying reduction of the EOD pulse-rate 2014;Schaan et al, 2009;Silva et al, 2002). Some species of Brachyhypopomus appear to live for only one year, with mortality following a terminal reproductive effort -including B. bennetti (Crampton, 1996a) (listed therein as 'B.…”

Population density and habitat of an endangered cave fish Eigenmannia vicentespelaea Triques, 1996 (Ostariophysi: Gymnotiformes) from a karst area in central Brazil

“…Ecological studies on gymnotiforms are scarce (Lissmann, 1961;Steinbach, 1970;Hagedorn, 1988;Westby, 1988;Alves-Gomes, 1997;Crampton, 1998), and few data on basic aspects of their natural history have been available up to now, most of which consider aspects of their reproduction and feeding biology (Giora et al, 2005;Schaan et al, 2009;Giora et al, 2011). Further, relatively few troglobitic fishes have been studied in detail, focusing on population traits such as population sizes and densities or individual movements and growth (as a life history component) (see Trajano, 2001;Trajano & Bichuette, 2010).…”