Reproductive aspects of Hyalella carstica (Amphipoda: Hyalellidae) in a natural environment in southeastern Brazil

Abstract

Th e reproductive aspects of populations are important determinants of their ability to maintain themselves throughout time. In the case of amphipods from the genus Hyalella Smith, 1874, the reproductive period is easily determined by the presence of ovigerous females and pre-copula pairs in the population. Th is study evaluated the fecundity, pairing patterns and reproduction period of Hyalella carstica Bastos-Pereira and Bueno, 2012 in a karst environment in the West of Minas Gerais, Brazil. Monthly, from April, 2010 to April, 2011, amphipods were sampled using a hand net with 15 cm diameter and 250 µm mesh size. In the laboratory, animals were sexed and measured, and the ovigerous state of females was evaluated. Couples in pre-copula and ovigerous females were found throughout the year, with the exception of the dry months (September−November). During drought, the stream's superfi cial water dried out, and only a few refuges for the population remained. Although couples were found in all months with a water fl ow, a higher number of unpaired males and females was found after the dry season. In all months, ovigerous females were more abundant than non-ovigerous, and the relationship between head length and the number of eggs in the marsupium was positive. Most eggs were in the fi rst developmental stage, although all other stages were found before the dry season. Considering the frequency of pre-copula pairs, as well as ovigerous females, the reproduction in this H. carstica population seems to be continuous throughout the year, without a distinct peak.

Population and reproductive traits of a freshwater amphipod (Crustacea, Peracarida, Hyalellidae) from northwest of the state of Rio Grande do Sul, Brazil

“…The number of pairs in precopulatory mate-guarding behavior in the population of H. palmeirensis was slightly low, when compared to unpaired adults. The same was observed in Hyalella castroi and H. pleoacuta (Castiglioni & Bond-Buckup 2008b), H. carstica (Torres et al 2015) and H. bonariensis (Castiglioni et al 2018). The low occurrence of pairs in this population can be related to the fact that the individuals stay in precopulatory mate-guarding for a short time, approximately 3-4 days (personal observation), since this behavior can make individuals more vulnerable to predation (Strong 1972;Wellborn 1995;Castiglioni & Bond-Buckup 2008b).…”

“…The mean fecundity of H. palmeirensis is relatively lower than other species of Hyalella that occur in the state of Rio Grande do Sul, such as H. pleoacuta and H. castroi (Castiglioni & Bond-Buclup 2009), and H. gauchensis and H. georginae (Ozga & Castiglioni 2017) and similar to H. bonariensis (Castiglioni et al 2018). Castiglioni et al (2018) observed for H. bonariensis greater fecundity compared to other Brazilian tropical species, such as H. carstica (Torres et al 2015) and H. longistila (Bastos-Pereira & Bueno 2016) and one North American species, H. azteca (Othman & Pascoe 2001;Wellborn et al 2005). Probably, this difference in fecundity between species of the genus Hyalella may be associated with differences in habitats and microclimate in which species live, a fact already verified by Poweel (1992) and Appadoo & Myers (2004) for other amphipod species.…”

“…Reduction in the number of eggs in summer may be associated with decreased macrophyte coverage and consequently shelter and food during the warmer months where specimens were sampled suggesting what may be related to a reproductive strategy of this amphipod (Castiglioni & Bond Buckup 2009;Castiglioni et al2018). Already results obtained by Torres et al (2015) for H. carstica showed that higher egg production peaked in summer after a long drought period suggesting that females produced more eggs at this time to recover and recolonize the habitat. Differences in seasonal fertility fluctuations observed in these species demonstrate that environmental conditions can directly interfere with reproductive biology as already observed by Maranhão et al (2001), that cites temperatures and rainfall as factors that may influence the reproduction of amphipods.…”

Ecological aspects of natural populations of Hyalella pampeana (Crustacea, Amphipoda, Hyalellidae) from the Natural Reserve Island of Martín García (Río de La Plata, Argentina)

“…Ovigerous females of H. pampeana were collected in most of the months, indicating that reproduction is continuous in this species throughout the year, in agreement with data reported by lopretto (1983) in ponds of the province of Buenos Aires, Argentina. Continuous reproduction has been reported in other Hyalella species that inhabit natural populations in tropical and subtropical temperature regimes (edwards and Cowell 1992, Castiglioni and Bond-Buckup 2009, Bastos-Pereira and Bueno 2016, Ozga and Castiglioni 2017, Torres et al 2015, Castiglioni et al 2016). According to Sainte-Marie (1991), gammaridean populations exhibit reproductive patterns that can be associated with latitude.…”

Reproductive strategies of a population of a freshwater amphipod (Crustacea, Amhipoda, Hyalellidae) from southern Brazil

“…A positive correlation between the female size and the number of eggs/juveniles was observed in H. bonariensis. Several authors observed an association between females' size/weight and the number of embryos in other Hyalella species (Strong 1972;Othman & Pascoe 2001;Alcocer et al 2002;Castiglioni & Bond-Buckup 2007Torres et al 2015;Bastos-Pereira & Bueno 2016). According to Hines (1988), this association may be linked to the fact that the egg mass is restricted by the space available for energetic accumulation and gonadal development.…”